4 Application information

STw4141

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4.4

External clock synchronization

Figure 14. Application using external clock synchronization

4.5

Checking Transient response versus external components

The regulator loop response can be checked by looking at the load transient response.

Switching regulators take several cycles to respond to a step in load current. When a load step

value. In order to improve the transient response, it is better to use two 10

µF ceramic

capacitors on each output to reduce ESR.

4.6

Bill of Material

4.6.1

Inductor selection

The choice of which inductor to use depends on the price and size versus performance

required with the STw4141 application.

Table 9 shows some typical surface mount inductors

that work well in STw4141 applications.

Table 9.

Bill of material: inductor selection

Part number

Supplier

Value

(µH)

DCR

( max)

Max DC

current (mA)

Size (mm)

W x L x H

VFL4012A-4R7M1R1

TDK

4.7

0.14

1100

3.5 x 3.7 x 1.2

VFL3012A-4R7MR74

TDK

4.7

0.16

740

2.6 x 2.8 x 1.2

744031004

WUERTH

4.7

0.085

900

3.8 x 3.8 x 1.8

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

C

1

100 nF

C

2

100 nF

MODE_INFO

CLK

SLEEP

AUTO

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

C

1

100 nF

C

2

100 nF

MODE_INFO

CLK

SLEEP

AUTO