4
LTC1286/LTC1298
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
t
SMPL
Analog Input Sample Time See Operating Sequence 1.5 CLK Cycles
f
SMPL(MAX)
Maximum Sampling Frequency LTC1286 ● 12.5 kHz
LTC1298 ● 11.1 kHz
t
CONV
Conversion Time See Operating Sequence 12 CLK Cycles
t
dDO
Delay Time, CLK↓ to D
OUT
Data Valid See Test Circuits ● 250 600 ns
t
dis
Delay Time, CS↑ to D
OUT
Hi-Z See Test Circuits ● 135 300 ns
t
en
Delay Time, CLK↓ to D
OUT
Enable See Test Circuits ● 75 200 ns
t
hDO
Time Output Data Remains Valid After CLK↓ C
LOAD
= 100pF 230 ns
t
f
D
OUT
Fall Time See Test Circuits ● 20 75 ns
t
r
D
OUT
Rise Time See Test Circuits ● 20 75 ns
C
IN
Input Capacitance Analog Inputs, On Channel 20 pF
Analog Inputs, Off Channel 5 pF
Digital Input 5 pF
AC CHARACTERISTICS
(Note 5)
The ● denotes specifications which apply over the full operating
temperature range.
Note 1: Absolute maximum ratings are those values beyond which the life
of a device may be impaired.
Note 2: All voltage values are with respect to GND.
Note 3: These devices are specified at 5V. For 3V specified devices, see
LTC1285 and LTC1288.
Note 4: Increased leakage currents at elevated temperatures cause the S/H
to droop, therefore it is recommended that f
CLK
≥ 120kHz at 85°C, f
CLK
≥
75kHz at 70° and f
CLK
≥ 1kHz at 25°C.
Note 5: V
CC
= 5V, V
REF
= 5V and CLK = 200kHz unless otherwise specified.
Note 6: Linearity error is specified between the actual end points of the
A/D transfer curve.
Note 7: Two on-chip diodes are tied to each reference and analog input
which will conduct for reference or analog input voltages one diode drop
below GND or one diode drop above V
CC
. This spec allows 50mV forward
bias of either diode for 4.5V ≤ V
CC
≤ 5.5V. This means that as long as the
reference or analog input does not exceed the supply voltage by more than
50mV the output code will be correct. To achieve an absolute 0V to 5V
input voltage range will therefore require a minimum supply voltage of
4.950V over initial tolerance, temperature variations and loading. For 5.5V
< V
CC
≤ 9V, reference and analog input range cannot exceed 5.55V. If
reference and analog input range are greater than 5.55V, the output code
will not be guaranteed to be correct.
Note 8: The supply voltage range for the LTC1286 is from 4.5V to 9V, but
the supply voltage range for the LTC1298 is only from 4.5V to 5.5V.
Note 9: Recommended operating conditions
Note 10: Channel leakage current is measured after the channel selection.
TYPICAL PERFORMANCE CHARACTERISTICS
U
W
Shutdown Supply Current vs Clock
Rate with CS High and CS LowSupply Current vs Sample Rate
SAMPLE RATE (kHz)
0.1k
1
10
100
1000
1k 10k 100k
LT1286/98 G03
SUPPLY CURRENT (µA)
T
A
= 25°C
V
CC
= V
REF
= 5V
f
CLK
= 200kHz
LTC1286
LTC1298
Supply Current vs Temperature
TEMPERATURE (°C)
–55
200
SUPPLY CURRENT (µA)
250
350
400
450
–15
25
45 125
LT1286/98 G04
300
–35 5
65
85
105
T
A
= 25°C
V
CC
= V
REF
= 5V
f
CLK
= 200kHz
LTC1298 f
SMPL
=11.1kHz
LTC1286 f
SMPL
=12.5kHz
FREQUENCY (kHz)
1
0.002
SUPPLY CURRENT (µA)
5
1
0
15
20
25
35
20
100
140
LT1286/98 G01
10
30
80
180
200
40
60
120 160
CS = 0
(AFTER CONVERSION)
T
A
= 25°C
V
CC
= V
REF
= 5V
CS = V
CC
