Datasheet

MCP3909
DS22025C-page 28  2006-2012 Microchip Technology Inc.
FIGURE 5-5: Dual Channel Output Mode.
5.6 Filter Input Mode
The filter input mode allows the user to feed the
MCP3909 device an input to the LPF1. Data is
received MSB first. The MCP3909 will treat this data
as if it were the output of the multiplier and will LPF
and D-F the result as normal, giving the resulting out-
put frequency on HF
OUT
, F
OUT0
and F
OUT1
. See
Tables 4-2 and 4-3 for transfer functions of the output
frequencies.
When using filter input mode, the user must wait for
the data ready flag (DR) to appear on SDO before
attempting to clock in data to the device. The user can
not access either the multiplier output or the dual
channel output while in this mode.
FIGURE 5-6: Filter Input Mode.
D15
D14
D1 D0
Hi-z
Hi-z
D16D17
1
215
17 18 31 32
Hi-z
X 32
X 32
16
DR D30D31
F1 / SDI
F2 / SCK
NEG / SDO
F0 / CS
X 16
X 16
X 16
X 16
Channel 1
Channel 0
D3 D2 D1 D0
Hi-z
D16D18
D17
1
23
17 18 19 20
X 20
X 20
4
D19
Hi-z
DR
F1 / SDI
F2 / SCK
NEG / SDO
F0 / CS