1
HV100 Demo Board
01/21/02
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indemnification insurance agreement." Supertex does not assume responsibility for use of devices described and limits its liability to the replacement of devices determined to be defective due to
workmanship. No responsibility is assumed for possible omissions or inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product specifications, refer to the
Supertex website: http://www.supertex.com. For complete liability information on all Supertex products, refer to the most current databook or to the Legal/Disclaimer page on the Supertex website.
HV100DB1
Introduction
The Supertex HV100DB1 demo board contains all necessay
circuitry to demonstrate the features of the HV100 hotswap
controller. Intended primarily as a negative hotswap controller,
the HV100 controls the negative supply path.
Included on board is a 100
F capacitor (C
3
) to provide a
capacitive load for testing. Additional capacitance may be
connected to the V
OUT
terminals. Or the 100
F may be removed
altogether
The board may be modified to meet custom requirements.
Instructions are provided on the next page for modifications.
3-Pin Hotswap Controller
Specifications
Input Voltage
10V to 72V
Peak Inrush Limit
1.4A typ
Max Short Circuit Current
1
4A typ
Circuit Breaker Response Time
1
1ms typ
Auto Retry
2.5s typ
On Resistance
210mW_ max
Undervoltage Trip
37V on, 34V off
1
During inrush limiting
V
IN
Connect the supply voltage to these terminals. Supply voltage
may range from 10 volts to 72 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 follow-
ing to avoid oscillations:
R
I
SOURCE
LOAD
=
1 5
. V
V
OUT
Connect the power supply or other load to these terminals. V
OUT+
is connected to V
IN+
, it is V
OUT
that is switched.
Application of a DC load during start-up and/or additional load
capacitance extends the time inrush limiting is active. If this time
exceeds 100ms, the HV100 shuts off, retrying 2.5s 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.
Note that the circuit breaker functions during inrush only.
Board Layout and Connections
Q1
U1
C
3
R
1
C
2
R
2
C
1
DRAIN
V
PP
OUT
VPP IN
V
NN
IN
alt Q1
+OUT
-OUT
GATE
+
Current
Probe
Power Supply
or Load
V
IN
V
OUT
2
HV100 Demo Board
1235 Bordeaux Drive, Sunnyvale, CA 94089
TEL: (408) 744-0100 FAX: (408) 222-4895
www.supertex.com
01/21/02
2001 Supertex Inc. All rights reserved. Unauthorized use or reproduction prohibited.
A very high dV/dt on the input can overload the HV100's internal
gate clamp, causing turn-on transients. A capacitor in the C
2
position may be used to clamp the gate, preventing the tran-
sients. A 1nF value is usually adequate. Voltage rating should be
16 volts.
To limit short-at-turn-on current, zero-ohm resistor R
1
may be
replaced with a low value resistor. This resistor causes a voltage
drop that tends to cancel-out the applied gate voltage, thus
limiting drain current.
To reduce peak inrush current, a capacitor from gate to drain (C
1
)
may be employed. A resistor (R
2
) is also needed in this configu-
ration for loop stability. Please refer to the HV100 data sheet for
further information.
Note: When making positive-ground measurements, scope
probe loading on the GATE pin may interfere with normal
operation. To observe gate voltages, use negative-ground mea-
surements.
HV100 Demo Board Schematic
HV100
current
probe
GATE
V
PP
V
NN
C
1
not used
C
2
not used
R
2
not used
C
3
100
F
R
1
0
Q
1
IRFR120N
V
PP
IN
V
NN
IN
OUT+
OUT-
DRAIN
GATE
V
PP
OUT
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