ADR291 datasheet(15/20 Pages) AD

15 / 20 page

ADR291/ADR292

Rev. F | Page 15 of 20

VOLTAGE REGULATOR FOR PORTABLE

EQUIPMENT

The ADR291/ADR292 family of references is ideal for provid-

ing a stable, low cost, and low power reference voltage in

portable equipment power supplies. Figure 36 shows how the

ADR291 and ADR292 can be used in a voltage regulator that

not only has low output noise (as compared to switch mode

design) and low power, but also a very fast recovery after

current surges. Some precautions should be taken in the

selection of the output capacitors. Too high an ESR (effective

series resistance) could endanger the stability of the circuit. A

solid tantalum capacitor, 16 V or higher, and an aluminum

electrolytic capacitor, 10 V or higher, are recommended for C1

and C2, respectively. Also, the path from the ground side of C1

and C2 to the ground side of R1 should be kept as short as

possible.

VOUT

GND

VIN

0.1µF

LEAD-ACID

BATTERY

CHARGER

INPUT

402kΩ

+ C2

1000µF

ELECT

68µF

TANT

5V, 100mA

IRF9530

OP20

ADR291/

ADR292

510kΩ

Figure 36. Voltage Regulator for Portable Equipment

ADR291 Datasheet(PDF) 15 Page - Analog Devices