ADC121C021CIMKX NSC [National Semiconductor], ADC121C021CIMKX Datasheet - Page 16

• Manufacturer Part Number: ADC121C021CIMKX
• Description: I2C-Compatible, 12-Bit Analog-to-Digital Converter (ADC) with Alert Function
• Manufacturer: NSC [National Semiconductor]

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1.6 INTERNAL REGISTERS
The ADC121C021 is equipped with 8 internal data registers
and one address pointer register. The registers provide addi-
tional ADC functions such as storing minimum and maximum
conversion results, setting alert threshold levels, and storing
data to configure the operation of the device. Figure 6 shows
all of the registers and their corresponding address pointer
values. All of the registers are read/write capable except the
conversion result register which is read-only.
1.6.2 Conversion Result Register
Pointer Address 00h (Read Only)
Default Value: 0000h
Alert Flag
D15
D7
FIGURE 6. Register Structure
D14
D6
Reserved
D13
D5
Conversion Result[7:0]
D12
30020969
D4
16
1.6.1 Address Pointer Register
The address pointer register controls which of the data reg-
isters is accessed by the I
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 relevant. The other bits must always be written as
zeros. After a power-on reset, the pointer register defaults to
all zeros (conversion result register).
Default Value: 00h
P2
P7
0
0
0
0
1
1
1
1
D11
0
D3
P1
P6
0
0
1
1
0
0
1
1
0
Conversion Result[11:8]
P5
P0
0
0
1
0
1
0
1
0
1
D10
D2
P4
0
Highest Conversion (read/write)
Lowest Conversion (read/write)
2
Conversion Result (read only)
C interface. The first data byte of
Configuration (read/write)
Alert Status (read/write)
Hysteresis (read/write)
High Limit (read/write)
Low Limit (read/write)
P3
0
D9
D1
REGISTER
P2
Register Select
P1
D8
D0
P0