BD9528AMUV Datasheet, PDF(26/30 Page) Rohm – High Performance Regulators for PCs Main Power Supply for Notebook PCs(With Built-in Linear Regulator)

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BD9528AMUV Datasheet, PDF (26/30 Pages) Rohm – High Performance Regulators for PCs Main Power Supply for Notebook PCs(With Built-in Linear Regulator)

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BD9528AMUV

âExample of PCB layout

Technical Note

Vo1

âSilentâGND

H-FET

(CH1)

High current GND

VIN

H-FET

(CH2)

High current GND

PGND1

LG1

Vo1

REG2

REG1

VIN

LG2

PGND2

MCTL2

FS1

FB1

AGND

REF

FB2

FS2

CTL

âSilentâGND

Vo2

â Because high pulse current rush into power loop, consisted of input capacitor Cin, output inductor L and output

capacitor Co, this part layout should be built at parts side (upper side) including GND pattern.

Also, drawing via formation in power loop line should be avoided.

(The reason is that it will be a factor of noise because via oneself holds some nH parasitic inductance)

â¡ FB pin has comparatively high impedance, so floating capacity should be minimum as possible.

And feedback wiring from output should be taken properly, and shielding, not going through around L (because of

magnetic). Please be careful in drawing.

â¢ Trace from SW node pin to inductor should be cut short. And both inductor element pattern should be kept away.

(Closer wiring has SW node noise influence Vo by parasitic capacity between wiring). This layout example shows that

SW node is outside, but if the application board will be like that, SW node should be shielded.

Please consider the influence to other circuit.

â£ Input capacitor Cin should be placed close to IC with low inductance.

If that is difficult, please place a capacitor for high frequency removal with PKG size small like 0.1uF (ESL small).

â¤ 2nd layer and 3rd layer are plain GND, so connect from parts side GND to plain GND by low impedance with many via as

possible. Inner GND is only for shielding, so that no to form loop for high current.

â¥ Please take GND pattern space widely, and design layout to be able to increase radiation efficiency.

â¦ FS pin and ILIM pin has high impedance. External resistor should be connected to âSilent GNDâ.

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2011.11 - Rev.A

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