AMC7836 Datasheet, PDF (29/88 Pages) Texas Instruments – AMC7836 High-Density, 12-Bit Analog Monitor and Control Solution With Multichannel ADC, Bipolar DACs, Temperature Sensor, and GPIO Ports

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AMC7836
SLAS986C – NOVEMBER 2014 – REVISED APRIL 2016
7.3.2 Analog-to-Digital Converter (ADC)
The AMC7836 features a monitoring system centered on a 12-bit SAR (successive approximation register) ADC
fronted by a 22-channel multiplexer and an on-chip track-and-hold circuit. The monitoring systems is capable of
sensing up to 16 external bipolar inputs (–12.5 to 12.5 V range), five external unipolar inputs (0 to 5 V range),
and an internal analog temperature sensor.
The ADC operates from an internal 2.5 V reference (V_ref, measured at the REF_CMP pin) and the input range is
0 V to 2 × V_ref. The external bipolar inputs to the ADC are internally mapped to this range. The ADC timing
signals are derived from an on-chip temperature-compensated oscillator. The conversion results can be
accessed through the device serial interface.
7.3.2.1 Analog Inputs
The AMC7836 has 21 analog inputs for external voltage sensing. Sixteen of these inputs (ADC_0 through
ADC_15) are bipolar and the other five (LV_ADC16 through LV_ADC20) are unipolar. Figure 51 shows the
equivalent circuit for the external analog-input pins. All switches are open while the ADC is in the IDLE state.
Scaling Network
3.125 V
ADC_0
3.125 V
R(MUX)
S(W)
RS
C(SAMPLE)
S(W) is closed during acquisition.
S(W) is open during conversion.
ADC_15
AVDD
LV_ADC16
AVDD
LV_ADC20
AGND
Figure 51. ADC External Inputs Equivalent Circuit
To achieve the specified performance, especially at higher input frequencies, driving each analog input pin with a
low impedance source is recommended. An external amplifier can also be used to drive the input pins.
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