AD7625BCPZ Datasheet, PDF (17/24 Pages) Analog Devices – 16-Bit, 6 MSPS, PulSAR Differential ADC

Data Sheet
VOLTAGE REFERENCE OPTIONS
The AD7625 allows flexible options for creating and buffering
the reference voltage. The AD7625 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).
AD7625
Table 8. Voltage Reference Options¹
Option EN1 EN0 Reference Mode
A
1
1
Use internal reference and internal
reference buffer (both are enabled).
B
0
1
Use external 1.2 V reference with
internal reference buffer enabled.
The internal reference is disabled.
C
1
0
Use external 4.096 V reference with
an external reference buffer. The
internal reference and reference
buffer are disabled.
1 _{EN1 = 0 and EN0 = 0 is an illegal state.}
V+
V+
ADR434
ADR444
V–
C
SETTING EN1 = 1 AND EN0 = 0
DISABLES THE INTERNAL REFERENCE
AND REFERENCE BUFFER. CONNECT THE
BUFFERED 4.096V SIGNAL TO
THE REF PIN.
10µF
A
SETTING EN1 = 1 AND EN0 = 1 ENABLES THE INTERNAL
REFERENCE AND REFERENCE BUFFER. DECOUPLE
THE REF AND REFIN PINS EXTERNALLY.
10µF
ADR280
V+
IN+ ^{REF REFIN}
AD7625
IN–
B
SETTING EN1 = 0 AND EN0 = 1
DISABLES THE INTERNAL REFERENCE
AND ENABLES THE INTERNAL REFERENCE BUFFER.
CONNECT A 1.2V REFERENCE TO THE REFIN PIN. THE 1.2V
APPLIED TO THE REFIN PIN IS BUFFERED INTERNALLY
TO CREATE A 4.096V REFERENCE FOR THE ADC.
Figure 25. Voltage Reference Options
Rev. A | Page 17 of 24