ad7790brm-reel Analog Devices, Inc., ad7790brm-reel Datasheet - Page 8

• Manufacturer Part Number: ad7790brm-reel
• Description: Low Power, 16-bit Buffered Sigma-delta Adc
• Manufacturer: Analog Devices, Inc.

AD7790
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
Table 4. Pin Function Descriptions
Pin
No.
1
2
3
4
5
Mnemonic
SCLK
CS
AIN(+)
AIN(–)
REFIN(+)
REF(+)
AIN(+)
AIN(–)
SCLK
CS
Function
Serial Clock Input for Data Transfers to and
from the ADC. The SCLK has a Schmitt-
triggered input, making the interface
suitable for opto-isolated applications. The
serial clock can be continuous with all data
transmitted in a continuous train of pulses.
Alternatively, it can be a noncontinuous
clock with the information being trans-
mitted to or from the ADC in smaller
batches of data.
Chip Select Input. This is an active low logic
input used to select the ADC. CS can be
used to select the ADC in systems with
more than one device on the serial bus or as
a frame synchronization signal in communi-
cating with the device. CS can be hardwired
low, allowing the ADC to operate in 3-wire
mode with SCLK, DIN, and DOUT used to
interface with the device.
Analog Input. AIN(+) is the positive terminal
of the fully differential analog input.
Analog Input. AIN(–) is the negative termi-
nal of the fully differential analog input.
Positive Reference Input. REFIN(+) can lie
anywhere between V
The nominal reference voltage (REFIN(+) –
REFIN(–)) is 2.5 V, but the part functions
with a reference from 0.1 V to V
Figure 5. Pin Configuration
1
2
3
4
5
(Not to Scale)
AD7790
TOP VIEW
03538-0-005
10
9
8
7
6
DIN
DOUT/RDY
V
GND
REF(–)
DD
DD
and GND + 0.1 V.
DD
.
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Pin
No.
6
7
8
9
10
Mnemonic
REFIN(–)
GND
V
DOUT/RDY
DIN
DD
Function
Negative Reference Input. This reference
input can lie anywhere between GND and
V
Ground Reference Point.
Supply Voltage, 2.5 V to 5.25 V.
Serial Data Output/Data Ready Output.
DOUT/RDY serves a dual purpose. It functions
as a serial data output pin to access the out-
put shift register of the ADC. The output shift
register can contain data from any of the on-
chip data or control registers. In addition,
DOUT/RDY operates as a data ready pin,
going low to indicate the completion of a
conversion. If the data is not read after the
conversion, the pin will go high before the
next update occurs.
The DOUT/RDY falling edge can be used as an
interrupt to a processor, indicating that valid
data is available. With an external serial clock,
the data can be read using the DOUT/RDY pin.
With CS low, the data/control word informa-
tion is placed on the DOUT/RDY pin on the
SCLK falling edge and is valid on the SCLK
rising edge.
The end of a conversion is also indicated by
the RDY bit in the status register. When CS is
high, the DOUT/RDY pin is three-stated but
the RDY bit remains active.
Serial Data Input to the Input Shift Register
on the ADC. Data in this shift register is
transferred to the control registers within
the ADC, the register selection bits of the
communications register identifying the
appropriate register.
DD
– 0.1 V.