EVAL-AD7763EBZ Analog Devices Inc, EVAL-AD7763EBZ Datasheet - Page 21

• Manufacturer Part Number: EVAL-AD7763EBZ
• Manufacturer: Analog Devices Inc

Specifications of EVAL-AD7763EBZ

• Lead Free Status / Rohs Status: Supplier Unconfirmed

Sampling Switch SS1 and Sampling Switch SS3 are driven by ICLK,
whereas Sampling Switch SS2 and Sampling Switch SS4 are driven
by ICLK . When ICLK is high, the analog input voltage is connected
to CS1. On the falling edge of ICLK, the SS1 and SS3 switches
open, and the analog input is sampled on CS1. Similarly, when
ICLK is low, the analog input voltage is connected to CS2. On
the rising edge of ICLK, the SS2 and SS4 switches open, and the
analog input is sampled on CS2.
Capacitor CPA, Capacitor CPB1, and Capacitor CPB2 represent
parasitic capacitances that include the junction capacitances
associated with the MOS switches.
Table 11. Equivalent Component Values
Mode
Normal
Low Power
USING THE AD7763
Following is the recommended sequence for powering up and
using the AD7763.
1. Apply power.
2. Start clock oscillator, applying MCLK.
3. Take RESET low for a minimum of 1 MCLK cycle.
4. Wait a minimum of 2 MCLK cycles after RESET has been
5. Write to Control Register 2 to power up the ADC and the
6. Write to Control Register 1 to set up the output data rate.
7. In circumstances where multiple parts are being
released.
differential amplifier, as required.
synchronized, a SYNC pulse must be applied to the parts;
otherwise, no SYNC pulse is required.
CS1
51 pF
13 pF
CS2
51 pF
13 pF
CPA
12 pF
12 pF
CPB1/CPB2
20 pF
5 pF
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The following are conditions for applying the SYNC pulse:
• The issuing of a SYNC pulse to the part must not coincide
• The SYNC pulse should be applied a minimum
• Ensure that the SYNC pulse is taken low for a minimum of
Data can now be read from the part using the default filter,
offset, gain, and overrange threshold values. The conversion
data read is not valid, however, until the settling time of the
filter has passed. When this has occurred, the DVALID bit read
is set, indicating that the data is indeed valid.
The user can then download a user-defined filter, if required
(see Downloading a User-Defined Filter). Values for gain, offset,
and overrange threshold registers can also be written or read at
this stage.
BIAS RESISTOR SELECTION
The AD7763 requires a resistor to be connected between the
R
the reference voltage being applied to the device. The resistor
value should be selected to give a current of 25 μA through the
resistor to ground. For a 2.5 V reference voltage, the correct
resistor value is 100 k Ω ; for a 4.096 V reference voltage, the
correct resistor value is 160 k Ω .
BIAS
with a write to the part.
of 2.5 ICLK cycles after the FSI signal for the previous write
to the part has returned to logic high.
2.5 ICLK cycles.
pin and AGND. The value for this resistor is dependent on
AD7763