REV. A

–4–

ADM706P/R/S/T, ADM708R/S/T

PIN FUNCTION DESCRIPTIONS

Pin No.

Pin No.

Mnemonic

ADM706

ADM708

Function

MR

1

1

Manual Reset Input. When taken below 0.6 V a RESET is generated.

MR can be

driven from TTL, CMOS logic or from a manual reset switch as it is internally

debounced. An internal 70

µA pull-up current holds the input high when floating.

2

2

Power Supply Input.

GND

3

3

0 V. Ground reference for all signals.

PFI

4

4

Power Fail Input. PFI is the noninverting input to the Power Fail Comparator.

When PFI is less than 1.25 V, PFO goes low. If unused, PFI should be connected

to GND.

PFO

5

5

Power Fail Output.

PFO is the output from the Power Fail Comparator. It goes

low when PFI is less than 1.25 V.

WDI

6

N/A

Watchdog Input. WDI is a three level input. If WDI remains either high or low

for longer than the watchdog timeout period, the watchdog output

WDO goes

low. The timer resets with each transition at the WDI input. Either a high-to-low

or a low-to-high transition will clear the counter. The internal timer is also

cleared whenever reset is asserted. The Watchdog Timer is disabled when WDI is

left floating or connected to a three-state buffer.

NC

N/A

6

No Connect.

RESET

7 (R/S/T Only)

7

Logic Output.

RESET goes low for 200 ms when triggered. It can be triggered

reset (

MR) input. RESET will remain low whenever V

MR goes from low to high. A watchdog timeout will not trigger RESET unless

WDO is connected to MR.

RESET

7 (P Only)

8

Logic Output. RESET is an active high output suitable for systems which use

active high RESET logic. It is the inverse of

RESET.

WDO

8

N/A

Logic Output. The Watchdog Output,

WDO, goes low if the internal watchdog

timer times out as a result of inactivity on the WDI input. It remains low until

the watchdog timer is cleared.

WDO also goes low during low line conditions.

goes above the reset threshold,

WDO goes high immediately.

PIN CONFIGURATIONS

MR

GND

PFI

WDO

RESET

WDI

PFO

1

2

3

4

8

7

6

5

TOP VIEW

(Not to Scale)

ADM706

P

MR

GND

PFI

NC = NO CONNECT

RESET

RESET

NC

PFO

1

2

3

4

8

7

6

5

TOP VIEW

(Not to Scale)

ADM708

R/S/T

MR

GND

PFI

WDO

RESET

WDI

PFO

1

2

3

4

8

7

6

5

TOP VIEW

(Not to Scale)

ADM706

R/S/T