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MCP19111

DS22331A-page 18

 2013 Microchip Technology Inc.

3.8

Protection Features

3.8.1

INPUT UNDER VOLTAGE LOCKOUT

The input under voltage lockout (UVLO) threshold is

configurable by the VINLVL register, Register 6-1.

When the voltage at the VIN pin of the MCP19111 is

below the configurable threshold, the PIR2<VINIF>

flag will be set. This flag is cleared by hardware once

the VIN voltage is greater than the configurable

threshold. By enabling the global interrupts or polling

the VINIF bit, the MCP19111 can be disabled when the

VIN voltage is below the threshold.

Some techniques that can be used to disable the

switching of the MCP19111 while the VINIF flag is set

include setting the ATSTCON<DVRDIS> bit, setting

the reference voltage to 0V, setting the PE1<PUEN>

bit,

setting

the

ATSTCON<HIDIS>

and

ATSTCON<LODIS> bits.

3.8.2

OUTPUT OVERCURRENT

The MCP19111 senses the voltage drop across the

high-side MOSFET to determine when an output over

current (OC) exists. This voltage drop is configurable

the

OCCON

(Register 6-2),

and

measured when the high-side MOSFET is conducting.

To avoid false OC events, leading edge blanking is

applied to the measurements. The amount of blanking

is controlled by the OCLEB<1:0> bits in the OCCON

more information.

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 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.

3.8.3

OUTPUT UNDER VOLTAGE

When the output under voltage DAC is enabled by

setting the ABECON<UVDCEN> bit, the voltage

measured between the +VSEN and -VSEN pins is

monitored

and

compared

the

threshold

controlled by the OUVCON register (Register 6-12).

When the output voltage is below the threshold, the

PIR2<UVIF> flag will be set. Once set, firmware can

determine how the MCP19111 responds to the fault

condition and it must clear the UVIF flag.

By setting the PE1<UVTEE> bit, the HDRV and LDRV

signals will be asserted low when the UVIF flag is set.

The signals will remain low until the flag is cleared.

3.8.4

OUTPUT OVERVOLTAGE

When the output overvoltage DAC is enabled by setting

the ABECON<OVDCEN> bit, the voltage measured

between the +VSEN and -VSEN pins is monitored and

compared to the OV threshold controlled by the

OOVCON register (Register 6-13). When the output

voltage is above the threshold, the PIR2<OVIF> flag

will be set. Once set, firmware can determine how the

MCP19111 responds to the fault condition and it must

clear the OVIF flag.

By setting the PE1<OVTEE> bit, the HDRV and LDRV

signals will be asserted low when the OVIF flag is set.

The signals will remain low until the flag is cleared.

Note 1: The UVLO DAC must be enabled by set-

ting the VINLVL<UVLOEN> bit.

2: Interrupt flag bits are set when an inter-

rupt condition occurs, regardless of the

state of its corresponding enable bit or

the Global Enable bit (GIE) of the

INTCON register.

Note 1: The OC DAC must be enabled by setting

the OCCON<OCEN> bit.

Note 1: The UV DAC must be enabled by setting

the ABECON<UVDCEN> bit.

2: Interrupt flag bits are set when an inter-

rupt condition occurs, regardless of the

state of its corresponding enable bit or

the Global Enable bit (GIE) of the

INTCON register.

3: The output of the remote sense compar-

ator is compared to the UV threshold.

Therefore, the offset in this comparator

should be considered when calculating

the UV threshold.

Note 1: The OV DAC must be enabled by setting

the ABECON<UVDCEN> bit.

2: Interrupt flag bits are set when an inter-

rupt condition occurs, regardless of the

state of its corresponding enable bit or

the Global Enable bit (GIE) of the

INTCON register.

3: The output of the remote sense compar-

ator is compared to the OV threshold.

Therefore, the offset in this comparator

should be considered when calculating

the OV threshold.

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