LP2953QML, LP2953QML-SP

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SNVS395C – NOVEMBER 2010 – REVISED APRIL 2013

This gives a value of about 0.1

μF. When this is used, the output capacitor must be 6.8 μF (or greater) to

maintain stability. The 0.1

μF capacitor reduces the high frequency gain of the circuit to unity, lowering the output

noise from 260

μV to 80 μV using a 10 Hz to 100 kHz bandwidth. Also, noise is no longer proportional to the

output voltage, so improvements are more pronounced at high output voltages.

Auxiliary Comparator

The LP2953 contains an auxiliary comparator whose inverting input is connected to the 1.23V reference. The

auxiliary comparator has an open-collector output whose electrical characteristics are similar to the dropout

detection comparator. The non-inverting input and output are brought out for external connections.

SHUTDOWN Input

A logic-level signal will shut off the regulator output when a "LOW" (<1.2V) is applied to the Shutdown input.

To prevent possible mis-operation, the Shutdown input must be actively terminated. If the input is driven from

open-collector logic, a pull-up resistor (20 k

Ω to 100 kΩ recommended) should be connected from the Shutdown

input to the regulator input.

If the Shutdown input is driven from a source that actively pulls high and low (like an op-amp), the pull-up resistor

is not required, but may be used.

If the shutdown function is not to be used, the cost of the pull-up resistor can be saved by simply tying the

Shutdown input directly to the regulator input.

IMPORTANT: Since the Absolute Maximum Ratings state that the Shutdown input can not go more than 0.3V

below ground, the reverse-battery protection feature which protects the regulator input is sacrificed if the

Shutdown input is tied directly to the regulator input.

If reverse-battery protection is required in an application, the pull-up resistor between the Shutdown input and the

regulator input must be used.

Typical Applications

Figure 33. Basic 5V Regulator

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