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19-0516; Rev 1; 9/08
KIT ATION EVALU BLE AVAILA
Dual 300mA Pin-Programmable LDO Linear Regulators
General Description Features
Pin-Programmable Output Voltages 300mA Output Current Low 90mV Dropout at 100mA Load Open-Drain, Active-Low RESET (MAX8633) Low 45VRMS Output Noise (MAX8634/MAX8636) Low 54A Quiescent Supply Current Low < 1A Maximum Shutdown Current Output Current Limit Thermal Shutdown
MAX8633-MAX8636
The MAX8633-MAX8636 offer low-dropout (LDO) voltage and ultra-low-power regulation in a subminiaturized 2mm x 2mm DFN package. The devices operate from a 2.7V to 5.5V supply and deliver up to 300mA from each output, with a typical dropout voltage of 90mV at 100mA load current. Each device is designed with internal p-channel MOSFET pass transistors to ensure a low-quiescent supply current of 54A (typical, both LDOs on). Other features include low-noise operation (MAX8634/MAX8636), output current limiting, and thermal shutdown. The MAX8633 features an open-drain, active-low RESET output to monitor OUT2, eliminating external components and adjustments. The MAX8633 asserts a RESET signal (120ms minimum timeout) when VOUT2 drops below 87% of the nominal output voltage. The MAX8634/MAX8636 feature a noise bypass input to the internal reference for low output noise (45VRMS typ). The MAX8634/MAX8635 provide independent SHDN inputs for disabling the regulators, while the MAX8633/ MAX8636 provide a single SHDN input for disabling both regulators. The MAX8633/MAX8635/MAX8636 have two logic inputs that select one of nine preset output-voltage combinations, eliminating external 1% resistors, as well as inventory burden. The MAX8634 has one logic input to select three output-voltage options. The MAX8633-MAX8636 are available in an 8-pin, 2mm x 2mm DFN package for minimizing footprint, and an 8-pin, 3mm x 3mm TDFN package for higher power dissipation. The devices are specified over the extended temperature range (-40C to +85C). All packages are lead free.
Ordering Information
PART TEMP RANGE PINPACKAGE 8 DFN 2mm x 2mm 8 TDFN 3mm x 3mm 8 DFN 2mm x 2mm TOP MARK AAH AOQ AAI
MAX8633ELA+ -40C to +85C MAX8633ETA+ -40C to +85C MAX8634ELA+ -40C to +85C
+Denotes a lead-free/RoHS-compliant package.
Ordering Information continued at end of data sheet.
Typical Operating Circuits
INPUT 2.7V TO 5.5V IN CIN 2.2F OUT1 COUT1 2.2F
Applications
Cellular and Cordless Phones PDAs and Digital Cameras Small LCD Displays Notebook Computers Wireless LAN Cards Handheld Instruments
MAX8633 OUT2
P1 P2 SHDN GND RESET COUT2 2.2F OUT2
Pin Configurations and Selector Guide appear at end of data sheet.
Typical Operating Circuits continued at end of data sheet.
