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19-2584; Rev 0; 10/02
Low-Noise, Low-Dropout, 200mA Linear Regulator
General Description
The MAX1598 low-noise, low-dropout linear regulator operates from a 2.5V to 6.5V input and delivers up to 200mA. Typical output noise is 30VRMS, and typical dropout is only 236mV at 200mA. The output voltage is preset to voltages from 2.5V to 5V in 100mV increments. Designed with an internal P-channel MOSFET pass transistor, the MAX1598 maintains a low 100A supply current independent of the load current and dropout voltage. Other features include a 10nA logic-controlled shutdown mode, short-circuit and thermal-shutdown protection, and reverse battery protection. The device also includes an autodischarge function, which actively discharges the output voltage to ground when the device is placed in shutdown. The MAX1598 comes in a thin 5-pin SOT23 package. o 200mA Output Current o Low Output Noise: 30VRMS o Low 55mV Dropout at 50mA Output o Low 85A No-Load Supply Current o Low 100A Operating Supply Current, Even in Dropout o Thermal-Overload and Short-Circuit Protection o Reverse Battery Protection o Output Current Limit o Preset Output Voltages o 10nA Logic-Controlled Shutdown
Features
MAX1598
Applications
Cellular, Cordless, and PCS Phones PCMCIA Cards Modems Hand-Held Instruments Palmtop Computers Electronic Planners
PART MAX1598EZKxy-T*
Ordering Information
TEMP RANGE -40C to +85C PIN-PACKAGE Thin SOT23-5
*xy is the output voltage code (see the Selector Guide at end of data sheet).
Typical Operating Circuit
TOP VIEW
INPUT 2.5V TO 6.5V IN CIN 1F ON OFF CBP 0.01F OUT COUT 2.2F OUTPUT PRESET 2.5V TO 5V 200mA
Pin Configuration
IN 1
5
OUT
MAX1598
SHDN BP GND
GND 2
MAX1598
SHDN 3
4
BP
THIN SOT23-5
________________________________________________________________ Maxim Integrated Products
1
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Low-Noise, Low-Dropout, 200mA Linear Regulator MAX1598
ABSOLUTE MAXIMUM RATINGS
IN to GND ....................................................................-7V to +7V Output Short-Circuit Duration ............................................Infinite SHDN to GND..............................................................-7V to +7V SHDN to IN ...............................................................-7V to +0.3V OUT, BP to GND ..........................................-0.3V to (VIN + 0.3V) Continuous Power Dissipation (TA = +70C) 5-Pin Thin SOT23 (derate 9.1mW/C above +70C) ....727mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C JB (thin).........................................................................110C/W Storage Temperature.........................................-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 = (VOUT(NOMINAL) + 0.5V) or 2.5V (whichever is greater), TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER Input Voltage Output Voltage Accuracy Maximum Output Current Current Limit Ground-Pin Current ILIM IQ No load IOUT = 150mA IOUT = 1mA Dropout Voltage (Note 2) IOUT = 50mA IOUT = 200mA Line Regulation Load Regulation Output Voltage Noise SHUTDOWN SHDN Input Threshold SHDN Input Bias Current Shutdown Supply Current VIH VIL I SHDN IQ(SHDN) VIN = 2.5V to 5.5V VIN = 2.5V to 5.5V V SHDN = VIN VOUT = 0V CBP = 0.1F COUT = 1F, no load (Note 3) TA = +25C TA = +85C TA = +25C TA = +85C TA = +25C TA = -40C to +85C 300 0.01 0.5 0.01 0.2 30 150 s 300 1 2.0 0.4 1 V A A VLNR VLDR en VIN = 2.5V or (VOUT + 0.1V) to 6.5V, IOUT = 1mA IOUT = 0.1mA to 120mA, COUT = 1F f = 10Hz to 100kHz, CBP = 0.01F COUT = 10F COUT = 100F -0.15 SYMBOL VIN IOUT = 0.1mA, TA = +25C, VOUT 2.5V IOUT = 0.1mA to 120mA, TA = -40C to +85C, VOUT 2.5V CONDITIONS MIN 2.5 -1.4 -3 200 220 458 85 100 1.1 55 236 0 0.01 30 20 +0.15 0.04 %/V %/mA VRMS 120 mV 180 TYP MAX 6.5 +1.4 +2 % mA mA A UNITS V
Shutdown Exit Delay Resistance Shutdown Discharge
2
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Low-Noise, Low-Dropout, 200mA Linear Regulator
ELECTRICAL CHARACTERISTICS (continued)
(VIN = (VOUT(NOMINAL) + 0.5V) or 2.5V (whichever is greater), TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER THERMAL PROTECTION Thermal-Shutdown Temperature Thermal-Shutdown Hysteresis TSHDN TSHDN 155 15 C C SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX1598
Note 1: Limits are 100% production tested at TA = +25C. Limits over the operating temperature range are guaranteed through correlation using guaranteed by design (GBD) methods. Note 2: The dropout voltage is defined as VIN - VOUT, when VOUT is 100mV below the value of VOUT for VIN = VOUT + 0.5V. Note 3: Time needed for VOUT to reach 95% of final value.
