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19-0996; Rev 0; 9/07
KIT ATION EVALU BLE AVAILA
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector
General Description
The MAX15008 features a 300mA LDO regulator, a voltage tracker, and an overvoltage protection (OVP) controller to protect downstream circuits from high-voltage load dump. The MAX15010 includes only the 300mA LDO voltage regulator and voltage tracker. Both devices operate over a wide 5V to 40V supply voltage range and are able to withstand load-dump transients up to 45V. The MAX15008/MAX15010 feature short-circuit and thermalshutdown protection. These devices offer highly integrated power-management solutions for automotive applications such as instrument clusters, climate control, and a variety of automotive power-supply circuits. The 300mA LDO regulator consumes less than 70A quiescent current at light loads and is well suited to power always-on circuits during "key off" conditions. The LDO features independent enable and hold inputs as well as a microprocessor (P) reset output with an adjustable reset timeout period. The voltage tracker accurately (3mV) tracks a voltage applied to its input from either the LDO output or an external source. It can supply up to 50mA of current to a remote sensor, allowing for precise ratiometric tracking in automotive applications. A separate enable input turns the tracker on or off, reducing supply current when the tracker is unused. The voltage tracker also features protection against battery reversal, an output short circuit to the battery, or an output-voltage excursion below ground potential to as much as -5V. The MAX15008 OVP controller operates with an external enhancement mode n-channel MOSFET. While the monitored voltage remains below the adjustable threshold, the MOSFET stays on. When the monitored voltage exceeds the OVP threshold, the OVP controller quickly turns off the external MOSFET. The OVP controller is configurable as a load-disconnect switch or a voltage limiter. The MAX15008/MAX15010 are available in a thermally enhanced, 32-pin (5mm x 5mm) TQFN package and are fully specified over the -40C to +125C automotive operating temperature range.
Features
300mA LDO Regulator, Voltage Tracker, and OVP Controller (MAX15008) 300mA LDO Regulator and Voltage Tracker (MAX15010) 50mA Voltage Tracker with 3mV Tracking Accuracy 5V to 40V Wide Operating Supply Voltage Range 45V Load Dump Protection 70A Quiescent Current LDO Regulator OVP Controller Disconnects or Limits Output from Battery Overvoltage Conditions (MAX15008) LDO Regulator with Enable, Hold, and Reset Features
MAX15008/MAX15010
Ordering Information
PART MAX15008ATJ+ MAX15010ATJ+* TEMP RANGE PINPACKAGE PKG CODE
-40C to +125C 32 TQFN-EP** T3255-4 -40C to +125C 32 TQFN-EP** T3255-4
+Denotes a lead-free package. *Future product--contact factory for availability. **EP = Exposed pad.
Selector Guide
PART MAX15008 MAX15010 LDO TRACKER OVP CONTROLLER --
Pin Configurations
OUT_LDO OUT_LDO EN_TRK 17 16 15 14 13 EN_LDO FB_LDO REF SOURCE GATE N.C. FB_PROT CT 12 11 10 9 1 N.C. 2 N.C. 3 OUT_TRK 4 ADJ 5 SGND 6 PGND 7 RESET 8 N.C.
TOP VIEW
N.C. N.C.
24 HOLD 25 N.C. 26 N.C. 27 N.C. 28 FB_TRK 29
23
22
21
20
19
18
Applications
Instrument Clusters Climate Control AM/FM Radio Power Supply Multimedia Power Supply Telematics Power Supply
MAX15008
TRACK 30 N.C. 31 N.C. 32
+
*EP
*EP = EXPOSED PAD
TQFN (5mm x 5mm)
Typical Operating Circuits appear at end of data sheet.
Pin Configurations continued at end of data sheet.
1
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
EN_PROT
IN
IN
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector MAX15008/MAX15010
ABSOLUTE MAXIMUM RATINGS
(All pins referenced to SGND, unless otherwise noted.) IN, GATE.................................................................-0.3V to +45V TRACK.....................................................................-20V to +45V EN_LDO, EN_PROT, EN_TRK .....................-0.3V to (VIN + 0.3V) SOURCE ......................................................-0.3V to (VIN + 0.3V) TRACK to OUT_TRK................................................-40V to +40V OUT_TRK, FB_TRK, ADJ...........................................-5V to +45V OUT_LDO, FB_LDO, FB_PROT, RESET.................-0.3V to +12V GATE to SOURCE ..................................................-0.3V to +12V HOLD................................................-0.3V to (VOUT_LDO + 0.3V) REF to SGND............................................................-0.3V to +6V CT to SGND............................................................-0.3V to +12V SGND to PGND .....................................................-0.3V to +0.3V IN, OUT_LDO Current .......................................................700mA TRACK, OUT_TRK Current ...............................................350mA Current Sink/Source (all remaining pins) ............................50mA Continuous Power Dissipation (TA = +70C) 32-Pin TQFN (derate 34.5mW/C above +70C) .............2.7W* Thermal Resistance JA ..............................................................................29.0C/W JC ................................................................................1.7C/W Operating Temperature Range .........................-40C to +125C Junction Temperature ......................................................+150C Storage Temperature Range .............................-60C to +150C Lead Temperature (soldering, 10s) .................................+300C *As per JEDEC51 Standard, Multilayer Board (PCB).