1
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
Dual 300mA Pin-Programmable LDO Linear Regulators MAX8633-MAX8636
ABSOLUTE MAXIMUM RATINGS
(All voltages refer to GND, unless otherwise noted.) IN ...........................................................................-0.3V to +6.0V SHDN, SHDN1, SHDN2, RESET, P, P1, P2, BP, OUT1, OUT2 .....................-0.3V to (VIN + 0.3V) Continuous Output Short-Circuit Duration..................Continuous Continuous Power Dissipation (TA = +70C) 8-Pin DFN 2mm x 2mm (derate 4.8mW/C above +70C) .................................380mW 8-Pin TDFN 3mm x 3mm (derate 23.8mW/C above +70C) .............................1904mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
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 = 3.7V, SHDN = SHDN1 = SHDN2 = IN, P = P1 = P2 = GND, CIN = 2.2F, COUT1 = 2.2F, COUT2 = 2.2F, CBP = 0.01F, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER Input Voltage Input Undervoltage Lockout Ground Current Shutdown Supply Current OUT1, OUT2 IOUT_ = 70mA; TA = +25C Output Voltage Accuracy (for Any Output Voltage) Current Limit Drop-Out Voltage ILIM VIN - VOUT IOUT_ = 70mA IOUT_ = 0.1mA to 300mA; VIN = (VOUT_ + 0.5V) to 5.5V OUT_ = 0V VOUT_ = 2.8V (MAX8633); VOUT_ = 2.85V (MAX8634/MAX8635/MAX8636); IOUT_ = 100mA (Note 2) MAX8633 MAX8635 MAX8634 MAX8636 f < 1kHz PSRR IOUT_ = 30mA f < 10kHz 55 -0.7 -1 -1.8 400 500 90 +0.7 +1 +1.7 600 200 mA mV % SYMBOL VIN VUVLO VIN rising; hysteresis = 95mV (typ) IOUT_ = 0mA IQ IOUT_ = 100mA IOUT_ = 10mA, dropout (Note 2) IOFF SHDN_ = GND TA = +25C TA = +85C CONDITIONS MIN 2.7 2.15 2.25 54 60 60 0.005 0.01 1 A TYP MAX 5.5 2.35 75 A UNITS V V
450 VRMS 45 60 dB
Output Noise
f = 10Hz to 100kHz; IOUT_ = 10mA
Output AC PowerSupply Rejection Ratio
2
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Dual 300mA Pin-Programmable LDO Linear Regulators
ELECTRICAL CHARACTERISTICS (continued)
(VIN = 3.7V, SHDN = SHDN1 = SHDN2 = IN, P = P1 = P2 = GND, CIN = 2.2F, COUT1 = 2.2F, COUT2 = 2.2F, CBP = 0.01F, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER Input Voltage High Input Voltage Low Input Bias Current Turn-On Delay TRI-LEVEL INPUTS (P, P1, P2) Termination Resistance to IN or GND for Setting High, Open, and Low States Input Load Capacitance for Open State RESET RESET High Threshold RESET Threshold Hysteresis RESET Output Voltage Low RESET Output High Leakage Current RESET Delay THERMAL PROTECTION Thermal-Shutdown Threshold Thermal-Shutdown Hysteresis TSHDN TSHDN +165 15 C C ILEAK tRP Percent of nominal OUT2; OUT2 rising Percent of nominal OUT2; OUT2 falling IRESET = 20A; VIN = 1.0V IRESET = 500A; VIN = 3.7V VRESET = VIN = 5.5V TA = +25C TA = +85C 120 84 87 4.5 10 5 0.1 1 150 180 100 100 300 90 % % mV nA ms For high or low state IN = 2.7 to 5.5V For open state 100 1 k SYMBOL VIH VIL ISHDN_ VIN = 2.7V to 5.5V VIN = 2.7V to 5.5V VIN = 2.7V to 5.5V; VSHDN_ = GND or IN TA = +25C TA = +85C 0.1 1 90 CONDITIONS MIN 1.5 0.5 1000 TYP MAX UNITS SHUTDOWN INPUTS (SHDN, SHDN1, AND SHDN2) V nA s
MAX8633-MAX8636
From SHDN = high to 87% of VOUT_; IOUT_ = 70mA
Design guide only
50
pF
From OUT2 rising to RESET rising
Note 1: All units are 100% tested at TA = +25C. Limits over the operating temperature range are guaranteed by design. Note 2: The dropout voltage is defined as VIN - VOUT_ when VOUT_ drops by 100mV from VOUT_ when measured at VIN = +3.7V. Note 3: Connect P_ to IN or GND through a resistor less than 1k.
