MAX11203 Datasheet, PDF (13/27 Pages) Maxim Integrated Products – 16-Bit, Single-Channel, Ultra-Low-Power, Delta-Sigma ADCs with Programmable Gain and GPIO

16-Bit, Single-Channel, Ultra-Low-Power, Delta-
Sigma ADCs with Programmable Gain and GPIO
MAX313
LOGIC SWITCH
0
OFF
1
ON
IN1
IN2
AIN1
IN3
AIN2
IN4
AIN3
AIN4
MAX313
COM1
COM2
COM3
COM4
GPIO1
GPIO2
GPIO3
GPIO4
MAX11203
AINP
AINN
Figure 3. MAX11203 GPIOs Drive an External 4-Channel
Switch (MAX313)
It is not always necessary to transition to a high-imped-
ance state between channel selections, but depends on
the source analog signals as well as the control structure
of the multiplexed switches.
Digital Programmable Gain (MAX11213)
The MAX11213 offers programmable gain settings that
can be digitally set to 1, 2, 4, 8, 16, 32, 64, or 128. The
DGAIN_ bits in the CTRL3 register (see Table 14) config-
ure the digital gain setting and control the input referred
gain. The MAX11213’s input range is 0V to VREF/
gain (unipolar) or ±V_REF/gain (bipolar). The MAX11213
always outputs 16 bits of data. But as this is a digital
programmable gain, the noise floor remains constant,
depending on the output rate setting. At an output rate of
10sps, as shown in Figure 4, the noise floor is such that
all gain settings from 1 to 64 provide 16 bits of noise-free
resolution. A gain setting of 128 at 10sps means the LSB
is below the noise floor. The MAX11213 digital gain is
beneficial for low-voltage applications that only require a
small portion of the 0V to VREF or ±VREF ranges.
Table 4c. Data Command to Select Channel AIN3 in Figure 3
BIT
BIT NAME
VALUE
B7
DIR4
1
B6
DIR3
1
B5
DIR2
1
B4
DIR1
1
B3
DIO4
0
B2
DIO3
1
B1
DIO2
0
B0
DIO1
0
16-BIT OUTPUT DATA CYCLE
MSB
VREF = 3V
LSB
NOISE FLOOR
REMAINS CONSTANT
AT 0.57µVRMS
SUB-LSBs
BITS USED FOR GAIN = 1
BITS USED FOR GAIN = 2
BITS USED FOR GAIN = 16
BITS USED FOR GAIN = 128
Figure 4. MAX11213 Digital Programmable Gain Example (10sps Output Rate)
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