__________________________________________Typical Operating Characteristics
(VIN = (VOUT(NOMINAL) + 0.5V) or 2.5V (whichever is greater), CIN = 1F, COUT = 2.2F, CBP = 0.01F, TA = +25C, unless otherwise noted.)
OUTPUT VOLTAGE vs. LOAD CURRENT (MAX1598EZK25)
MAX1598-01
OUTPUT VOLTAGE vs. LOAD CURRENT (MAX1598EZK50)
MAX1598-02
GROUND-PIN CURRENT vs. LOAD CURRENT
105 GROUND-PIN CURRENT (A) 100 95 90 85 80 75 70 65 MAX1598EZK25 MAX1598EZK50
MAX1598-03
2.60
5.2
110
OUTPUT VOLTAGE (V)
2.50
OUTPUT VOLTAGE (V)
2.55
5.1
5.0
2.45
4.9
2.40 0 50 100 150 200 LOAD CURRENT (mA)
4.8 0 50 100 150 200 LOAD CURRENT (mA)
60 0 50 100 150 200 LOAD CURRENT (mA)
GROUND-PIN CURRENT vs. INPUT VOLTAGE (MAX1598EZK25)
MAX1598-04
GROUND-PIN CURRENT vs. INPUT VOLTAGE (MAX1598EZK50)
MAX1598-05
OUTPUT VOLTAGE vs. INPUT VOLTAGE
NO LOAD 5 OUTPUT VOLTAGE (V) MAX1598EZK50 4 3 2 1 0 MAX1598EZK25
MAX1598-06
120 ILOAD = 50mA GROUND-PIN CURRENT (A) 100 80 NO LOAD 60 40 20 0 0 1 2 3 4 5 6 INPUT VOLTAGE (V)
120 100 80
ILOAD = 50mA
6
GROUND-PIN CURRENT (A)
NO LOAD 60 40 20 0 0 1 2 3 4 5 6 INPUT VOLTAGE (V)
0
1
2
3
4
5
6
INPUT VOLTAGE (V)
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3
Low-Noise, Low-Dropout, 200mA Linear Regulator MAX1598
Typical Operating Characteristics (continued)
(VIN = (VOUT(NOMINAL) + 0.5V) or 2.5V (whichever is greater), CIN = 1F, COUT = 2.2F, CBP = 0.01F, TA = +25C, unless otherwise noted.)