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Dual 300mA Pin-Programmable LDO Linear Regulators MAX8633-MAX8636
Typical Operating Characteristics
(VIN = 3.8V, P = P1 = P2 = GND, IOUT1, 2 = 70mA, COUT1 = 2.2F, COUT2 = 2.2F, CBP = 0.01F, CIN = 2.2F, and TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE (MAX8633ELA+)
MAX8633 toc01
SUPPLY CURRENT vs. LOAD CURRENT (MAX8635ELA+)
MAX8633 toc02
SUPPLY CURRENT vs. TEMPERATURE (MAX8633ELA+)
IOUT1 = IOUT2 = 70mA
MAX8633 toc03
70 IOUT1 = IOUT2 = 70mA 60 SUPPLY CURRENT (A) 50 40 30 20 10 IOUT1 = IOUT2 = 0mA
70
70 65 SUPPLY CURRENT (A) 60 55 IOUT1 = IOUT2 = 0mA 50 45
SUPPLY CURRENT (A)
65
60
55 P1 = P2 = IN
0 0 1 2 3 4 5 6 SUPPLY VOLTAGE (V)
50 0 50 100 150 200 250 300 LOAD CURRENT (mA)
40 -40 -15 10 35 60 85 TEMPERATURE (C)
DROPOUT VOLTAGE vs. LOAD CURRENT (MAX8633ELA+)
MAX8633 toc04
DROPOUT VOLTAGE vs. OUT1 VOLTAGE (MAX8633ELA+)
MAX8633 toc05
OUTPUT VOLTAGE ACCURACY vs. TEMPERATURE (MAX8633ELA+)
1.5 OUT1 VOLTAGE ACCURACY (%) 1.0 0.5 0 -0.5 -1.0 -1.5 -2.0 -40 -15 10 35 60 85 OUT1
MAX8633 toc06
0.30 0.25 DROPOUT VOLTAGE (V) 0.20 0.15 0.10 0.05 OUT1 0 0 50 100 150 200 250
80
2.0
DROPOUT VOLTAGE (mV)
70
60
50 OUT1 P1 = P2 = IN 40 2.60 2.65 2.70 2.75 2.80 2.85 OUT1 VOLTAGE (V) 2.90 2.95
300
LOAD CURRENT (mA)
TEMPERATURE (C)
PSRR vs. FREQUENCY (MAX8636ELA+)
MAX8633 toc07
CHANNEL-TO-CHANNEL ISOLATION vs. FREQUENCY (MAX8636ELA+)
MAX8633 toc08
OUTPUT SPECTRAL NOISE DENSITY vs. FREQUENCY (MAX8636ELA+)
OUT1 P1 = IN P2 = GND
MAX8633 toc09
70 60 50 PSRR (dB) 40 30 20 10 0 ROUT1 = 100 P1 = IN P2 = GND 0.01 0.1 1 FREQUENCY (kHz) 10
70 60 50 PSRR (dB) 40 30 20 10 ROUT1 = 100 0
10,000
NOISE DENSITY (nV/ Hz)
1000
100
10 0.01 0.1 1 FREQUENCY (kHz) 10 100 0.01 0.1 1 10 100 1000 FREQUENCY (kHz)
100
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Dual 300mA Pin-Programmable LDO Linear Regulators
Typical Operating Characteristics (continued)
(VIN = 3.8V, P = P1 = P2 = GND, IOUT1, 2 = 70mA, COUT1 = 2.2F, COUT2 = 2.2F, CBP = 0.01F, CIN = 2.2F, and TA = +25C, unless otherwise noted.)
OUTPUT NOISE DC TO 100kHz (MAX8636ELA+)
MAX8633 toc10
MAX8633-MAX8636
LINE TRANSIENT RESPONSE (MAX8633ELA+)
MAX8633 toc11
4.8V VIN 3.8V 1V/div 0
50V/div AC VOUT1 MAX8633 IOUT1 = 70mA 1ms/div 40s/div 10mV/div
LOAD TRANSIENT (MAX8633ELA+ OUT1 ILOAD = 1mA TO 70mA)
MAX8633 toc12
LOAD TRANSIENT NEAR DROPOUT (VIN = VOUT + 0.1V, MAX8633ELA+ OUT1)
MAX8633 toc13
70mA IOUT1 1mA 100mA/div 0 IOUT1 1mA
70mA 100mA/div 0
AC VOUT1 MAX8633 VIN = 3.8V 40s/div
20mV/div
AC VOUT1 MAX8633 VIN = VOUT1 + 0.1V 40s/div
20mV/div
RESET TIMING (MAX8633ELA+)
MAX8633 toc14
OUT1 AND OUT2 TURN-ON SEQUENCE (MAX8633ELA+)
MAX8633 toc15
EXITING SHUTDOWN (MAX8634ELA+)
MAX8633 toc16
SHDN OUT1
5V/div SHDN 0 2V/div 0 OUT1
MAX8633 P1 = P2 = GND IOUT1 = IOUT2 = 70mA 2V/div 0 2V/div 0
SHDN1
0
2V/div 2V/div
OUT1
RESET
SHDN2
0
2V/div
2V/div 0 MAX8633
OUT2
2V/div 0 40s/div
OUT2
2V/div MAX8634 P = IN ROUT1 = ROUT2 = 100 40s/div
40ms/div
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Dual 300mA Pin-Programmable LDO Linear Regulators MAX8633-MAX8636
Pin Description
