AMC7832_15 Datasheet, PDF (25/72 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
8.3 Feature Description
8.3.1 Digital-to-Analog Converters (DACs)
The AMC7832 features an analog control system centered on twelve, 12-bit DACs that operate from the device
internal reference. Each DAC core consists of a string DAC and output voltage buffer.
The resistor string structure consists of a series of resistors, each of value R. The code loaded to the DAC
determines at which node on the string the voltage is tapped off to be fed into the output amplifier. The voltage is
tapped off by closing one of the switches connecting the string to the amplifier. This architecture has inherent
monotonicity, voltage output, and low glitch. It is also linear because all the resistors are of equal value.
8.3.1.1 DAC Output Range and Clamp Configuration
The twelve DACs are split into four total groups: two groups of two DACs (DAC groups B and C) and two groups
of four DACs (DAC groups A and D). All of the DACs in a given group share the same output range and clamp
voltage value however these settings can be set independently for each DAC group. After power-on or a reset
event, the DAC output are directed automatically to their corresponding clamp value and all DAC buffer and
active registers are set to their default values.
The output range for each DAC group is configured as either positive or negative through its corresponding
VRANGE terminal. The VRANGE terminals can be driven directly by the REF_OUT1 and REF_OUT2 +2.5-V
outputs. When a DAC group is in positive output range the DAC Range register (address 0x1E) can be set to
specify an output range of 0 to +5-V instead of the default range of 0 to +10-V.
Additionally the power-on-reset and clamp voltage value of each DAC group is set by its corresponding AVSS
terminal. It is imperative that the clamp voltage setting for a DAC group matches its operating voltage range. The
recommended connections for AVSS are: AGND for the positive output ranges, in which case the clamp voltage
is 0-V; and -12-V for the negative output range, in which case the clamp voltage is AVSS + 2-V.
The full-scale output range for each DAC group is limited by the power supplies AVCC and its corresponding
AVSS. The maximum and minimum outputs cannot exceed AVCC or be lower than AVSS, respectively.
DAC
GROUP
DACs
OUTPUT
POLARITY
SELECTION
DAC_A8
A
DAC_A9
DAC_A10
VRANGE_A
DAC_A11
B
DAC_B6
DAC_B7
VRANGE_B
C
DAC_C0
DAC_C1
VRANGE_C
DAC_D2
D
DAC_D3
DAC_D4
VRANGE_D
DAC_D5
Table 1. DAC Group Configuration
CLAMP
VOLTAGE
SELECTION
POSITIVE OUTPUT RANGE
VRANGE = GND
VALID CLAMP
OUTPUT RANGE VOLTAGE
CONNECTION
AVSS_A
0 to +5-V
0 to +10-V
GND
AVSS_B
AVSS_C
0 to +5-V
0 to +10-V
0 to +5-V
0 to +10-V
GND
GND
AVSS_D
0 to +5-V
0 to +10-V
GND
NEGATIVE OUTPUT RANGE
VRANGE = +2.5-V
OUTPUT
RANGE
VALID CLAMP
VOLTAGE
CONNECTION
-10 to 0-V
-12-V
-10 to 0-V
-10 to 0-V
-12-V
-12-V
-10 to 0-V
-12-V
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