ACT8865 datasheet(26/32 Pages) QORVO

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ACT8865

Advanced PMU for Atmel SAMA5Dx Series & SAM9 Series Processors

Data Sheet Rev. H, September 2019 | Subject to change without notice

26 of 32

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OK[ ] and Output Fault Interrupt

Each DC/DC features a power-OK status bit that can

be read by the system microprocessor via the I

interface. If an output voltage is lower than the power-

OK threshold, typically 7% below the programmed

regulation voltage, that regulator's OK[ ] bit will be 0.

If a DC/DC's nFLTMSK[ ] bit is set to 1, the ACT8865

will interrupt the processor if that DC/DC's output voltage

falls below the power-OK threshold. In

this

case,

nIRQ will assert low and remain asserted until the

OK[ ] bit has been read via I

2C.

PCB Layout Considerations

High switching frequencies and large peak currents

make PC board layout an important part of step-

down DC/DC converter design.

Step-down DC/DCs exhibit discontinuous input current,

so the input capacitors should be placed as

close as possible to the IC, and avoiding the use of via

if possible. The inductor, input filter capacitor, and

output filter capacitor should be connected as close

together as possible, with short, direct, and wide

traces. The ground nodes for each regulator's power

loop should be connected at a single point in a star-

ground

configuration,

and

this

point

should

connected to the backside ground plane with multiple

via. The output node for each regulator should be

connected to its corresponding OUTx pin through the

shortest

possible

route,

while

keeping

sufficient

distance

from

switching

nodes

prevent

noise

injection. Finally, the exposed pad should be directly

connected to the backside ground plane using multiple

via to achieve low electrical and thermal resistance.

Table 4:

REGx/VSET[ ] Output Voltage Setting

REGx/VSET[2:0]

REGx/VSET[5:3]

000

001

010

011

100

101

110

111

000

0.600

0.800

1.000

1.200

1.600

2.000

2.400

3.200

001

0.625

0.825

1.025

1.250

1.650

2.050

2.500

3.300

010

0.650

0.850

1.050

1.300

1.700

2.100

2.600

3.400

011

0.675

0.875

1.075

1.350

1.750

2.150

2.700

3.500

100

0.700

0.900

1.100

1.400

1.800

2.200

2.800

3.600

101

0.725

0.925

1.125

1.450

1.850

2.250

2.900

3.700

110

0.750

0.950

1.150

1.500

1.900

2.300

3.000

3.800

111

0.775

0.975

1.175

1.550

1.950

2.350

3.100

3.900

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