Supervisory Circuit Evaluation Kit

2

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Quick Start

Before you begin, you will need the following equip-

ment:

flat-blade screwdriver)

Table 1 lists the features that can be emulated by the

SUPEVKIT. Refer to the corresponding device’s data

sheet to look up the specifications for these features.

To configure the supervisory circuit, take the following

steps:

1) Install jumpers JU2–JU5 in the positions listed in

Table 1.

Example: For the MAX6320PUK33BX-T, the jumper

settings are JU2 = 2-3, JU3 = open, JU4 = closed,

and JU5 = closed.

2) Set the reset timeout period, referring to Table 2 to

determine which trace (if any) needs to be cut.

Example: For the MAX6320PUK33BX-T, the reset

timeout period is 20ms, so it is necessary to cut the

trace between C5 and C6.

3) If the selected supervisory circuit has a watchdog

timeout feature, consult Table 3 to determine which

capacitor value to use for C2 and which position to

use for jumper JU1.

Example: For the MAX6320PUK33BX-T, the watch-

dog timeout period is 71ms. Use a value of 0.039µF

for capacitor C2. Jumper JU1 should be in the 2-3

position.

4) Turn on the power supply and connect it to the volt-

meter. Set the power-supply voltage to the desired

reset threshold voltage. The accuracy of the trip

threshold is determined by the accuracy of the volt-

meter.

Example: For the MAX6320PUK33BX-T, set the

power supply to 3.30V.

5) Connect the power supply to the SUPEVKIT at the

ates from +1V to +5.5V. The supply voltage must

not exceed +5.5V.

6) Connect the voltmeter to the pads labeled TP and

GND.

7) Turn potentiometer R18 clockwise until the volt-

meter reading goes high (approximately equal to

clockwise until the voltmeter reading decreases

to 0. The reset threshold voltage on the SUPEVKIT

is now set.

8) Connect the SUPEVKIT to the test circuit, using the

device inputs and outputs listed in Table 1.

WDI, and RESETOD.

Detailed Description

Watchdog Circuit

A watchdog circuit consists of an input (WDI) and an

output (RESET). If WDI is not toggled within the watch-

dog timeout period (which is a predetermined amount

of time), then a RESET is issued. Disable the watchdog

function by installing jumper JU3.

Capacitor C2 selects the watchdog timeout period. To

choose a value for this capacitor, refer to Table 3 or use

the following formula:

is in pF.

The SUPEVKIT features two modes of watchdog timer

operation: normal mode and extended mode. In normal

mode (JU1 = 2-3), the formula shown above deter-

mines the watchdog timeout period. In extended mode

a factor of 500.

Note: In extended mode operation, leaving pad WDI

floating disables the watchdog feature.

Reset Outputs

The SUPEVKIT has five reset outputs: active-low

push/pull (RESET), active-low bidirectional (RESETBD),

active-low open-drain (RESETOD), active-high push/pull

(RESET), and active-high open-drain (RESETOD).

timeout period is the amount of time RESET is asserted

Capacitors C1, C5, C6, and C7 set the reset timeout

period. The SUPEVKIT comes with the period set at

1120ms. To change the period to either 1ms, 20ms, or

140ms, cut a PC board trace as specified in Table 2.

The bidirectional reset output of the SUPEVKIT is valid

only for reset threshold voltages down to 2.63V.

Undervoltage Setup

Potentiometer R18 sets the undervoltage reset thresh-

old. To enable the undervoltage reset feature, install the

jumpers in the positions specified in Table 4. Use a volt-

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