4

FN8092.5

January 12, 2009

Pin Descriptions

ISL88705,

ISL88706

ISL88716,

ISL88813

ISL88707,

ISL88708

NAME

DESCRIPTION

111

MR

Manual Reset Input. A reset signal is generated when this input is pulled low. The MR input is an

active low debounced input to which a user can connect a push-button to add manual reset capability

or drive with a signal. The MR pin has an internal 20k

Ω pull-up.

222

Power Supply Terminal. The voltage at this pin is compared against an internal factory-programmed

The device is designed with hysteresis to help prevent chattering due to noise and is immune to brief

333

GND

Ground Connection

444

PFI

Power-Fail Input This is an auxiliary monitored voltage input with a 1.25V threshold that causes PFO

state to follow the PFI input state.

555

PFO

Power-Fail Output. This output goes high if the voltage on PFI is greater than 1.25V, otherwise PFO

stays low.

66

WDI

Watchdog Input. The Watchdog Input takes an input from a microprocessor and ensures that it

periodically toggles the WDI pin, otherwise the internal nominal 1.6s watchdog timer runs out, then

reset is asserted and WDO is pulled low. The internal Watchdog Timer is cleared whenever the WDI

sees a rising or falling edge or the device is manually reset. Floating WDI or connecting WDI to a

high-impedance three-state buffer disables the watchdog feature.

77

RST

Active-Low Reset Output. The RST output is an active low output with an internal PMOS pull-up

that is pulled low to GND when reset is asserted. Reset is asserted whenever:

1. The device is first powered up

3. MR is asserted.

threshold or MR input goes from low to high. A watchdog time-out will not trigger a reset unless WDO

is connected to MR.

78

RST

Active-High Reset Output. The RST pin functions identically to its complementary RST output but

Descriptions” on page 4 for more details on conditions that cause a reset.

88

WDO

Watchdog Output. This output is pulled low when the nominal 1.6s internal Watchdog Timer expires

with no delay.

ISL88705, ISL88706, ISL88707, ISL88708, ISL88716, ISL88813