voltage. Connect a voltmeter or oscilloscope to the TP

pad. Turn R18 clockwise until the voltage at TP goes

voltage goes low. The SUPEVKIT is now set to trip when

the supply voltage decreases to this voltage. To disable

undervoltage reset, open jumper JU4.

Overvoltage Setup

Potentiometer R19 sets the overvoltage reset threshold.

To enable the overvoltage reset feature, install the

jumpers in the positions specified in Table 5. Use a volt-

meter to set the power-supply voltage to the desired trip

voltage. Connect a voltmeter or oscilloscope to the TP

pad. Turn R19 clockwise until the voltage at TP goes

voltage goes low. The SUPEVKIT is now set to trip when

the supply voltage increases to this voltage. To disable

overvoltage reset, move JU2’s shunt to position 2-3.

Note: If the voltage at TP does not pull high after turning

R19 clockwise for 14 turns, turn R18 counterclockwise.

The undervoltage trip point might be set higher than the

supply voltage, holding the SUPEVKIT in reset.

The SUPEVKIT is relatively immune to short-duration

negative-going transients (glitches). If more immunity is

required, install 0.1µF bypass capacitors for C3 and C4.

Supervisory Circuit Evaluation Kit

4

_______________________________________________________________________________________

MINIMUM

TIMEOUT PERIOD (ms)

CUT TRACE

BETWEEN:

1

C1 and C5

20

C5 and C6

140

C6 and C7

1120

No cutting necessary*

JUMPER

STATE

JU2

2-3

JU3

Closed

JU4

Closed

JU5

Closed

Table 2. Selecting the Reset Timeout

Period

Table 4. Undervoltage Setup

Table 5. Overvoltage Setup

JUMPER

STATE

JU2

1-2

JU3

Closed

JU4

Closed

JU5

Closed

*

Default jumper state.

MINIMUM

WATCHDOG

C1 VALUE

JU1 STATE

4.3ms

2200pF ±20%

2-3

71ms

0.039µF ±20%

2-3

1.12sec

1200pF ±20%

1-2

17.9sec

0.018µF ±20%

1-2

Table 3. Capacitance Values for

Common Watchdog Timeout Periods

JUMPER

STATE

FUNCTION

JU1

1-2

(extended mode).

Closed*

2-3*

Watchdog-select connected to GND

(normal mode).

JU2

1-2

Use R19 to set overvoltage threshold.

Open

2-3*

Disable overvoltage comparator.

JU3

Open

Use OVRSTIN pad.

Open

Use watchdog function (insert C2).

JU5

Closed*

Disable watchdog function.

JU4

Open

Use RSTIN1 pad.

Closed*

Use R18 to set undervoltage threshold.

Use RSTIN2 pad.

Disable RSTIN2 undervoltage

comparator.

*

Default jumper state.

Table 6. Jumper Function Table