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MAX1735EUK30+T

P1-P3P4-P6P7-P9P10-P10
MAX1735
200mA, Negative-Output, Low-Dropout
Linear Regulator in SOT23
4 _______________________________________________________________________________________
0.001
0.01
0.1
1
10
100
0 80 10040 6020 120 140 160 180 200
REGION OF STABLE ESR
vs. LOAD CURRENT
MAX1735 toc10
LOAD CURRENT (mA)
REGION OF STABLE ESR C
OUT
(Ω)
C
OUT
= 1
µ
F
REGION OF STABILITY
LINE-TRANSIENT RESPONSE
MAX1735 toc11
TIME (100
µ
s/div)
V
OUT
50mV/div
V
IN
1V/div
LOAD-TRANSIENT RESPONSE
(NORMAL OPERATION)
MAX1735 toc12
TIME (100µs/div)
I
LOAD STEP
0 to 50mA
V
OUT
10mV/div
LOAD-TRANSIENT RESPONSE
(NEAR DROPOUT)
MAX1735 toc13
TIME (100µs/div)
I
LOAD STEP
0 to 50mA
V
OUT
10mV/div
Typical Operating Characteristics (continued)
(Circuit of Figure 2, V
IN
= -4.0V, V
OUT
= -3.0V, T
A
= +25°C, unless otherwise specified.)
0
20
10
40
30
60
50
70
1
100
10
1k 10k
100k
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX1735 toc07
FREQUENCY (Hz)
PSRR (dB)
1M
C
OUT
= 10
µ
F
C
OUT
= 1.0
µ
F
10
0.01
10 1k 100k
OUTPUT NOISE DENSITY
vs. FREQUENCY
MAX1735 toc08
FREQUENCY (Hz)
OUTPUT NOISE (µV
RMS
/√Hz)
0.1
1
OUTPUT NOISE
(10Hz TO 1MHz)
MAX1735 toc09
TIME (1ms/div)
500
µ
V/div
C
OUT
= 1
µ
F
I
LOAD
= 50mA
MAX1735
200mA, Negative-Output, Low-Dropout
Linear Regulator in SOT23
_______________________________________________________________________________________ 5
SHUTDOWN RESPONSE
(DRIVEN FROM A POSITIVE VOLTAGE)
MAX1735 toc14a
TIME (200
µ
s/div)
V
SHDN
2V/div
0
V
OUT
2V/div
0
SHUTDOWN RESPONSE
(DRIVEN BY A NEGATIVE VOLTAGE)
MAX1735 toc14b
TIME (200
µ
s/div)
V
SHDN
2V/div
V
OUT
2V/div
0
0
-0.5
0
0.5
1.0
1.5
2.0
-6.5 -2.0 -0.5-5.0 -3.5 1.0 2.5 4.0 5.5
SHUTDOWN-PIN BIAS CURRENT
vs. SHUTDOWN-PIN VOLTAGE
MAX1735 toc15
SHUTDOWN-PIN VOLTAGE (V)
SHUTDOWN-PIN BIAS CURRENT (µA)
INVALID LOGIC VOLTAGE
INVALID LOGIC VOLTAGE
Pin Description
PIN NAME FUNCTION
1 GND Ground
2IN
Regulator Input. Supply voltage can range from -2.5V to -6.5V. Bypass with a 1µF capacitor to GND
(see Capacitor Selection and Regulator Stability). This pin also functions as a heatsink. Solder to a
large PC board pad or directly to the PC board power plane to maximize thermal dissipation.
3 SHDN
Shutdown Input. Drive SHDN to GND to turn the regulator off, reducing the input current to less than
1nA. Drive SHDN above +1.6V or below -1.6V to enable the regulator. Connect SHDN to IN for
always-on operation.
4 SET
Dual Mode™ Regulator Feedback Input. Connect SET to GND for the preset output voltage. Use a
resistive voltage-divider from OUT to SET to set the output voltage between -1.25V and -5.5V.
Regulation setpoint is -1.25V.
5 OUT
Regulator Output. OUT supplies up to 200mA in regulation. Bypass to GND with a 1µF ceramic
capacitor.
Typical Operating Characteristics (continued)
(Circuit of Figure 2, V
IN
= -4.0V, V
OUT
= -3.0V, T
A
= +25°C, unless otherwise specified.)
Dual Mode is a trademark of Maxim Integrated Products, Inc.
MAX1735
200mA, Negative-Output, Low-Dropout
Linear Regulator in SOT23
Detailed Description
The MAX1735 is a low-dropout negative linear voltage
regulator. It features Dual Mode operation, allowing a
fixed -5.0V, -3.0V, or -2.5V output voltage or an
adjustable output from -1.25V to -5.5V. The regulator is
guaranteed to supply 200mA of output current. It fea-
tures 60dB power-supply rejection for noise-sensitive
applications and a low 85µA operating current that opti-
mizes it for battery-operated devices.
As Figure 1 illustrates, the device consists of an internal
-1.25V reference, an error amplifier, an N-channel
MOSFET, an internal precision-trimmed feedback volt-
age-divider, and a Dual Mode comparator.
The -1.25V reference is connected to the inverting input
of the error amplifier. The error amplifier compares the
reference voltage with the selected feedback voltage
and amplifies the difference. The error amplifier drives
the MOSFET to control the output voltage.
The feedback voltage for regulation is generated by
either an internal or external resistive voltage-divider
connected from OUT to SET. The internal Dual Mode
comparator selects the feedback path based on V
SET
.
Connect SET to GND to use the internal feedback path,
setting the output voltage to the preset value. If an
external voltage-divider is used, see Output Voltage
Selection.
Internal N-Channel MOSFET
The MAX1735 features an N-channel MOSFET pass
transistor. Unlike similar designs using NPN bipolar
pass transistors, N-channel MOSFETs require extreme-
ly low drive currents, reducing overall quiescent cur-
rent. Also, NPN-based regulators consume still more
base current in dropout conditions when the pass tran-
sistor saturates. The MAX1735 does not suffer from
these problems, consuming only 125µA total current at
full load and in dropout.
Output Voltage Selection
The MAX1735 features Dual Mode operation, allowing for
a preset or adjustable output voltage. In preset voltage
mode, the output of the MAX1735 is set to -5.0V, -3.0V, or
-2.5V (see Ordering Information). Select this mode by
connecting SET to GND (Figure 2).
ON
OFF
ON
THERMAL
SENSOR
NMOS
PASS
TRANSISTOR
OUT
C
OUT
R1
R2
SET
GND
Dual Mode
COMPARATOR
ERROR
AMPLIFIER
V
REF
-1.25V
-270mV
SHUTDOWN
LOGIC
SHDN
C
IN
IN
MAX1735
GND
Figure 1. Functional Diagram
6 _______________________________________________________________________________________
P1-P3P4-P6P7-P9P10-P10

MAX1735EUK30+T

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Buy MAX1735EUK30+T
Manufacturer:
Maxim Integrated
Description:
LDO Voltage Regulators 200mA Negative Output
Lifecycle:
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