HV310_09 Datasheet, PDF (1/7 Pages) Supertex, Inc – Hotswap, Inrush Current Limiter Controllers (Negative Supply Rail)

HV310
Hotswap, Inrush Current Limiter Controllers
(Negative Supply Rail)
Features
► PWRGD = Active Low
► -10V to -90V input voltage range
► Few external components
► 0.33mA typical standby supply current
► Programmable over/under voltage limits with
hysteresis
► Programmable current limit
► Active control during all phases of start-up
► Programmable timing
► 8-Lead SOIC package
Applications
► Central office switching
► Servers
► POTS line cards
► ISDN line cards
► xDSL line cards
► PBX Systems
► Powered Ethernet for VoIP
► Distributed power systems
► Negative power supply control
► Antenna and fixed wireless systems
General Description
The Supertex HV310, Hotswap Controller, Negative Supply controls the power
supply connection during insertion of cards or modules into live backplanes.
It may be used in traditional ‘negative 48V’ powered systems or for higher
voltage busses up to negative 90V.
Operation during the initial power up prevents turn-on glitches, and after
complete charging of load capacitors (typically found in filters at the input
of DC-DC converters) the HV310 issues a power good signal. This signal is
typically used to enable the DC-DC converter. Once a PWRGD signal has
been established, the device sleeps in a low power state, important for large
systems with many individual hotswap cards or modules.
An external power MOSFET is required as the pass element, plus a ramp
capacitor, and resistors to establish current limiting and over and under voltage
lockouts. There is no need for additional external snubber components.
Features are programmable over voltage and under voltage detection of the
input voltage which locks out the load connection if the bus (input) voltage
is out of range. An internal voltage regulator creates a stable reference,
and maintains accurate gate drive voltage. The unique control loop scheme
provides full current control and limiting during start up.
Theory of Operation
Initially the external N-channel MOSFET is held off by the gate signal,
preventing an input glitch. After a delay (while internal circuits are activated)
the inrush current to the load is limited by the gate control output. The current
may ramp up and limit at a maximum value programmed by an external
resistor. Initial time delay, to allow for contact bounce, and charging operation
is determined by the single external ramp capacitor connected to the RAMP
pin. When the load capacitor is fully charged, the controller emerges from
current limit mode, an additional time delay occurs before the external N-
channel MOSFET pass transistor is switched to full conduction, and the
PWRGD output signal is activated. The controller will then transition to a low
power standby mode.
Typical Application Circuit
GND
-48V
Long Pin
Jumper
GND
Short Pin
R1
487kΩ
R2
6.81kΩ
R3
9.76kΩ
Long Pin
8
VDD
3 _UV
2 _OV
RAMP
7
C1
10nF
PWRGD ₁
HV310
VEE
4
SENSE GATE
5
6
ENABLE
+5V
C_LOAD
DC/DC
PWM
CONVERTER
COM
NOTES: 1. Undervoltage Shutdown (UV) set to 35V.
2. Overvoltage Shutdown (OV) set to 65V.
3. Remove jumper if short pin is used.
R4
50mΩ
Q1
IRF530
● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: [phone] ● www.supertex.com