AD7866(Rev0) データシートの表示（PDF） - Analog Devices
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AD7866 Datasheet PDF : 20 Pages
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AD7866
ORDERING GUIDE
Model
Temperature Range
Resolution
(Bits)
Package Description
Package
Option
AD7866ARU
–40°C to +85°C
12
AD7866BRU
–40°C to +85°C
12
EVAL-AD7866CB1
Evaluation Board
EVAL-CONTROL BRD22 Controller Board
Thin Shrink SO (TSSOP)
Thin Shrink SO (TSSOP)
(TSSOP)
RU-20
RU-20
NOTES
1This can be used as a stand-alone evaluation board or in conjunction with the evaluation board controller for evaluation/demonstration purposes.
2This evaluation board controller is a complete unit, allowing a PC to control and communicate with all Analog Devices evaluation boards ending in the CB designators.
PIN CONFIGURATION
REF SELECT 1
20 A0
DCAPB 2
AGND 3
19 CS
18 SCLK
VB2 4
17 VDRIVE
VB1 5 AD7866 16 DOUTB
VA2
6 TOP VIEW 15
(Not to Scale)
DOUTA
VA1 7
14 DGND
AGND 8
DCAPA 9
VREF 10
13 DVDD
12 AVDD
11 RANGE
Pin No. Mnemonic
1
REF SELECT
2, 9
DCAPB, DCAPA
3, 8
AGND
4, 5
VB2, VB1
6, 7
VA2, VA1
10
VREF
PIN FUNCTION DESCRIPTIONS
Function
Internal/External Reference Selection Pin. Logic Input. If this pin is tied to GND, the on-chip
2.5 V reference is used as the reference source for both ADC A and ADC B. In addition, pins VREF,
DCAPA, and DCAPB must be tied to decoupling capacitors. If the REF SELECT pin is tied to a
logic high, an external reference can be supplied to the AD7866 through the VREF pin, in which
case decoupling capacitors are required on DCAPA and DCAPB. However, if the VREF pin is tied to
AGND while REF SELECT is tied to a logic low, an individual external reference can be applied
to both ADC A and ADC B through pins DCAPA and DCAPB, respectively. See Reference section.
Decoupling capacitors are connected to these pins to decouple the reference buffer for each respective
ADC. The on-chip reference can be taken from these pins and applied externally to the rest of a
system. Depending on the polarity of the REF SELECT pin and the configuration of the VREF pin,
these pins can also be used to input a separate external reference to each ADC. The range of the
external reference is dependent on the analog input range selected. See Reference section.
Analog Ground. Ground reference point for all analog circuitry on the AD7866. All analog input
signals and any external reference signal should be referred to this AGND voltage. Both of these
pins should connect to the AGND plane of a system. The AGND and DGND voltages should
ideally be at the same potential and must not be more than 0.3 V apart even on a transient basis.
Analog Inputs of ADC B. Single-ended analog input channels. The input range on each channel is 0 V
to VREF or a 2 × VREF range depending on the polarity of the RANGE pin upon the falling edge of CS.
Analog Inputs of ADC A. Single-ended analog input channels. The input range on each channel is 0 V
to VREF or a 2 × VREF range depending on the polarity of the RANGE pin upon the falling edge of CS.
Reference Decoupling Pin and External Reference Selection Pin. This pin is connected to the inter-
nal reference and requires a decoupling capacitor. The nominal reference voltage is 2.5 V and this
appears at the pin; however, if the internal reference is to be used externally in a system, it must be
taken from either the DCAPA or DCAPB pins. This pin is also used in conjunction with the REF SELECT
pin when applying an external reference to the AD7866. See REF SELECT pin description.
REV. 0
–5–
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