MP8861 – 2.85V - 18V, 6A, SYNCHRONOUS, STEP-DOWN CONVERTER

MP8861 Rev. 1.1

www.MonolithicPower.com

22

5/28/2020

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REGISER DESCRIPTION

Register Map

The MP8861 contains six write or read registers.

Register 00 is the output voltage selection

register. Register 01 is the first system control

register and can be used to set the slew rate,

hiccup OCP, etc. Register 02 is the second

system control register and can be used to set

the switching frequency, current limit, etc.

Register 03 and register 04 are output current

and

output

voltage

indicating

registers,

respectively. Register 05 is the IC ID register.

Register 06 is the IC status indication register

and can be used to check if the IC is in OCP,

OTP, etc. The register map is shown below.

ADD

NAME

R/W

D7

D6

D5

D4

D3

D2

D1

D0

00

VSEL

r/w

Reserved

Output Reference

01

SysCntlreg1

r/w

EN

GO_BIT

Slew Rate

Retry

OVP

Hiccup

OCP

Mode

02

SysCntlreg2

r/w

PG Deglitch Time

Switching

Frequency

Soft

Stop

Current Limit Adjust

03

Output

Current

r

Output Current

04

Output

Voltage

r

Output Voltage

05

ID1

r

Vendor ID

Die ID

06

Status

r

Reserved

OC

OTEW

OT

PG

Register Description

1) Reg00 VSEL

Register 00 is the output reference voltage

selection register. The MP8861 default output

voltage is determined by the FB resistor divider

after the MP8861 power start-up or EN start-up.

The reference voltage is adjustable from 0.6V

to

1.108V.

Before

adjusting

the

output

reference voltage, the bit GO_BIT of the first

system control register 01 should be set to 1,

and then the reference voltage can be adjusted

by the lower seven bits of register 00. When the

output reference voltage setting command is

finished, GO_BIT auto-resets to 0 to prevent

false operation of the VOUT scaling. GO_BIT

should be set to 1 before adjusting the output

reference voltage via the I2C.

Table 3 shows the output reference voltage

selection chart from 0.6V to 1.108V via the I2C.

NAME

BITS

DEFAULT

DESCRIPTION

Reserved

D[7]

1

Reserved for further use.

Output

Reference

D[6:0]

001 1110

Sets the output voltage from 0.6V to 1.108V (see Table 3). The default

value is 0.72V.