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 30µVRMS, 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 100µA 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.
Applications
Cellular, Cordless, and PCS Phones
PCMCIA Cards
Modems
Hand-Held Instruments
Palmtop Computers
Electronic Planners
Features
♦200mA Output Current
♦Low Output Noise: 30µVRMS
♦Low 55mV Dropout at 50mA Output
♦Low 85µA No-Load Supply Current
♦Low 100µA Operating Supply Current,
Even in Dropout
♦Thermal-Overload and Short-Circuit Protection
♦Reverse Battery Protection
♦Output Current Limit
♦Preset Output Voltages
♦10nA Logic-Controlled Shutdown
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX1598
Low-Noise, Low-Dropout, 200mA
Linear Regulator
________________________________________________________________ Maxim Integrated Products 1
GND
BP
SHDN
15OUT
IN
MAX1598
THIN SOT23-5
TOP VIEW
2
34
Pin Configuration
MAX1598
INPUT
2.5V TO 6.5V
IN OUT
SHDN
BP GND
OUTPUT
PRESET
2.5V TO 5V
200mA
CBP
0.01µF
COUT
2.2µF
CIN
1µF
OFF
ON
Typical Operating Circuit
19-2584; Rev 0; 10/02
Ordering Information
*xy is the output voltage code (see the Selector Guide at end of
data sheet).
PART TEMP RANGE PIN-PACKAGE
MAX1598EZKxy-T* -40°C to +85°C Thin SOT23-5
MAX1598
Low-Noise, Low-Dropout, 200mA
Linear Regulator
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN = (VOUT(NOMINAL) + 0.5V) or 2.5V (whichever is greater), TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA=
+25°C.) (Note 1)
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.
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= +70°C)
5-Pin Thin SOT23 (derate 9.1mW/°C above +70°C)....727mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
θJB (thin).........................................................................110°C/W
Storage Temperature.........................................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Voltage VIN 2.5 6.5 V
IOUT = 0.1mA, TA = +25°C, VOUT ≥ 2.5V -1.4 +1.4
Output Voltage Accuracy IOU T = 0.1m A to 120m A, TA = - 40° C to + 85°C ,
VOUT ≥ 2.5V -3 +2 %
Maximum Output Current 200 mA
Current Limit ILIM 220 458 mA
No load 85 180
Ground-Pin Current IQIOUT = 150mA 100 µA
IOUT = 1mA 1.1
IOUT = 50mA 55 120
Dropout Voltage (Note 2)
IOUT = 200mA 236
mV
Line Regulation ∆VLNR VIN = 2.5V or (VOUT + 0.1V) to 6.5V,
IOUT = 1mA -0.15 0 +0.15 %/V
Load Regulation ∆VLDR IOUT = 0.1mA to 120mA, COUT = 1µF 0.01 0.04 %/mA
COUT = 10µF 30
Output Voltage Noise enf = 10Hz to 100kHz,
CBP = 0.01µF COUT = 100µF 20 µVRMS
SHUTDOWN
VIH VIN = 2.5V to 5.5V 2.0
SHDN Input Threshold VIL VIN = 2.5V to 5.5V 0.4 V
TA = +25°C 0.01 1
SHDN Input Bias Current I SHDN V SHDN = VIN TA = +85°C 0.5 µA
TA = +25°C 0.01 1
Shutdown Supply Current IQ
(
SHDN
)
VOUT = 0V TA = +85°C 0.2 µA
TA = +25°C 30 150
Shutdown Exit Delay
CBP = 0.1µF
COUT = 1µF, no load
(Note 3) TA = -40°C to +85°C 300
µs
Resistance Shutdown Discharge 300 Ω
MAX1598
Low-Noise, Low-Dropout, 200mA
Linear Regulator
_______________________________________________________________________________________ 3
2.40
2.45
2.50
2.55
2.60
0 50 100 150
OUTPUT VOLTAGE vs. LOAD CURRENT
(MAX1598EZK25)
MAX1598-01
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
200
4.8
4.9
5.0
5.1
5.2
0 50 100 150
OUTPUT VOLTAGE vs. LOAD CURRENT
(MAX1598EZK50)
MAX1598-02
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
200
60
65
70
75
80
85
90
95
100
105
110
050
100 150
GROUND-PIN CURRENT
vs. LOAD CURRENT
MAX1598-03
LOAD CURRENT (mA)
GROUND-PIN CURRENT (µA)
MAX1598EZK25
MAX1598EZK50
200
0
40
20
80
60
100
120
0231 456
GROUND-PIN CURRENT vs. INPUT VOLTAGE
(MAX1598EZK25)
MAX1598-04
INPUT VOLTAGE (V)
GROUND-PIN CURRENT (µA)
NO LOAD
ILOAD = 50mA
0
40
20
80
60
100
120
0231 456
GROUND-PIN CURRENT vs. INPUT VOLTAGE
(MAX1598EZK50)
MAX1598-05
INPUT VOLTAGE (V)
GROUND-PIN CURRENT (µA)
NO LOAD
ILOAD = 50mA
0
2
1
4
3
5
6
0231 456
OUTPUT VOLTAGE vs. INPUT VOLTAGE
MAX1598-06
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
MAX1598EZK25
NO LOAD
MAX1598EZK50
__________________________________________Typical Operating Characteristics
(VIN = (VOUT(NOMINAL) + 0.5V) or 2.5V (whichever is greater), CIN = 1µF, COUT = 2.2µF, CBP = 0.01µF, TA= +25°C, unless other-
wise noted.)
