Datasheet
AD677
REV. A
–4–
(T
MIN
to T
MAX
, V
CC
= +12 V 6 5%, V
EE
= –12 V 6 5%, V
DD
= +5 V 6 10%)
1
TIMING SPECIFICATIONS
Parameter Symbol Min Typ Max Units
Conversion Period
2, 3
t
C
10 1000 µs
CLK Period
4
t
CLK
480 ns
Calibration Time t
CT
85532 t
CLK
Sampling Time t
S
2 µs
Last CLK to SAMPLE Delay
5
t
LCS
2.1 µs
SAMPLE Low t
SL
100 ns
SAMPLE to Busy Delay t
SS
30 75 ns
1st CLK Delay t
FCD
50 ns
CLK Low
6
t
CL
50 ns
CLK High
6
t
CH
50 ns
CLK to BUSY Delay t
CB
180 300 ns
CLK to SDATA Valid t
CD
50 100 175 ns
CLK to SCLK High t
CSH
100 180 300 ns
SCLK Low t
SCL
50 80 ns
SDATA to SCLK High t
DSH
50 80 ns
CAL High Time t
CALH
50 ns
CAL to BUSY Delay t
CALB
15 50 ns
NOTES
1
See the “CONVERSION CONTROL” and “AUTOCALIBRATION” sections for detailed explanations of the above timing.
2
Depends upon external clock frequency; includes acquisition time and conversion time. The maximum conversion period is specified to account for the droop of the
internal sample/hold function. Operation at slower rates may degrade performance.
3
t
C
= t
FCD
+ 16 × t
CLK
+ t
LCS
.
4
580 ns is recommended for optimal accuracy over temperature (not necessary during calibration cycle).
5
If SAMPLE goes high before the 17th CLK pulse, the device will start sampling approximately 100 ns after the rising edge of the 17th CLK pulse.
6
t
CH
+ t
CL
= t
CLK
and must be greater than 480 ns.
CAL
(INPUT)
BUSY
(OUTPUT)
CLK
*
(INPUT)
t
CT
t
CALH
t
CALB
t
CB
t
FCD
85530
85531 85532
1
23
t
CL
t
CH
t
CLK
*
SHADED PORTIONS OF INPUT SIGNALS ARE OPTIONAL. FOR BEST PERFORMANCE, WE
RECOMMEND THAT THESE SIGNALS BE HELD LOW EXCEPT WHEN EXPLICITY SHOWN HIGH.
Figure 1. Calibration Timing
t
CB
BUSY
(OUTPUT)
t
FCD
t
CH
*
SHADED PORTIONS OF INPUT SIGNALS ARE OPTIONAL. FOR BEST PERFORMANCE, WE
RECOMMEND THAT THESE SIGNALS BE HELD LOW EXCEPT WHEN EXPLICITY SHOWN HIGH.
SAMPLE*
(INPUT)
t
S
CLK
*
(INPUT)
1
23
15 16 17
t
S
t
LCS
MSB
BIT
2
BIT
15
BIT
13
BIT
14
BIT
16
SCLK
(OUTPUT)
SDATA
(OUTPUT)
OLD BIT 16
t
C
t
CD
t
SCL
t
DSH
t
SB
t
SL
t
CLK
t
CSH
t
CL
Figure 2. General Conversion Timing