AD9289 Analog Devices, AD9289 Datasheet - Page 18

• Manufacturer Part Number: AD9289
• Description: Quad 8-Bit, 65 MSPS, Serial LVDS A/D Converter
• Manufacturer: Analog Devices

Specifications of AD9289

• Resolution (bits): 8bit
• # Chan: 4
• Sample Rate: 65MSPS
• Interface: Ser
• Analog Input Type: Diff-Uni
• Ain Range: 1 V p-p,2 V p-p
• Adc Architecture: Pipelined
• Pkg Type: CSP

AD9289
10µF
10µF
AVDD
SHARED_REF
SHARED_REF
VIN+C (+D)
VIN+A (+B)
VIN–A (–B)
VIN–C (–D)
0.1µF
VIN+C (+D)
VIN+A (+B)
VIN–A (–B)
VIN–C (–D)
0.1µF
SENSE
SENSE
V
V
REF
REF
Figure 33. Internal Reference Configuration
Figure 32. Shared Reference Mode Enabled
V
V
V
V
REF
REF
REF
REF
CONTROL
CONTROL
SELECT
LOGIC
SELECT
LOGIC
0.5V
0.5V
A CORE
B CORE
C CORE
D CORE
B CORE
C CORE
D CORE
A CORE
REFT_A
REFB_A
REFT_B
REFB_B
REFT_A
REFB_A
REFT_B
REFB_B
0.1µF
0.1µF
0.1µF
0.1µF
0.1µF
0.1µF
0.1µF
0.1µF
0.1µF
0.1µF
+
+
+
+
10µF
10µF
10µF
10µF
Rev. 0 | Page 18 of 32
If the internal reference of the AD9289 is used to drive multiple
converters to improve gain matching, the loading of the refer-
ence by the other converters must be considered. Figure 35
depicts how the internal reference voltage is affected by loading.
10µF
SHARED_REF
–0.05
–0.10
–0.15
–0.20
–0.25
–0.30
–0.35
–0.40
0.05
VIN+A (+B)
VIN+C (+D)
VIN–C (–D)
VIN–A (–B)
SENSE
0
0.1µF
0
Figure 34. Programmable Reference Configuration
R2
R1
V
REF
Figure 35. VREF Accuracy vs. Load
V
V
0.5
REF
REF
CONTROL
SELECT
LOGIC
1.0
I
LOAD
V
REF
0.5V
(mA)
= 1.0V
A CORE
B CORE
C CORE
D CORE
1.5
V
REFT_A
REFB_A
REFT_B
REFB_B
REF
2.0
0.1µF
0.1µF
0.1µF
= 0.5V
0.1µF
0.1µF
2.5
+
+
10µF
10µF