AMC7832IPAP datasheet(57/74 Pages) TI2

57 / 74 page

0.12F

DVDD

GND

LM50

LV_ADC15

AMC7832

www.ti.com

SLAS836 – MARCH 2014

To reduce DC error in sampling, it is recommended to decrease the ADC input impedance and reduce any input

capacitance to ground. Increasing the input capacitance essentially increases CIN, and therefore increases the

required amount of input current (IIN).

In applications where the signal source has high impedance, it is recommended that the analog input is buffered

before applying to the ADC channel.

Special care must be taken when biasing the two input classes, as both classes have different voltages – with

respect to GND – that they cannot exceed. These voltage values are located in Absolute Maximum Ratings.

9.2.3.2 DAC Output Range Selection

The AMC7832 contains 12 DACs that are arranged by different DAC banks, where each channel within a bank

shares a common programmable voltage range. Each DAC bank is fully programmable with up to three different

voltage ranges: -10 to 0-V, 0 to +10-V, and 0 to +5-V. The VRANGE terminals combined with the DAC

configuration register sets the different DAC voltage ranges.

The output buffer is capable of generating rail-to rail voltages on its output, giving an output range of AVSS to

AVCC. The maximum source and sink capability of this internal amplifier is listed in the Electrical Characteristics

DAC Output Characteristics.

The graphs listed in the Application plots section illustrate the relationship of both stability and settling time with

different capacitive and resistive loading structures.

9.2.3.3 Temperature Sensing Applications

The AMC7832 contains one local temperature and 5 low-voltage unipolar channels that are easily configurable to

remote temperature sensor circuits. The integrated temperature sensor and analog input registers automatically

update with every conversion. An example of a remote temperature sensor connection is displayed in Figure 59.

The temperature sensor described is a LM50, a high precision integrated-circuit temperature sensor that can

sense a -40°C to +125°C temperature range using a single positive supply. The full-scale output of the

temperature sensor ranges from +100mV to +1.75V for a -40°C to +125°C temperature range. In an extremely

noisy environment it may be necessary to add some filtering to minimize noise pickup. A typical recommended

value for the bypass capacitor is 0.1µF from V+ to GND. A high-quality ceramic type NP0 or X7R is

recommended for its optimal performance across temperature, and very low dissipation factor.

Figure 59. External Remote Temperature IC (LM50) Connected to AMC7832 (LV_ADC15) Input Pin

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