AD7880
REV. 0
–3–
TIMING CHARACTERISTICS
1
Limit at +258C Limit at T
MIN
, T
MAX
Parameter (All Versions) (All Versions) Units Conditions/Comments
t
1
50 50 ns min CONVST Pulse Width
t
2
130 130 ns min CONVST to BUSY Falling Edge
t
3
0 0 ns min BUSY to CS Setup Time
t
4
0 0 ns min CS to RD Setup Time
t
5
0 0 ns min CS to RD Hold Time
t
6
60 75 ns min RD Pulse Width
t
7
2
57 70 ns max Data Access Time after RD
t
8
3
55 ns min Bus Relinquish Time after RD
50 50 ns max
NOTES
1
Timing specifications in bold print are 100% production tested. All other times are sample tested at +25°C to ensure compliance. All input signals are specified with
tr = tf = 5 ns (10% to 90% of 5 V) and timed from a voltage level of 1.6 V.
2
t
7
is measured with the load circuit of Figure 2 and defined as the time required for an output to cross 0.8 V or 2.4 V.
3
t
8
is derived from the measured time taken by the data outputs to change by 0.5 V when loaded with the circuit of Figure 2. The measured number is then extrapo-
lated back to remove the effects of charging the 50 pF capacitor. This means that the time, t
8
, quoted in the timing characteristics is the true bus relinquish time of
the part and as such is independent of external bus loading capacitances.
(V
DD
= +5 V 6 5%, V
REF
= V
DD
, AGND = DGND = 0 V)
Table I. Truth Table
CS CONVST RD Function
1 1 X Not Selected
1 j 1 Start Conversion g
0 1 0 Enable ADC Data
0 1 1 Data Bus Three Stated
ABSOLUTE MAXIMUM RATINGS*
V
DD
to AGND . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +7 V
V
DD
to DGND . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +7 V
AGND to DGND . . . . . . . . . . . . . . . . . –0.3 V to V
DD
+ 0.3 V
V
INA
, V
INB
to AGND (Figure 5) . . . . . . –0.3 V to V
DD
+ 0.3 V
V
INA
to AGND (Figure 6) . . . . . . . . . –0.6 V to 2 V
DD
+ 0.6 V
V
INA
to AGND (Figure 7) . . . . . –V
DD
– 0.3 V to V
DD
+ 0.3 V
V
REF
to AGND . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 V to V
DD
Digital Inputs to DGND . . . . . . . . . . . –0.3 V to V
DD
+ 0.3 V
Digital Outputs to DGND . . . . . . . . . . –0.3 V to V
DD
+ 0.3 V
Operating Temperature Range
Industrial (B, C Versions) . . . . . . . . . . . . . –40°C to +85°C
Storage Temperature Range . . . . . . . . . . . –65°C to +150°C
Lead Temperature (Soldering, 10 secs) . . . . . . . . . . . . +300°C
Power Dissipation (Any Package) to +75°C . . . . . . . . 450 mW
Derates above +75°C by . . . . . . . . . . . . . . . . . . . . . 10 mW/°C
*Stresses above those listed under “Absolute Maximum Ratings” may cause
permanent damage to the device. This is a stress rating only and functional
operation of the device at these or any other conditions above those listed in the
operational sections of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
WARNING!
ESD SENSITIVE DEVICE
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the AD7880 features proprietary ESD protection circuitry, permanent damage may
occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD
precautions are recommended to avoid performance degradation or loss of functionality.
DB0 – DB11
DATA
VALID
t
1
t
CONVERT
t
2
t
3
t
4
t
5
t
6
t
7
t
8
CONVST
BUSY
CS
RD
THREE-STATE
TRACK/HOLD
GOES INTO HOLD
Figure 1. Timing Diagram
TO OUTPUT
PIN
1.6mA
2.1V+
200µA
50pF
Figure 2. Load Circuit for Access and Relinquish Time
