Datasheet

ADC12130, ADC12132, ADC12138

SNAS098G –MARCH 2000–REVISED MARCH 2013

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2.0 THE ANALOG MULTIPLEXER

For the ADC12138, the analog input multiplexer can be configured with 4 differential channels or 8 single ended

channels with the COM input as the zero reference or any combination thereof (see Figure 67). The difference

between the voltages at the V

REF

and V

REF

−

pins determines the input voltage span (V

REF

). The analog input

voltage range is 0 to V

. Negative digital output codes result when V

−

> V

. The actual voltage at V

−

or V

cannot go below AGND.

8 Single-Ended Channels

4 Differential with COM

Channels as Zero Reference

Figure 67. Input Multiplexer Options

Differential Single-Ended

Configuration Configuration

A/DIN1 and A/DIN2 can be assigned as the + or − input

A/DIN1 is + input

A/DIN2 is − input

Figure 68. MUXOUT connections for multiplexer option

CH0, CH2, CH4, and CH6 can be assigned to the MUXOUT1 pin in the differential configuration, while CH1,

CH3, CH5, and CH7 can be assigned to the MUXOUT2 pin. In the differential configuration, the analog inputs

are paired as follows: CH0 with CH1, CH2 with CH3, CH4 with CH5 and CH6 with CH7. The A/DIN1 and A/DIN2

pins can be assigned positive or negative polarity.

With the single-ended multiplexer configuration, CH0 through CH7 can be assigned to the MUXOUT1 pin. The

COM pin is always assigned to the MUXOUT2 pin. A/DIN1 is assigned as the positive input; A/DIN2 is assigned

as the negative input. (See Figure 68).

The Multiplexer assignment tables for these ADCs (Table 2 and Table 3) summarize the aforementioned

functions for the different versions of ADCs.

2.1 Biasing for Various Multiplexer Configurations

Figure 69 is an example of device connections for single-ended operation. The sign bit is always low. The digital

output range is 0 0000 0000 0000 to 0 1111 1111 1111. One LSB is equal to 1 mV (4.1V/4096 LSBs).

Product Folder Links: ADC12130 ADC12132 ADC12138