Datasheet

SLUU171A - September 2003

TPS2350 −48-V Hot Swap/Supply Selector Evaluation Module

1 Introduction

The TPS2350 is a negative voltage hot swap controller intended for use in systems needing to hot swap telecom

distribution-level voltages. It integrates inrush current control, peak current limiting, electronic circuit breaker,

and overvoltage and undervoltage protection. In addition, it monitors and selects from two power supplies the

larger magnitude supply, reducing OR-ing losses in redundant supply systems. The EVM is a PCB-based tool

featuring the TPS2350 in a hot swap circuit, and can be used to evaluate device operation in simulated live

insertion events.

1.1 Features

The following list highlights some of the features of the TPS2350 device.

D Wide input supply range of −12 V to −80 V

D Transient rating to −100 V

D Programmable current limit

D Programmable linear inrush slew rate

D Redundant supply selector function

D Programmable UV/OV thresholds/hysteresis

D Fault timer to eliminate nuisance trips

D Open-drain power good (PG) output

D Open-drain fault output (FLT)

D 14-pin TSSOP package

1.2 Description

The TPS2350 integrated circuit is a hot swap power manager optimized for use in nominal −48-V systems. It

operates over a supply voltage range of −12 V to −80 V, and is rated to withstand spikes to −100 V. In conjunction

with an external N-channel FET and sense resistor, it can be used to enable live insertion of plug-in cards and

modules into powered systems. It provides load current slew rate control and peak magnitude limiting.

Undervoltage and overvoltage shutdown thresholds are easily programmed via a three-resistor divider network.

A power good (PG) output enables downstream converters. The TPS2350 also provides the basic hot swap

functions of electrical isolation of faulty cards, filtered protection against nuisance overcurrent trips, and

single-line fault reporting.

The TPS2350 also provides a unique feature for redundant-supply systems. The supply selection function can

be used to reduce power losses of diode-OR systems. A selection comparator monitors the two input supplies,

and selects the supply with the larger magnitude. Internal driver circuits provide the gate drive needed to control

two external N-channel FETs, providing a low-loss switch closure for the active supply, while disconnecting the

lower voltage supply.

For input capacitor charging and load current faults, the TPS2350 provides an internal fault timer to filter out

spurious current glitch events. In the event of a persistent fault which exceeds the programmable timer setting,

the TPS2350 turns off the hot swap FET, disconnecting the load. A retry mode periodically tests for continued

existence of the fault at a low duty cycle, thus protecting the pass FET from excessive dissipation.