EVAL-CED1Z View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
EVAL-CED1Z
Analog Devices
'EVAL-CED1Z' PDF : 29 Pages View PDF
AD7264
+5V
ANALOG
SUPPLY
10µF1 100nF
100nF
100nF
100nF
100nF
100nF
100nF
10µF1
COMPARATOR
SUPPLY 3V TO 5V2
17 44 5 6 8 19 42 28 2 7 11 20 41 12 1 33
100nF
3.125V
VA– AND VA+
CONNECT
DIRECTLY
TO SENSOR
OUTPUTS
2.500V
1.875V
3.125V
2.500V
1.875V
GAIN 2
GAIN 2
THIS REFERENCE SIGNAL
MUST BE BUFFERED
BEFORE IT CAN BE
USED ELSEWHERE IN
THE CIRCUIT
3.125V
VB– AND VB+
CONNECT
DIRECTLY
TO SENSOR
OUTPUTS
2.500V
1.875V
3.125V
2.500V
1.875V
GAIN 2
GAIN 2
3 VA–
4 VA+
43
1µF
VREFA
18
1µF
VREFB
9 VB+
10 VB–
13 14 15 16
AD7264
VDRIVE 27
40
G0
G1 39
G2 38
G3 37
34
SCLK
35
CS
DOUTA 32
DOUTB 31
REFSEL 24
CAL 36
VDRIVE
100nF
VDRIVE
GAIN 2
SETUP
SERIAL
INTERFACE
3V OR 5V
SUPPLY
10µF1
MICROPROCESSOR/
MICROCONTROLLER
VDRIVE
23
PD0/DIN
PD1 22
PD2 21
VDRIVE
VDRIVE
BOTH
COMPARATORS
AND ADCs
POWERED ON
45 46 47 48 25 26 29 30
FAST PROPAGATION DELAY
LOW POWER
COMPARATOR INPUTS COMPARATOR INPUTS
1THESE CAPACITORS ARE PLACED AT THE SUPPLY SOURCE AND MAY NOT BE REQUIRED IN ALL SYSTEMS.
2THIS SUPPLY CAN BE CONNECTED TO THE ANALOG 5V SUPPLY IF REQUIRED.
Figure 27. Typical Connection Diagram for the AD7264 in Pin Driven Mode with Gain of 2 and Both ADCs and Comparators Fully Powered On
Comparator Application Details
The comparators on the AD7264 have been designed with no
internal hysteresis, allowing users the flexibility to add external
hysteretic if required for systems operating in noisy environments.
If the comparators on the AD7264 are used with external hyste-
resis, some external resistors and capacitors are required, as
shown in Figure 28. The value of RF and RS, the external resistors,
can be determined using the following equation, depending on
the amount of hysteresis required in the application:
VHYS
=
RS
RS + RF
× CX_CXVCC
The amount of hysteresis chosen must be sufficient to eliminate
the effects of analog noise at the comparator inputs, which may
affect the stability of the comparator outputs. The level of
hysteresis required in any system depends on the noise in the
system; thus, the value of RF and RS needs to be carefully selected
to eliminate any noise effects. To increase the level of hysteresis in
the system, increase the value of RS or RF. For example, RF = 10 MΩ,
RS = 1 kΩ gives 330 μV of hysteresis with a Cx_CxVCC of 3.3 V; if
hysteresis is increased to 1 mV, RS = 3.1 kΩ. In certain applications,
a load capacitor (100 pF) may be required on the comparator
outputs to suppress high frequency transient glitches.
where CX_CXVCC = CA_CBVCC or CC_CDVCC.
Rev. A | Page 18 of 32
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