Datasheet

ADS1255
ADS1256
SBAS288K − JUNE 2003 − REVISED SEPTEMBER 2013
www.ti.com
31
MUX : Input Multiplexer Control Register (Address 01h)
Reset Value = 01h
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
PSEL3 PSEL2 PSEL1 PSEL0 NSEL3 NSEL2 NSEL1 NSEL0
Bits 7-4 PSEL3, PSEL2, PSEL1, PSEL0: Positive Input Channel (AIN
P
) Select
0000 = AIN0 (default)
0001 = AIN1
0010 = AIN2 (ADS1256 only)
0011 = AIN3 (ADS1256 only)
0100 = AIN4 (ADS1256 only)
0101 = AIN5 (ADS1256 only)
0110 = AIN6 (ADS1256 only)
0111 = AIN7 (ADS1256 only)
1xxx = AINCOM (when PSEL3 = 1, PSEL2, PSEL1, PSEL0 are “don’t care”)
NOTE: When using an ADS1255 make sure to only select the available inputs.
Bits 3-0 NSEL3, NSEL2, NSEL1, NSEL0: Negative Input Channel (AIN
N
)Select
0000 = AIN0
0001 = AIN1 (default)
0010 = AIN2 (ADS1256 only)
0011 = AIN3 (ADS1256 only)
0100 = AIN4 (ADS1256 only)
0101 = AIN5 (ADS1256 only)
0110 = AIN6 (ADS1256 only)
0111 = AIN7 (ADS1256 only)
1xxx = AINCOM (when NSEL3 = 1, NSEL2, NSEL1, NSEL0 are “don’t care”)
NOTE: When using an ADS1255 make sure to only select the available inputs.
ADCON: A/D Control Register (Address 02h)
Reset Value = 20h
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
0 CLK1 CLK0 SDCS1 SDCS0 PGA2 PGA1 PGA0
Bit 7 Reserved, always 0 (Read Only)
Bits 6-5 CLK1, CLK0: D0/CLKOUT Clock Out Rate Setting
00 = Clock Out OFF
01 = Clock Out Frequency = f
CLKIN
(default)
10 = Clock Out Frequency = f
CLKIN
/2
11 = Clock Out Frequency = f
CLKIN
/4
When not using CLKOUT, it is recommended that it be turned off. These bits can only be reset using the RESET
pin.
Bits 4-2 SDCS1, SCDS0: Sensor Detect Current Sources
00 = Sensor Detect OFF (default)
01 = Sensor Detect Current = 0.5μA
10 = Sensor Detect Current = 2μA
11 = Sensor Detect Current = 10μA
The Sensor Detect Current Sources can be activated to verify the integrity of an external sensor supplying a signal to the
ADS1255/6. A shorted sensor produces a very small signal while an open-circuit sensor produces a very large signal.
Bits 2-0 PGA2, PGA1, PGA0: Programmable Gain Amplifier Setting
000 = 1 (default)
001 = 2
010 = 4
011 = 8
100 = 16
101 = 32
110 = 64
111 = 64