HV312DB1
Hotswap Controller
Introduction
The Supertex HV312DB1 demo board contains all circuitry
necessary to demonstrate the features of the HV312
hotswap controller. Intended primarily as a negative
hotswap controller, the HV312 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
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.
Specifications
Input Voltage
Inrush Limit
Circuit Breaker Trip
Retry Interval
On Resistance
Undervoltage Trip
Overvoltage Trip
Power Good Signals
PWRGD A
PWRGD B
PWRGD C
PWRGD D
10V to 90V
1A ±20%
6.7A ±20%
16sec typ
40m
8
max
38.0V on, 32.2V off
64.5V on, 70.0V off
Active Low
~5ms after C
LOAD
charged
~200ms after ‘A’
~100ms after ‘B’
~5ms after ‘C’
Board Layout and Connections
R10
R9
HV312
R8
R4
C3
C1
C2
R6
R7
C4
R5
Q1
C6
+
enable
+
enable
+
enable
+
enable
DC/DC
Converter
–
last enabled
DC/DC
Converter
–
DC/DC
Converter
–
DC/DC
Converter
–
first enabled
V
IN
V
IN
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:
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
whenever V
IN
is lower than the undervoltage trip point or
greater than the overvoltage trip point, PWRGD assumes a
high impedance state. Once V
IN
is within the proper range
and the load capacitance has fully charged, PWRGD is
pulled down to V
IN-
.
R
SOURCE
<
3V
I
LOAD
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 extends the time
inrush limiting is active. If this time exceeds 100ms, the
HV312 shuts off, retrying as quickly as 12s later. For this
rev 2 12SEP02
1
SUPERTEX [ Supertex, Inc ]
