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HV300/HV310

08/26/02

Supertex Inc. does not recommend the use of its products in life support applications and will not knowingly sell its products for use in such applications unless it receives an adequate "products liability

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.

HV300

HV310

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 HV300 (and HV310),

Hotswap Controller, Negative

Supply control power supply connection during insertion of

cards or modules into live backplanes. They 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 HV300 (and

HV310) issues a power good signal. This signal is typically

used to enable the DC-DC converter.

The only difference between the HV300 and the HV310 is the

polarity of the PWRGD signal line to accommodate different

DC-DC converter models. Once 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.

The HV300LG PWRGD is active high (open drain), while the

Ordering Information

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Demo

Kit

Available

Features

❏

HV300, PWRGD=Active HIGH

❏

HV310, 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

Hotswap, Inrush Current Limiter Controllers

(Negative Supply Rail)