STw4141

4 Application information

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4.2

Automatic PWM/PFM mode

This user mode is designed to allow STw4141 to switch automatically between PWM and PFM

modes. This feature improves the application efficiency because STw4141 enters in PFM mode

according to application processor current consumption.

Figure 12. Automatic PWM/PFM switch schematic example

4.3

User selected PWM/PFM mode

STw4141 PWM/PFM mode can also be controlled by the application processor. This feature is

accessible through MODE/SYNC pin state. It is useful to users who want to use STw4141 with

the modem digital processor. Therefore, MODE/SYNC pin is connected to SLEEP mobile

phone signal.

Figure 13. PWM/PFM forced mode schematic example

V

VOUT1

FB1

C

OUT1

22 µF

6.3 V

VOUT2

FB2

C

OUT2

22 µF

6.3 V

PVDD

C

IN

10 µF

6.3 V

PGND

VDD

EN

VLX1

VLX2

GND

MODE/SYNC

T_MODE

L 4.7 µH

STw4141

VSEL

STATE

B1

D3

D4

C2

C3

C1

A4

D1

B4

D2

B2

A2

A3

A1

B3

C4

APE I/O

APE CORE

GND

APPLICATION

PROCESSOR

MODE_INFO

SLEEP

AUTO

C

1

100 nF

C

2

100 nF

V

VOUT1

FB1

C

OUT1

22 µF

6.3 V

VOUT2

FB2

C

OUT2

22 µF

6.3 V

PVDD

C

IN

10 µF

6.3 V

PGND

VDD

EN

VLX1

VLX2

GND

MODE/SYNC

T_MODE

L 4.7 µH

STw4141

VSEL

STATE

B1

D3

D4

C2

C3

C1

A4

D1

B4

D2

B2

A2

A3

A1

B3

C4

APE I/O

APE CORE

GND

APPLICATION

PROCESSOR

MODE_INFO

SLEEP

AUTO

C

1

100 nF

C

2

100 nF

V

VOUT1

FB1

C

OUT1

22 µF

6.3 V

VOUT2

FB2

C

OUT2

22 µF

6.3 V

PVDD

C

IN

10 µF

6.3 V

PGND

VDD

EN

VLX1

VLX2

GND

MODE/SYNC

T_MODE

L 4.7 µH

STw4141

VSEL

STATE

B1

D3

D4

C2

C3

C1

A4

D1

B4

D2

B2

A2

A3

A1

B3

C4

APE I/O

APE CORE

GND

APPLICATION

PROCESSOR

MODE_INFO

SLEEP

AUTO

PWR_EN

C

1

100 nF

C

2

100 nF

V

VOUT1

FB1

C

OUT1

22 µF

6.3 V

VOUT2

FB2

C

OUT2

22 µF

6.3 V

PVDD

C

IN

10 µF

6.3 V

PGND

VDD

EN

VLX1

VLX2

GND

MODE/SYNC

T_MODE

L 4.7 µH

STw4141

VSEL

STATE

B1

D3

D4

C2

C3

C1

A4

D1

B4

D2

B2

A2

A3

A1

B3

C4

APE I/O

APE CORE

GND

APPLICATION

PROCESSOR

MODE_INFO

SLEEP

AUTO

PWR_EN

C

1

100 nF

C

2

100 nF