ACT4910 datasheet(14/37 Pages) QORVO

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Data Sheet Rev. E August 2021 | Subject to change without notice

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ACT4910

Power Loss Protection with 6A eFuse

changes to these registers are lost when power is

recycled. The default values can be modified at the

factory

optimize

functionality

for

specific

applications. Please consult Qorvo for custom options

and minimum order quantities.

When modifying only certain bits within a register, take

care

not

inadvertently

change

other

bits.

Inadvertently changing register contents can lead to

unexpected device behavior.

State Machine

ACT4910 contains an internal state machine with seven

internal states: UV/POR, SOFT-START, NORMAL,

HEALTH CHECK, SUPPLEMENT, SHUTDOWN1, and

SHUTDOWN2.

UV/POR State

The IC enters the UV/POR state on power up. It also

enters UV/POR from SUPPLEMENT state in the

following conditions:

When the input voltage drops below the EN_UV

threshold.

When the storage capacitor voltage drops

below 3.6V.

When the buck converter output voltage goes

OV or UV.

The user may force the IC into UV/POR by writing a 1

into the FORCE_PWROFF bit, register 0x0Ah, bit 0.

When entering UV/POR from power up, all registers

reset to their default state. The registers retain their

existing values when the IC enters from SUPPLEMENT

state or from SHUTDOWN2 EFUSE. The IC transitions

to the SOFT-START state when EN pin is above 0.64V

and the input voltage is above UVLO.

SOFTSTART State

In the SOFTSTART state, the IC slowly turns on the

eFuse to minimize inrush currents. The output voltage

dV/dt ramp rate is controlled by the SS pin. The SS pin

directly controls the maximum output voltage dV/dt

while the ILIM pin indirectly controls it by limiting the

current into the output capacitance. The IC stays in the

SOFTSTART state until VIN-VOUT < 200mV and a

10ms timer times out. Note that the output voltage may

be fully charged up to VIN even though the IC in still in

the SOFTSTART state. The storage caps charge up to

the output voltage in this state.

NORMAL State

The NORMAL state is the normal operating state after

startup with no faults. The eFuse is fully on, VOUT =

VIN, and the IC provides full operating current. Note that

the IC charges the storage capacitors to their

programmed value at the beginning of NORMAL state.

HEALTH CHECK State

The HEALTH CHECK state can be considered a sub-

state of NORMAL. The IC operates identical to the

NORMAL state with the addition of activating the

circuitry that check the storage capacitor health. The IC

automatically

enters

HEALTH

STATE

every

four

minutes. The user may also manually enter this state by

writing a 1 into the FORCE_HLTHCHK bit which is bit 1

in register 0x0Ah. This bit automatically resets to 0 after

the

health

check

routine

completes.

The

automatically

exits

HEALTH

CHECK

and

enters

SUPPLEMENT state in a fault condition.

SUPPLEMENT State

The IC enters SUPPLEMENT state when it detects a

fault condition. It opens the eFuse to bi-directionally

disconnect the input from the output. It automatically

turn on the buck converter to power the output from the

storage capacitors. The following five conditions move

the IC into SUPPLEMENT state.

EN voltage below UV threshold

EN voltage above the OV threshold

Input voltage above the OV threshold

eFuse current above the OC threshold

VIN – VOUT > 560mV

SHUTDOWN1 State

SHUTDOWN1

protects

against

over

temperature

(145 °C), internal LDO failure, or boot capacitor failure.

The eFuse remains on and continues to provide power

to the output, but the boost converter is disabled. The

ADC remains on and I2C functionality is still operational.

The IC transitions to SHUTDOWN2 state if the die

temperature increases to 155°C. If transitions back to

the NORMAL state if the fault conditions go away.

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