AMC7812SPAPR Datasheet, PDF (34/92 Pages) Texas Instruments – 12-Bit Analog Monitoring and Control Solution with Multichannel ADC, DACs, and Temperature Sensors

AMC7812
SBAS513E – JANUARY 2011 – REVISED SEPTEMBER 2013
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Data Available Pin (DAV)
DAV is an output pin that indicates the completion of ADC conversions. The DAVF bit in AMC Configuration
Register 0 determines the status of the DAV pin. In direct mode, after the selected group of input channels have
been converted and the ADC has been stopped, the DAVF bit is set to '1' and the DAV pin is driven to logic low
(active). In ADC auto mode, each time the group of input channels have been sequentially converted, a 1µs
pulse (low) appears on the DAV pin.
Convert Pin (CNVT)
CNVT is the input pin for the external ADC trigger signal. ADC channel conversions begin on the falling edge of
the CNVT pulse. If a CNVT pulse occurs when the ADC is already converting, then the ADC continues
conversion of the current channel. After the completion of the current channel, the existing conversion cycle
finishes and a new conversion cycle starts. The selected channels specified in the ADC Channel Registers are
converted sequentially in order of enabled channels.
Analog Input Out-of-Range Detection (see the Analog Input Out-of-Range Alarm Section)
The analog inputs of CH0 to CH3 and the temperature inputs are implemented with out-of-range detection. When
any one of them is out of the preset range, the corresponding alarm flag in the Status Register is set. If any
inputs are out of range, the global out-of-range pin (ALARM) goes low. To avoid a false alarm, the device is
implemented with false-alarm protection. See the Alarm Operation section for more details.
Full-Scale Range of the Analog Input
The Gain bit of the ADC Gain Register determines the full-scale range of the analog input. Full-scale range is
V_REF when ADGn = 0, or (2 · V_REF) when ADGn = 1. If a channel pair is configured for differential operation, the
input ranges are either ±V_REF or ±(2 · V_REF). In (2 · V_REF) mode, the input is effectively divided by two before the
conversion takes place. Each input must not exceed the supply value of AV_DD + 0.2V or AGND - 0.2V. When the
REF-OUT pin is connected to the REF-ADC pin, the internal reference is used as the ADC reference. When an
external reference voltage is applied to the REF-ADC pin, the external reference is used as the ADC reference.
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