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VIN = VTRACK = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10F (ESR 1.5), COUT_LDO = 22F (ceramic), CTRACK = 3.3F (ceramic) (ESR 1.5), COUT_TRK = 10F (ESR 1.5), CREF = 1000pF, VOUT_LDO = 5V, TA = TJ = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER Supply Voltage Range SYMBOL VIN EN_LDO = IN, EN_TRK = EN_PROT = 0V, IOUT_LDO = 0A, LDO on, tracker off, protector off, measured from SGND EN_LDO = EN_TRK = IN, EN_PROT = 0V, LDO on, IOUT_LDO = 100A, tracker on, IOUT_TRK = 0A, protector off, VFB_TRK = VOUT_TRK, VADJ = VREF, measured from SGND EN_LDO = EN_TRK = EN_PROT = IN, LDO on, IOUT_LDO = 100A, tracker on, IOUT_TRK = 0A, protector on, VFB_TRK = VOUT_TRK; VADJ = VREF, measured from SGND EN_LDO = EN_TRK = IN, LDO on, IOUT_LDO = 100A, tracker on, IOUT_TRK = 0A, measured from SGND CONDITIONS MIN 5 TYP MAX 40 UNITS V
70
92
120
180
MAX15008
Supply Current
IIN
A
190
280
MAX15010
120
180
Shutdown Supply Current
ISHDN
EN_LDO = EN_PROT = TA = -40C to +85C EN_TRK = 0V, measured TA = -40C to +125C from SGND
16
30 A 40
2
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Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VTRACK = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10F (ESR 1.5), COUT_LDO = 22F (ceramic), CTRACK = 3.3F (ceramic) (ESR 1.5), COUT_TRK = 10F (ESR 1.5), CREF = 1000pF, VOUT_LDO = 5V, TA = TJ = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER IN Undervoltage Lockout IN Undervoltage Lockout Hysteresis Internal Voltage Reference Internal Voltage Reference Maximum Current Thermal-Shutdown Temperature Thermal Hysteresis LDO ILOAD = 1mA, FB_LDO = SGND Output Voltage VOUT_LDO ILOAD = 300mA, VIN = 8V, FB_LDO = SGND With respect to SGND, ILOAD = 1mA, VOUT_LDO = 5V (adjustable output option) FB_LDO rising FB_LDO falling VFB_LDO = 1V Adjustable output option (Note 2) ILOAD = 300mA ILOAD = 200mA (Note 4) OUT_LDO = GND, VIN = 6V 6V VIN 40V, ILOAD = 1mA, VOUT_LDO = 5V VOUT/ VIN 6V VIN 40V, ILOAD = 1mA, VOUT_LDO = 3.3V 6V VIN 40V, ILOAD = 20mA, FB_LDO = SGND, VOUT_LDO = 5V 6V VIN 40V, ILOAD = 20mA, VOUT_LDO = 3.3V VOUT/ IOUT 1mA to 300mA, VIN = 8V, FB_LDO = SGND, VOUT_LDO = 5V 1mA to 300mA, VIN = 6.3V, VOUT_LDO = 3.3V ILOAD = 10mA, f = 100Hz, 500mVP-P, COUT_LDO = 22F, VOUT_LDO = 5V 300 330 500 0.03 0.03 0.27 0.27 0.054 0.038 60 700 0.2 0.1 mV/V 1 0.5 0.15 mV/mA 0.1 dB -100 1.8 775 520 4.92 4.80 1.21 5 5 1.235 0.125 0.064 +100 11.0 1500 1000 5.09 5.11 1.26 V SYMBOL VUVLO VUVLO_HYST REF IREF TSHDN THYST IREF = 0A VREF = 200mV 1.21 -6 +160 20 CONDITIONS VIN falling, GATE disabled MIN 4.10 TYP 4.27 260 1.235 1.26 +6 MAX 4.45 UNITS V mV V A C C
MAX15008/MAX15010
FB_LDO Set-Point Voltage Dual ModeTM FB_LDO Threshold FB_LDO Input Current LDO Output Voltage Range LDO Dropout Voltage (Note 3) LDO Output Current LDO Output Current Limit
VFB_LDO VFB_LDO_TH IFB_LDO VLDO_ADJ VDO IOUT_LDO ILIM_LDO
V V nA V mV mA mA
OUT_LDO Line Regulation
OUT_LDO Load Regulation
OUT_LDO Power-Supply Rejection Ratio
PSRR
Dual Mode is a trademark of Maxim Integrated Products, Inc.
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3
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector MAX15008/MAX15010
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VTRACK = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10F (ESR 1.5), COUT_LDO = 22F (ceramic), CTRACK = 3.3F (ceramic) (ESR 1.5), COUT_TRK = 10F (ESR 1.5), CREF = 1000pF, VOUT_LDO = 5V, TA = TJ = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER OUT_LDO Startup Delay Time OUT_LDO Overvoltage Protection Threshold OUT_LDO Overvoltage Protection Sink Current ENABLE/HOLD INPUTS EN_LDO, EN_PROT, EN_TRK Input Threshold Voltage EN_LDO, EN_PROT, EN_TRK Input Pulldown Current HOLD Input Threshold Voltage HOLD Input Pullup RESET RESET Voltage Threshold High RESET goes HIGH when rising VOUT_LDO crosses this threshold, FB_LDO = SGND RESET goes HIGH when rising VOUT_LDO crosses this threshold RESET goes LOW when falling VOUT_LDO crosses this threshold, FB_LDO = SGND RESET goes LOW when falling VOUT_LDO crosses this threshold VOUT_LDO falling, 0.1V/s VCT = 0V VCT rising ISINK = 1mA, output asserted Output not asserted 1.50 1.19 90.0 92.5 95.0 %VOUT_LDO %VFB_LDO %VOUT_LDO %VFB_LDO s 2.35 1.27 0.1 150 A V V nA VIH VIL IEN_PD VIH VIL IHOLD_PU HOLD is internally pulled high to OUT_LDO 0.6 EN_ is internally pulled low to SGND 1.4 0.4 1 2 V 0.7 A SYMBOL tSTARTUP_DELAY VOV_TH IOV CONDITIONS IOUT_LDO = 0mA, from EN_LDO rising to 10% of VOUT_LDO (nominal), FB_LDO = SGND 1mA sink from OUT_LDO VOUT_LDO = VOUT (nominal) x 1.15 8 MIN TYP 30 MAX UNITS s
105 19
110
%VOUT_LDO mA
V A
V RESET_H
90.0
92.5
95.0
RESET Voltage Threshold Low VOUT_LDO to RESET Delay CT Ramp Current CT Ramp Threshold RESET Output-Voltage Low RESET Open-Drain Leakage Current FB_PROT Threshold Voltage FB_PROT Threshold Hysteresis FB_PROT Input Current Startup Response Time
88
90
92
V R ESET _L
88
90 19 2.0 1.235
92
tRESET_FALL ICT VCT_TH VOL ILEAK_RESET
LOAD DUMP PROTECTOR (MAX15008 only) VTH_PROT VHYST IFB_PROT tSTART VFB_PROT = 1.4V EN_PROT rising, EN_LDO = IN, to VGATE = 0.5V -100 20 FB_PROT rising 1.20 1.235 4 +100 1.27 V %VTH_PROT nA s
4
