ADS7862YB Burr-Brown Corporation, ADS7862YB Datasheet - Page 9

• Manufacturer Part Number: ADS7862YB
• Description: Dual 500kHz/ 12-Bit/ 2 2 Channel Simultaneous Sampling ANALOG-TO-DIGITAL CONVERTER
• Manufacturer: Burr-Brown Corporation

FIGURE 2. Using the ADS7862 in the Single-Ended and Differential Input Modes.
FIGURE 3. Single-Ended Input: Common-Mode Voltage
In each case, care should be taken to ensure that the output
impedance of the sources driving the +IN and –IN inputs are
matched. Otherwise, this may result in offset error, which
will change with both temperature and input voltage.
The input current on the analog inputs depend on a number
of factors: sample rate, input voltage, and source impedance.
Essentially, the current into the ADS7862 charges the inter-
nal capacitor array during the sampling period. After this
–1
5
4
3
2
1
0
1.0
1.2
Range vs V
CM +1/2V
CM –1/2V
CM Voltage
CM Voltage
NOTES: Common-Mode Voltage (Differential Mode) =
The maximum differential voltage between +IN and –IN of the ADS7862 is V
explanation of the common voltage range for single-ended and differential inputs.
4.1
0.9
CM +V
CM –V
Single-Ended Input
1.5
REF
REF
REF
REF
REF
.
V
REF
2.0
+V
+IN
–IN
REF
(V)
+V
REF
V
CC
2.5
= 5V
2.6
2.7
2.3
Single-Ended Inputs
–V
Differential Inputs
REF
–V
REF
3.0
(IN+) + (IN–)
+IN
2
9
–IN = CM Voltage
FIGURE 4. Differential Input: Common-Mode Voltage
capacitance has been fully charged, there is no further input
current. The source of the analog input voltage must be able
to charge the input capacitance (15pF) to a 12-bit settling
level within 2 clock cycles. When the converter goes into the
hold mode, the input impedance is greater than 1G .
Care must be taken regarding the absolute analog input
voltage. The +IN input should always remain within the
range of GND – 300mV to V
Common-Mode Voltage (Single-Ended Mode) = IN–.
–1
5
4
3
2
1
0
1.0
REF
. See Figures 3 and 4 for a further
Range vs V
1.2
4.7
0.3
Differential Input
1.5
REF
.
V
DD
REF
ADS7862
2.0
+ 0.3V.
(V)
V
CC
2.5
= 5V
t
t
2.6
4.05
0.90
3.0
®