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AS1321

Datasheet - D e t a i l e d D e s c r i p t i o n

Low-Battery Cutoff

The AS1321 SHDNN trip threshold (1.228V) can be used as an input voltage detector that disables the device when

the battery input voltage falls to a pre-set level. An external resistor-divider network can be used to set the battery-

detection voltage (see Figure 18).

Figure 18. Low-Battery Cutoff Application Diagram

(EQ 1)

Where:

Ω and 1MΩ to minimize battery drain.

Note: Input ripple can cause false shutdowns, therefore to minimize the effect of ripple, a low-value capacitor from

SHDNN to GND should be used to filter out input noise. The value of the capacitor should be such that the R/C

time constant is > 2ms.

Power-On Reset

The AS1321 provides a power-on reset output (RESETN) that goes high-impedance when the output reaches 90% of

its regulation point. RESETN goes low when the output is below 90% of the regulation point. A 100k

Ω to 1MΩ pullup

resistor between pin RESETN and pin OUT can provide a microprocessor logic control signal.

Note: Connect pin RESETN to GND when the power-on reset feature is not used.

+1.5 to +5.0V

Battery

+5.0V

Output

22µF

22µF

L1

10µH

Power-On

Reset

100k

Ω

10nF

220k

Ω

1M

Ω

AS1321

4

LX

3

GND

2

BATT

6

RESETN

1

SHDNN

5

OUT