PIN MAX8633 MAX8634 MAX8635 MAX8636 NAME FUNCTION Regulator Input. Supply voltage from 2.7V to 5.5V. Bypass IN with a ceramic capacitor of at least 2.2F to GND (see the Capacitor Selection and Regulator Stability section). Shutdown Input, Active Low. Drive SHDN logic low to shut down both regulators. Connect SHDN to IN or drive logic high for normal operation (see the Power-On Sequence (MAX8633/Max8636 Only) section). LDO1 Shutdown Input, Active Low. Drive SHDN1 logic low to shut down OUT1. Connect SHDN1 to IN or drive logic high for normal operation. LDO2 Shutdown Input, Active Low. Drive SHDN2 logic low to shut down OUT2. Connect SHDN2 to IN or drive logic high for normal operation. Programming Input 2. The state of P1 and P2 selects one of nine output-voltage options (see Tables 1, 3). Programming Input 1. The state of P1 and P2 selects one of nine output-voltage options (see Tables 1, 3). Programming Input. The state of P selects one of three output-voltage options for the MAX8634 (see Table 2). Reset Output, Active Low, Open Drain. RESET goes high impedance 120ms (min) after VOUT2 rises above 87% of the nominal output voltage. RESET is forced logic low when VOUT2 is below 82.5% of the nominal output voltage. Connect RESET to OUT1, OUT2, or another voltage of VIN or lower with a pullup resistor. Reference Noise Bypass. Bypass BP to GND with a 0.01F ceramic capacitor to reduce output noise. Ground Regulator 2 Output. Guaranteed 300mA output current (see the Calculating Maximum Output Power section). Bypass OUT2 with a ceramic capacitor of at least 2.2F to GND (see the Capacitor Selection and Regulator Stability section). Regulator 1 Output. Guaranteed 300mA output current (see the Calculating Maximum Output Power section). Bypass OUT1 with a ceramic capacitor of at least 2.2F to GND (see the Capacitor Selection and Regulator Stability section). Exposed Paddle. Solder the exposed paddle to a large pad or circuit-board ground plane to increase thermal dissipation.
1
1
1
1
IN
2
--
--
2
SHDN
--
2
2
--
SHDN1
--
3
5
--
SHDN2
3 4 --
-- -- 4
3 4 ----
3 4 --
P2 P1 P
5
--
--
--
RESET
-- 6
5 6
-- 6
5 6
BP GND
7
7
7
7
OUT2
8
8
8
8
OUT1
EP*
EP*
EP*
EP*
EP
*TDFN package only.
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Dual 300mA Pin-Programmable LDO Linear Regulators
Functional Diagram
MAX8633-MAX8636
IN * SHDN ** SHDN1 SHDN2 ** UVLO/ SHUTDOWN AND POWER-ON CONTROL
ERROR AMP
MOS DRIVER WITH ILIMIT OUT1
THERMAL SENSOR P1 P2 P (MAX8634 ONLY) GND
1.50V REF OUTPUTVOLTAGE CONTROL
87% REF DELAY
RESET (MAX8633 ONLY)
BP*** IN LD02
OUT2
*MAX8633, MAX8636 ONLY **MAX8634, MAX8635 ONLY ***MAX8634, MAX8636 ONLY
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Dual 300mA Pin-Programmable LDO Linear Regulators MAX8633-MAX8636
Detailed Description
The MAX8633-MAX8636 are low-power, low-quiescent current, low-dropout linear regulators designed primarily for battery-powered applications. Pin-programmable inputs allow easy configuration of OUT1 and OUT2 voltages without external 1% resistors. The devices can supply up to 300mA from each output, provided they do not exceed the maximum package power dissipation. The MAX8633-MAX8636 regulate OUT1 and OUT2 by using simple control loops incorporating internal 1.50V reference, error amplifiers, p-channel pass transistors, and internal feedback voltage-dividers. Reset circuitry ensures controlled startup and provides undervoltage lockout. The MAX8633-MAX8636 determine output voltages at OUT1 and OUT2 based on the state of P1 and P2 (P for MAX8634) at power-on. MAX8634) at power-on. Subsequent changes to P, or P1 and P2 do not change the output voltages unless the supply power is cycled, or all SHDN inputs are simultaneously driven low to shut down the device.
