HV302DB1 Ver la hoja de datos (PDF) - Supertex Inc
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HV302DB1 Datasheet PDF : 2 Pages
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HV302DB1
Hotswap Controller
VIN+
R1
487k
R2
9.09k
R3
9.09k
VIN-
Schematic
6 UV
5 OV
VEE
7
RAMP
10
14
VDD
HV302
SENSE
8
PWRGDA
PWRGDB
PWRGDC
PWRGDD
TB
TC
TD
GATE
9
4
3
2
1
R8
121k
11
12
13
R10
3.01k
Cno5t used
R9
60.4k
R4
not used
Cno2t used
C1
10nF
R6
0
C3
680pF
not usRe7d
R5
15m
Cno4t used
Q1
IRF3710S
VOUT+
C6
100+F
VOUT-
Inrush Limit
As supplied, the inrush current limit is set at 1 amp. To set
inrush limit to another value, please refer to the HV302/312
data sheet.
The circuit breaker trip point is set at 6.7 Amps. To set at a
different level, change R5 according to the following
equation:
I CB
=
100mV
R5
The power rating of R5 should be selected based on
maximum current during normal operation, which could be
just under the circuit breaker trip point.
P5 = 100mV ICB
Timing
Timing capacitor C1 determines start-up delay, rise time, and
circuit breaker retry interval,. Changing C1 will alter these
timings. Refer to the HV302/312 datasheet for the equations
that relate these timings to the value of C1. For use in the
equations, the nominal gate threshold voltage (VGS) of the
supplied IRFR3710 is 3V and transconductance is about 10
siemens.
Resistors R8, R9, and R10 set the delays for PWRGDs B, C,
and D according to the following equation:
tD = 1.67µF RX
Circuit Breaker Transient Immunity
The HV302 has built-in transient immunity of 2–5+s. To
increase transient immunity, an RC low-pass filter (R6C2)
may be placed on the SENSE input. (The demo board is
supplied with no filtering.)
Be aware that filtering the sense input will cause the inrush
current limit to overshoot at turn-on – the greater the filtering,
the greater the overshoot.
Undervoltage/Overvoltage Lockout
Resistors R1, R2, and R3 set the undervoltage and
overvoltage trip points. New trip points may be programmed
by changing the values of these resistors. Refer to the
HV302/312 data sheet for more information.
Additional Components
The RC network (R7C4) across the gate-source of the
external FET provides control loop compensation which
prevents inrush current peaking.
If the PWRGD A signal is used and experiences large
voltage swings, a 10nF capacitor should be installed at C5.
This limits dV/dt which may otherwise cause undesirable
coupling to internal circuits.
To defeat the circuit breaker auto-retry, install a 2.4M
resistor at location R4.
For servo-mode inrush control, remove C3. Inrush limit will
then be 3.3 Amps. See the HV302/312 data sheet for
details.
rev 1 24MAY02
2
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