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Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VTRACK = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10F (ESR 1.5), COUT_LDO = 22F (ceramic), CTRACK = 3.3F (ceramic) (ESR 1.5), COUT_TRK = 10F (ESR 1.5), CREF = 1000pF, VOUT_LDO = 5V, TA = TJ = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER GATE Rise Time FB_PROT to GATE Turn-Off Propagation Delay SYMBOL tGATE tOV CONDITIONS GATE rising to +8V, VSOURCE = 0V FB_PROT step from VTH_PROT - 250mV to VTH_PROT + 250mV VSOURCE = VIN = 5.5V, RGATE to IN = 1M VSOURCE = VIN; VIN 14V, RGATE to IN = 1M VGATE = 5V, VEN_PROT = 0V GATE = SGND 12 IN + 3.2 IN + 7.0 IN + 3.5 IN + 8.1 63 45 16 18 MIN TYP 1 0.6 IN + 3.8 IN + 9.5 100 MAX UNITS ms s
MAX15008/MAX15010
GATE Output High Voltage
VGATE
V
GATE Output Pulldown Current GATE Charge-Pump Current GATE-to-SOURCE Clamp Voltage TRACKER Tracker Supply Voltage Range ADJ, FB_TRK Input Voltage Tracker Output CommonMode Range Tracking Accuracy Over Line Tracking Accuracy Over Load ADJ, FB_TRK Input Current Dropout Voltage Tracker Output Current Output Current Limit Current Consumption
IGATEPD IGATE VCLMP
mA A V
VTRACK VADJ, VFB_TRK VCM VQ_LINE IOUT_LDO = 20mA, VFB_TRK = VOUT_TRK = 5V, VTRACK = 6V to 28V, VQ = VFB_TRK - VADJ VTRACK = 6V, 0.1mA IOUT_TRK 50mA, VADJ = VOUT_TRK = 5V, VQ = VFB_TRK - VADJ VFB_TRK = VADJ = 5V VOUT_TRK = 5V, IOUT_TRK = 50mA VADJ = VOUT_TRK = 5V VOUT_TRK = 0V IQ = ITRACK - IOUT_TRK, IOUT_TRK = 50mA, VADJ = VFB_TRK = 5V, EN_LDO = EN_PROT = SGND, EN_TRK = IN IOUT_LDO = 10mA, f = 100Hz, 500mVP-P, VOUT_TRK = VFB_TRK, VADJ = 5V VTRACK = 14V, VOUT_TRK = VFB_TRK = 40V, VADJ = 5V
5 1.1 1.1
40 TRACK - 0.5 TRACK - 0.5 +3
V V V
-3
mV
VQ_LOAD IFB_TRK, IADJ VDO IOUT_TRK IOUT_TRK_LIM IQ
-3 0.03 0.28 50 85 100 2.7
+3 0.2 0.5 115 6
mV A V mA mA mA
OUT_TRK Power-Supply Rejection Ratio OUT_TRK Reverse Current
PSRR
60
dB
IOUT_TRK_REVERSE
10
A
Note 1: Note 2: Note 3: Note 4:
Limits to -40C are guaranteed by design. 1.8V is the minimum limit for proper HOLD functionality. Dropout is defined as VIN - VOUT_LDO when VOUT_LDO is 98% of the value of VOUT_LDO for VIN = VOUT_LDO + 1.5V. Maximum output current may be limited by the power dissipation of the package.
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5
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector MAX15008/MAX15010
Typical Operating Characteristics
(VIN = VEN_ = +14V, CIN = 10F, COUT_LDO = 22F, CTRACK = COUT_TRK = 10F, VOUT_LDO = 5V, FB_LDO = SGND, TA = +25C, unless otherwise specified.)
LDO GROUND CURRENT vs. LOAD CURRENT
MAX15008 toc01
LDO GROUND CURRENT vs. LOAD CURRENT
MAX15008 toc02
SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE
MAX15008 toc03
90 TA = -40C 85 GROUND CURRENT (A) 80 75 70 65 60 55 0 TA = +85C TA = +125C TA = +25C
140 130 GROUND CURRENT (A) 120 110 100 90 TA = +85C 80 70 TA = +125C TA = +25C TA = -40C
30 25 20
ISHDN (A) 0 25 50 75 100 125 150 175 200 225 250 275 300 LOAD CURRENT (mA)
15 10 5 0 -60 -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C)
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 LOAD CURRENT (mA)
60
LDO POWER-SUPPLY REJECTION RATIO
MAX15008 toc04
TRACKER POWER-SUPPLY REJECTION RATIO
MAX15008 toc05
VIN UVLO HYSTERESIS vs. TEMPERATURE
MAX15008 toc06
0 -10 -20 PSRR (dB) -30 -40 -50 -60 IOUT_LDO = 10mA -70 0.01 0.1 1 10 100
0 -10 TRACKER PSRR (dB) -20 -30 -40 -50 -60 -70
IOUT_LDO = 10mA
400 350 UVLO HYSTERESIS (mV) 300 250 200 150 100
1000
0.1
1
10 FREQUENCY (kHz)
100
1000
-50
-25
0
25
50
75
100 125 150
FREQUENCY (Hz)
TEMPERATURE (C)
REF VOLTAGE vs. TEMPERATURE
MAX15008 toc07
LDO OUTPUT VOLTAGE vs. INPUT VOLTAGE
IOUT_LDO = 10mA
MAX15008 toc08
1.245
6 5 4 3 2
1.240
VREF (V)
1.235
1.230
1.225
VOUT_LDO (V)
IOUT_LDO = 300mA (PULSED)
1 0 -50 -25 0 25 50 75 100 125 150 0 10 20 VIN (V) 30 40 TEMPERATURE (C)
1.220
6
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Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector
Typical Operating Characteristics (continued)
(VIN = VEN_ = +14V, CIN = 10F, COUT_LDO = 22F, CTRACK = COUT_TRK = 10F, VOUT_LDO = 5V, FB_LDO = SGND, TA = +25C, unless otherwise specified.)
LDO OUTPUT VOLTAGE vs. TEMPERATURE
MAX15008 toc11
MAX15008/MAX15010
LDO LOAD-TRANSIENT RESPONSE
MAX15008 toc09
LDO LOAD-TRANSIENT RESPONSE
MAX15008 toc10
5.10 IOUT_LDO 100mA/div VOUT_LDO (V) 5.05 5.00 4.95 4.90 4.85 VIN = 8V 4.80 2ms/div 400s/div -50 -25 0 25 50 75 IOUT_LDO = 100mA IOUT_LDO = 300mA IOUT_LDO = 100A IOUT_LDO = 10mA
IOUT_LDO 100mA/div 0A
0A
VOUT_LDO 5V, AC-COUPLED 20mV/div
VOUT_LDO 5V, AC-COUPLED 100mV/div
100 125 150
TEMPERATURE (C)
TRACKER LOAD-TRANSIENT RESPONSE
MAX15008 toc12
TRACKER ACCURACY vs. LOAD CURRENT
MAX15008 toc13
TRACKER ACCURACY (VFB_TRK = VADJ) vs. TEMPERATURE
MAX15008 toc14
0 -0.5 VADJ - VOUT_TRK (mV) -1.0 -1.5 -2.0 -2.5 -3.0
3 2 TRACKER ACCURACY (mV) 1 IOUT_TRK = 100A 0 -1 -2 IOUT_TRK = 1mA -3 -4 -75 -50 -25 0 25 50 IOUT_TRK = 70mA
IOUT_TRK 50mA/div 0A
VOUT_TRK 5V, AC-COUPLED 20mV/div
ADJ = OUT_LDO FB_TRK = OUT_TRK 0 10 20 30 40 50 60 70
400s/div
75 100 125 150
IOUT_TRK (mA)
TEMPERATURE (C)
LINE-TRANSIENT RESPONSE
MAX15008 toc15
LINE-TRANSIENT RESPONSE
MAX15008 toc16
VIN 20V/div 0V VOUT_LDO 3.3V, AC-COUPLED 50mV/div VOUT_TRK 3.3V, AC-COUPLED 50mV/div VOUT_PROT 20V/div 40ms/div
VIN 10V/div 0V VOUT_LDO 3.3V, AC-COUPLED 20mV/div VOUT_TRK 3.3V, AC-COUPLED 20mV/div VOUT_PROT 10V/div 40ms/div
0V
0V
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7
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector MAX15008/MAX15010
Typical Operating Characteristics (continued)
(VIN = VEN_ = +14V, CIN = 10F, COUT_LDO = 22F, CTRACK = COUT_TRK = 10F, VOUT_LDO = 5V, FB_LDO = SGND, TA = +25C, unless otherwise specified.)
