ASM690AESA datasheet(2/15 Pages) PULSECORE

2 / 15 page

ASM690A/692A

ASM802L/802M

April 2008

ASM805L

rev 1.7

µP Power Supply Supervisor With Battery Backup Switch

2 of 15

Notice: The information in this document is subject to change without notice.

Pin Configuration

Pin Description

Pin Number

ASM690A/

ASM692A

ASM802L/

ASM802M

ASM805L

Name

Function

VOUT

Voltage supply for RAM. When VCC is above the reset threshold, VOUT

connects to VCC through a P-Channel MOS device. If VCC falls below the

reset threshold, this output will be connected to the backup supply at VBATT

(or VCC, whichever is higher) through the MOS switch to provide continuous

power to the CMOS RAM.

VCC

+5V power supply input.

GND

Ground

PFI

Power failure monitor input. PFI is connected to the internal power fail

comparator which is referenced to 1.25V. The power fail output (PFO) is

active LOW but remains HIGH if PFI is above 1.25V. If this feature is

unused, the PFI pin should be connected to GND or VOUT.

PFO

Power-fail output. PFO is active LOW whenever the PFI pin is less than

1.25V.

WDI

Watchdog input. The WDI input monitors microprocessor activity. An internal

timer is reset with each transition of the WDI input. If the WDI is held HIGH

or LOW for longer than the watchdog timeout period, typically 1.6 seconds,

RESET (or RESET) is asserted for the reset pulse width time, tRS, of

140ms, minimum.

RESET

Active-LOW reset output. When triggered by VCC falling below the reset

threshold or by watchdog timer timeout, RESET pulses low for the reset

pulse width tRS, typically 200ms. It will remain low if VCC is below the reset

threshold (4.65V in ASM690A / ASM802L and 4.4V in the ASM692A /

ASM802L) and remains low for 200ms after VCC rises above the reset

threshold.

RESET

Active-HIGH reset output. The inverse of RESET.

VBATT

Auxiliary power or backup-battery input. VBATT should be connected to GND

if the function is not used. The input has about 40mV of hysteresis to

prevent rapid toggling between VCC and VBATT.

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