TLC320AD50C-I Datasheet, PDF (31/53 Pages) Texas Instruments – SIGMA-DELTA ANALOG INTERFACE CIRCUITS WITH MASTER-SLAVE FUNCTION

3.2.1 Hardware Secondary Serial Communication Request
The FC requests a secondary communication when it is asserted. The FC terminal is latched at the rising edge of
FS (primary communication), so FC should be pulled high before the rising edge of the primary frame sync (FS).
Figures 3–3 and 3–4 show the FS output from a master device.
FS
P
S
Secondary
Request
P
No Secondary
Request
FC
DOUT
ADC Data Out
Register
Read/Write
ADC Data Out
DIN
DAC Data In
Register
Read/Write
DAC Data In
Figure 3–3. FS Output When Hardware Secondary Serial Communication Is Requested Only Once
(No Slave)
P
FS
(Master)
M
FC
(See Note)
P
P
P
S1
S2
S3
S
S
S
S
P
M
S1
S2
S3
M
NOTE: FC of master device and slave devices should connect together.
Figure 3–4. FS Output When Hardware Secondary Serial Communication Is Requested Only Once
(Three Slaves)
3.2.2 Software Secondary Serial Communication Request
The LSB of the DAC data within a primary transfer can request a secondary communication when the device is in
the 15-bit mode.
For all serial communications, the most significant bit is transferred first. For a 16-bit ADC word and a 16-bit DAC word,
D15 is the most significant bit and D0 is the least significant bit. For a 15-bit DAC data word in a primary
communication, D15 is the most significant bit and D1 is the least significant bit. Bit D0 is then used for the secondary
communication request control. All digital data values are in 2s complement data format (Figure 3–5).
If the data format is set to the 16-bit word mode, all 16 bits are either ADC or DAC data and secondary communication
can then be requested only by hardware (FC terminal).
P
S
P
FS
DIN
Data (D0 = 1)
Register
Read/Write
Data (D0 = 0)
Secondary Communication Request
No Secondary Communication Request
NOTE: See Figure 3–8 for secondary communication DIN data format.
Figure 3–5. FS Output During Software Secondary Serial Communication Request (No Slave)
3–3