LDO DROPOUT VOLTAGE vs. LOAD CURRENT
MAX15008 toc17
STARTUP RESPONSE THROUGH VIN
MAX15008 toc18
STARTUP RESPONSE THROUGH EN
MAX15008 toc19
1000 900 LDO DROPOUT VOLTAGE (mV) 800 700 600 500 400 300 200 100 0 0 100 200
VIN 10V/div IOUT_LDO = 100mA IOUT_TRK = 100mA EN_LDO = EN_TRK = IN 0V
VIN 20V/div VEN_LDO 5V/div IOUT_LDO = 100mA IOUT_TRK = 100mA VEN_TRK = VEN_LDO
0V 0V
VRESET 5V/div VOUT_LDO 5V/div VOUT_TRK 5V/div 300
0V
VRESET 5V/div VOUT_LDO 5V/div VOUT_TRK 5V/div
0V
0V
0V
0V 20ms/div
0V 20ms/div
IOUT_LDO (mA)
SHUTDOWN RESPONSE THROUGH VIN
MAX15008 toc20
SHUTDOWN RESPONSE THROUGH EN
VIN 20V/div VEN_LDO 5V/div
MAX15008 toc21
LDO, EN_LDO, AND HOLD TIMING
MAX15008 toc22
VIN 10V/div IOUT_LDO = 100mA IOUT_TRK = 70mA VEN_TRK = VEN_LDO = VIN 0V
0V 0V
VEN_LDO 5V/div VOUT_LDO 5V/div HOLD PULLED UP TO OUT_LDO HOLD 5V/div RESET 5V/div 200ms/div
0V
VRESET 5V/div VOUT_LDO 5V/div
0V
VRESET 5V/div VOUT_LDO 5V/div
0V
0V
0V VOUT_TRK 5V/div 20ms/div VOUT_TRK 5V/div EN_LDO = EN_TRK IOUT_LDO = 100mA IOUT_TRK = 70mA 400s/div
0V
0V
0V
0V
0V
GROUND CURRENT DISTRIBUTION HISTOGRAM (-40C)
MAX15008 toc23
GROUND CURRENT DISTRIBUTION HISTOGRAM (+125C)
MAX15008 toc24
70 60 NUMBER OF PARTS 50 40 30 20 10 0 44 47 50 53 56 59 62 65 68 71 74 77 80 GROUND CURRENT (A)
70 60 NUMBER OF PARTS 50 40 30 20 10 0 44 47 50 53 56 59 62 65 68 71 74 77 80 GROUND CURRENT (A)
8
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Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector
Typical Operating Characteristics (continued)
(VIN = VEN_ = +14V, CIN = 10F, COUT_LDO = 22F, CTRACK = COUT_TRK = 10F, VOUT_LDO = 5V, FB_LDO = SGND, TA = +25C, unless otherwise specified.)
PROTECTOR GATE VOLTAGE vs. INPUT VOLTAGE (MAX15008 ONLY)
45 40 GATE VOLTAGE (V) 35 30 25 20 15 10 5 0 0 5 10 15 20 VIN (V) 25 30 35 40 10ms/div 400s/div VIN VOUT_PROT 10V/div IOUT_PROT = 1A 0V VOUT_PROT 20V/div VGATE 10V/div 0V VGATE 20V/div 0V VGATE
MAX15008 toc25
MAX15008/MAX15010
PROTECTOR STARTUP RESPONSE (MAX15008 ONLY)
MAX15008 toc26
OVERVOLTAGE SWITCH FAULT (MAX15008 ONLY)
MAX15008 toc27
50
VIN 10V/div 0V
VIN 10V/div IOUT_PROT = 1A VOV = 25V
0V
0V
OVERVOLTAGE LIMIT FAULT (MAX15008 ONLY)
MAX15008 toc28
RESET TIMEOUT DELAY vs. CRESET
MAX15008 toc29
RESET TIMEOUT DELAY vs. TEMPERATURE
1.8 RESET TIMEOUT DELAY (ms) 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 CRESET = 220pF CRESET = 2.2nF
MAX15008 toc30
7 6 RESET TIMEOUT DELAY (ms) 0V 5 4 3 2 1 0V 0 0 2 4 6 8
2.0
VIN 20V/div
VGATE 20V/div IOUT_PROT = 1A OV THRESHOLD = 35V VOUT_PROT 20V/div 40ms/div
0V
10
-50
-25
0
25
50
75
100 125 150
CRESET (nF)
TEMPERATURE (C)
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9
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector MAX15008/MAX15010
Pin Description
PIN MAX15008 1, 2, 8, 11, 23, 24, 26, 27, 28, 31, 32 3 4 5 MAX15008 1, 2, 8, 10-13, 18, 23, 24, 26, 27, 28, 31, 32 3 4 5 NAME FUNCTION
N.C.
No Connection. Not internally connected.
OUT_TRK ADJ SGND
Tracker Output. Bypass OUT_TRK to SGND with a 10F (min) capacitor with low ESR ( 1.5). Tracker Amplifier Input. Connect ADJ to OUT_LDO or to an external source to track. Alternatively, connect ADJ to REF to provide the reference voltage to the tracker. Signal Ground Ground. PGND is also the return path for the overvoltage protector pulldown current for the MAX15008. In this case, connect PGND to SGND at the negative terminal of the bypass capacitor connected to the source of the external MOSFET. For the MAX15010, connect PGND to SGND together to the local ground plane. Active-Low Open-Drain Reset Output. RESET is low while OUT_LDO is below the reset threshold. Once OUT_LDO has exceeded the reset threshold, RESET remains low for the duration of the reset timeout period before going high. Reset Timeout Adjust Input. Connect a capacitor (CRESET) from CT to ground to adjust the reset timeout period. See the Setting the RESET Timeout Period section. Overvoltage Threshold Adjustment Input. Connect FB_PROT to an external resistive voltage-divider network to adjust the desired overvoltage threshold. Use FB_PROT to monitor a system input or output voltage. See the Setting the Overvoltage Threshold (MAX15008 Only) section. Protector Gate Drive Output. Connect GATE to the gate of an external n-channel MOSFET. GATE is the output of a charge pump with a 45A pullup current to 7.1V (typ) above IN during normal operation. GATE is quickly turned off through a 63mA internal pulldown during an overvoltage condition. GATE then remains low until FB_PROT has decreased 96% below the threshold. GATE pulls low when EN_PROT is low. Output-Voltage Sense Input. Connect SOURCE to the source of the external n-channel MOSFET. 1.235V Voltage Reference Output. Bypass REF to SGND with a 1nF or larger capacitor.