Note 1: Limits are 100% production tested at TA= +25°C. 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.
ELECTRICAL CHARACTERISTICS (continued)
(VIN = (VOUT(NOMINAL) + 0.5V) or 2.5V (whichever is greater), TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA=
+25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
THERMAL PROTECTION
Thermal-Shutdown Temperature TSHDN 155 °C
Thermal-Shutdown Hysteresis ∆TSHDN 15 °C
MAX1598
Low-Noise, Low-Dropout, 200mA
Linear Regulator
4 _______________________________________________________________________________________
0
50
200
150
250
300
0 40 60 120 160 200
DROPOUT VOLTAGE vs. LOAD CURRENT
(MAX1598EZK25)
MAX1598-10
LOAD CURRENT (mA)
DROPOUT VOLTAGE (mV)
TA = +85°C
TA = +25°C
TA = -40°C
100
0
50
200
250
300
0 40 80 120 160 200
DROPOUT VOLTAGE vs. LOAD CURRENT
(MAX1598EZK50)
MAX1598-11
LOAD CURRENT (mA)
DROPOUT VOLTAGE (mV)
TA = +85°C
TA = +25°C
TA = -40°C
100
150
70
0
10
20
30
40
50
60
0.01 0.1 1 10 100 1000
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX1598-12
FREQUENCY (kHz)
PSRR (dB)
ILOAD = 50mA
CBP = 0.1µF
COUT = 10µF
COUT = 1µF
10
0.01
0101 1000
OUTPUT NOISE SPECTRAL DENSITY
vs. FREQUENCY
0.1
1
MAX1598-13
FREQUENCY (kHz)
OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz)
100
CBP = 0.01µF
ILOAD = 10mA
COUT = 10µF
COUT = 1µF
80
0
10
20
30
40
50
60
70
0.001 0.01 0.1
OUTPUT NOISE vs. BP CAPACITANCE
MAX1598-14
BP CAPACITANCE (µF)
OUTPUT NOISE (µVRMS)
MAX1598EZK50
COUT = 10µF
ILOAD = 10mA
f = 10Hz to 100kHz
MAX1598EZK30
MAX1598EZK25
0
20
10
40
30
50
60
1 10 100 1000
OUTPUT NOISE vs. LOAD CURRENT
MAX1598-15
LOAD CURRENT (mA)
OUTPUT NOISE (µVRMS)
MAX1598EZK50
COUT = 10µF
CBP = 0.01µF
f = 10Hz to 100kHz
MAX1598EZK30
MAX1598EZK25
2.40
2.45
2.50
2.55
2.60
-40 40200-20 60 80 100
OUTPUT VOLTAGE vs. TEMPERATURE
(MAX1598EZK25)
MAX1598-07
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
ILOAD = 50mA
4.8
4.9
5.0
5.1
5.2
-40 40200-20 60 80 100
OUTPUT VOLTAGE vs. TEMPERATURE
(MAX1598EZK50)
MAX1598-08
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
ILOAD = 50mA
0
60
40
20
100
80
180
160
140
120
200
-40 -20 0 20 40 60 80 100
GROUND-PIN CURRENT
vs. TEMPERATURE
MAX1598-09
TEMPERATURE (°C)
GROUND-PIN CURRENT (µA)
MAX1598EZK50
MAX1598EZK25
ILOAD = 50mA
Typical Operating Characteristics (continued)
(VIN = (VOUT(NOMINAL) + 0.5V) or 2.5V (whichever is greater), CIN = 1µF, COUT = 2.2µF, CBP = 0.01µF, TA= +25°C, unless other-
wise noted.)
