AD7625 Analog Devices, AD7625 Datasheet - Page 16

• Manufacturer Part Number: AD7625
• Description: 16-Bit, 6MSPS PulSAR Differential ADC
• Manufacturer: Analog Devices

Specifications of AD7625

• Resolution (bits): 16bit
• # Chan: 1
• Sample Rate: 6MSPS
• Interface: LVDS,Ser
• Analog Input Type: Diff-Uni
• Ain Range: Bip 4.096V
• Adc Architecture: SAR
• Pkg Type: CSP

AD7625
DRIVING THE AD7625
Differential Analog Input Source
Figure 24 shows an ADA4899-1 driving each differential input
to the AD7625.
Single-Ended-to-Differential Driver
For applications using unipolar analog signals, a single-ended-
to-differential driver, as shown in Figure 23, allows for a differ-
ential input into the part. This configuration, when provided
with an input signal of 0 V to 4.096 V, produces a differential
±4.096 V with midscale at 2.048 V. The one-pole filter using
R = 33 Ω and C = 56 pF provides a corner frequency of 86 MHz.
The VCM output of the AD7625 can be buffered and then used
to provide the required 2.048 V common-mode voltage.
1
2
BUFFERED VCM PIN OUTPUT
GIVES THE REQUIRED 2.048V
COMMON-MODE SUPPLY FOR
ANALOG INPUTS.
SEE THE VOLTAGE REFERENCE OPTIONS SECTION. CONNECTION TO EXTERNAL REFERENCE SIGNALS
C
IS DEPENDENT ON THE EN1 AND EN0 SETTINGS.
THE REF AND REFIN PINS ARE DECOUPLED REGARDLESS OF EN1 AND EN0 SETTINGS.
REF
IS USUALLY A 10µF CERAMIC CAPACITOR WITH LOW ESL AND ESR.
V
0V TO V
REF
ADA4899-1
ADA4899-1
VCM
TO 0V
REF
Figure 24. Driving the AD7625 from a Differential Analog Source
–V
+V
–V
+V
S
S
S
S
0.1µF
56pF
56pF
33Ω
33Ω
Rev. 0 | Page 16 of 24
+V
–V
REF
S
S
1
AD8031, AD8032
IN+
IN–
(UNIPOLAR 0V TO 4.096V)
C
10µF
REF
2
GND
REF
AD7625
ANALOG INPUT
Figure 23. Single-Ended-to-Differential Driver Circuit
REFIN
VCM
100nF
2.048V
C
10µF
50Ω
REF
U1
ADA4899-1
2
590Ω
590Ω
U2
ADA4899-1
REF
1
33Ω
33Ω
V+
V–
56pF
AD8031, AD8032
56pF
100nF
IN+
IN–
AD7625
VCM