MCP3909 datasheet(26/44 Pages) MICROCHIP

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MCP3909

DS22025B-page 26

FIGURE 5-3:

Dual Functionality Pin Serial Mode Entry Protocol.

5.2

Serial Mode Entry Codes

The MCP3909 devices contains three different serial

modes with data presented in 2's complement coding.

• Multiplier Output

• Dual Channel Output

•Filter Input

After entering any of these modes the active power

calculation block is still functional and presents output

pulses on FOUT0, FOUT1, and HFOUT. For this reason,

the F2, F1, F0 output frequency selection constant can

be changed with multiple command bytes for serial

mode entry.

The command bytes to enter these modes are

described in Table 5-1.

D3 D2 D1 D0

D5 D4

D7 D6

MCLR

tWINSET

tWINDOW

F1 / SDI

F2 / SCK

F0 / CS

TABLE 5-1:

ENTRY CODES

Command

D7......D0

Serial Mode

Internal State of F2, F1, F0 Constants Frequency

Selection During Serial Mode (1)

1 0 1 0 0 0 0 1

Multiplier Output

F1 pin

1 0 1 0 1 0 0 1

Multiplier Output

F1 pin

1 0 1 0 0 1 0 0

Dual Channel Output Pre HPF1

F1 pin

1 0 1 0 1 1 0 0

Dual Channel Output Post HPF1

F1 pin

1 0 1 0 1 0 1 0

Filter Input

F0 pin

1 0 1 0 1 1 1 0

Filter Input

F0 pin

1 0 1 0 0 0 1 0

Filter Input

F0 pin

1 0 1 0 0 1 1 0

Filter Input

F0 pin

Note 1: The active power frequency outputs FOUT0, FOUT1, and HFOUT remain active after serial mode entry.

Leaving the SDI (F1) and CS (F0) pins at a known state after serial communication will control the

frequency selection. The HPF pin controls the state of the HPF for the multiplier mode output and the

output pulses from the active power D to F block.

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