Texas Instruments ADS79 EVM-PDK Series, Руководство пользователя

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ADS7950, ADS7951, ADS7952, ADS7953, ADS7954, ADS7955
ADS7956, ADS7957, ADS7958, ADS7959, ADS7960, ADS7961
www.ti.com SLAS605C – JUNE 2008 – REVISED JULY 2018
Product Folder Links: ADS7950 ADS7951 ADS7952 ADS7953 ADS7954 ADS7955 ADS7956 ADS7957 ADS7958
ADS7959 ADS7960 ADS7961
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Table 6. Program Register Settings for Auto-2 Mode
BITS
RESET
STATE LOGIC
STATE
FUNCTION
DI15-12 NA 1001 Auto-2 program register is selected for programming
DI11-10 NA Do not care
DI09-06 NA aaaa This 4-bit data represents the address of the last channel in the scanning sequence. During device
operation in Auto-2 mode, the channel counter starts at CH-00 and increments every frame until it
equals “aaaa”. The channel counter roles over to CH-00 in the next frame.
DI05-00 NA Do not care
8.4.7 Continued Operation in a Selected Mode
Once a device is programmed to operate in one of the modes, the user may want to continue operating in the
same mode. Mode Control Register settings to continue operating in a selected mode are detailed in
Table 7 .
Table 7. Continued Operation in a Selected Mode
BITS
RESET
STATE LOGIC
STATE
FUNCTION
DI15-12 0001 0000 The device continues to operate in the selected mode. In Auto-1 and Auto-2 modes the channel
counter increments normally, whereas in the Manual mode it continues with the last selected
channel. The device ignores data on DI11-DI00 and continues operating as per the previous
settings. This feature is provided so that SDI can be held low when no changes are required in the
Mode Control Register settings.
DI11-00 All '0' Device ignores these bits when DI15-12 is set to 0000 logic state
8.5 Programming
8.5.1 Digital Output
As discussed previously in Overview , the digital output of the ADS79xx devices is SPI compatible. The following
tables list the output codes corresponding to various analog input voltages.
Table 8. Ideal Input Voltages for 12-Bit Devices and Output Codes for 12-Bit Devices (ADS7950/51/52/53)
DESCRIPTION ANALOG VALUE DIGITAL OUTPUT
Full scale range Range 1 → V
REF
Range 2 → 2×V
REF
STRAIGHT BINARY
Least significant bit (LSB) V
REF
/ 4096 2V
REF
/ 4096 BINARY CODE HEX CODE
Full scale V
REF
– 1 LSB 2V
REF
– 1 LSB 1111 1111 1111 FFF
Midscale V
REF
/ 2 V
REF
1000 0000 0000 800
Midscale – 1 LSB V
REF
/ 2 – 1 LSB V
REF
– 1 LSB 0111 1111 1111 7FF
Zero 0 V 0 V 0000 0000 0000 000
Table 9. Ideal Input Voltages for 10-Bit Devices and Digital Output Codes for 10-Bit Devices
(ADS7954/55/56/57)
DESCRIPTION ANALOG VALUE DIGITAL OUTPUT
Full scale range Range 1 → V
REF
Range 2 → 2×V
REF
STRAIGHT BINARY
Least significant bit (LSB) V
REF
/ 1024 2V
REF
/ 1024 BINARY CODE HEX CODE
Full scale V
REF
– 1 LSB 2V
REF
– 1 LSB 0011 1111 1111 3FF
Midscale V
REF
/ 2 V
REF
0010 0000 0000 200
Midscale – 1 LSB V
REF
/ 2 – 1 LSB V
REF
– 1 LSB 0001 1111 1111 1FF
Zero 0 V 0 V 0000 0000 0000 000