HV9901

Features

and hold current

coils’ inductance

Applications

General Description

The Supertex HV9901 is a BiCMOS/DMOS universal relay driver that

employsPWMswitchingtechniques.Itisdesignedforefficientandenergy-

saving operation of a low voltage relay with supply voltages ranging from

10 to 450V DC through utilization of the relay coils’ inductance.

The circuit is capable of operating over a wide input voltage range without

requiring a change of any external components. For example, this will

enable users to use 5.0V coil relays for DC voltages 10 to 450V or AC

voltages up to 240V.

The HV9901 has an internal high-voltage regulator to power internal

PWM circuitry. Additionally, it includes an adjustable auxiliary regulator

with a 1.0mA capability that can be used to supply low power micro

controllers.

The pull-in current, pull-in time and hold current are all program-mable

using only two resistors and a capacitor. The PWM switching frequency

can be either:

- Synchronized to an external clock, or

- Synchronized to other HV9901s, where the synchronized

frequency is the highest free-running frequency.

The enable (ENI) logic input is used to turn the relay on/off. Enable

polarity may be selected via the POL input. Audible noise is prevented

using fixed switching frequencies above 20kHz.

WARNING!!! Galvanic isolation is not provided. Dangerous voltages are

present when connected to the AC line. It is the responsibility of the

designer to ensure adequate safeguards are in place to protect the end

user from electrical shock.

Universal Relay Driver

Typical Boost Application Circuit