Power-On Sequence (MAX8633/MAX8636 Only)
The MAX8633/MAX8636 provide a single shutdown input (SHDN) to disable OUT1 and OUT2. During power-on, inrush current is limited by a built-in startup sequence. At power-on, OUT1 is disabled until OUT2 reaches 87% of its regulation voltage, then OUT1 is enabled. If SHDN is connected to IN and the input voltage drops below the undervoltage-lockout (UVLO) threshold, both LDOs are disabled. The LDOs will not power on again until both of the following conditions are satisfied: 1) The input voltage is raised above the UVLO threshold 2.25V (typ). 2) OUT2 is discharged below 1.2V (typ).
RESET (MAX8633)
The MAX8633 features an integrated reset circuit. RESET is logic-low on power-up and goes high impedance 150ms after OUT2 reaches 87% of its nominal regulation voltage. During power-down or undervoltage conditions, RESET is driven low when OUT2 falls below 82.5% of its nominal regulation voltage.
Internal p-Channel Pass Transistor
The MAX8633-MAX8636 feature 0.9 p-channel MOSFET pass transistors; p-channel MOSFETs provide several advantages over similar designs using pnp pass transistors, resulting in higher efficiency and longer battery life. MOSFET pass transistors do not require base drive current of pnps, reducing quiescent current
Output Programming Inputs (P1, P2, P)
Output voltages for OUT1 and OUT2 are determined at power-up by the state of P1 and P2. Programming inputs P1 and P2 eliminate external 1% feedback resistors while providing nine preset output-voltage options (see Table 1 for the MAX8633; see Table 3 for the MAX8635/MAX8636). The MAX8634 provides three preset output-voltage options with one programming input (see Table 2). The MAX8633-MAX8636 configure output voltages at OUT1 and OUT2 based on the state of P1 and P2 (P for
Table 2. Output-Voltage Programming (MAX8634)
P Open GND IN OUT1 (V) 2.85 3.00 2.60 OUT2 (V) 2.85 2.85 2.60
Table 1. Output-Voltage Programming (MAX8633)
P1 Open Open Open GND GND GND IN IN IN P2 Open GND IN Open GND IN Open GND IN OUT1 (V) 2.80 2.90 3.00 3.00 2.80 2.60 2.90 2.80 3.00 (OUT2) (V) 1.50 1.50 1.50 1.60 1.80 1.85 1.85 2.60 2.80
Table 3. Output-Voltage Programming (MAX8635/MAX8636)
P1 Open Open Open GND GND GND IN IN IN P2 Open GND IN Open GND IN Open GND IN OUT1 (V) 2.80 2.90 3.00 2.60 2.80 3.00 3.00 2.85 3.00 OUT2 (V) 1.50 1.50 1.50 1.80 1.80 2.50 2.80 2.85 3.00
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Dual 300mA Pin-Programmable LDO Linear Regulators
considerably. Under heavy loads, pnp base-drive current becomes large, further reducing efficiency; pnpbased regulators also require considerable current in dropout when the pass transistor saturates. The MAX8633-MAX8636 do not suffer from these problems. With both outputs active, the devices consume only 54A of quiescent current at no load, and 60A with 100mA load current for each output (see Typical Operating Characteristics). A pnp-based regulator has a high dropout voltage that is independent of the load. The dropout voltage of a p-channel MOSFET is proportional to load current providing for low-dropout voltage at heavy loads and extremely low dropout at lighter loads. ture range. Output capacitors can be reduced to 1F for load currents less than 150mA. The MAX8633- MAX8636 are optimized for ceramic capacitors and require low equivalent-series resistance (ESR) to achieve the stated specifications for low-output noise and power-supply rejection. To ensure proper operation over the specified temperature range, dielectrics such as X7R or X5R are recommended. If Z5U or Y5V dielectrics are used, it may be necessary to increase the value of the output capacitors to ensure stability at temperatures below -10C. Tantalum capacitors are not recommended due to their higher ESR. For loads up to 300mA, or for improved load-transient response, 2.2F or larger output capacitors can be used.
