AMC7834 Datasheet, PDF (79/93 Pages) Texas Instruments – AMC7834 12-Bit Integrated Power-Amplifier Monitor and Control System with Temperature, Current and Voltage Supervision Capabilities

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AMC7834
SLAS972B – NOVEMBER 2014 – REVISED MARCH 2016
8.2.2 Detailed Design Procedure
Use the following parameters to facilitate the design process:
• AV_CC and AV_SS voltage values
• ADC and high-side current-sense input voltage range
• DAC output voltage ranges
• Remote temperature applications
8.2.2.1 ADC Input Conditioning
The AMC7834 monitoring system is centered on a single ADC core that features a multichannel input stage to a
successive approximation register (SAR) ADC. The analog inputs include four external analog inputs, four
internal inputs for bipolar DAC monitoring, four high-side current-sense amplifiers for PA current monitoring, two
remote temperature sensors, and an internal analog temperature sensor.
The external analog inputs (ADC1 through ADC4) feature a range of 0 to V_ref (V_ref corresponds to either an
external 2.5 V reference or the device internal reference), while the internal inputs accept a full-scale range of –5
to 2.5 V. The current-sense inputs feature a 4 to 60 V common-mode voltage range, and accept a differential
input range of 0 to 200 mV. A 4.7 µF capacitor is recommended between the REF_CMP pin and the AGND4 pin.
The value of this capacitor must exceed 470 nF to ensure reference stability. A high-quality ceramic capacitor,
type NP0 or X7R, is recommended because of the optimal performance of the capacitor across temperature and
very-low dissipation factor.
It is recommended that all external analog inputs are driven with a low impedance source to ensure correct
functionality. In applications where the signal-source impedance is high, the analog inputs can be conditioned
through a buffer amplifier, such as a voltage follower.
8.2.2.2 DAC Output Range Selection
The AMC7834 device has four bipolar and four unipolar DACs with programmable output ranges. The bipolar
DACs feature the ranges –4 to 1 V, –5 to 0 V, and 0 to 5 V. The unipolar DACs feature the ranges 0 to 5 V and
2.5 to 7.5 V. The DAC ranges are configurable by setting the DAC range register (see the DAC Range Register
(address = 0x16) [reset = 0x0000] section).
The maximum source and sink capability of the DAC internal amplifiers are listed as part of the DAC output
characteristics in the Electrical Characteristics—DAC Specifications table.
The graph in the Application Performance Curve section show the relationship of both stability and settling time
with different capacitive and resistive loading structures.
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