ACT41000-102 datasheet(27/72 Pages) QORVO

27 / 72 page

ACT41000

Programmable Voltage, Programmable Current, Low Noise

RFPoL Step-Down Voltage Regulator

Mini-buck Switching Operations

Mini-buck Forced Continuous Conduction Operation

By setting I

2C Reg0F[5] to Logic-H, the device operates in a forced continuous conduction mode (FCCM). With this FCCM

operation, the regulator maintains its switching frequency to meet the fSW(V5V) target. This fSW(V5V) parameter ensures that

its operation frequency do not interfere with AM radio frequency by staying above the AM band.

Mini-buck Pulse-skip Operation

By setting I

2C Reg0F[5] to Logic-L, the device operates in a pulse-skipping mode, or so-called, in a light-load efficiency

mode.

When its load current goes low, the inductor (coil) current starts flowing in reverse direction (negative current). As the

regulator detects continuous reverse current flow cycles, it activates the pulse-skip operation by blocking the reverse current

flow.

By blocking a reverse current flow, an energy amount delivered during one switching period is bigger than the one period

energy amount of FCCM operation and the output has a bigger ripple voltage. This bigger ripple results in less switching

events to reduce power loss related to a switching action. So it improves its conversion efficiency.

During this pulse-skip operation, its switching frequency may stay inside AM radio frequency band.

Mini-buck 100% Duty Operation

When the VIN pin voltage is close to the target output voltage VO(V5V), the mini-buck gets into 100% duty mode by setting

2C Reg0F[7].

Without this 100% duty mode (disabled), the device is designed to output a minimum OFF period at each cycle, even

though its internal PWM comparator continuously demands more ON duty. This minimum OFF pulse helps to stay at its

target switching frequency but it is not desirable when the input voltage is very close to the output as the output voltage

starts dropping.

When the 100% duty mode is enabled, the device stops forcing the minimum OFF pulse and the high-side FET maintains

ON for multiple cycles without turning OFF as long as the PWM comparator indicates low feedback voltage. This 100% duty

operation helps bringing the output voltage close to the input.

Reg03[5] is set logic-H to indicate that the regulator is in 100% duty operation.

This 100% duty operation lowers its switching frequency and may stay at AM radio frequency band.

Mini-buck Spread-spectrum Operation

The mini-buck provides a spread-spectrum switching frequency control by setting I

2C Reg0F[6].

By activating the spread-spectrum function, the regulator modulates its switching frequency in the range of the fSPSP(V5V)

parameter and it repeats this frequency dithering action by the NSPSP(V5V) times of switching period. The spread-spectrum

operation improves its EMI performance by lowering noise peaks.

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

Subject to change without notice

ACT41000-102 Datasheet(PDF) 27 Page - Qorvo, Inc