MAX8633-MAX8636
Current Limit
The MAX8633-MAX8636 provide independent current limiting for OUT1 and OUT2. Output current is limited to 500mA (typ) and 400mA (min) for each regulator.
PSRR and Operation from Sources Other than Batteries
The MAX8633-MAX8636 deliver low-dropout voltages and low-quiescent currents in battery-powered systems. When operating from sources other than batteries, improved supply-noise rejection and transient response can be achieved by increasing the values of the input and output capacitors and through passive filtering techniques. Power-supply rejection is 60dB at frequencies below 1kHz (see the Power-Supply Rejection Ratio vs. Frequency in the Typical Operating Characteristics).
Shutdown (SHDN1, SHDN2, SHDN)
The MAX8634/MAX8635 have independent shutdown control inputs (SHDN1 and SHDN2) and the MAX8633/ MAX8636 have one shutdown control input (SHDN) for both outputs. Drive SHDN1 low to shut down OUT1. Drive SHND2 low to shut down OUT2. Drive both SHDN1 and SHDN2 low to shut down the entire device, reducing supply current to 1A max. For the MAX8634, drive SHDN low to shut down the entire device. Connect SHDN1, SHDN2, or SHDN to a logic-high or IN to permanently enable the corresponding LDO(s).
P1 and P2 (P for MAX8634) External Termination
The pin-programmable inputs (P1 and P2 for MAX8633/MAX8635/MAX8636, P for MAX8634) should be connected to IN, GND, or left open. If P_ inputs are left open, ensure the external capacitance is less than 50pF. If P_ inputs are set high or low, ensure the resistance to IN or GND is less than 1k. The MAX8633- MAX8636 configure output voltages at OUT1 and OUT2 based on the state of P1 and P2 (P for MAX8634) at power-on. Subsequent changes to P, or P1 and P2 do not change the output voltages unless the supply power is cycled, or all SHDN inputs are simultaneously driven low to shut down the device.
Thermal-Overload Protection
Thermal-shutdown circuitry protects the MAX8633- MAX8636 from damage due to excessive junction temperature. The shutdown circuit disables OUT1 and OUT2 when the junction temperature (TJ) exceeds +165C. Both regulators are reenabled when TJ falls by 15C.
Low-Noise Operation (MAX8634/MAX8636)
An external 0.01F bypass capacitor at BP in conjunction with an internal resistor creates a lowpass filter. The MAX8634/MAX8636 exhibit less than 45VRMS of output voltage noise with CBP = 0.01F and COUT = 2.2F. These values are shown in the Output Noise Spectral Density graph in the Typical Operating Characteristics section. If output noise is not critical, omit the BP capacitor to reduce total solution size and cost.
Load-Transient Considerations
The MAX8633-MAX8636 load-transient response graphs (see Typical Operating Characteristics) show two components of the output response: a DC step in the output voltage due to the change in load current, and the transient response. Increase the value and decrease the ESR of the output capacitor to attenuate transient spikes.
Applications Information
Capacitor Selection and Regulator Stability
Use a ceramic input capacitor of at least 2.2F and a ceramic output capacitor of at least 2.2F for each output to ensure stable operation over the entire tempera-
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9
Dual 300mA Pin-Programmable LDO Linear Regulators MAX8633-MAX8636
Input-Output Voltage (Dropout Voltage)
A regulator's minimum input-output voltage differential (or dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this determines the useful end-of-life battery voltage. Because the MAX8633-MAX8636 use a p-channel MOSFET pass transistor, dropout voltage is a function of drainto-source on-resistance (RDS(ON)) multiplied by the load current (see Typical Operating Characteristics).
PC Board Layout Guidelines
Follow these guidelines for good PC board layout: * Keep the input and output traces short and wide if possible, especially at the ground terminals. * Use thick copper PC boards to enhance thermal performance. Connect the exposed paddle of the TDFN package to the ground plane or a large copper pad. Place output, input, and bypass capacitors as close as possible to the IC. Ensure the noise bypass capacitor and associated PC board traces are routed away from noise sources to ensure low-output voltage noise.
