Electrical characteristics – Rainbow Electronics ADC08138 User Manual
Page 5
Electrical Characteristics
(Continued)
The following specifications apply for V
CC
e
a
5 V
DC
V
REF
e
a
2 5 V
DC
and t
r
e
t
f
e
20 ns unless otherwise specified
Boldface limits apply for T
A
e
T
J
e
T
MIN
to T
MAX
all other limits T
A
e
T
J
e
25 C
Symbol
Parameter
Conditions
Typical
Limits
Units
(Note 8)
(Note 9)
(Limits)
f
CLK
Clock Frequency
10
kHz (min)
1
MHz (max)
Clock Duty Cycle
40
% (min)
(Note 14)
60
% (max)
T
C
Conversion Time (Not Including
f
CLK
e
1 MHz
8
1 f
CLK
(max)
MUX Addressing Time)
8
m
s (max)
t
CA
Acquisition Time
1 f
CLK
(max)
t
SELECT
CLK High while CS is High
50
ns
t
SET-UP
CS Falling Edge or Data Input
25
ns (min)
Valid to CLK Rising Edge
t
HOLD
Data Input Valid after CLK
20
ns (min)
Rising Edge
t
pd1
t
pd0
CLK Falling Edge to Output
C
L
e
100 pF
Data Valid (Note 15)
Data MSB First
250
ns (max)
Data LSB First
200
ns (max)
t
1H
t
0H
TRI-STATE Delay from Rising Edge
C
L
e
10 pF R
L
e
10 kX
50
ns
of CS to Data Output and SARS Hi-Z
(see TRI-STATE Test Circuits)
C
L
e
100 pF R
L
e
2 kX
180
ns (max)
C
IN
Capacitance of Logic Inputs
5
pF
C
OUT
Capacitance of Logic Outputs
5
pF
Note 1
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur
Note 2
Operating Ratings indicate conditions for which the device is functional These ratings do not guarantee specific performance limits For guaranteed
specifications and test conditions see the Electrical Characteristics The guaranteed specifications apply only for the test conditions listed Some performance
characteristics may degrade when the device is not operated under the listed test conditions
Note 3
All voltages are measured with respect to AGND
e
DGND
e
0 V
DC
unless otherwise specified
Note 4
When the input voltage (V
IN
) at any pin exceeds the power supplies (V
IN
k
(AGND or DGND) or V
IN
l
AV
CC
) the current at that pin should be limited to
5 mA The 20 mA maximum package input current rating limits the number of pins that can safely exceed the power supplies with an input current of 5 mA to four
pins
Note 5
The maximum power dissipation must be derated at elevated temperatures and is dictated by T
JMAX
i
JA
and the ambient temperature T
A
The maximum
allowable power dissipation at any temperature is P
D
e
(T
JMAX
b
T
A
) i
JA
or the number given in the Absolute Maximum Ratings whichever is lower For devices
with suffixes BIN CIN BIJ CIJ BIWM and CIWM T
JMAX
e
125 C For devices with suffix CMJ T
JMAX
e
150 C The typical thermal resistances (i
JA
) of these
parts when board mounted follow ADC08131 with BIN and CIN suffixes 120 C W ADC08134 with BIN and CIN suffixes 95 C W ADC08138 with BIN and CIN
suffixes 80 C W ADC08134 with BIWM and CIWM suffixes 140 C W ADC08138 with BIWM and CIWM suffixes 91 C W
Note 6
Human body model 100 pF capacitor discharged through a 1 5 kX resistor
Note 7
See AN450 ‘‘Surface Mounting Methods and Their Effect on Product Reliability’’ or
Linear Data Book section ‘‘Surface Mount’’ for other methods of
soldering surface mount devices
Note 8
Typicals are at T
J
e
25 C and represent the most likely parametric norm
Note 9
Guaranteed to National’s AOQL (Average Outgoing Quality Level)
Note 10
Total unadjusted error includes zero full-scale linearity and multiplexer error Total unadjusted error with V
REF
e a
5V only applies to the ADC08134
and ADC08138 See Note 16
Note 11
Cannot be tested for the ADC08131
Note 12
For V
IN(
b
)
t
V
IN(
a
)
the digital code will be 0000 0000 Two on-chip diodes are tied to each analog input (see Block Diagram) which will forward-conduct
for analog input voltages one diode drop below ground or one diode drop greater than V
CC
supply During testing at low V
CC
levels (e g 4 5V) high level analog
inputs (e g 5V) can cause an input diode to conduct especially at elevated temperatures This will cause errors for analog inputs near full-scale The specification
allows 50 mV forward bias of either diode this means that as long as the analog V
IN
does not exceed the supply voltage by more than 50 mV the output code will
be correct Exceeding this range on an unselected channel will corrupt the reading of a selected channel Achievement of an absolute 0 V
DC
to 5 V
DC
input voltage
range will therefore require a minimum supply voltage of 4 950 V
DC
over temperature variations initial tolerance and loading
Note 13
Channel leakage current is measured after a single-ended channel is selected and the clock is turned off For off channel leakage current the following
two cases are considered one with the selected channel tied high (5 V
DC
) and the remaining seven off channels tied low (0 V
DC
) total current flow through the off
channels is measured two with the selected channel tied low and the off channels tied high total current flow through the off channels is again measured The two
cases considered for determining on channel leakage current are the same except total current flow through the selected channel is measured
Note 14
A 40% to 60% duty cycle range insures proper operation at all clock frequencies In the case that an available clock has a duty cycle outside of these
limits the minimum time the clock is high or low must be at least 450 ns The maximum time the clock can be high or low is 100 ms
Note 15
Since data MSB first is the output of the comparator used in the successive approximation loop an additional delay is built in (see Block Diagram) to
allow for comparator response time
Note 16
For the ADC08131 V
REF
IN is internally tied to the on chip 2 5V band-gap reference output therefore the supply current is larger because it includes the
reference current (700 mA typical 2 mA maximum)
Note 17
Load regulation test conditions and specifications for the ADC08131 differ from those of the ADC08134 and ADC08138 because the ADC08131 has the
on-board reference as a permanent load
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