HV302DB1

Hotswap Controller

rev 0 21MAY021

1

Introduction

The Supertex HV302DB1 demo board contains all circuitry

necessary to demonstrate the features of the HV302

hotswap controller. Intended primarily as a negative

hotswap controller, the HV302 controls the negative supply

path. Four sequenced power-good signals are provided,

with timing controlled via 3 resistors.

Included on board is a 100+F capacitor to provide a

capacitive load for testing. Additional capacitance may be

removed altogether

The board may be modified to meet custom requirements.

Instructions are provided on the next page for modifications.

Specifications

Input Voltage

10V to 90V

Inrush Limit

1A ±20%

Circuit Breaker Trip

6.7A ±20%

Retry Interval

16sec typ

On Resistance

40m 8 max

Undervoltage Trip

38.0V on, 32.2V off

Overvoltage Trip

64.5V on, 70.0V off

Power Good Signals

PWRGD A

PWRGD B

PWRGD C

PWRGD D

Active High

~200ms after ‘A’

~100ms after ‘B’

~5ms after ‘C’

Board Layout and Connections

Connect the supply voltage to these terminals. Supply

voltage may range from 10 volts to 90 volts.

A high source impedance may cause oscillations when the

input voltage is near the undervoltage trip point. A high

source impedance results in a large voltage drop when

loaded, causing undervoltage lockout to kick in,

disconnecting the load. With the load removed, input voltage

rises, causing undervoltage to release and reconnecting the

load. The cycle repeats, resulting in oscillations. Source

impedance must be less than the following to avoid

oscillations:

LOAD

SOURCE

I

R

V

3

<

Connect the power supply or other load to these terminals.

Application of a DC load during start-up extends the time

inrush limiting is active. If this time exceeds 100ms, the

HV302 shuts off, retrying as quickly as 12s later. For this

reason, DC load at start-up should be less than 900mA.

Note that DC start-up load limitation decreases with added

load capacitance.

Connecting additional load capacitance alters the inrush

current limit. See the HV302/312 data sheet for details.

PWRGD

Connect to the power supply’s ENABLE inputs. Depending

on the power supply, it may be necessary to level-translate

this signal via opto-isolator or discrete circuit. Refer to the

HV302/312 data sheet for a description of PWRGD and

related application circuits.

PWRGD is an open-drain output. During start-up and

greater than the overvoltage trip point, PWRGD is pulled

load capacitance has fully charged, PWRGD assumes a high

impedance state.

HV302

R10

R9

R8

R4

C3

R7

C4

R6

C2

C1

R5

Q1

C6

DC/DC

Converter

DC/DC

Converter

DC/DC

Converter

DC/DC

Converter

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–

+

–

+

–

+

–

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