EVAL-CED1Z3 View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
'EVAL-CED1Z3' PDF : 28 Pages View PDF
AD7626
VOLTAGE REFERENCE OPTIONS
The AD7626 allows flexible options for creating and buffering
the reference voltage. The AD7626 conversions refer to 4.096 V
only. The various options creating this 4.096 V reference are
controlled by the EN1 and EN0 pins (see Table 8).
Table 8. Voltage Reference Options
Option EN1 EN0 Reference Mode
A
1
1
Power-up
Internal reference and internal
reference buffer in use
B
0
1
External 1.2 V reference applied to
REFIN pin required
C
1
0
External 4.096 V reference applied to
REF pin required.
0
0
Power-down mode
DECOUPLE THE REF AND
REFIN PINS EXTERNALLY.
10µF
10µF
A
IN+ REF REFIN
AD7626
IN–
EN1 = 1 AND EN0 = 1
POWER-UP—INTERNAL REFERENCE AND REFERENCE BUFFER IN USE.
NO EXTERNAL REFERENCE CIRCUITRY REQUIRED.
Figure 35. Powered Up, Internal Reference and Internal Reference Buffer
CONNECT 1.2V EXTERNAL REFERENCE TO REFIN PIN.
1.2V REFIN INPUT IS BUFFERED INTERNALLY.
IT CREATES A 4.096V REFERENCE FOR THE ADC.
DECOUPLE THE REF AND REFIN PINS EXTERNALLY
10µF
10µF
1.2V
0.1µF
ADR280
VOUT
V+
V–
(2.4V ≤ V+ ≥ 5.5V)
V+
0.1µF
B
IN+ REF REFIN
AD7626
IN–
EN1 = 0 AND EN0 = 1
EXTERNAL 1.2V REFERENCE CONNECTED TO REFIN PIN IS REQUIRED.
Figure 36. External 1.2 V Reference Using Internal Reference Buffer
(6.1V ≤ VIN ≥ 18V)
VIN
10µF 0.1µF
ADR434/
ADR444
VIN
VOUT
GND
4.096V
0.1µF
V+
AD8031
10µF
CONNECT BUFFERED 4.096V SIGNAL TO REF PIN.
DECOUPLE THE REF PIN EXTERNALLY.
REFIN IS A NO CONNECT.
NO CONNECT
C
IN+ REF REFIN
AD7626
IN–
EN1 = 1 AND EN0 = 0
EXTERNAL 4.096V REFERENCE CONNECTED TO REF PIN IS REQUIRED.
Figure 37. External 4.096 V Reference Applied to REF Pin
Rev. A | Page 20 of 2
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