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

MP8861 Rev. 1.1

www.MonolithicPower.com

23

5/28/2020

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Table 3: Output Reference Voltage Selection Chart

D[6:0]

VOUT (V)

D[6:0]

VOUT (V)

D[6:0]

VOUT (V)

D[6:0]

VOUT (V)

000 0000

0.6

010 0000

0.728

100 0000

0.856

110 0000

0.984

000 0001

0.604

010 0001

0.732

100 0001

0.86

110 0001

0.988

000 0010

0.608

010 0010

0.736

100 0010

0.864

110 0010

0.992

000 0011

0.612

010 0011

0.74

100 0011

0.868

110 0011

0.996

000 0100

0.616

010 0100

0.744

100 0100

0.872

110 0100

1

000 0101

0.62

010 0101

0.748

100 0101

0.876

110 0101

1.004

000 0110

0.624

010 0110

0.752

100 0110

0.88

110 0110

1.008

000 0111

0.628

010 0111

0.756

100 0111

0.884

110 0111

1.012

000 1000

0.632

010 1000

0.76

100 1000

0.888

110 1000

1.016

000 1001

0.636

010 1001

0.764

100 1001

0.892

110 1001

1.02

000 1010

0.64

010 1010

0.768

100 1010

0.896

110 1010

1.024

000 1011

0.644

010 1011

0.772

100 1011

0.9

110 1011

1.028

000 1100

0.648

010 1100

0.776

100 1100

0.904

110 1100

1.032

000 1101

0.652

010 1101

0.78

100 1101

0.908

110 1101

1.036

000 1110

0.656

010 1110

0.784

100 1110

0.912

110 1110

1.04

000 1111

0.66

010 1111

0.788

100 1111

0.916

110 1111

1.044

001 0000

0.664

011 0000

0.792

101 0000

0.92

111 0000

1.048

001 0001

0.668

011 0001

0.796

101 0001

0.924

111 0001

1.052

001 0010

0.672

011 0010

0.8

101 0010

0.928

111 0010

1.056

001 0011

0.676

011 0011

0.804

101 0011

0.932

111 0011

1.06

001 0100

0.68

011 0100

0.808

101 0100

0.936

111 0100

1.064

001 0101

0.684

011 0101

0.812

101 0101

0.94

111 0101

1.068

001 0110

0.688

011 0110

0.816

101 0110

0.944

111 0110

1.072

001 0111

0.692

011 0111

0.82

101 0111

0.948

111 0111

1.076

001 1000

0.696

011 1000

0.824

101 1000

0.952

111 1000

1.08

001 1001

0.7

011 1001

0.828

101 1001

0.956

111 1001

1.084

001 1010

0.704

011 1010

0.832

101 1010

0.96

111 1010

1.088

001 1011

0.708

011 1011

0.836

101 1011

0.964

111 1011

1.092

001 1100

0.712

011 1100

0.84

101 1100

0.968

111 1100

1.096

001 1101

0.716

011 1101

0.844

101 1101

0.972

111 1101

1.1

001 1110

0.72

011 1110

0.848

101 1110

0.976

111 1110

1.104

001 1111

0.724

011 1111

0.852

101 1111

0.98

111 1111

1.108

2) Reg01 SysCntlreg1

Register 01 is the first system control register.

The highest bit, EN, can be used to turn the

part on or off when the external EN is high.

When the external EN is high, after part shuts

down by setting the EN bit to 0, and then the

HS-FET and LS-FET stop switching. The part

resumes switching by setting the EN bit to 1

again. When the external EN is low, the

converter is off, and the I2C shuts down.

Set GO_BIT to 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.

The IC switches to forced PWM mode when

GO_BIT is set to 1 to achieve a smooth output

waveform during the output dynamic scaling.

After the output scaling is complete, GO_BIT is

set to 0 automatically, and the IC operation

mode switches to the original mode set by the

Mode bit.

The 3-bit Slew Rate D[5:3] is used for slew rate

selection during the output voltage dynamic

scaling. A proper slew rate reduces the inrush

current,

voltage

overshoot,

and

voltage

undershoot. Eight different slew rate levels can

be selected.