AD7705/AD7706
TIMING CHARACTERISTICS
1, 2
Parameter
f
CLKIN3, 4
t
CLKIN LO
t
CLKIN HI
t
1
t
2
Read Operation
t
3
t
4
t
5 5
t
6
t
7
t
8
t
9 6
t
10
Write Operation
t
11
t
12
t
13
t
14
t
15
t
16
Limit at T
MIN
, T
MAX
(B Version)
400
2.5
0.4
×
t
CLKIN
0.4
×
t
CLKIN
500
×
t
CLKIN
100
0
120
0
80
100
100
100
0
10
60
100
100
120
30
20
100
100
0
(V
DD
= +2.7 V to +5.25 V; GND = 0 V; f
CLKIN
= 2.4576 MHz; Input Logic 0 = 0 V, Logic 1 = V
DD
unless otherwise noted.)
Units
kHz min
MHz max
ns min
ns min
ns nom
ns min
ns min
ns min
ns min
ns max
ns max
ns min
ns min
ns min
ns min
ns max
ns max
ns max
ns min
ns min
ns min
ns min
ns min
ns min
Conditions/Comments
Master Clock Frequency: Crystal Oscillator or Externally Supplied
for Specified Performance
Master Clock Input Low Time. t
CLKIN
= 1/f
CLKIN
Master Clock Input High Time
DRDY
High Time
RESET
Pulsewidth
DRDY
to
CS
Setup Time
CS
Falling Edge to SCLK Rising Edge Setup Time
SCLK Falling Edge to Data Valid Delay
V
DD
= +5 V
V
DD
= +3.0 V
SCLK High Pulsewidth
SCLK Low Pulsewidth
CS
Rising Edge to SCLK Rising Edge Hold Time
Bus Relinquish Time after SCLK Rising Edge
V
DD
= +5 V
V
DD
= +3.0 V
SCLK Falling Edge to
DRDY
High
7
CS
Falling Edge to SCLK Rising Edge Setup Time
Data Valid to SCLK Rising Edge Setup Time
Data Valid to SCLK Rising Edge Hold Time
SCLK High Pulsewidth
SCLK Low Pulsewidth
CS
Rising Edge to SCLK Rising Edge Hold Time
NOTES
1
Sample tested at +25°C to ensure compliance. All input signals are specified with tr = tf = 5 ns (10% to 90% of V
DD
) and timed from a voltage level of 1.6 V.
2
See Figures 16 and 17.
3
f
CLKIN
Duty Cycle range is 45% to 55%. f
CLKIN
must be supplied whenever the AD7705/AD7706 is not in Standby mode. If no clock is present in this case, the device
can draw higher current than specified and possibly become uncalibrated.
4
The AD7705/AD7706 is production tested with f
CLKIN
at 2.4576 MHz (1 MHz for some I
DD
tests). It is guaranteed by characterization to operate at 400 kHz.
5
These numbers are measured with the load circuit of Figure 1 and defined as the time required for the output to cross the V
OL
or V
OH
limits.
6
These numbers are derived from the measured time taken by the data output to change 0.5 V when loaded with the circuit of Figure 1. The measured number is
then extrapolated back to remove effects of charging or discharging the 50 pF capacitor. This means that the times quoted in the timing characteristics are the
true bus relinquish times of the part and as such are independent of external bus loading capacitances.
7
DRDY
returns high after the first read from the device after an output update. The same data can be read again, if required, while
DRDY
is high, although care
should be taken that subsequent reads do not occur close to the next output update.
I
SINK
(800 A AT V
DD
= +5V
100 A AT V
DD
= +3V)
TO OUTPUT
PIN
50pF
+1.6V
I
SOURCE
(200 A AT V
DD
= +5V
100 A AT V
DD
= +3V)
Figure 1. Load Circuit for Access Time and Bus Relinquish Time
–4–
REV. A
AD [ ANALOG DEVICES ]
