Datasheet

AD7863
Rev. B | Page 7 of 24
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
DB1
DB2
DB3
DB4
DB5
DB6
CONVST
DB12
DB11
DB10
DB9
DGND
DB7
DB8
V
A2
V
REF
A0
CS
DB13
AGND
V
B1
V
A1
RD
BUSY
V
DD
V
B2
AGND
DB0
06411-004
AD7863
TOP VIEW
(Not to Scale)
Figure 4. Pin Configuration
Table 4. Pin Function Descriptions
Pin
No.
Mnemonic Description
1 to 6 DB12 to DB7 Data Bit 12 to Data Bit 7. Three-state TTL outputs.
7 DGND Digital Ground. Ground reference for digital circuitry.
8
CONVST Convert Start Input. Logic input. A high-to-low transition on this input puts both track/holds into their hold mode
and starts conversion on both channels.
9 to 15 DB6 to DB0 Data Bit 6 to Data Bit 0. Three-state TTL outputs.
16 AGND Analog Ground. Ground reference for mux, track/hold, reference, and DAC circuitry.
17 V
B2
Input Number 2 of Channel B. Analog input voltage ranges of ±10 V (AD7863-10), ±2.5 V (AD7863-3), and 0 V to
2.5 V (AD7863-2).
18 V
A2
Input Number 2 of Channel A. Analog input voltage ranges of ±10 V (AD7863-10), ±2.5 V (AD7863-3), and 0 V to
2.5 V (AD7863-2).
19 V
REF
Reference Input/Output. This pin is connected to the internal reference through a series resistor and is the output
reference source for the analog-to-digital converter. The nominal reference voltage is 2.5 V, and this appears at the pin.
20 A0
Multiplexer Select. This input is used in conjunction with
CONVST to determine on which pair of channels the
conversion is to be performed. If A0 is low when the conversion is initiated, then channels V
A1
and V
A2
are
selected. If A0 is high when the conversion is initiated, channels V
B1
and V
B2
are selected.
21
CS
Chip Select Input. Active low logic input. The device is selected when this input is active.
22
RD Read Input. Active low logic input. This input is used in conjunction with CS low to enable the data outputs and
read a conversion result from the AD7863.
23 BUSY
Busy Output. The busy output is triggered high by the falling edge of
CONVST and remains high until conversion
is completed.
24 V
DD
Analog and Digital Positive Supply Voltage, 5.0 V ± 5%.
25 V
A1
Input Number 1 of Channel A. Analog input voltage ranges of ±10 V (AD7863-10), ±2.5 V (AD7863-3), and 0 V to
2.5 V (AD7863-2).
26 V
B1
Input Number 1 of Channel B. Analog input voltage ranges of ±10 V (AD7863-10), ±2.5 V (AD7863-3), and 0 V to
2.5 V (AD7863-2).
27 AGND Analog Ground. Ground reference for mux, track/hold, reference, and DAC circuitry.
28 DB13
Data Bit 13 (MSB). Three-state TTL output. Output coding is twos complement for the AD7863-10 and AD7863-3.
Output coding is straight (natural) binary for the AD7863-2.