ADM1232AARW View Datasheet(PDF) - Analog Devices

Part Name

Description

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ADM1232AARW

Microprocessor Supervisory Circuit

Analog Devices 

ADM1232A

CIRCUIT INFORMATION

PB RESET

The PB RESET input makes it possible to manually reset a system

using either a standard push-button switch or a logic low

input. An internal debounce circuit provides glitch immunity

when used with a switch, reducing the effects of glitches on the

line. The debounce circuit is guaranteed to cause the ADM1232A

to assert a reset if PB RESET is brought low for more than 20 ms

and is guaranteed to ignore low inputs of less than 1 ms.

VCC

VCC

TD

ADM1232A

ADM1232

PB RESET

STREOSBEET

GND

SRTERSOEBTE

TTOOLLEERRAANNCCEE

MICROPROCESSOR

I/O

RESET

Figure 2. Typical Push Button Reset Application

PB RESET

RESET

PB RESET TIME

PB RESET

DELAY

VIL

VIH

RESET ACTIVE

TIME

RESET

Figure 3. PB RESET

STROBE Timeout Selection

TD or time delay set is used to set the Strobe Timeout Period.

The Strobe Timeout Period is defined as being the maximum

time between high-to-low transitions (Figure 4) that STROBE

will accept before a reset will be asserted. The Strobe timeout

settings are listed in Table I.

Condition

TD = 0 V

TD = Floating

TD = VCC

Table I.

Min

Typ

62.5

150

250

600

500

1200

Max

250

1000

2000

Units

ms

ms

ms

STROBE

PULSEWIDTH

STROBE

STROBE TIMEOUT PERIOD

Figure 4. STROBE Parameters

+5V

VCC

RESET OUTPUT DELAY

WHEN IS VCCFALLING

RESET

+4.5V (5% TRIP POINT)

+4.25V (10% TRIP POINT)

+5V

RESET OUTPUT DELAY

WHEN IS VCC RISING

RESET

Figure 5. Reset Output Delay

TOLERANCE

The TOLERANCE input is used to determine the level VCC can

vary below 5 V without the ADM1232A asserting a reset. Con-

necting TOLERANCE to ground will select a –5% tolerance

level and will cause the ADM1232A to generate a reset if VCC

falls below 4.75 V (typical). If TOLERANCE is connected to

VCC a –10% tolerance level is selected and will cause the

ADM1232A to generate a reset if VCC falls below 4.5 V (typical).

Check the parameters for the VCC trip point in the ADM1232A

Specifications for more information.

RESET AND RESET OUTPUTS

While RESET is capable of sourcing and sinking current,

RESET is an open drain MOSFET which sinks current only.

Therefore, it is necessary to pull this output high.

REV. 0

–5–

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