Datasheet

SLUU171A - September 2003

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

2 The TPS2350 −48-V Hot Swap/Supply Selector EVM Kit

2.1 Module Description

The TPS2350 −48-V hot swap/supply selector EVM kit is a PCB-based platform that enables designers to

rapidly learn about the TPS2350 operation, and evaluate its performance during hot swap events. The assembly

(TI part number HPA021−001) features a TPS2350 device as it may be connected in the power interface section

of a hot swap-capable plug-in card. The assembly also provides additional controls and components to simplify

testing and for quick modifications of the circuit characteristics. Input power to the module is connected at three

banana jacks located on the left-hand side of the board. A toggle switch is provided to rapidly apply power to

and remove it from the circuit.

The hot swap circuit on the EVM board contains the TPS2350 HSPM device, a power MOSFET switch, sense

resistor and some configuration capacitors. Two through-hole patterns are provided on the load side for the

installation of large-value aluminum electrolytic capacitors. These capacitors simulate the input bulk

capacitance that may be found on the target module’s back-end supply plane. The EVM is supplied from the

factory with a 100-µF capacitor installed in one of the locations. The second pattern, connected in parallel with

the first, can be used to increase or otherwise modify the amount of load capacitance. With the TPS2350, both

inrush slew rate limiting and a fault time-out period are externally programmable using capacitors. On the EVM

board, several options are provided for slew rate limit setting, for quick comparison of the effect of capacitor

value on this function. The capacitors can be quickly switched in and out of the circuit via the DIP switch SW1.

Fault timing programming is set up in a similar manner; some amount of capacitance is hard-wired into the

circuit, with the option of switching in additional capacitance.

N-channel FETs are also provided on-board to exercise or demonstrate the supply selection operation of the

TPS2350 when two supplies are connected to the board.

The board also contains the component patterns and connections to exercise the undervoltage (UVLO) and

overvoltage (OVLO) lockout functions. A slide switch is also tied into the UV input pin to provide an alternate

means of enabling and disabling the output voltage. The powergood output can be monitored directly at the

device pin, or through the on-board opto-coupler.

Test points are provided throughout the circuit for easy voltage monitoring via oscilloscope or voltmeter. The

test point connections are listed in Table 6.