OUTPUT VOLTAGE vs. TEMPERATURE (MAX1598EZK25)
MAX1598-07
OUTPUT VOLTAGE vs. TEMPERATURE (MAX1598EZK50)
MAX1598-08
GROUND-PIN CURRENT vs. TEMPERATURE
180 GROUND-PIN CURRENT (A) 160 140 120 100 80 60 40 20 MAX1598EZK25 MAX1598EZK50 ILOAD = 50mA
MAX1598-09 MAX1598-15 MAX1598-12
2.60 ILOAD = 50mA 2.55
5.2 ILOAD = 50mA 5.1
200
OUTPUT VOLTAGE (V)
2.50
OUTPUT VOLTAGE (V)
5.0
2.45
4.9
2.40 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
4.8 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
DROPOUT VOLTAGE vs. LOAD CURRENT (MAX1598EZK25)
MAX1598-10
DROPOUT VOLTAGE vs. LOAD CURRENT (MAX1598EZK50)
MAX1598-11
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
70 60 50 PSRR (dB)
300 250 DROPOUT VOLTAGE (mV) 200 TA = +85C 150 100 TA = -40C 50 0 0 40 60 120 160 TA = +25C
300 250 DROPOUT VOLTAGE (mV) 200 150 100 50 0 TA = -40C TA = +85C TA = +25C
COUT = 10F
40 30 20 10 0 ILOAD = 50mA CBP = 0.1F 0.01 0.1 1 10 100 1000 COUT = 1F
200
0
40
80
120
160
200
LOAD CURRENT (mA)
LOAD CURRENT (mA)
FREQUENCY (kHz)
OUTPUT NOISE SPECTRAL DENSITY vs. FREQUENCY
MAX1598-13
OUTPUT NOISE vs. BP CAPACITANCE
70 OUTPUT NOISE (VRMS) 60 50 MAX1598EZK50 40 30 20 MAX1598EZK25 10 0 10 0 0.001 0.01 BP CAPACITANCE (F) 0.1 1 MAX1598EZK30 COUT = 10F ILOAD = 10mA f = 10Hz to 100kHz
MAX1598-14
OUTPUT NOISE vs. LOAD CURRENT
60 50 OUTPUT NOISE (VRMS) 40 MAX1598EZK30 30 20 COUT = 10F CBP = 0.01F f = 10Hz to 100kHz 10 100 1000 MAX1598EZK25 MAX1598EZK50
OUTPUT NOISE SPECTRAL DENSITY (V/Hz)
10 CBP = 0.01F ILOAD = 10mA
80
1
COUT = 1F 0.1 COUT = 10F 0.01 0 1 10 FREQUENCY (kHz) 100 1000
LOAD CURRENT (mA)
4
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Low-Noise, Low-Dropout, 200mA Linear Regulator
Typical Operating Characteristics (continued)
(VIN = (VOUT(NOMINAL) + 0.5V) or 2.5V (whichever is greater), CIN = 1F, COUT = 2.2F, CBP = 0.01F, TA = +25C, unless otherwise noted.)
OUTPUT NOISE 10Hz TO 100kHz
MAX1598-16
MAX1598
REGION OF STABLE COUT ESR vs. LOAD CURRENT
MAX1598-17
100
10 COUT ESR ()
COUT = 10F
VOUT 50V/div
1
COUT = 2.2F STABLE REGION
0.1
0.01
1ms/div MAX1598EZK25, COUT = 10F, ILOAD = 10mA, CBP = 0.1F
0
50
100
150
200
LOAD CURRENT (mA)
LINE-TRANSIENT RESPONSE
MAX1598-18
LOAD-TRANSIENT RESPONSE
MAX1598-19
LOAD-TRANSIENT RESPONSE NEAR DROPOUT
MAX1598-20
4V 3V
3.01V VIN 3.00V 2.99V VOUT
3.01V 3.00V 2.99V VOUT
3.001V 3.000V 2.999V VOUT 50mA ILOAD 50mA ILOAD
100s/div MAX1598EZK30, ILOAD = 50mA
10s/div MAX1598EZK30, VIN = VOUT + 0.5V, CIN = 10F, ILOAD = 0 TO 50mA
10s/div MAX1598EZK30, VIN = VOUT + 0.1V, CIN = 10F, ILOAD = 0 TO 50mA
MAX1598EZK25 SHUTDOWN EXIT DELAY
MAX1598-21
MAX1598EZK50 SHUTDOWN EXIT DELAY
MAX1598-22
ENTERING SHUTDOWN
MAX1598-23
2V 0V CBP = 0.01F
VSHDN
2V 0V CBP = 0.01F
VSHDN
2V 0V 5V
V SHDN
2V CBP = 0.1F
VOUT
4V
CBP = 0.1F
VOUT VOUT
1V
2V 0V 0V 5s/div ILOAD = 50mA 500s/div NO LOAD
0V 5s/div ILOAD = 50mA
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5
Low-Noise, Low-Dropout, 200mA Linear Regulator MAX1598
______________________________________________________________Pin Description
PIN 1 2 3 4 5 NAME IN GND SHDN BP OUT FUNCTION Regulator Input. Supply voltage can range from 2.5V to 6.5V. Bypass with a 1F capacitor to GND (see the Capacitor Selection and Regulator Stability section). Ground. This pin also functions as a heatsink. Solder to a large pad or the circuit-board ground plane to maximize power dissipation. Active-Low Shutdown Input. A logic low reduces the supply current to 10nA and causes the output voltage to discharge to GND. Connect to IN for normal operation. Reference-Noise Bypass. Bypass with a low-leakage, 0.01F ceramic capacitor for reduced noise at the output. Regulator Output. Sources up to 200mA. Bypass with a 2.2F (<0.2 typical ESR) capacitor to GND.
