AS1320 查看數據表（PDF） - austriamicrosystems AG

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AS1320

200mA Step-Up DC-DC Converter

austriamicrosystems AG 

AS1320

Data Sheet - Detailed Description

Low-Battery Cutoff

The AS1320 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 16).

Figure 16. Low-Battery Cutoff Application Diagram

+1.5 to +3.5V

Battery

CIN

22µF

R1

220kΩ

R2

1MΩ

2

BATT

4

L1

LX

10µH

10nF

1

SHDNN

AS1320

5

OUT

R3

100kΩ

6

RESETN

3

GND

COUT

22µF

+3.3V

Output

Power-On

Reset

For the resistor-divider network shown in Figure 16, calculate the value for R1 by:

R1 = R2 x ((VOFF/VSHDNN) - 1)

Where:

VOFF is the battery voltage at which the AS1320 shuts down.

VSHDNN = 1.228V

The value of R2 should be between 100kΩ and 1MΩ to minimize battery drain.

(EQ 1)

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 AS1320 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 100kΩ 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.

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Revision 1.03

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