6
6
PGND
7
7
RESET
9
9
CT
10
--
FB_PROT
12
--
GATE
13 14
-- 14
SOURCE REF
10
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Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector
Pin Description (continued)
PIN MAX15008 15 MAX15010 15 NAME FUNCTION LDO Voltage Feedback Input. Connect FB_LDO to SGND to select the preset +5V output voltage. Connect FB_LDO to an external resistive voltage-divider for adjustable output operation. See the Setting the Output Voltage section. Active-High LDO Enable Input. Connect EN_LDO to IN or to a logic-high voltage to turn on the regulator. To place the LDO in shutdown, pull EN_LDO low or leave unconnected and leave HOLD unconnected. EN_LDO is internally pulled to SGND through a 1A current sink. See the Control Logic section. Active-High Tracker Enable Input. Connect EN_TRK to IN or to a logic-high voltage to turn on the tracker. Pull EN_TRK low or leave unconnected to place tracker in shutdown. EN_TRK is internally pulled to SGND through a 1A current sink. Protector Enable Input. Drive EN_PROT low to force GATE low and turn off the external n-channel MOSFET. EN_PROT is internally pulled to SGND by a 1A sink. Connect EN_PROT to IN for normal operation. Regulator Input. Bypass IN to SGND with a 10F capacitor (ESR 1.5). LDO Regulator Output. Bypass OUT_LDO to SGND with a low-ESR capacitor with a minimum value of 22F. Fixed +5V or adjustable output (+1.8V to +11V). See the Setting the Output Voltage section. Active-Low Hold Input. If EN_LDO is high when HOLD is forced low, the regulator latches the state of the EN_LDO input and allows the regulator to remain turned on when EN_LDO is subsequently pulled low. To shut down the regulator, release HOLD after EN_LDO is pulled low. If HOLD functionality is unused, connect HOLD to OUT_LDO or leave unconnected. HOLD is internally pulled up to OUT_LDO through a 0.6A current source. See the Control Logic section. Tracker Amplifier Feedback. Connect FB_TRK directly to OUT_TRK or through an external resistive voltage-divider. Tracker Input. Bypass TRACK to the SGND with a 3.3F ceramic capacitor. Exposed Pad. Connect EP to SGND plane. EP also functions as a heatsink to maximize thermal dissipation. Do not use as the main ground connection.
MAX15008/MAX15010
FB_LDO
16
16
EN_LDO
17
17
EN_TRK
18 19, 20 21, 22
-- 19, 20 21, 22
EN_PROT IN OUT_LDO
25
25
HOLD
29 30 EP
29 30 EP
FB_TRK TRACK EP
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11
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector MAX15008/MAX15010
Functional Diagram
IN 5V TO 40V VIN IN
LDO BIAS AND VOLTAGE REFERENCE VREF 1.235V
ENABLE LDO HOLD
EN_LDO HOLD CONTROL LOGIC OUT_LDO REF VREF M U X 5V LDO OUTPUT
FB_LDO
-20V TO +40V
TRACK 2A 0.125V CT
0.92 x VREF
VREF
RESET
RESET OUTPUT
REVERSE-BATTERY PROTECTION ADJ TRACKER ENABLE TRACKER EN_TRK
OUT_TRK
TRACKER OUTPUT
FB_TRK IN GATE UVLO 4.75V VREF GATE VIN
ENABLE PROTECTOR
EN_PROT
SOURCE
PROTECTOR OUTPUT
OVERVOLTAGE PROTECTOR (MAX15008 ONLY) EP SGND PGND
FB_PROT
12
______________________________________________________________________________________
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector
Detailed Description
The MAX15008/MAX15010 integrate a 300mA LDO voltage regulator, a voltage tracker, and an OVP controller. These devices operate over a wide 5V to 40V supply voltage range and are able to withstand loaddump transients up to 45V. The MAX15008/MAX15010 feature a 300mA LDO regulator that consumes less than 70A of current under light-load conditions and feature a fixed 5V or an adjustable output voltage (1.8V to 11V). Connect FB_LDO to ground to select a fixed 5V output voltage or select the LDO output voltage by connecting an external resistive voltage-divider at FB_LDO. The regulator sources at least 300mA of current and includes a current limit of 330mA (min). Enable the LDO by pulling EN_LDO high. The tracker can be powered from the LDO input supply voltage or an independent voltage source. It is designed to supply power to a remote sensor and is able to handle the severe conditions in automotive applications. Set the tracker output voltage by connecting a resistive voltage-divider to OUT_TRK and connecting ADJ to the tracking source. The tracker feedback, FB_TRK, and a separate tracker reference voltage input, ADJ, offer the flexibility of setting the tracker output to be lower, equal to, or higher than the main (LDO) output. Pull EN_TRK to SGND to turn the tracker off and keep the device in always-on, lowquiescent-current operation. The OVP controller (MAX15008 only) relies on an external MOSFET with adequate voltage rating (VDSS) to protect downstream circuitry from overvoltage transients. The OVP controller drives the gate of the external n-channel MOSFET, and is configurable to operate as an overvoltage protection switch or as a closed-loop voltage limiter. discharge. The voltage clamp also prevents the GATEto-SOURCE voltage from exceeding the absolute maximum rating for the VGS of the external MOSFET in case the source terminal is accidentally shorted to 0V.
MAX15008/MAX15010
Overvoltage Monitoring (MAX15008 Only)
The OVP controller monitors the voltage at FB_PROT and controls an external n-channel MOSFET, isolating, or limiting the load during an overvoltage condition. Operation in OVP switch mode or limiter mode depends on the connection between FB_PROT and the external MOSFET.
Overvoltage Switch Mode When operating in OVP switch mode, the FB_PROT divider is connected to the drain of the external MOSFET. The feedback path consists of the voltagedivider tapped at FB_PROT, FB_PROT's internal comparator, the internal gate charge pump/gate pulldown, and the external n-channel MOSFET (Figure 1). When the programmed overvoltage threshold is exceeded, the internal comparator quickly pulls GATE to ground and turns off the external MOSFET, disconnecting the power source from the load. In this configuration, the voltage at the source of the MOSFET is not monitored. When the voltage at FB_PROT decreases below the overvoltage threshold, the MAX15008 raises the voltage at GATE, reconnecting the load to the power source.
