AD7938 Analog Devices, AD7938 Datasheet - Page 7

• Manufacturer Part Number: AD7938
• Description: 8-Channel, 1.5 MSPS, 12-Bit Parallel ADCs with a Sequencer
• Manufacturer: Analog Devices

Specifications of AD7938

• Resolution (bits): 12bit
• # Chan: 8
• Sample Rate: 1.5MSPS
• Interface: Byte,Par
• Analog Input Type: Diff-Uni,SE-Uni
• Ain Range: (2Vref) p-p,5V p-p,Uni (Vref),Uni (Vref) x 2,Uni 2.5V,Uni 5.0V
• Adc Architecture: SAR
• Pkg Type: CSP,QFP

Data Sheet
TIMING SPECIFICATIONS
V
T
Table 4.
Parameter
f
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
1
2
3
4
CLKIN
QUIET
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
1.6 V. All timing specifications given above are with a 25 pF load capacitance (see Figure 36, Figure 37, Figure 38, and Figure 39).
Sample tested during initial release to ensure compliance. All input signals are specified with t
Minimum CLKIN for specified performance, with slower SCLK frequencies performance specifications apply typically.
The time required for the output to cross 0.4 V or 2.4 V.
t
discharging the 25 pF capacitor. This means that the time, t
bus loading.
MAX
14
DD
3
4
is derived from the measured time taken by the data outputs to change 0.5 V. The measured number is then extrapolated back to remove the effects of charging or
= V
2
, unless otherwise noted.
DRIVE
1
= 2.7 V to 5.25 V, internal/external V
AD7938
700
25.5
30
10
15
50
0
0
10
10
10
10
0
0
30
30
3
50
0
0
10
0
10
40
15.7
7.8
Limit at T
MIN
AD7939
700
25.5
30
10
15
50
0
0
10
10
10
10
0
0
30
30
3
50
0
0
10
0
10
40
15.7
7.8
, T
MAX
Unit
kHz min
MHz max
ns min
ns min
ns min
ns max
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns max
ns min
ns max
ns min
ns min
ns min
ns min
ns min
ns max
ns min
ns min
Description
CLKIN frequency.
Minimum time between end of read and start of next conversion; in other words, time
from when the data bus goes into three-state until the next falling edge of CONVST.
CONVST pulse width.
CONVST falling edge to CLKIN falling edge setup time.
CLKIN falling edge to BUSY rising edge.
CS to WR setup time.
CS to WR hold time.
WR pulse width.
Data setup time before WR.
Data hold after WR.
New data valid before falling edge of BUSY.
CS to RD setup time.
CS to RD hold time.
RD pulse width.
Data access time after RD.
Bus relinquish time after RD.
Bus relinquish time after RD.
HBEN to RD setup time.
HBEN to RD hold time.
Minimum time between reads/writes.
HBEN to WR setup time.
HBEN to WR hold time.
CLKIN falling edge to BUSY falling edge.
CLKIN low pulse width.
CLKIN high pulse width.
14
REF
, quoted in the timing characteristics is the true bus relinquish time of the part and is independent of the
= 2.5 V, unless otherwise noted; f
Rev. C | Page 7 of 36
RISE
= t
FALL
= 5 ns (10% to 90% of V
CLKIN
= 25.5 MHz, f
SAMPLE
DD
) and timed from a voltage level of
= 1.5 MSPS; T
AD7938/AD7939
A
= T
MIN
to