SPX1581(2004) View Datasheet(PDF) - Signal Processing Technologies

Part Name

Description

Manufacturer

SPX1581
(Rev.:2004)

5A Ultra Low Dropout Voltage Regulator Fast Response, Adjustable & Fixed

Signal Processing Technologies 

PIN NUMBER

1

2

3

4

5

PIN DESCRIPTION

PIN NAME

SENSE

ADJ

VOUT

VCTRL

VIN

DESCRIPTION

Allows Kelvin sense of VOUT at the load. (Positive side of the reference

voltage of the device).

Negative side of the reference voltage for the device. Adding a small

bypass capacitor from the ADJ pin to ground will improve the transient

response.

Power output of the device.

Supply pin for the control circuitry of the device. The current flow into this

pin will be about 1% of the output current. VCTRL must be between 1.0V

and 1.3V greater than the output voltage for the

device to regulate.

Output load current is supplied through this pin. VIN must be between 0.1V

and 0.8V greater than the output voltage for this device to regulate.

(4) VCTRL

FUNCTIONAL DIAGRAM

VIN (5)

S.O.A

CURRENT

LIMIT

AMPLIFIER

LIMIT

SENSE

THERMAL OVERLOAD

VOLTAGE

REGULATION

AMPLIFIER

VREF

VOUT (3)

SENSE (1)

ADJ (2)

The SPX1581 is designed as a high performance

and low cost solution for application requiring a

lower dropout than traditional NPN regulators.

The SPX1581 uses a separate input voltage VCTRL

( VCTRL ≥ VOUT + 1.3V) to minimize the dropout

voltage. This allows the 2.5V power for the load

to come from a 3.3V system supply.

As added benefit this will reduce the heat dissi-

pation*, and lower heatsink and cooling fan cost.

APPLICATION NOTES

A typical application would use 5V for VIN and

3.3V for VCTRL from a motherboard power

supply to provide a nominal 2.5V output. Using

the sense pin allows Kelvin measure the output,

reducing resistance-associated errors.

The SPX1581 can power the 2.5V core voltage

for microprocessors such as a PentiumTM,

P55CTM, AMD5k86TM and K6TM and the IBM

PowerPCTM 603EV and 604EV processors.

* The reduction of heat dissipation is a result of the

increase of the regulator efficiency (efficiency = VOUT/VIN).

Date 5/25/04

SPX1581 5A Ultra Low Dropout Voltage Regulator

3

©Copyright 2004 Sipex Corporation

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