Detailed Description
The MAX1598 is a low-noise, low-dropout, low-quiescent-current linear regulator designed primarily for battery-powered applications. The part is available with preset output voltages from 2.5V to 5V in 100mV increments. This device can supply loads up to 200mA. As illustrated in Figure 1, the MAX1598 consists of a 1.25V reference, error amplifier, P-channel pass transistor, and internal feedback voltage-divider. The 1.25V bandgap reference is connected to the error amplifier's inverting input. The error amplifier compares this reference with the feedback voltage and amplifies the difference. If the feedback voltage is lower than the reference voltage, the pass-transistor gate is pulled
lower, which allows more current to pass to the output and increases the output voltage. If the feedback voltage is too high, the pass-transistor gate is pulled up, allowing less current to pass to the output. The output voltage is fed back through an internal resistor voltagedivider connected to the OUT pin. An external bypass capacitor connected to the BP pin reduces noise at the output. Additional blocks include a current limiter, reverse battery protection, thermal sensor, and shutdown logic. The MAX1598 also includes an autodischarge function, which actively discharges the output voltage to ground when the device is placed in shutdown mode.
IN SHDN
REVERSE BATTERY PROTECTION
MAX1598
SHUTDOWN AND POWER-ON CONTROL
ERROR AMP
MOS DRIVER WITH ILIMIT
P
OUT N
THERMAL SENSOR
1.25V REF
GND BP
Figure 1. Functional Diagram 6 _______________________________________________________________________________________
Low-Noise, Low-Dropout, 200mA Linear Regulator
Output Voltage
The MAX1598 is supplied with factory-set output voltages from 2.5V to 5V in 100mV increments. Except for the MAX1598EZK29 and the MAX1598EZK32 (which have an output voltage preset at 2.84V and 3.15V, respectively), the two-digit suffix allows the customer to choose the output voltage in 100mV increments. For example, the MAX1598EZK33 has a preset output voltage of 3.3V (see the Selector Guide). where TJ - TA is the temperature difference between the MAX1598 die junction and the surrounding air, JB (or JC) is the thermal resistance of the package, and BA is the thermal resistance through the PC board, copper traces, and other materials to the surrounding air. The GND pin of the MAX1598 performs the dual functions of providing an electrical connection to ground and channeling heat away. Connect the GND pin to ground using a large pad or ground plane.
MAX1598
Internal P-Channel Pass Transistor
The MAX1598 features a 1.1 typical P-channel MOSFET pass transistor. This provides several advantages over similar designs using PNP pass transistors, including longer battery life. The P-channel MOSFET requires no base drive, which reduces quiescent current considerably. PNP-based regulators waste considerable current in dropout when the pass transistor saturates. They also use high base-drive currents under large loads. The MAX1598 does not suffer these problems and consumes only 100A of quiescent current whether in dropout, lightload, or heavy-load applications (see the Typical Operating Characteristics).
Reverse Battery Protection
The MAX1598 has a unique protection scheme that limits the reverse supply current to 1mA when either VIN or V SHDN falls below ground. Their circuitry monitors the polarity of these two pins and disconnects the internal circuitry and parasitic diodes when the battery is reversed. This feature prevents device damage.
Noise Reduction
An external 0.01F bypass capacitor at BP, in conjunction with an internal 200k resistor, creates an 80Hz lowpass filter for noise reduction. The MAX1598 exhibits 30VRMS of output voltage noise with CBP = 0.01F and COUT = 10F. This is negligible in most applications. Startup time is minimized by a power-on circuit that precharges the bypass capacitor. The Typical Operating Characteristics section shows graphs of Noise vs. BP Capacitance, Noise vs. Load Current, and Output Noise Spectral Density.
Current Limit
The MAX1598 includes a current limiter, which monitors and controls the pass transistor's gate voltage, limiting the output current to 458mA. For design purposes, consider the current limit to be 220mA minimum to 1.1A maximum. The output can be shorted to ground indefinitely without damaging the part.
