ACT41000-104 datasheet(26/72 Pages) QORVO

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ACT41000

Programmable Voltage, Programmable Current, Low Noise

RFPoL Step-Down Voltage Regulator

Mini-buck Regulator

Most of ACT41000 device circuit blocks are designed to operate under a 5 V supply from the V5V pin and this 5 V mini-buck

switching regulator generates the 5 V bias at the VO(V5V) target. The mini-buck employs an internally compensated, constant

ON time (COT) control.

The mini-buck supplies up to 350 mA of output current by step-down converting power from the VIN pin.

From the SW5V pin to the GND5V pin, a Mini-buck LC Output Filter is required. The output of this LC filter is connected to

the V5V pin.

Figure 48. Mini-buck Regulator with an LC Output Filter

The V5V pin is the supply of control circuits in the Main-buck Regulator and characterized at 5.0 V. The

device is designed to be functional down to the VUVP(V5V) threshold but near 4 V supply may not deliver its

full performance. A short event at the V5V pin may cause a potential damage.

Mini-buck Enable

The mini-buck regulator generates a fundamental 5 V bias supply of the entire device operation, by default, the Control

Logic state-machine enables the mini-buck as soon as both Under-Voltage Lock-Out and Over-Voltage Lock-Out are

released. And the mini-buck keeps ON all the time.

V5V, External 5V Supply

When there is a 5 V power supply always available in target systems, the mini-buck can be disabled by setting the I

Reg09[1] to logic-L to save power loss from its switching.

Mini-buck Power-Good

Whether the mini-buck is enabled or disabled, there is a voltage comparator monitoring the V5V pin to the VIT(V5V) target.

See PGBIAS Indicator Output.

Mini-buck Soft-start

The mini-buck regulator executes a soft-start (slow-start) operation when enabled so to avoid in-rush current. This soft-

start time is specified by the tSS(V5V) parameter and the device sweep its internal reference voltage from 0% to 100% in the

tSS(V5V) period.

During this soft-start period, the mini-buck forces to use, so called, pulse-skip operation so to achieve smooth ramp up of

the output voltage and it ignores the I

2C Reg0F[5] setting.

Mini-buck Start-up into Pre-biased Output

The mini-buck supports a start-up into a pre-biased output without any huge discharge current from the output.

Without this feature, a regulator circuit may discharge huge amount of current from its output capacitance so to force the

output voltage closer to a reference voltage target of its soft-start operation during the internal reference voltage is lower

than the pre-biased output by starting from 0%.

See Mini-buck Soft-start.

By preventing its switching operation until the reference target of the soft-start reaches to its pre-biased level, the ACT41000

device avoids the discharge event and achieves a smooth ramp up of the 5 V bias.

ACT41000 Data Sheet, Rev. B, 01-Apr-2022

Subject to change without notice

ACT41000-104 데이터시트(PDF) 26 Page - Qorvo, Inc