Datasheet

21Maxim Integrated
18-Bit, Single-Channel, Ultra-Low-Power, Delta-
Sigma ADCs with Programmable Gain and GPIO
MAX11209/MAX11211
DATA: Data Register
The data register is a 24-bit read-only register. Any attempt to write data to the data register has no effect. The data
read from this register is clocked out MSB first. The data register holds the conversion result. D17 is the MSB, and D0
is the LSB. The result is stored in a format according to the FORMAT bit in the CTRL1 register.
The data format while in unipolar mode is always straight binary. In straight binary format, the most negative value is
0x00000 (V
AINP
- V
AINN
= 0V), the midscale value is 0x20000 (V
AINP
- V
AINN
= V
REF
/2), and the most positive value
is 0x3FFFF (V
AINP
- V
AINN
= V
REF
).
In bipolar mode, if the FORMAT bit = 1, then the data format is offset binary. If the FORMAT bit = 0, then the data
format is two’s complement. In two’s complement the negative full-scale value is 0x20000 (V
AINP
- V
AINN
= -V
REF
), the
midscale is 0x00000 (V
AINP
- V
AINN
= 0V), and the positive full scale is 0x1FFFF (V
AINP
- V
AINN
= V
REF
). Any input
exceeding the available input range is limited to the minimum or maximum data value.
Table 15. DATA Register (Read Only)
Table 16a. Output Data Format for the Unipolar Input Range
BIT D17 D16 D15 D14 D13 D12 D11 D10
DEFAULT
0 0 0 0 0 0 0 0
BIT D9 D8 D7 D6 D5 D4 D3 D2
DEFAULT
0 0 0 0 0 0 0 0
BIT D1 D0
0 0 0 0 0 0
DEFAULT
0 0 0 0 0 0 0 0
INPUT VOLTAGE
V
AINP
- V
AINN
DIGITAL OUTPUT CODE FOR UNIPOLAR RANGE
STRAIGHT BINARY FORMAT
≥ V
REF
0x3FFFF
0x3FFFF
0x00001
0 0x00000
REF
18
1
V1
21

×−

 −
REF
18
V
21−