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Bit 0 (LSB)
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Bit 15 (MSB)
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
6
7
8
9
10
11
12
13
14
23
22
21
20
19
18
17
16
15
ADS8505
BYTE LOW
Bit 8
Bit 9
Bit 10
Bit 11
Bit 12
Bit 13
Bit 14
Bit 15 (MSB)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0 (LSB)
6
7
8
9
10
11
12
13
14
23
22
21
20
19
18
17
16
15
ADS8505
BYTE HIGH
+5 V
ADS8505
SLAS180B – SEPTEMBER 2005 – REVISED JUNE 2007
The number of control lines can be reduced by tying CS low while using the falling edge of R/ C to initiate
conversions and the rising edge of R/ C to activate the output mode of the converter. See Figure 23 .
Table 3. Conversion Timing
SYMBOL DESCRIPTION MIN TYP MAX UNITS
t
w1
Pulse duration, convert 40 1750 ns
t
a
Access time, data valid after R/ C low 2.2 3.2 µ s
t
pd
Propagation delay time, BUSY from R/ C low 15 25 ns
t
w2
Pulse duration, BUSY low 2.2 µ s
t
d1
Delay time, BUSY after end of conversion 5 ns
t
d2
Delay time, aperture 5 ns
t
conv
Conversion time 2.2 µ s
t
acq
Acquisition time 1.8 µ s
t
dis
Disable time, bus 10 30 83 ns
t
d3
Delay time, BUSY after data valid 35 50 ns
t
v
Valid time, previous data remains valid after R/ C low 1.5 2 µ s
t
conv
+ t
acq
Throughput time 4 µ s
t
su
Setup time, R/ C to CS 10 ns
t
c
Cycle time between conversions 4 µ s
t
en
Enable time, bus 10 30 83 ns
t
d4
Delay time, BYTE 5 10 30 ns
Figure 22. Bit Locations Relative to State of BYTE (Pin 23)
11
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