Datasheet HV9901DB1 Datasheet (Supertex)

HV9901DB1

Universal Relay Driver

Introduction

The HV9901 is a universal relay driver employing PWM

switching techniques utilizing the relay coils inductance to

provide efficient operation over a wide supply voltage range.

Relay drive is constant-current. Pull-in current, pull-in time,

and hold current are all programmable via 2 resistors and a

capacitor. An adjustable regulator provides 1mA for external

circuitry.

The HV9901DB1 demo board contains all the circuitry

necessary to demonstrate the operation of the HV9901.

Included on-board are a full-wave input rectifier, fuse, the

HV9901, and a 10A relay. Provisions for connecting an

external relay are available. The circuit may be modified to

accomodate the drive requirements of other relays.

WARNING!!!

Board Layout and Connections

Do not connect earth-grounded

instruments when connected to the

AC line. Doing so will short the AC

line, resulting in damage to the demo

board and/or the instrument. Use an

isolation transformer on the AC line,

use high voltage differential probes,

or use a floating instrument to make

measurements when connected to

the AC line.

Input

Voltage

Normally Closed

Relay

Contacts

Common

Normally Open

Specifications

Input Voltage 10400VDC, 24277VAC

Relay Drive Current 72mA pull-in, 24mA hold

Pull-in Time 20ms

Contact Form SPDT (1FormC)

Contact Rating 10A@125VAC, 6A@277VAC

Auxillary Regulator (V

) 5.0V@1mA

CC

Enable <1.5V off, >3.5V on

Switching Frequency 21kHz



~

D1

~

F1

K1

+

D2

C1

D3

Q1

C2

C4

R1

R2

IC1

R4

R5

R3

C5

R6

C3

R7

Enable Polarity

Selector

WARNING!!!

No galvanic isolation. Dangerous voltages

are present when connected to the AC line.

Input Voltage

Supply voltage. May be a DC source in the range of

10400VDC, or an AC source in the range of 24277VACrms.

A full-wave bridge rectifier on board rectifies the AC. Also

included is a 250mA 2AG fuse.

Relay Contacts

For connecting an external load. The PCB traces are rated at

10A for a 20°C rise.

Relay Selector

In the Int position, the on-board relay is operated. In the Ext

position, a relay connected to the External Relay terminals is

operated.

External Relay

For connection of an off-board relay.

Relay

Selector

Ground

V

External

Relay

Sync

Enable

CC

Sync

Synchronizes multiple HV9901s to the same frequency or to a

master clock. Frequency will be the highest independent

frequency. Connect to the Sync pins of other HV9901s or to a

master clock.

Enable

Logic-level enable for relay operation. See Enable Polarity

Selector for polarity.

V

CC

Supplies 5V at 1mA for external circuitry.

Ground

Circuit common. Since galvanic isolation is not provided,

ground will be at the AC line potential!

Enable Polarity Selector

Sets Enable polarity. In the 0 position, Enable is active low. In

the 1 position, Enable is active high.

HV9901DB1 Schematic

F

1

250mA

V

IN

D

1

DF06

D

S1J

C

C

2

VIN

100nF

1

D

ES1J

3

INT

EXT

RELAY

NC

NO

K

1

NAIS JS1-5V

VDD

GND

V

CC

5.0V @ 1mA

226kΩ

8.25kΩ

C

1.0µF

R

1

R

2

5

C

4.7µF

100nF

1.0µF

374kΩ

124kΩ

2

VREF

C

3

H/D

C

4

VCC

R

3

R

4

Modifications

External Relay

Connect the coil of the external relay to the External Relay

terminals and move the Relay Selector shunt to the Ext

position.

Pull-in Current, Pull-in Time, and Hold Current

For use with other relays, these parameters may be changed

via resistors R

data sheet for details.

and R2 and capacitor C4. Refer to the HV9901

1

Int

Reg

V

REF

Aux

Reg

PWM

SYNC

GT

CS

RT

POL

ENI

ENOFB

R

6

1.21MΩ

R

270kΩ

Q

VN2450

R

11Ω

7

1

5

EN

SYNC

V

CC

1

POL

0

Switching Frequency

To change the PWM switching frequency, change R

to the following equation:

f

PWM

=

3.23kHz

21.8GHz

+

⋅

Ω

R

6

This equation is valid for frequencies 25kHz and above. Be

advised that frequencies below 20kHz may cause the relay coil

to emit audible noise. And avoid higher frequencies that

approach the coils resonant frequency.

according

6

Monitoring Relay Current

For the on-board relay, coil current may be monitored by

replacing the Relay Selector shunt with either a wire loop (for

current probe use) or with a low value sense resistor (for

voltage probe use). Remember that galvanic isolation is not

provided! See warnings on the first page.

V

CC

As provided, the HV9901DB1 supplies 5V for external circuitry.

Other volltages in the range 2.0V to 5.5V may be obtained by

changing R

Note that changing V

. Current rating remains at 1mA.

3



V

CC

CC






also changes the Enable logic levels.

<

3.0

)(

>

7.0

)(



R

3



+=

1V25.1



R



4

VV

CCloEN

VV

CChiEN