ad7782bru-reel7 Analog Devices, Inc., ad7782bru-reel7 Datasheet - Page 6

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ad7782bru-reel7

Manufacturer Part Number
ad7782bru-reel7
Description
Read Only, Pin Configured 24-bit Adc
Manufacturer
Analog Devices, Inc.
Datasheet
AD7782
Pin No. Mnemonic
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
XTAL1
REFIN(+)
REFIN(–)
AIN1(+)
AIN1(–)
AIN2(+)
AIN2(–)
CH1/CH2
RANGE
SCLK
CS
DOUT/RDY Serial Data Output/Data Ready Output. DOUT/RDY serves a dual purpose in this interface. When a con-
MODE
GND
V
XTAL2
DD
Analog Input. AIN1(+) is the positive terminal of the fully-differential analog input pair AIN1(+)/AIN1(–).
Analog Input. AIN2(+) is the positive terminal of the fully-differential analog input pair AIN2(+)/AIN2(–).
Function
Input to the 32.768 kHz Crystal Oscillator Inverter.
Positive Reference Input. REFIN(+) can lie anywhere between V
voltage (REFIN(+) – REFIN(–)) is 2.5 V, but the part functions with a reference from 1 V to V
Negative Reference Input. This reference input can lie anywhere between GND and V
Analog Input. AIN1(–) is the negative terminal of the fully-differential analog input pair AIN1(+)/AIN1(–).
Analog Input. AIN2(–) is the negative terminal of the fully-differential analog input pair AIN2(+)/AIN2(–).
Channel Select, Logic Input. With CH1/CH2 = 0, channel AIN1(+)/AIN1(–) is selected while the active
channel is AIN2(+)/AIN2(–) when CH1/CH2 = 1.
Logic Input which configures the input range on the internal PGA. With RANGE = 0, the full-scale input
range is ± 160 mV while the full-scale input range equals ± 2.56 V when RANGE = 1 for a +2.5 V Reference.
Serial Clock Input/Output for Data Transfers from the ADC. When the device is operated in master mode,
SCLK is an output with one SCLK period equal to one XTAL period. In slave mode, SCLK is generated
by an external source. In slave mode, all the data can be transmitted on a continuous train of pulses.
Alternatively, SCLK can be a noncontinuous clock with the information being transmitted from the AD7782
in smaller batches of data. SCLK is Schmitt triggered (slave mode) making the interface suitable for opto-
isolated applications.
Chip Select Input. CS is an active low logic input used to select the AD7782. When CS is low, the PLL
establishes lock and allows the AD7782 to initiate a conversion on the selected channel. When CS is high,
the conversion is aborted, DOUT and SCLK are three-stated, the AD7782 enters standby mode and any
conversion result in the output shift register is lost.
version is initiated, DOUT/RDY goes high and remains high until the conversion is complete. DOUT/RDY
will then return low to indicate that valid data is available to be read from the device. In slave mode, this acts
as an interrupt to the processor indicating that valid data is available. If data is not read after a conversion,
DOUT/RDY will go high before the next update occurs. In master mode, DOUT/RDY goes low for at least
half an SCLK cycle before the device produces SCLKs. When SCLK becomes active, data is output on
the DOUT/RDY pin. Data is output on the falling SCLK edge and is valid on the rising edge.
The MODE pin selects master or slave mode of operation. When MODE = 0, the AD7782 operates in
master mode while the AD7782 is configured for slave mode when MODE = 1.
Ground Reference Point for the AD7782.
Supply Voltage, 3 V or 5 V Nominal.
Output from the 32.768 kHz Crystal Oscillator Inverter.
PIN FUNCTION DESCRIPTIONS
REFIN(+)
REFIN(–)
CH1/CH2
AIN1(+)
AIN1(–)
AIN2(+)
AIN2(–)
XTAL1
PIN CONFIGURATION
1
2
3
4
5
6
7
8
(Not to Scale)
AD7782
TOP VIEW
16
15
14
13
12
11
10
9
XTAL2
V
GND
MODE
DOUT/RDY
CS
SCLK
RANGE
DD
DD
and GND +1 V. The nominal reference
DD
– 1 V.
DD
.

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