ADC121C021_15 Datasheet, PDF (18/44 Pages) Texas Instruments – 12-Bit Analog-to-Digital Converter with Alert Function

ADC121C021, ADC121C021Q, ADC121C027
SNAS415F – JANUARY 2008 – REVISED MARCH 2013
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Address Pointer Register
The address pointer determines which of the data registers is accessed by the I²C interface. The first data byte
of every write operation is stored in the address pointer register. This value selects the register that the following
data bytes will be written to or read from. Only the three LSBs of this register are variable. The other bits must
always be written to as zeros. After a power-on reset, the pointer register defaults to all zeros (conversion result
register).
Default Value: 00h
P7
P6
P5
P4
P3
P2
P1
P0
0
0
0
0
0
Register Select
P2
P1
P0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
REGISTER
Conversion Result (read only)
Alert Status (read/write)
Configuration (read/write)
Low Limit (read/write)
High Limit (read/write)
Hysteresis (read/write)
Lowest Conversion (read/write)
Highest Conversion (read/write)
Conversion Result Register
This register holds the result of the most recent conversion. In the normal mode, a new conversion is started
whenever this register is read. The conversion result data is in straight binary format with the MSB at D11.
Pointer Address 00h (Read Only)
Default Value: 0000h
D15
D14
D13
D12
Alert Flag
Reserved
D11
D10
D9
D8
Conversion Result [11:8]
D7
D6
D5
D4
D3
D2
D1
D0
Conversion Result [7:0]
Bits
Name
15
Alert Flag
14:12
11:0
Reserved
Conversion Result
Description
This bit indicates when an alert condition has occurred. When the Alert Bit Enable is set in the
Configuration Register, this bit will be high if either alert flag is set in the Alert Status Register.
Otherwise, this bit is a zero. The I²C controller will typically read the Alert Status register and other data
registers to determine the source of the alert.
Always reads zeros.
The Analog-to-Digital conversion result. The Conversion result data is a 12-bit data word in straight
binary format. The MSB is D11.
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