MP8869WGL datasheet(28/41 Pages) MPS

28 / 41 page

MP8869W

– 3V - 18V, 12A, SYNCHRONOUS STEP-DOWN CONVERTER

MP8869W Rev. 1.02

www.MonolithicPower.com

1/18/2018

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

The bit Retry OVP defines the protection mode

when OVP is triggered. When Retry OVP is set to

1, the part enters auto-recovery when OVP is

removed. When Retry OVP is set to the part

latches off once output OVP occurs, and VIN OVP

is triggered until VIN or EN are toggled.

The bit Hiccup OCP defines the over-current

protection mode. When Hiccup OCP is set to 1,

the part enters hiccup mode when OCP and UVP

are both triggered. When Hiccup OCP is set to 0,

the part enters latch-off when OCP and UVP are

both triggered.

The lowest bit, Mode, is used for selecting forced

PWM or auto PFM/PWM mode at light load. When

Mode is set to 0, auto-PFM/PWM mode is enabled

at light load. When Mode is set to 1, forced PWM

mode is enabled at light load.

NAME

BITS

DEFAULT

DESCRIPTION

D[7]

I2C controlled turn-on or turn-off of the part. When the external EN is low, the

converter is off and I2C shuts down. When EN is high, the EN bit takes over.

The default EN bit is 1.

GO_BIT

D[6]

Switch bit of the I2C writing authority for output reference command only. Set

GO_BIT = 1 to enable the I2C authority of writing the output reference. When

the command is finished, GO_BIT auto-resets to 0 to prevent false operation

of the VOUT scaling. Write the GO_BIT = 1 first, then write the output

reference voltage and change the V_BOOT status.

Voltage scaling examples:

1) Set GO_BIT = 1.

2) Write register 00: set V_BOOT = 0 and set the output reference.

3) Read back the GO_BIT value to see if the output scaling is finished. If

GO_BIT = 0, the voltage scaling is done. Otherwise, VOUT is still in

adjustment.

4) Set GO_BIT = 1 if output voltage scaling is needed a second time.

5) Write register 00: set V_BOOT = 0 and set the output reference.

Slew rate

D[5:3]

100

The slew rate during the I2C-controlled voltage changing is defined by three

bits. The output voltage changes linearly from the previous voltage to the new

set voltage with a below slew rate. This helps to reduce the inrush current,

voltage overshoot, and voltage undershoot greatly.

D[5:3]

Slew Rate

D[5:3]

Slew Rate

000

mV/μs

100

mV/μs

001

mV/μs

101

2.5

mV/μs

010

mV/μs

110

1.25

mV/μs

011

mV/μs

111

0.62

5mV/μs

Retry

OVP

D[2]

FB or VOUT over-voltage protection mode selection bit. 1 means the part

auto-recovers when OVP is removed. 0 means the part latches off once output

OVP and VIN OVP are both triggered until VIN or EN is power reset.

Hiccup

OCP

D[1]

Over-current protection mode selection. 1 means hiccup mode OCP. 0 means

latch-off type OCP.

Mode

D[0]

Set Mode to 0 to enable PFM mode; set Mode to 1 to disable auto-PFM/PWM

mode. Default is auto-PFM/PWM mode for light load.

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