VIN
IN
GATE
MAX15008
FB_PROT SOURCE
GATE Voltage (MAX15008 Only)
The MAX15008 uses a high-efficiency charge pump to generate the GATE voltage for the external n-channel MOSFET. Once the input voltage, VIN, exceeds the undervoltage lockout (UVLO) threshold, the internal charge pump fully enhances the external n-channel MOSFET. An overvoltage condition occurs when the voltage at FB_PROT goes above the threshold voltage, VTH_PROT. After VTH_PROT is exceeded, GATE is quickly pulled to PGND with a 63mA pulldown current. The MAX15008 includes an internal clamp from GATE to SOURCE that ensures that the voltage at GATE never exceeds one diode drop below SOURCE during gate
PROTECTOR OUTPUT
SGND
Figure 1. Overvoltage Switch Configuration (MAX15008)
______________________________________________________________________________________
13
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector MAX15008/MAX15010
Overvoltage-Limiter Mode When operating in overvoltage-limiter mode, the feedback path consists of SOURCE, FB_PROT's internal comparator, the internal gate charge pump/gate pulldown, and the external n-channel MOSFET (Figure 2). This configuration results in the external MOSFET operating as a hysteretic voltage regulator. During normal operation, GATE is enhanced 8.1V above V IN. The external MOSFET source voltage is monitored through a resistive voltage-divider between SOURCE and FB_PROT. When VSOURCE exceeds the adjustable overvoltage threshold, an internal pulldown switch discharges the gate voltage and quickly turns the MOSFET off. Consequently, the source voltage begins to fall. The VSOURCE fall time is dependent on the MOSFET's gate charge, the internal charge-pump current, the output load, and any load capacitance at SOURCE. When the voltage at FB_PROT is below the overvoltage threshold by an amount equal to the hysteresis, the charge pump restarts and turns the MOSFET back on. In this way, the OVP controller attempts to regulate VSOURCE around the overvoltage threshold. SOURCE remains high during overvoltage transients and the MOSFET continues to conduct during an overvoltage event. The hysteresis of the FB_PROT comparator and the gate turn-on delay force the external MOSFET to operate in a switched on/off sequence during an overvoltage event. Exercise caution when operating the MAX15008 in voltage-limiting mode for long durations. Care must be taken against prolonged or repeated exposure to overvoltage events while delivering large amounts of load current as the power dissipation in the external MOSFET may be high under these conditions. To prevent damage to the MOSFET, implement proper heatsinking. The capacitor connected between SOURCE and ground can also be damaged if the ripple current rating for the capacitor is exceeded. As the transient voltage decreases, the voltage at SOURCE falls. For fast-rising transients and very large MOSFETs, connect an additional capacitor from GATE to PGND. This capacitor acts as a voltage-divider work-
VIN
IN
GATE
MAX15008
SOURCE
PROTECTOR OUTPUT
FB_PROT SGND
Figure 2. Overvoltage Limiter (MAX15008)
ing against the MOSFET's drain-to-gate capacitance. If using a very low gate charge MOSFET, additional capacitance from GATE to ground might be required to reduce the switching frequency.
Control Logic
The MAX15008/MAX15010 LDO features two logic inputs, EN_LDO and HOLD, making these devices suitable for automotive applications. For example, when the ignition key signal drives EN_LDO high, the regulator turns on and remains on even if EN_LDO goes low, as long as HOLD is forced low and stays low after initial regulator power-up. In this state, releasing HOLD turns the regulator output (OUT_LDO) off. This feature makes it possible to implement a self-holding circuit without external components. Forcing EN_LDO low and HOLD high (or unconnected) places the regulator into shutdown mode reducing the supply current to less than 16A. Table 1 shows the state of OUT_LDO with respect to EN_LDO and HOLD. Leave HOLD unconnected or connect directly to OUT_LDO to allow the EN_LDO input to act as a standard on/off logic input for the regulator.
14
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Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector
H Table 1. EN_LDO/HOLD Truth Table/State Table
OPERATION STATE Initial State EN_LDO Low HOLD Don't care OUT_LDO OFF COMMENT EN_LDO is pulled to SGND through an internal pulldown. HOLD is unconnected and is internally pulled up to OUT_LDO. The regulator is disabled. EN_LDO is externally driven high turning regulator on. HOLD is pulled up to OUT_LDO. HOLD is externally pulled low while EN_LDO remains high (latches EN_LDO state). EN_LDO is driven low or left unconnected. HOLD remains externally pulled low keeping the regulator on. HOLD is driven high or left unconnected while EN_LDO is low. The regulator is turned off and EN_LDO/HOLD logic returns to the initial state.
MAX15008/MAX15010
Turn-On State Hold Setup State Hold State
High High Low
Don't care Low Low High or unconnected
ON ON ON
Off State
Low
OFF
Applications Information
Load Dump
Most automotive applications run off a multicell 12V lead-acid battery with a nominal voltage that swings between 9V and 16V, depending on load current, charging status, temperature, and battery age, etc. The battery voltage is distributed throughout the automobile and is locally regulated down to voltages required by the different system modules. Load dump occurs when the alternator is charging the battery and the battery becomes disconnected. Power in the alternator (behaving now essentially as an inductor) flows into the distributed power system and elevates the voltage seen at each module. The voltage spikes have rise times typically greater than 5ms and decay within several hundred milliseconds but can extend out to 1s or more depending on the characteristics of the charging system. These transients are capable of destroying semiconductors on the first fault event. The MAX15008/MAX15010 feature load-dump transient protection up to +45V.
put voltage (VOUT_LDO) to 5V. To select the preset 5V output voltage, connect FB_LDO to SGND. To select an adjustable output voltage between 1.8V and 11V, use two external resistors connected as a voltage-divider to FB_LDO (Figure 3). Set the output voltage using the following equation: VOUT_LDO = VFB_LDO x (R1 + R2) / R2 where VFB_LDO = 1.235V and R2 50k.
VIN
IN
OUT_LDO
MAX15008 MAX15010
FB_LDO
R1
R2
Setting the Output Voltage
The MAX15008/MAX15010 feature dual-mode operation: these devices operate in either a preset voltage mode or an adjustable mode. In preset voltage mode, internal feedback resistors set the linear regulator out-
SGND
Figure 3. Setting the LDO Output Voltage
______________________________________________________________________________________
15
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector MAX15008/MAX15010
Setting the RESET Timeout Period
The reset timeout period is adjustable to accommodate a variety of applications. Set the reset timeout period by connecting a capacitor, C RESET , between CT and SGND. Use the following formula to select the reset timeout period, tRESET: tRESET = CRESET x VCT_TH / ICT where t RESET is in seconds and C RESET is in F. VCT_TH is the CT ramp threshold in volts and ICT is the CT ramp current in A, as described in the Electrical Characteristics table. Leave CT open to select an internally fixed timeout period of 10s. To maintain reset timeout accuracy, use a low-leakage (< 10nA) type capacitor. ting the tracker output to be lower, equal to, or higher than the main (LDO) output. Other external voltages can also be tracked. Connect ADJ to OUT_LDO and FB_TRK to OUT_TRK to track the LDO output voltage directly (Figure 4a). To track a voltage higher than VOUT_LDO, directly connect ADJ to OUT_LDO and connect FB_TRK to OUT_TRK through a resistive voltage-divider (Figure 4b). To track a voltage lower than the LDO regulator output, VOUT_LDO, directly connect FB_TRK to OUT_TRK and connect ADJ to OUT_LDO through a resistive voltagedivider (Figure 4c). To track an external voltage VX with a generic attenuation/amplification ratio, connect resistive voltage-dividers between ADJ and the voltage input or output to be tracked (VX), and between OUT_TRK and FB_TRK (Figure 4d). Pay attention to the resistive loading of the voltage VX due to the divider R5, R6. To track the internal REF voltage (1.235V), directly connect ADJ to REF. The voltage at FB_TRK or ADJ should be greater than or equal to 1.1V and less than VTRACK - 0.5V. Resistors should have a tolerance of 1% or better. Their values should be low enough to ensure that the divider current is at least 100x the maximum input bias current at pins FB_TRK and ADJ (IFB_TRK_ADJ, max = 0.2A).
