LM4962 datasheet(12/22 Pages) NSC

12 / 22 page

Application Information (Continued)

OVER-CURRENT AND OVER-VOLTAGE PROTECTION

FUNCTION

Flagout Pin: The Flagout pin indicates a fault when an over

current or over voltage condition has been detected. The

Flagout pin is high impedance when inactive. When active,

the Flagout pin is pulled down to a 50

Ω short to GND.

Over-Voltage Protection (OVP) Operation: When a volt-

age (Vamp) greater than 8.5V (min) is detected at the

OC/OV Detect pin, the LM4962 indicates a fault by activating

the Flagout pin. The boost converter momentarily shutdown

and reinitialize the soft-start sequence. The Flagout pin will

remain active until both shutdowns pins are pulled low.

Over-Current Protection (OCP) Operation: The OCP cir-

cuitry monitors the voltage across Rocd to detect the output

current of the boost converter. If a voltage greater than

185mV (typ) is detected the device will shutdown and the

Flagout pin will be activated. For the device to return to

normal operation both shutdown pins need to be pulled low

to reset the Flagout pin.

Disable OCP: The Over-Current Protection Circuitry can be

disabled by shorting out R

S. In this configuration the OVP

circuitry is still active.

Disable both OVP and OCP: Both features can be disabled

by grounding the OC/OV Detect pin. In this configuration the

Flagout pin will be inactive.

Timing Diagrams

20142203

FIGURE 4. OCP Timing Diagram

LM4962 Datasheet(PDF) 12 Page - National Semiconductor (TI)