Datasheet

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.
V
OUT
NC
GND
V
IN
0.1µF
LEAD-ACID
BATTERY
+
6V
CHARGER
INPUT
R1
402kΩ
1%
R2
402kΩ
1%
+
C2
1000µF
ELECT
C1
68µF
TANT
+
5V, 100mA
IRF9530
OP20
2
6 2
7
6
4
3
3
4
0
0163-035
ADR291/
ADR292
R3
510kΩ
Figure 36. Voltage Regulator for Portable Equipment