Datasheet

 2006-2012 Microchip Technology Inc. DS22025C-page 25
MCP3909
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 F
OUT0
, F
OUT1
, and HF
OUT
. 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 Ta bl e 5-1.
D3 D2 D1 D0
D5 D4D7 D6
1
23
45678
MCLR
t
WINSET
t
WINDOW
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)
F2 F1 F0
1 0 1 0 0 0 0 1 Multiplier Output 0 F1 pin 1
1 0 1 0 1 0 0 1 Multiplier Output 1 F1 pin 1
1 0 1 0 0 1 0 0 Dual Channel Output Pre HPF1 0 F1 pin 1
1 0 1 0 1 1 0 0 Dual Channel Output Post HPF1 1 F1 pin 1
1 0 1 0 1 0 1 0 Filter Input 1 0 F0 pin
1 0 1 0 1 1 1 0 Filter Input 1 1 F0 pin
1 0 1 0 0 0 1 0 Filter Input 0 0 F0 pin
1 0 1 0 0 1 1 0 Filter Input 0 1 F0 pin
Note 1: The active power frequency outputs F
OUT0
, F
OUT1
, and HF
OUT
remain active after serial mode entry. Leav-
ing 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.