ILC1832 데이터 시트보기 (PDF) - Impala Linear Corporation

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ILC1832

µP Supervisory Circuit

Impala Linear Corporation 

µP Supervisory Circuit

Preliminary

Pin Functions

Pin

Number

1

2

3

4

5

6

7

8

Pin

Name

PBRST

TD

TOL

GND

RST

RST

ST

VCC

Description

Pushbutton reset input. This input is debounced and can be driven with external logic

signals or a mechanical pushbutton to actively force a reset. All pulses less than 1ms in

duration on the PBRST pin are ignored. Any pulse with a duration of 20ms or greater is

guaranteed to cause a reset. PBRST has an internal 40kΩ (typical) pull-up resistor to VCC.

Time delay input. This input selects the timebase used by the watchdog timer. When TD =

0V, the watchdog timeout period is set to a nominal value of 150ms, when TD = open, the

watchdog timeout period is set to a nominal value of 600ms and when TD = VCC, the

watchdog timeout period is 1.2 sec nominally.

Tolerance select input. Selects whether 5% or 10% of VCC is used as the reset threshold

voltage. When TOL = 0V, the 5% tolerance level is selected and when TOL = VCC, a 10%

tolerance level is selected.

Ground pin, 0V reference.

RST is asserted high if either VCC goes below the reset threshold, the watchdog times out or

PBRST is pulled low for a minimum of 20ms. RST remains asserted for one reset timeout

period after VCC exceeds the reset threshold or after the watchdog times out or after PBRST

goes high.

RST is asserted low if either VCC goes below the reset threshold, the watchdog times out or

PBRST is pulled low for a minimum of 20ms. RST remains asserted for one reset timeout

period after VCC exceeds the reset threshold or after the watchdog times out or after PBRST

goes high. Open-drain output.

Input to the watchdog timer. If ST does not see a transition from high to low within the

watchdog timeout period, RST and RST will be asserted.

Power supply input.

Block Diagram

VCC 8

Trip Point

Select

+

-

TOL 3

Ref

PBRST 1

Manual Reset

Debounce

ST 7

TD 2

Timeout

Select

Reset

Generator

Watchdog

Timer

6 RST

5 RST

4 GND

Impala Linear Corporation

ILC1832 1.1

(408) 574-3939 www.impalalinear.com

October 1999 3

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