SUPERTEX HV9901DB1

HV9901DB1
Universal Relay Driver
Introduction
Specifications
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.
Input Voltage
Relay Drive Current
SPDT (1FormC)
Contact Rating
10A@125VAC, 6A@277VAC
Auxillary Regulator (VCC)
5.0V@1mA
Enable
<1.5V off, >3.5V on
Switching Frequency
21kHz
Board Layout and Connections
C1
K1
Common
Normally Open
WARNING!!!
No galvanic isolation. Dangerous voltages
are present when connected to the AC line.
Relay
Selector
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.
Enable Polarity
Selector
+
C2
IC1
D3
Q1
R6
R3 R1
C4
F1
~
–
D2
Input
Voltage
D1
C3
~
Normally Closed
External Relay
For connection of an off-board relay.
20ms
Contact Form
R5
Relay
Contacts
72mA pull-in, 24mA hold
Pull-in Time
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!!!
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.
10–400VDC, 24–277VAC
External
Relay
Sync
R7
R2
R4
C5
VCC
Ground
Enable
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.
VCC
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
F1
250mA
D1
DF06
VIN
C1
100nF
D2
S1J
GND
VDD
C2
4.7µF
R1
226kΩ
R2
8.25kΩ
VCC
5.0V @ 1mA
C5
1.0µF
VREF
C3
100nF
C4
1.0µF
R3
374kΩ
R4
NC
NO
C
D3
ES1J
VIN
Int
Reg
VREF
H/D
K1
NAIS JS1-5V
INT
RELAY
EXT
SYNC
PWM
SYNC
GT
Q1
VN2450
CS
R5
RT
11Ω
R6
VCC
FB
Aux
Reg
124kΩ
VCC
1.21MΩ
POL
ENI
ENO
R7
EN
1
POL
0
270kΩ
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 R1 and R2 and capacitor C4. Refer to the HV9901
data sheet for details.
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.
Switching Frequency
To change the PWM switching frequency, change R6 according
to the following equation:
f PWM = 3.23kHz +
21.8GHz ⋅ Ω
R6
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.
VCC
As provided, the HV9901DB1 supplies 5V for external circuitry.
Other volltages in the range 2.0V to 5.5V may be obtained by
changing R3. Current rating remains at 1mA.

R 
VCC = 1.25V1 + 3 
R4 

Note that changing VCC also changes the Enable logic levels.
V EN ( lo ) < 0.3VCC
V EN ( hi ) > 0.7VCC