LTC1285 データシートの表示（PDF） - Linear Technology
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LTC1285 Datasheet PDF : 24 Pages
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LTC1285/LTC1288
AC CHARACTERISTICS (Note 5)
SYMBOL PARAMETER
tSMPL
Analog Input Sample Time
fSMPL (MAX) Maximum Sampling Frequency
tCONV
tdDO
tdis
ten
thDO
tf
tr
CIN
Conversion Time
Delay Time, CLK↓ to DOUT Data Valid
Delay Time, CS↑ to DOUT Hi-Z
Delay Time, CLK↓ to DOUT Enable
Time Output Data Remains Valid After CLK↓
DOUT Fall Time
DOUT Rise Time
Input Capacitance
CONDITIONS
See Operating Sequence
LTC1285
LTC1288
See Operating Sequence
See Test Circuits
See Test Circuits
See Test Circuits
CLOAD = 100pF
See Test Circuits
See Test Circuits
Analog Inputs, On Channel
Analog Inputs, Off Channel
Digital Input
MIN TYP MAX
UNITS
1.5
CLK Cycles
q 7.5
kHz
q 6.6
kHz
12
CLK Cycles
q
600 1500
ns
q
220 660
ns
q
180 500
ns
520
ns
q
60 180
ns
q
80 180
ns
20
pF
5
pF
5
pF
The q 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 3V. For 5V specified devices, see
LTC1286 and LTC1298.
Note 4: Increased leakage currents at elevated temperatures cause the
sample-and-hold to droop, therefore it is recommended that fCLK ≥ 75kHz
at 70° and fCLK ≥ 1kHz at 25°C.
Note 5: VCC = 2.7V, VREF = 2.5V and CLK = 120kHz 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 VCC. This spec allows 50mV forward
bias of either diode for 2.7V ≤ VCC ≤ 6V. 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 2.7V
input voltage range will therefore require a minimum supply voltage of
2.650V over initial tolerance, temperature variations and loading. For 2.7V
< VCC ≤ 6V, reference and analog input range cannot exceed 6.05V. If
reference and analog input range are greater than 6.05V, the output code
will not be guaranteed to be correct.
Note 8: The supply voltage range for the LTC1285 and the LTC1288 is
from 2.7V to 6V.
Note 9: Recommended operating conditions
Note 10: Channel leakage current is measured after the channel selection.
TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current vs Sample Rate
1000
100
TA = 25°C
VCC = 2.7V
VREF = 2.5V
fCLK = 120kHz
LTC1288
10
LTC1285
1
0.1
1
10
SAMPLE RATE (kHz)
LTC1285/88 • TPC01
Supply Current vs Temperature
250
LTC1288
fSMPL = 6.6kHz
200
LTC1285
fSMPL = 7.5kHz
150
100
50 VCC = 2.7V
VREF = 2.5V
fCLK = 120kHz
0
–55 –35 –15 5
25 45 65 85
TEMPERATURE (°C)
105 125
LTC1285/88 • TPC02
Shutdown Supply Current vs Clock
Rate with CS High and CS Low
9
TA = 25°C
8 VCC = 2.7V
7 VREF = 2.5V
6
5
4
CS = 0
3
(AFTER CONVERSION)
2
1
0.002
0
1
CS = VCC
20 40 60 80 100 120
FREQUENCY (kHz)
LTC1285/88 • TPC03
4
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