Datasheet
REV. A
AD7719
–9–
PIN CONFIGURATION
14
13
12
11
10
17
16
15
19
18
20
28
27
26
25
24
23
22
21
9
8
1
2
3
4
7
6
5
TOP VIEW
(Not to Scale)
AD7719
IOUT1
DGND
DV
DD
XTAL2
XTAL1
IOUT2
AV
DD
AGND
RDY
DOUT
DIN
REFIN1(–)
REFIN1(+)
AIN1
AIN2
AIN3
AIN4
RESET
SCLK
CS
AIN5
AIN6
REFIN2
P4
P1/SW1
P3
P2/SW2
PWRGND
PIN FUNCTION DESCRIPTIONS
Pin No. Mnemonic Function
1 IOUT1 Output for Internal 200 µA Excitation Current Source. Current source IEXC1 and/or IEXC2 can be
switched to this output.
2 IOUT2 Output for Internal 200 µA Excitation Current Source. Current source IEXC1 and/or IEXC2 can be
switched to this output.
3AV
DD
Analog Supply Voltage.
4 AGND Analog Ground.
5 REFIN1(–) Negative Reference Input for Main ADC Channel. This reference input can lie anywhere between AGND
and AV
DD
– 1 V.
6 REFIN1(+) Positive Reference Input for Main ADC Channel. REFIN1(+) can lie anywhere between AV
DD
and
AGND + 1 V. The nominal reference voltage (REFIN1(+) – REFIN1(–)) is 2.5 V, but the part is functional
with a reference range from 1 V to AV
DD
.
7 AIN1 Analog Input. AIN1 is dedicated to the main channel.
8 AIN2 Analog Input. AIN2 is dedicated to the main channel.
9 AIN3 Analog Input. AIN3 can be multiplexed to either the main or auxiliary channel.
10 AIN4 Analog Input. AIN4 can be multiplexed to either the main or auxiliary channel.
11 AIN5 Analog Input. AIN5 is dedicated to the auxiliary channel and is referenced to AIN6 or AGND.
12 AIN6 Analog Input. AIN6 is dedicated to the auxiliary channel. It forms a differential input pair with AIN5 in
fully differential input mode or is referenced to AGND in pseudodifferential mode.
13 REFIN2 Single-Ended Reference Input for Auxiliary Channel. The nominal input reference is 2.5 V. The auxiliary
channel will function with an input reference range from 1 V to AV
DD
.
14 P4 General-Purpose I/O Bit. The input and output voltage levels are referenced to AV
DD
and AGND.
15 P3 General-Purpose I/O Bit. The input and output voltage levels are referenced to AV
DD
and AGND.
The serial interface can be reset by exercising the RESET input
on the part. It can also be reset by writing a series of 1s on the
DIN input. If a logic 1 is written to the AD7719 DIN line for at
least 32 serial clock cycles, the serial interface is reset. This ensures
that in 3-wire systems, if the interface gets lost, either via a software
error or by some glitch in the system, it can be reset back to a
known state. This state returns the interface to where the AD7719
is expecting a write operation to its Communications register. This
operation resets the contents of all registers to their power-on
reset values.
Some microprocessor or microcontroller serial interfaces have a
single serial data line. In this case, it is possible to connect the
AD7719’s DATA OUT and DATA IN lines together and connect
them to the single data line of the processor. A 10 kΩ pull-up
resistor should be used on this single data line. In this case, if the
interface gets lost, because the read and write operations share
the same line, the procedure to reset it to a known state is
somewhat different than previously described. It requires a read
operation of 24 serial clocks followed by a write operation where
a logic 1 is written for at least 32 serial clock cycles to ensure
that the serial interface is back in a known state.