LDO OUTPUT
Tracker Input/Feedback Adjustment
The tracker can be powered from the LDO input supply voltage or an independent voltage source. It is designed to supply power to a remote sensor and its supply input, TRACK, is able to handle the severe conditions in automotive applications such as battery reversal and load-dump transients up to 45V. The tracker feedback, FB_TRK, and a separate tracker reference voltage input, ADJ, offer the flexibility of setVIN IN OUT_LDO LDO OUTPUT
VIN
IN
OUT_LDO
TRACK
MAX15008 MAX15010
ADJ
MAX15008 MAX15010
TRACK TRACKER OUTPUT
ADJ TRACKER OUTPUT R3 FB_TRK R4
OUT_TRK
OUT_TRK FB_TRK TO TRACK VOUT_LDO: VOUT_TRK = VOUT_LDO
TO TRACK A VOLTAGE HIGHER THAN VOUT_LDO: VOUT_TRK = VOUT_LDO x (R3 + R4) / R4, R3 + R4 < VOUT_TRK / 20A (b) R5 ADJ R6 VX
(a) VIN IN OUT_LDO R5 LDO OUTPUT VIN IN
MAX15008 MAX15010
TRACK
ADJ R6 TRACKER OUTPUT TRACK
MAX15008 MAX15010
OUT_TRK R3
TRACKER OUTPUT
OUT_TRK FB_TRK TO TRACK A VOLTAGE LOWER THAN VOUT_LDO: VOUT_TRK = VOUT_LDO x R6 / (R5 + R6), R5 + R6 < VOUT_LDO / 20A (c)
FB_TRK R4 TO TRACK A GENERIC VOLTAGE VX: VOUT_TRK = VX x (R6 / (R5 + R6)) x ((R3 + R4) / R4), R5 + R6 < VX / 20A, R3 + R4 < VOUT_TRK / 20A (d)
Figure 4. Tracker Input and Feedback Adjustment
16 ______________________________________________________________________________________
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector
Setting the Overvoltage Threshold (MAX15008 Only)
The MAX15008 provides an accurate means to set the overvoltage threshold for the OVP controller using FB_PROT. Use a resistive voltage-divider to set the desired overvoltage threshold (Figure 5). FB_PROT has a rising 1.235V threshold with a 4% falling hysteresis. Begin by selecting the total end-to-end resistance, RTOTAL = R5 + R6. Choose RTOTAL to yield a total current equivalent to a minimum of 100 x I FB_PROT (FB_PROT's input maximum bias current) at the desired overvoltage threshold. See the Electrical Characteristics table. For example: With an overvoltage threshold (V OV ) set to 20V, RTOTAL < 20V / (100 x IFB_PROT), where IFB_PROT is FB_PROT's maximum 100nA bias current: RTOTAL < 2M Use the following formula to calculate R6: R6 = VTH_PROT x RTOTAL / VOV where VTH_PROT is the 1.235V FB_PROT rising threshold and VOV is the desired overvoltage threshold. R6 = 124k: RTOTAL = R5 + R6 where R5 = 1.88M. Use a standard 1.87M resistor. A lower value for total resistance dissipates more power, but provides better accuracy and robustness against external disturbances.
SGND
Input Transients Clamping
When the external MOSFET is turned off during an overvoltage event, stray inductance in the power path may cause additional input-voltage spikes that exceed the VDSS rating of the external MOSFET or the absolute maximum rating for the MAX15008 (IN, TRACK). Minimize stray inductance in the power path using wide traces and minimize the loop area included by the power traces and the return ground path. For further protection, add a zener diode or transient voltage suppressor (TVS) rated below the absolute maximum rating limits (Figure 6).
VIN
MAX15008/MAX15010
IN
MAX15008
TVS GATE SOURCE LOAD
Figure 6. Protecting the MAX15008 Input from High-Voltage Transients
VIN R5
IN
GATE
VIN
IN
GATE
MAX15008
FB_PROT SOURCE
PROTECTOR OUTPUT
MAX15008
SOURCE
PROTECTOR OUTPUT
R5 R6 SGND SGND FB_PROT R6
Figure 5. Setting the Overvoltage Threshold (MAX15008)
______________________________________________________________________________________ 17
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector MAX15008/MAX15010
External MOSFET Selection
Select the external MOSFET with adequate voltage rating, VDSS, to withstand the maximum expected loaddump input voltage. The on-resistance of the MOSFET, RDS(ON), should be low enough to maintain a minimal voltage drop at full load, limiting the power dissipation of the MOSFET. During regular operation, the power dissipated by the MOSFET is: PNORMAL = ILOAD2 x RDS(ON) Normally, this power loss is small and is safely handled by the MOSFET. However, when operating the MAX15008 in overvoltage-limiter mode under prolonged or frequent overvoltage events, select an external MOSFET with an appropriate power rating. During an overvoltage event, the power dissipation in the external MOSFET is proportional to both load current and to the drain-source voltage, resulting in high power dissipated in the MOSFET (Figure 7). The power dissipated across the MOSFET is: POV_LIMITER = VQ1 x ILOAD where VQ1 is the voltage across the MOSFET's drain and source during overvoltage-limiter operation, and ILOAD is the load current. quently switched on and off during an overvoltage event. The output voltage at SOURCE resembles a periodic sawtooth waveform. Calculate the period of the waveform, tOVP, by summing three time intervals (Figure 8): tOVP = t1 + t2 + t3 where t1 is the VSOURCE output discharge time, t2 is the GATE delay time, and t3 is the VSOURCE output charge time. During an overvoltage event, the power dissipated inside the MAX15008 is due to the gate pulldown current, I GATEPD . This amount of power dissipation is worse when ISOURCE = 0 (CSOURCE is discharged only by the internal current sink). The worst-case internal power dissipation contribution in overvoltage-limiter mode, P OVP , in watts can be approximated using the following equation: POVP = VOV x 0.98 x IGATEPD x t1 t OVP
where VOV is the overvoltage threshold voltage in volts and IGATEPD is the 63mA (typ) GATE pulldown current.
