Datasheet
REV. 0
AD7738
–7–
PIN FUNCTION DESCRIPTION
Pin No. Mnemonic Description
1 SCLK Serial Clock. Schmitt-Triggered Logic Input. An external serial clock is applied to this input to transfer
serial data to or from the AD7738.
2 MCLKIN Master Clock Signal for the ADC. This can be provided in the form of a crystal/resonator or external
clock. A crystal/resonator can be tied across the MCLKIN and MCLKOUT pins. Alternatively, the MCLKIN
pin can be driven with a CMOS compatible clock and MCLKOUT left unconnected.
3MCLKOUT When the master clock for the device is a crystal/resonator, the crystal/resonator is connected between
MCLKIN and MCLKOUT. If an external clock is applied to the MCLKIN, MCLKOUT provides an
inverted clock signal or can be switched off to lower the device power consumption. MCLKOUT is
capable of driving one CMOS load.
4 CS Chip Select. Active low Schmitt triggered logic input with an internal pull-up resistor. With this input
hardwired low, the AD7738 can operate in its 3-wire interface mode using SCLK, DIN, and DOUT. CS
can be used to select the device in systems with more than one device on the serial bus. It can also be used as
an 8-bit frame synchronization signal.
5 RESET Schmitt-Triggered Logic Input. Active low input that resets the control logic, interface logic, digital filter,
analog modulator, and all on-chip registers of the part to power-on status. Effectively, everything on the
part except the clock oscillator is reset when the RESET pin is exercised.
6AV
DD
Analog Positive Supply Voltage. 5 V to AGND nominal.
7 AINCOM/P0 Analog Inputs Common Terminal/Digital Output. The pin is determined by the P0 Dir bit; the digital
value can be written as the P0 bit in the I/O Port register. The digital voltage is referenced to analog
supplies. When configured as an input (P0 Dir bit set to 1), the single-ended Analog Inputs 0 to 7 can be
referenced to this pin’s voltage level.
8 SYNC/P1 SYNC/Digital Input/Digital Output. The pin direction is determined by the P1 Dir bit; the digital value
can be read/written as the P1 bit in the I/O Port register. When the SYNC Enable bit in the I/O Port
register is set to 1, the SYNC/P1 pin can be used to synchronize the AD7738 modulator and digital filter
with other devices in the system. The digital voltage is referenced to the analog supplies. When configured
as an input, the pin should be tied high or low.
9–12, AIN0–AIN7 Analog Inputs
17–20
13 MUXOUT(+) Analog Multiplexer Positive Output
14 MUXOUT(–) Analog Multiplexer Negative Output
PIN CONFIGURATION
TOP VIEW
(Not to Scale)
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
AD7738
SCLK
DGND
MCLKIN
DV
DD
MCLKOUT
DIN
CS
DOUT
RESET
RDY
AV
DD
AGND
AINCOM/P0
REFIN(–)
SYNC/P1
REFIN(+)
AIN7
AIN0
AIN6
AIN1
AIN5
AIN2
AIN4
AIN3
MUXOUT(+)
ADCIN(+)
MUXOUT(–)
ADCIN(–)