2

Date: 8/23/04

SPX2967 400mA Low Dropout Voltage Regulator

© Copyright 2004 Sipex Corporation

APPLICATIONS INFORMATION

The IC regulates an input voltage V

of V

delay can be set with an external capacitor. The device has two logic inputs. A voltage of V

given to the E2-pin (e.g. by ignition) turns the device on. Depending on the voltage on pin E6 the

IC may be hold in active-state even if V

implement a self-holding circuit without external components. When the device is turned off, the

output voltage drops to 0V and current consumption tends towards 0 µA.

DESIGN NOTES FOR EXTERNAL COMPONENTS

The input capacitor C

consisting of lead inductance and input capacitance can be damped by a resistor of approxi-

mately 1Ω in series with C

circuit. Stability is guaranteed at values of ≥ 22µF and an ESR of less than 3Ω within the operating

temperature range.

The control amplifier compares a reference voltage, which is kept highly accurate by resistance

adjustment, to a voltage that is proportional to the output voltage and drives the base of the series

transistor via a buffer. Saturation control as a function of the load current prevents and over-

saturation of the power element.

The reset output RO is in high state if the voltage on the delay capacitor C

to V

the reset threshold V

capacitor C

The reset delay can be set within wide range by dimensioning the capacitance of the external

capacitor.

CIRCUIT DESCRIPTION

PIN DESCRIPTION

N

I

P

R

E

B

M

U

N

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M

A

N

N

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PN

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