____________Applications Information
Capacitor Selection and Regulator Stability
Under normal conditions, use a 1F capacitor on the MAX1598 input and a 2.2F to 10F capacitor on the output. Larger input capacitor values and lower ESRs provide better supply-noise rejection and line-transient response. Reduce noise and improve load-transient response, stability, and power-supply rejection by using large output capacitors. For stable operation over the full temperature range and with load currents up to 200mA, a 2.2F (min) ceramic capacitor is recommended. Note that some ceramic dielectrics exhibit large capacitance and ESR variation with temperature. With dielectrics such as Z5U and Y5V, it may be necessary to increase the capacitance by a factor of 2 or more to ensure stability at temperatures below -10C. With X7R or X5R dielectrics, 2.2F should be sufficient at all operating temperatures. A graph of the Region of Stable COUT ESR vs. Load Current is shown in the Typical Operating Characteristics.
Thermal-Overload Protection
Thermal-overload protection limits total power dissipation in the MAX1598. When the junction temperature exceeds TJ = +155C, the thermal sensor signals the shutdown logic, turning off the pass transistor and allowing the IC to cool. The thermal sensor turns the pass transistor on again after the IC's junction temperature cools by 15C, resulting in a pulsed output during continuous thermal-overload conditions. Thermal-overload protection is designed to protect the MAX1598 in the event of fault conditions. For continual operation, do not exceed the absolute maximum junction-temperature rating of TJ = +150C.
Operating Region and Power Dissipation
The MAX1598 maximum power dissipation depends on the thermal resistance of the case and circuit board, the temperature difference between the die junction and ambient air, and the rate of air flow. The power dissipation across the device is P = IOUT (VIN - VOUT). The maximum power dissipation is: PMAX = (TJ - TA) / (JB + BA)
_______________________________________________________________________________________
7
Low-Noise, Low-Dropout, 200mA Linear Regulator MAX1598
Use a 0.01F bypass capacitor at BP for low output voltage noise. Increasing the capacitance slightly decreases output noise but increases startup time. Values above 0.1F provide no performance advantage and are not recommended (see the Shutdown Exit Delay graphs in the Typical Operating Characteristics).
Load-Transient Considerations
The MAX1598 load-transient response graphs (see the Typical Operating Characteristics) show two components of the output response: a DC shift from the output impedance due to the load current change, and the transient response. Typical transient for a step change in the load current from 0 to 50mA is 12mV. Increasing the output capacitor's value and decreasing the ESR attenuates the overshoot.
PSRR and Operation from Sources Other than Batteries
The MAX1598 are designed to deliver low dropout voltages and low quiescent currents in battery-powered systems. Power-supply rejection is 63dB at low frequencies and rolls off above 10kHz. See the PowerSupply Rejection Ratio Frequency graph in the Typical Operating Characteristics. 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 bypass capacitors, and through passive filtering techniques. The Typical Operating Characteristics show the MAX1598's line- and load-transient responses.
Input-Output (Dropout) Voltage
The 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 MAX1598 uses a P-channel MOSFET pass transistor, their dropout voltage is a function of drain-to-source on-resistance (RDS(ON)) multiplied by the load current (see the Typical Operating Characteristics).
_ __________________Chip Information
TRANSISTOR COUNT: 247 SUBSTRATE CONNECTED TO GND
_
OUTPUT VOLTAGE (xy) CODE THIN SOT23 MAX1598EZK25-T MAX1598EZK28-T MAX1598EZK29-T MAX1598EZK30-T MAX1598EZK32-T MAX1598EZK33-T MAX1598EZK36-T MAX1598EZK50-T Other xy**
Selector Guide
PRESET OUTPUT VOLTAGE (V) 2.50 2.80 2.84 3.00 3.15 3.30 3.60 5.00 x.y0 SOT TOP MARK MAX1598 THIN ADRM ADRJ ADRN ADRO ADRP ADRQ ADRR ADRS --
**Other xy between 2.5V and 5V are available in 100mV increments. Contact factory for other versions. Minimum order quantity is 25,000 units.
8
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Low-Noise, Low-Dropout, 200mA Linear Regulator
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.)
THIN SOT23.EPS
MAX1598
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 _____________________ 9 (c) 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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