Data Sheet
5.5 V Input, 300 mA, Low Quiescent
Current, CMOS Linear Regulator
ADP122/ADP123
FEATURES
Input voltage supply range: 2.3 V to 5.5 V
300 mA maximum output current
Fixed and adjustable output voltage versions
Very low dropout voltage: 85 mV at 300 mA load
Low quiescent current: 45 µA at no load
Low shutdown current: <1 µA
Initial accuracy: ±1% accuracy
Up to 31 fixed-output voltage options available from
1.75 V to 3.3 V
Adjustable-output voltage range
0.8 V to 5.0 V (ADP123)
Excellent PSRR performance: 60 dB at 100 kHz
Excellent load/line transient response
Optimized for small 1.0 μF ceramic capacitors
Current limit and thermal overload protection
Logic controlled enable
Compact packages: 5-lead TSOT and 6-lead 2 mm × 2 mm LFCSP
APPLICATIONS
Digital camera and audio devices
Portable and battery-powered equipment
Automatic meter reading (AMR) meters
GPS and location management units
Medical instrumentation
Point-of-sale equipment
GENERAL DESCRIPTION
The ADP122/ADP123 are low quiescent current, low dropout
linear regulators. They are designed to operate from an input
voltage between 2.3 V and 5.5 V and to provide up to 300 mA of
output current. The low 85 mV dropout voltage at a 300 mA load
improves efficiency and allows operation over a wide input
voltage range.
The low 170 μA of quiescent current at full load makes the ADP122
ideal for battery-operated portable equipment.
The ADP122 is capable of 31 fixed output voltages from 1.75 V
to 3.3 V. The ADP123 is the adjustable version of the device and
allows the output voltage to be set between 0.8 V and 5.0 V by
an external voltage divider.
The ADP122/ADP123 are specifically designed for stable operation
with tiny 1 µF ceramic input and output capacitors to meet the
requirements of high performance, space constrained applications.
TYPICAL APPLICATION CIRCUITS
VIN = 2.3V TO 5.5V
CIN
1µF
1 VIN VOUT 5
ADP122
2 GND
VOUT = 1.8V
COUT
1µF
ON
OFF
3 EN
NC 4
Figure 1. ADP122 with Fixed Output Voltage (TSOT Version)
VIN = 2.3V TO 5.5V
CIN
1µF
1 VIN VOUT 5
ADP123
2 GND
VOUT = 0.5V(1 + R1/R2)
COUT
1µF
R1
ON
OFF
3 EN
ADJ 4
R2
Figure 2. ADP123 with Adjustable Output Voltage (TSOT Version)
VOUT = 1.8V 1
C2
1µF
GND 2
VOUT
NC
3
GND
6 VIN = 2.3V TO 5.5V
VIN
C1
1µF
NC 5
GND
4
EN
ON
OFF
GND
ADP122
TOP VIEW
(Not to Scale)
NC = NOT CONNECT. THIS PIN CAN BE LEFT FLOATING
OR CONNECTED TO GROUND.
Figure 3. ADP122 with Fixed Output Voltage (LFCSP Version)
VOUT = 0.5V (1 + R1/R2) 1
C2
1µF
R1
2
GND
R2
3
GND
VOUT
ADJ
GND
6 VIN = 2.3V TO 5.5V
VIN
C1
1µF
NC 5
GND
4
EN
ON
OFF
GND
ADP123
TOP VIEW
(Not to Scale)
NC = NOT CONNECT. THIS PIN CAN BE LEFT FLOATING
OR CONNECTED TO GROUND.
Figure 4. ADP123 with Adjustable Output Voltage (LFCSP Version)
The ADP122/ADP123 have an internal soft start that gives a
constant start-up time of 350 µs. Short-circuit protection and
thermal overload protection circuits prevent damage in adverse
conditions. The ADP122/ADP123 are available in a tiny, 5-lead
TSOT package and 6-lead LFCSP package for the smallest
footprint solution to meet a variety of portable applications.
Rev. E
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