Datasheet

1 3 5 7
9
11
13
1516
3
5 7 9 11 13 1516
1
12 bitconversionresult
16 biti/pword 16 biti/pword
12 bitconversionresult
Sampling
instance
Muxchanchange
Analogi/
CS
SCLK
SDO
SDI
MUX
Acquisition
Conversion
Conversionphase
Conversionphase
GPO
GPI
Muxchanchange
Framen Framen+1
Datawritten (thrSDI) inframenDatawritten (thrSDI) inframen-1
GPIstatusislatchedinon CSfalling
edgeandtransferredtoSDOframen
tacq
tcnv
Top
4 bit
Top
4 bit
psettlingafterChanchange
Acquisitionphase
ADS7950, ADS7951, ADS7952, ADS7953
ADS7954, ADS7955, ADS7956, ADS7957
ADS7958, ADS7959, ADS7960, ADS7961
www.ti.com SLAS605A –JUNE 2008–REVISED JANUARY 2010
DETAILED DESCRIPTION
DEVICE OPERATION
The ADS7950 to ADS7961 are 12/10/8-bit multichannel devices. Figure 45, Figure 46, Figure 47, and Figure 48
show device operation timing. Device operation is controlled with CS, SCLK, and SDI. The device outputs its
data on SDO.
Figure 45. Device Operation Timing Diagram
Each frame begins with the falling edge of CS. With the falling edge of CS, the input signal from the selected
channel is sampled, and the conversion process is initiated. The device outputs data while the conversion is in
progress. The 16-bit data word contains a 4-bit channel address, followed by a 12-bit conversion result in MSB
first format. There is an option to read the GPIO status instead of the channel address. (Refer to Table 1,
Table 2, and Table 5 for more details.)
The device selects a new multiplexer channel on the second SCLK falling edge. The acquisition phase starts on
the fourteenth SCLK rising edge. On the next CS falling edge the acquisition phase will end, and the device
starts a new frame.
The TSSOP packaged device has four General Purpose IO (GPIO) pins, QFN versions have only one GPIO.
These four pins can be individually programmed as GPO or GPI. It is also possible to use them for preassigned
functions, refer to Table 10. GPO data can be written into the device through the SDI line. The device refreshes
the GPO data on the CS falling edge as per the SDI data written in previous frame.
Similarly the device latches GPI status on the CS falling edge and outputs the GPI data on the SDO line (if GPI
read is enabled by writing DI04=1 in the previous frame) in the same frame starting with the CS falling edge.
Copyright © 2008–2010, Texas Instruments Incorporated Submit Documentation Feedback 23
Product Folder Link(s): ADS7950, ADS7951, ADS7952, ADS7953 ADS7954, ADS7955, ADS7956, ADS7957 ADS7958,
ADS7959, ADS7960, ADS7961