Calculating Maximum Output Power
The maximum output power of the MAX8633-MAX8636 is limited by the maximum power dissipation of the package. By calculating the power dissipation of the device as a function of the input voltage, output voltages, and output currents, the worst-case power dissipation can be obtained. The worst-case power dissipation should not exceed the package's maximum power rating: where: PD = VIN(MAX) - VOUT1 x I OUT1 +
* *
An evaluation kit (MAX8633EVKIT) is available for a layout example to speed designs.
(VIN(MAX) - VOUT2 ) x IOUT2
VIN(MAX) = Maximum input voltage VOUT1 = Output voltage of OUT1 VOUT2 = Output voltage of OUT2 IOUT1 = Maximum output current of OUT1 IOUT2 = Maximum output current of OUT2 PD must be less than PDMAX, the maximum power dissipation of the package. If PD is greater than PDMAX, consider using the 8-pin TDFN package. P DMAX = 380mW for the 8-pin DFN. Derate by 4.8mW/C above +70C. P DMAX = 1904mW for the 8-pin TDFN. Derate by 23.8mW/C above +70C.
(
)
Selector Guide
PART MAX8633 MAX8634 MAX8635 MAX8636 OUTPUT VOLTAGE OPTIONS 9 3 9 9 SHDN INPUTS 1 2 2 1 LOW NOISE -- YES -- YES RESET YES -- -- --
Ordering Information (continued)
PART TEMP RANGE PINPACKAGE 8 TDFN 3mm x 3mm 8 DFN 2mm x 2mm 8 TDFN 3mm x 3mm 8 DFN 2mm x 2mm 8 TDFN 3mm x 3mm TOP MARK AOR AAJ AOS AAK AOT
MAX8634ETA+ -40C to +85C MAX8635ELA+ -40C to +85C MAX8635ETA+ -40C to +85C MAX8636ELA+ -40C to +85C MAX8636ETA+ -40C to +85C
+Denotes a lead-free/RoHS-compliant package.
10
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Dual 300mA Pin-Programmable LDO Linear Regulators
Pin Configurations
TOP VIEW
OUT1 OUT2 GND RESET 8 7 6 5 OUT1 OUT2 GND 8 7 6 BP 5
MAX8633-MAX8636
MAX8633
*EP 1 IN 2 SHDN 3 P2 4 P1 1 IN
MAX8634
*EP 2 3 4 P
SHDN1 SHDN2
2mm x 2mm DFN 3mm x 3mm TDFN
OUT1 OUT2 GND SHDN2 8 7 6 5
2mm x 2mm DFN 3mm x 3mm TDFN
OUT1 OUT2 GND 8 7 6 BP 5
MAX8635
*EP 1 IN 2 SHDN1 3 P2 4 P1 1 IN
MAX8636
*EP 2 SHDN 3 P2 4 P1
2mm x 2mm DFN 3mm x 3mm TDFN
2mm x 2mm DFN 3mm x 3mm TDFN
*EP = EXPOSED PADDLE. CONNECT EXPOSED PADDLE TO GND (TDFN ONLY).
Chip Information
PROCESS: BiCMOS CONNECT EXPOSED PADDLE TO GND.
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11
Dual 300mA Pin-Programmable LDO Linear Regulators MAX8633-MAX8636
Typical Operating Circuits (continued)
INPUT 2.7V TO 5.5V IN CIN 2.2F OUT1 COUT1 2.2F
MAX8634 OUT2
P SHDN1 SHDN2 GND INPUT 2.7V TO 5.5V IN CIN 2.2F P1 P2 SHDN1 SHDN2 GND OUT1 COUT1 2.2F CIN 2.2F INPUT 2.7V TO 5.5V IN OUT1 COUT1 2.2F BP CBP 0.01F COUT2 2.2F
MAX8635 OUT2
COUT2 2.2F P1 P2 SHDN
MAX8636 OUT2
COUT2 2.2F BP CBP 0.01F GND
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE 8 TDFN 8 DFN PACKAGE CODE T833-2 L822-1 DOCUMENT NO. 21-0137 21-0164
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Dual 300mA Pin-Programmable LDO Linear Regulators
Revision History
REVISION NUMBER 0 1 REVISION DATE 4/06 9/08 Initial release Added LDO SHDN restart conditions DESCRIPTION PAGES CHANGED -- 8
MAX8633-MAX8636
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 ____________________ 13
(c) 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

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