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3.3
Analog Input – Channel A1
3.4
Analog Inputs –Channels B0/B1 and C0/C1
4
Digital Interface
Digital Interface
The output from the buffer stage in each case applies 0-5 V to the CHA0(+) input when the applied signal
is connected to J2 pin 1 or J4 pin 2. The applied signal is directed to the CHA0(-) input when connected
via J2 pin 3 or J4 pin 4.
When operating the ADS836x with single-ended signals, it is important to keep the unused ADC input
biased to +2.5 V. This is easily accomplished on the EVM by changing the components associated with
either the inverting or noninverting input only, leaving the default component values shown in
Table 1
on
the unused input. For example, to achieve a bipolar input range of
±
10 V on CHA0(+), use the component
values shown for R1–R4 and move the shunt on W2 position 2-3. Components R24, R25, R28, and R29
and the shunt on W1 should remain in the default conditions shown in
Table 1
.
The analog input to the ADS8364/65MEVM board for channel A1 is composed of the INA159 difference
amplifier and the associated circuitry as shown in
Figure 2
. The INA159 is powered from the +5-V analog
supply, and arranged as a noninverting amplifier with a gain of 0.2. The in2.5-V reference voltage
of the ADS836x is applied to both REF1 and REF2 pins of the INA159 to provide a direct
±
10-V interface
with built-in level translation to the noninverting input of channel A1.
Figure 2. Channel A1 Input Circuit
The analog inputs to the remaining ADS836x input channels are routed to connector J3 and configured
with simple R/C filters only. This configuration allows the EVM user to apply any customized input circuit to
the data converter. Connector J3 is composed of a male/female pass-through combination of pin header
and socket with industry standard 0.1-inch centers.
When the ADS8364/65MEVM is used in combination with the 5-6K Interface Board or HPA-MCU Interface
Board, the DAP Signal Conditioning Board (
SLAU105
) can be used to drive the remaining input channels.
The ADS8364/65MEVM is designed for easy interfacing to multiple control platforms. Jumper options are
provided on the EVM to allow control over the state of Chip Select pin (CS) as well as the operating mode
pins (A0–A2), the Reset pin (RST), and the Conversion Start strobes (HOLD A, HOLDB, and HOLDC).
4
ADS8364/65MEVM
SLAU189 – September 2006
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