AD7262 Analog Devices, AD7262 Datasheet - Page 17

• Manufacturer Part Number: AD7262
• Description: 1 MSPS, 12-Bit, Simultaneous Sampling SAR ADC with PGA and Four Comparators
• Manufacturer: Analog Devices

Specifications of AD7262

• Resolution (bits): 12bit
• # Chan: 2
• Sample Rate: 1MSPS
• Interface: Ser,SPI
• Analog Input Type: Diff-Uni
• Ain Range: (2Vref) p-p,5V p-p
• Adc Architecture: SAR
• Pkg Type: CSP,QFP

REFERENCE
The AD7262/AD7262-5 can operate with either the internal
2.5 V on-chip reference or an externally applied reference. The
logic state of the REFSEL pin determines whether the internal
reference is used. The internal reference is selected for both ADCs
when the REFSEL pin is tied to logic high. If the REFSEL pin is
tied to AGND, an external reference can be supplied through
the V
must be tied to either a low or high logic state for the part to
operate. Suitable reference sources for the AD7262/AD7262-5
include AD780, AD1582, ADR431, REF193, and ADR391.
The internal reference circuitry consists of a 2.5 V band gap
reference and a reference buffer. When the AD7262/AD7262-5
are operated in internal reference mode, the 2.5 V internal
reference is available at the V
be decoupled to AGND using a 1 μF capacitor. It is recommended
that the internal reference be buffered before applying it elsewhere
in the system. The internal reference is capable of sourcing up
to 90 μA of current when the converter is static. If the internal
reference operation is required for the ADC conversion, the
REFSEL pin must be tied to logic high on power-up. The refer-
ence buffer requires 240 μs to power up and charge the 1 μF
decoupling capacitor during the power-up time.
REF
A and/or V
REF
B pins. On power-up, the REFSEL pin
REF
A and V
REF
B pins, which should
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TYPICAL CONNECTION DIAGRAMS
Figure 26 and Figure 27 are typical connection diagrams for the
AD7262/AD7262-5. In these configurations, the AGND pin is
connected to the analog ground plane of the system, and the
DGND pin is connected to the digital ground plane of the system.
The analog inputs on the AD7262/AD7262-5 are true differen-
tial and have an input impedance in excess of 1 GΩ; thus, no
driving op amps are required. The AD7262/AD7262-5 can operate
with either an internal or an external reference. In Figure 26, the
AD7262/AD7262-5 are configured to operate in control register
mode; thus, G0 to G3, PD1, and PD2 can be connected to ground
(low logic state). Figure 27 has the gain pins configured for a gain
of 2 setup; thus, the device is in pin-driven mode. Both circuit
configurations illustrate the use of the internal 2.5 V reference
The C
a 3 V or a 5 V supply voltage. The AV
to a 5 V supply. All supplies should be decoupled with a 100 nF
capacitor at the device pin, and some supply sources may require a
10 μF capacitor where the source is supplied to the circuit board.
The V
processor. The voltage applied to the V
voltage of the serial interface. V
A
DRIVE
_C
B
V
pin is connected to the supply voltage of the micro-
CC
and the C
C
_C
D
V
CC
DRIVE
pins can be connected to either
can be set to 3 V or 5 V.
CC
DRIVE
pin must be connected
input controls the
AD7262