MAX1598
Low-Noise, Low-Dropout, 200mA
Linear Regulator
_______________________________________________________________________________________ 5
3.00V
2.99V
3.01V
VOUT
ILOAD
50mA
10µs/div
LOAD-TRANSIENT RESPONSE
MAX1598-19
MAX1598EZK30, VIN = VOUT + 0.5V,
CIN = 10µF, ILOAD = 0 TO 50mA
3.00V
2.99V
3.01V
VOUT
ILOAD
50mA
10µs/div
LOAD-TRANSIENT RESPONSE
NEAR DROPOUT
MAX1598-20
MAX1598EZK30, VIN = VOUT + 0.1V,
CIN = 10µF, ILOAD = 0 TO 50mA
1V
0V
0V
2V
2V
5µs/div
ILOAD = 50mA
MAX1598EZK25
SHUTDOWN EXIT DELAY
MAX1598-21
VSHDN
VOUT
CBP = 0.01µF
CBP = 0.1µF
0V
0V
4V
2V
2V
5µs/div
ILOAD = 50mA
MAX1598EZK50
SHUTDOWN EXIT DELAY
MAX1598-22
VSHDN
VOUT
CBP = 0.01µF
CBP = 0.1µF
0V
0V
5V
2V
VSHDN
VOUT
500µs/div
NO LOAD
ENTERING SHUTDOWN
MAX1598-23
1ms/div
MAX1598EZK25, COUT = 10µF, ILOAD = 10mA, CBP = 0.1µF
OUTPUT NOISE 10Hz TO 100kHz
VOUT
50µV/div
MAX1598-16
100
0.01
0 10050 150 200
REGION OF STABLE COUT ESR
vs. LOAD CURRENT
0.1
MAX1598-17
LOAD CURRENT (mA)
COUT ESR (Ω)
1
10
STABLE REGION
COUT = 2.2µF
COUT = 10µF
3.000V
2.999V
3.001V
3V
4V VIN
VOUT
100µs/div
LINE-TRANSIENT RESPONSE
MAX1598-18
MAX1598EZK30, ILOAD = 50mA
Typical Operating Characteristics (continued)
(VIN = (VOUT(NOMINAL) + 0.5V) or 2.5V (whichever is greater), CIN = 1µF, COUT = 2.2µF, CBP = 0.01µF, TA= +25°C, unless other-
wise noted.)
MAX1598
Detailed Description
The MAX1598 is a low-noise, low-dropout, low-quies-
cent-current linear regulator designed primarily for bat-
tery-powered applications. The part is available with
preset output voltages from 2.5V to 5V in 100mV incre-
ments. 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 volt-
age 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 voltage-
divider 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 sen-
sor, 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.
Low-Noise, Low-Dropout, 200mA
Linear Regulator
6 _______________________________________________________________________________________
SHUTDOWN
AND
POWER-ON
CONTROL
ERROR
AMP
1.25V
REF
P
N
OUT
BP
GND
IN
SHDN
MAX1598
MOS DRIVER
WITH ILIMIT
THERMAL
SENSOR
REVERSE
BATTERY
PROTECTION
Figure 1. Functional Diagram
______________________________________________________________Pin Description
PIN NAME FUNCTION
1IN
Regulator Input. Supply voltage can range from 2.5V to 6.5V. Bypass with a 1µF capacitor to GND
(see the Capacitor Selection and Regulator Stability section).
2 GND Ground. This pin also functions as a heatsink. Solder to a large pad or the circuit-board ground
plane to maximize power dissipation.
3SHDN 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.
4BP
Reference-Noise Bypass. Bypass with a low-leakage, 0.01µF ceramic capacitor for reduced noise at
the output.
5 OUT Regulator Output. Sources up to 200mA. Bypass with a 2.2µF (<0.2Ω typical ESR) capacitor to GND.
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 out-
put voltage in 100mV increments. For example, the
MAX1598EZK33 has a preset output voltage of 3.3V (see
the Selector Guide).
