AN2512 datasheet(21/38 Pages) STMICROELECTRONICS

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AN2512

Layout rules

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Layout rules

Noise rejection is the main issue to work on when a three-phase multi-chip approach has

been chosen. In this case layout plays a crucial role.

Here some rules to follow in layout phase:

●

Components positioning

The components of measuring section (STPM01, Current Transformers, passive

components) are placed using the same layout for each phase. The phases are placed in a

symmetrical scheme. In this way reduction of the cross talking can be achieved.

The Current transformer is placed very close to the correspondent STPM01 to minimize the

captured noise.

●

Components routing

The passive components belonging to the analogue input channels must be placed between

the sensor and the STPM01 always respecting a symmetrical scheme.

Particular care should be given for the voltage channel path because the voltage inputs are

normally relatively further from the corresponding STPM01.

●

Quartz

The crystal network has been placed in the middle of the board ensuring a completely

symmetrical path between the devices. A copper plate has been used under the Crystal

both on the TOP and on the BOTTOM side of PCB.

●

Copper plate

The copper plate area should be extended under the entire digital section and under the

crystal oscillator which provides the clock for the three STPM01.

AN2512 Datasheet(PDF) 21 Page - STMicroelectronics