AD7626_09 AD [Analog Devices], AD7626_09 Datasheet - Page 20

• Manufacturer Part Number: AD7626_09
• Description: 16-Bit, 10 MSPS, PulSAR Differential ADC
• Manufacturer: AD [Analog Devices]

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).
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
VIN
10µF
(6.1V ≤ V
0.1µF
IN
≥ 18V)
V
IN
ADR434/
ADR444
Figure 35. Powered Up, Internal Reference and Internal Reference Buffer
POWER-UP—INTERNAL REFERENCE AND REFERENCE BUFFER IN USE.
GND
Figure 36. External 1.2 V Reference Using Internal Reference Buffer
A
EXTERNAL 1.2V REFERENCE CONNECTED TO REFIN PIN IS REQUIRED.
V
B
OUT
Figure 37. External 4.096 V Reference Applied to REF Pin
NO EXTERNAL REFERENCE CIRCUITRY REQUIRED.
4.096V
EXTERNAL 4.096V REFERENCE CONNECTED TO REF PIN IS REQUIRED.
C
0.1µF
REFIN PINS EXTERNALLY.
DECOUPLE THE REF AND
EN1 = 1 AND EN0 = 1
IN+
IN–
V+
10µF
Rev. 0 | Page 20 of 28
AD8031
EN1 = 0 AND EN0 = 1
IN+
IN–
REF
AD7626
10µF
REF
AD7626
REFIN
EN1 = 1 AND EN0 = 0
IN+
IN–
10µF
10µF
REFIN
Table 8. Voltage Reference Options
Option
A
B
C
REF
10µF
AD7626
CONNECT BUFFERED 4.096V SIGNAL TO REF PIN.
DECOUPLE THE REF PIN EXTERNALLY.
REFIN IS A NO CONNECT.
REFIN
0.1µF
NO CONNECT
EN1
1
0
1
0
1.2V
V
EN0
1
1
0
0
OUT
ADR280
V–
Reference Mode
Power-up
Internal reference and internal
reference buffer in use
External 1.2 V reference applied to
REFIN pin required
External 4.096 V reference applied to
REF pin required.
Power-down mode
V+
(2.4V ≤ V+ ≥ 5.5V)
0.1µF
V+