Date: 4/18/05

SP691A/693A/800L/800M Low Power Microprocessor Supervisor with Battery Switch-Over © Copyright 2005 Sipex Corporation

14

Chip-Enable Output

In the enabled mode, the impedance of CE

OUT

is equivalent to 65

Ω in series with the source

driving CE

transmission gate is off and CE

transmission gate is enabled.

LOWLINE Output

LOWLINE is the buffered output pin of the

reset threshold comparator. Refer to Figure 16.

LOWLINE typically sinks 3.2mA at 0.1V. For

normal operation where V

threshold, LOWLINE is pulled to V

Power-Fail Comparator

The power-fail comparator is an uncommitted

comparator that has no effect on the other

functions of the SP691A/693A/800L/800M

devices. Common uses include low battery

detection, as found in Figure 23, and early

power-fail detection when the unregulated power

is easily accessible as shown in Figure 17.

Power-Fail Input

The Power-Fail Input (PFI) has a guaranteed

input leakage of +25nA max over temperature.

The typical comparator delay is 25

input to ground if PFI is not used.

Power-Fail Output

The Power-Fail Output (PFO) goes low when

PFI goes below 1.25V. It sinks 3.2mA with a

saturation voltage of 0.1V. With PFI above

can be used to generate an NMI for the

µP, as

shown in Figure 17.

Battery-Backup Mode

The SP691A/693A/800L/800M requires two

conditions to switch to battery-backup mode:

status of the inputs and outputs in battery-

backup mode.

Battery-On Output

The Battery On Output (BATT ON) indicates

(ignoring the small hysteresis effect), BATT ON

is a logic low. For V

ON is a logic high. Use BATT ON to indicate

battery-switchover status or to supply base drive

to an external pass transistor for higher-current

applications. Refer to Figure 17.

12

2.8V

GND

1

13

4

PFO

+2.0V

to

+5.5V

+5V

GND

LOW BATT

PFI

Figure 22. Chip Enable Propagation Delay Test Circuit

Figure 23. Low-Battery Indicator Circuit