AMC7832 Datasheet, PDF (29/70 Pages) Texas Instruments – AMC7832 12-Bit Analog Monitor and Control Solution with Multi-Channel ADC, Bipolar DACs, Temperature Sensor and GPIO Ports

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AMC7832
SLAS836 – MARCH 2014
A typical application for the bipolar channels is monitoring of the twelve DAC outputs in the device. In this
application the bipolar inputs can be driven directly. However in applications where the signal source has high
impedance, it is recommended that the analog input is buffered prior to be input to the AMC7832. When driven
from a low impedance source such as the AMC7832 DAC outputs, the network is designed to settle well before
the start of conversion. Additional impedance may affect the settling and divider accuracy of this network.
8.3.2.1.2 Unipolar Analog Inputs
In addition to the bipolar input channels, the AMC7832 includes five unipolar analog inputs. The analog input
range for these channels is 0-V to 2 × VREF with the LSB size for these channels given by 2 × VREF/4096.
The unipolar analog input conversion values are stored in straight binary format in the ADC-Data registers
(address 0x38 – 0x41). With the internal reference equal to 2.5-V the voltage value is given by,
Voltage = ^{CODE × 5}
4096
(2)
In applications where the signal source has high impedance, it is recommended that the unipolar analog input is
buffereded externally.
8.3.2.2 ADC Sequencing
The AMC7832 ADC supports two conversion methods: direct-mode and auto-mode. The conversion method can
be selected in the ADC Configuration register (address 0x10). The default conversion method is direct-mode.
In both methods, the single channel or sequence of channels to be converted by the ADC must be first
configured in the ADC MUX Configuration registers (address 0x13 – 0x15). The input channels to the ADC
include 12 external bipolar inputs, 5 external unipolar inputs and the internal temperature sensor.
In direct-mode conversion, the selected ADC input channels are converted on demand by issuing an ADC trigger
signal. After the last enabled channel is converted, the ADC goes into idle state and waits for a new trigger.
In auto-mode conversion, the selected ADC input channels are converted continuously. The conversion cycle is
initiated by issuing an ADC trigger. Upon completion of the first conversion sequence another sequence is
automatically started. Conversion of the selected channels is done repeatedly until the auto-mode conversion is
stopped by issuing a second trigger signal. To ensure data for all channels is updated correctly in the ADC data
registers the auto-mode conversion stop trigger should be synchronized with the data available indicator signal
(DAV, terminal 12).
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