rtd DM6210, User Manual

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3-3
The DM6210 has three major circuits, the A/D, the timer/counters, and the digital I/O lines. Figure 3-1
shows the block diagram of the module. This chapter describes hardware which makes up the major circuits.
A/D Conversion Circuitry
The DM6210 performs analog-to-digital conversions on up to 16 analog input channels. The following
paragraphs describe the A/D circuitry.
Analog Inputs
Sixteen single-ended analog input channels are available on the DM6210. The analog input range is
jumper-selectable for -5 to +5 volts, -10 to +10 volts, or 0 to +10 volts, with ±35 Vdc overvoltage protection.
The channels are connected to a sample-and-hold amplifier through a multiplexing circuit. The active channel
is selected through software, as described in Chapter 4.
The S/H amplifier captures and holds the input signal at a constant level while the conversion is per-
formed, ensuring that dynamic analog signals are accurately digitized. This capacitive circuit quickly charges
to a level corresponding to the input voltage being sampled and holds the charge for the duration of the
conversion.
A/D Converter
The 12-bit A/D converter , when combined with the typical acquisition time of the sample-and-hold
circuitry, provides a throughput rate of up to 40,000 samples per second. The A/D output is a 12-bit data
word.
Fig. 3-1 — DM6210 Block Diagram
DC/DC
CONVERTER
±15 VOLTS
+5 VOLTS
9
PC
B
U
S
DATA
8
8
INTERRUPT
SELECT
12-BIT
A/D
CONVERTER
PORT 0
PORT 1
8254
PIT
ADDRESS
ADDRESS
DECODE
CONTROL
TIMER/
COUNTER
I/O
SELECT
8 MHz
OSC
RANGE
SELECT
±5 V
0 TO +10 V
±10 V
RESISTOR
CONFIG.
GAIN
MUX
PULL-UP/DOWN
RESISTORS
16 ANALOG
INPUTS
±5V
0 - +10V
±10V
+5 VOLTS
CONTROL
±12 VOLTS
S/H
EOC
I/
O
CONNE
CTO
R
DIGITAL
I/O
16