Internal P-Channel Pass Transistor
The MAX1598 features a 1.1Ωtypical 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 consider-
ably. 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 100µA of quiescent current whether in dropout, light-
load, or heavy-load applications (see the Typical
Operating Characteristics).
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.
Thermal-Overload Protection
Thermal-overload protection limits total power dissipa-
tion in the MAX1598. When the junction temperature
exceeds TJ= +155°C, 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 tempera-
ture cools by 15°C, 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 junc-
tion-temperature rating of TJ= +150°C.
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) / (θJB + θBA)
where TJ- TAis the temperature difference between the
MAX1598 die junction and the surrounding air, θJB (or
θJC) is the thermal resistance of the package, and θBA
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 func-
tions of providing an electrical connection to ground
and channeling heat away. Connect the GND pin to
ground using a large pad or ground plane.
Reverse Battery Protection
The MAX1598 has a unique protection scheme that limits
the reverse supply current to 1mA when either VIN or
VSHDN 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 0.01µF bypass capacitor at BP, in conjunc-
tion with an internal 200kΩresistor, creates an 80Hz
lowpass filter for noise reduction. The MAX1598 exhibits
30µVRMS of output voltage noise with CBP = 0.01µF and
COUT = 10µF. This is negligible in most applications.
Startup time is minimized by a power-on circuit that pre-
charges the bypass capacitor. The Typical Operating
Characteristics section shows graphs of Noise vs. BP
Capacitance, Noise vs. Load Current, and Output Noise
Spectral Density.
____________Applications Information
Capacitor Selection and
Regulator Stability
Under normal conditions, use a 1µF capacitor on the
MAX1598 input and a 2.2µF to 10µF capacitor on the out-
put. Larger input capacitor values and lower ESRs pro-
vide 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
2.2µF (min) ceramic capacitor is recommended.
Note that some ceramic dielectrics exhibit large capaci-
tance 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 -10°C. With X7R or
X5R dielectrics, 2.2µF 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.
MAX1598
Low-Noise, Low-Dropout, 200mA
Linear Regulator
_______________________________________________________________________________________ 7
MAX1598
Low-Noise, Low-Dropout, 200mA
Linear Regulator
8 _______________________________________________________________________________________
Use a 0.01µF bypass capacitor at BP for low output volt-
age noise. Increasing the capacitance slightly decreases
output noise but increases startup time. Values above
0.1µF provide no performance advantage and are not rec-
ommended (see the Shutdown Exit Delay graphs in the
Typical Operating Characteristics).
PSRR and Operation from Sources
Other than Batteries
The MAX1598 are designed to deliver low dropout volt-
ages and low quiescent currents in battery-powered
systems. Power-supply rejection is 63dB at low fre-
quencies and rolls off above 10kHz. See the Power-
Supply 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 fil-
tering techniques. The Typical Operating Charac-
teristics show the MAX1598’s line- and load-transient
responses.
Load-Transient Considerations
The MAX1598 load-transient response graphs (see the
Typical Operating Characteristics) show two compo-
nents 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.
Input-Output (Dropout) Voltage
The regulator’s minimum input-output voltage differen-
tial (or dropout voltage) determines the lowest usable
supply voltage. In battery-powered systems, this deter-
mines the useful end-of-life battery voltage. Because
the MAX1598 uses a P-channel MOSFET pass transis-
tor, their dropout voltage is a function of drain-to-source
on-resistance (RDS(ON)) multiplied by the load current
(see the Typical Operating Characteristics).
_Selector Guide
___________________Chip Information
**Other xy between 2.5V and 5V are available in 100mV increments.
Contact factory for other versions. Minimum order quantity is 25,000
units.
TRANSISTOR COUNT: 247
SUBSTRATE CONNECTED TO GND
OUTPUT VOLTAGE
(xy) CODE
SOT TOP
MARK
THIN SOT23
PRESET OUTPUT
VOLTAGE (V) MAX1598
THIN
MAX1598EZK25-T 2.50 ADRM
MAX1598EZK28-T 2.80 ADRJ
MAX1598EZK29-T 2.84 ADRN
MAX1598EZK30-T 3.00 ADRO
MAX1598EZK32-T 3.15 ADRP
MAX1598EZK33-T 3.30 ADRQ
MAX1598EZK36-T 3.60 ADRR
MAX1598EZK50-T 5.00 ADRS
Other xy** x.y0 —
Low-Noise, Low-Dropout, 200mA
Linear Regulator
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
© 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
THIN SOT23.EPS
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.)
