APFCON datasheet(36/222 Pages) MICROCHIP

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MCP19111

DS22331A-page 36

 2013 Microchip Technology Inc.

6.2

Output Overcurrent

The MCP19111 features a cycle-by-cycle peak current

limit. By monitoring the OCIF interrupt flag, custom

overcurrent fault handling can be implemented.

To detect an output overcurrent, the MCP19111 senses

the voltage drop across the high-side MOSFET while it

is conducting. Leading edge blanking is incorporated to

mask the overcurrent measurement for a given amount

of time. This helps prevent false overcurrent readings.

When the input voltage is greater than 20V, or if the

RDSON of the high-side MOSFET is such that the

programmed overcurrent threshold does not produce

acceptable peak overcurrent protection, an alternative

method must be used to determine an output

overcurrent situation. An alternative technique can use

the configurable output under voltage protection and

the PE1<UVTEE> bit to quickly terminate switching

when the output voltage drops because of an

overcurrent event.

When an output overcurrent is sensed, the OCIF flag is

set and the high-side drive signal is immediately

terminated. Without any custom overcurrent handling

implemented, the high-side drive signal will be asserted

high at the beginning of the next clock cycle. If the

overcurrent condition still exists, the high-drive signal

will again be terminated.

The OCIF interrupt flag must be cleared in software.

However, if a subsequent switching cycle without an

overcurrent condition has not occurred, hardware will

immediately set the OCIF interrupt flag.

both the output overcurrent limit and the amount of

leading edge blanking (see Register 6-2).

The OCCON<OCEN> bit must be set to enable the

input under voltage lockout circuitry.

Note:

The OCIF interrupt flag bit is set when an

interrupt condition occurs, regardless of

the state of its corresponding enable bit or

the Global Enable bit, GIE, of the INTCON

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