Overvoltage-Limiter Mode Switching Frequency
When the MAX15008 is configured in overvoltagelimiter mode, the external n-channel MOSFET is subseVMAX VSOURCE + VQ1 ILOAD IN GATE VSOURCE VOV
Output Discharge Time (t1) When the voltage at SOURCE exceeds the adjusted overvoltage threshold, GATE's internal pulldown is enabled until VSOURCE drops by 4%. The internal current sink, I GATEPD , and the external load current, I LOAD , discharge the external capacitance from SOURCE to ground.
MAX15008
TVS SOURCE LOAD
GATE
t2
FB_PROT
SOURCE
SGND
t1 tOVP
t3
Figure 7. Power Dissipated Across MOSFETs During an Overvoltage Fault (Overvoltage Limiter Mode)
18
Figure 8. MAX15008 Timing Diagram
______________________________________________________________________________________
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector
Calculate the discharge time, t1, using the following equation: t1 = CSOURCE x 0.04 x VOV ILOAD + IGATEPD where VSOURCE = (VOV x 0.04) + V2 in volts, and Crss is the MOSFET's reverse transfer capacitance in pF. Any external capacitance between GATE and PGND adds up to Crss.
MAX15008/MAX15010
Power Dissipation/Junction Temperature
During normal operation, the MAX15008/MAX15010 has two main sources of internal power dissipation: the LDO and the voltage tracker. Calculate the power dissipation due to the LDO as: PLDO = (VIN - VOUT_LDO) x IOUT_LDO where VIN is the LDO input supply voltage in volts, VOUT_LDO is the output voltage of the LDO in volts, and IOUT_LDO is the LDO total load current in mA. Calculate power dissipation due to the tracker as: PTRK = (VTRACK - VOUT_TRK) x IOUT_TRK where VTRACK is the tracker input supply voltage in volts, VOUT_TRK is the output voltage of the tracker in volts, and IOUT_TRK is the tracker load current in mA. The total power dissipation PDISS in mW as: PDISS = PLDO + PTRK For prolonged exposure to overvoltage events, use the VIN and VTRACK voltages expected during overvoltage conditions. Under these circumstances the corresponding internal power dissipation contribution, POVP, calculated in the Overvoltage-Limiter Mode Switching Frequency section should also be included in the total power dissipation, PDISS. For a given ambient temperature, T A, calculate the junction temperature, TJ, as follows: TJ = TA + PDISS x JA where TJ and TA are in C and JA is the junction-toambient thermal resistance in C/W as listed in the Absolute Maximum Ratings section. The junction temperature should never exceed +150C during normal operation.
where t 1 is in ms, V OV is the adjusted overvoltage threshold in volts, ILOAD is the external load current in mA, and IGATEPD is the 63mA (typ) internal pulldown current of GATE. CSOURCE is the value of the capacitor connected between the source of the MOSFET and PGND in F.
GATE Delay Time (t2) When SOURCE falls 4% below the overvoltage threshold voltage, the internal current sink is disabled and the internal charge pump begins recharging the external GATE voltage. Due to the external load, the SOURCE voltage continues to drop until the gate of the MOSFET is recharged. The time needed to recharge GATE and reenhance the external MOSFET is approximately:
t 2 = Ciss x VGS( TH) + VF IGATE
where t2 is in s, Ciss is the input capacitance of the MOSFET in pF, and VGS(TH) is the gate-to-source threshold voltage of the MOSFET in volts. VF is the 0.7V (typ) internal clamp diode forward voltage of the MOSFET in volts, and IGATE is the charge-pump current 45A (typ). Any external capacitance between GATE and PGND will add up to Ciss. During t2, the SOURCE capacitance, CSOURCE, loses charge through the output load. The voltage across CSOURCE, V2, decreases by V2 until the MOSFET reaches its VGS(TH) threshold. Approximate V2 using the following formula: I xt V2 = LOAD 2 CSOURCE
Thermal Protection
SOURCE Output Charge Time (t3) Once the GATE voltage exceeds the gate-to-source threshold, VGS(TH), of the external MOSFET, the MOSFET turns on and the charge through the internal charge pump with respect to the drain potential, QG, determines the slope of the output-voltage rise. The time required for the SOURCE voltage to rise again to the overvoltage threshold is:
t3 = Crss x VSOURCE IGATE When the junction temperature exceeds TJ = +160C, the MAX15008/MAX15010 shut down to allow the device to cool. When the junction temperature drops to +140C, the thermal sensor turns all enabled blocks on again, resulting in a cycled output during continuous thermal-overload conditions. Thermal protection protects the MAX15008/MAX15010 from excessive power dissipation. For continuous operation, do not exceed the absolute maximum junction temperature rating of +150C.
______________________________________________________________________________________
19
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector MAX15008/MAX15010
Typical Operating Circuits
DC-DC MAX5073 CSOURCE 5V TO 40V INPUT CIN OUT_TRK TRACK CTRACK FB_TRK COUT_TRK TRACKER OUTPUT 50mA GATE IN SOURCE FB_PROT PGND VOUT1 VOUT2
MAX15008
LDO ON/OFF PROTECTOR ON/OFF TRACKER ON/OFF HOLD EN_LDO EN_PROT EN_TRK HOLD CT CRESET REF CREF
ADJ OUT_LDO FB_LDO
5V 300mA COUT_LDO RPU
VCC C
RESET SGND
RESET/EN I/O
5V TO 40V INPUT IN CIN FB_TRK OUT_TRK COUT_TRK TRACK CTRACK TRACKER OUTPUT
MAX15010
LDO ON/OFF TRACKER ON/OFF HOLD CREF EN_LDO EN_TRK HOLD REF CT CRESET PGND
ADJ OUT_LDO FB_LDO RPU
5V 300mA COUT_LDO
VCC C
RESET SGND
RESET/EN I/O
20
______________________________________________________________________________________
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector
Pin Configurations (continued)
PROCESS: BiCMOS
EN_TRK
Chip Information
MAX15008/MAX15010
TOP VIEW
N.C. N.C.
OUT_LDO
OUT_LDO
24 HOLD 25 N.C. 26 N.C. 27 N.C. 28 FB_TRK 29 TRACK 30 N.C. 31 N.C. 32 1 N.C.
23
22
21
20
19
18
N.C.
IN
IN
17 16 15 14 13 EN_LDO FB_LDO REF N.C. N.C. N.C. N.C. CT
MAX15010
12 11
+
2 N.C. 3 OUT_TRK 4 ADJ 5 SGND 6 PGND
*EP
10 9
7 RESET
8 N.C.
TQFN (5mm x 5mm)
*EP = EXPOSED PAD
______________________________________________________________________________________
21
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector MAX15008/MAX15010
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
22
______________________________________________________________________________________
QFN THIN.EPS
Automotive 300mA LDO Voltage Regulators with Tracker Output and Overvoltage Protector
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
MAX15008/MAX15010
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 23
(c) 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

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