3
LTC1291
1291fa
AC CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IH
High Level Input Voltage V
CC
= 5.25V ● 2.0 V
V
IL
Low Level Input Voltage V
CC
= 4.75V ● 0.8 V
I
IH
High Level Input Current V
IN
= V
CC
● 2.5 µA
I
IL
Low Level Input Current V
IN
= 0V ● –2.5 µA
V
OH
High Level Output Voltage V
CC
= 4.75V, I
OUT
= –10µA 4.7 V
V
CC
= 4.75V, I
OUT
= – 360µA ● 2.4 4.0 V
V
OL
Low Level Output Voltage V
CC
= 4.75V, I
OUT
= 1.6mA ● 0.4 V
I
OZ
High Z Output Leakage V
OUT
= V
CC
, CS High ● 3 µA
V
OUT
= 0V, CS High ● –3 µA
I
SOURCE
Output Source Current V
OUT
= 0V –20 mA
I
SINK
Output Sink Current V
OUT
= V
CC
20 mA
I
CC
Positive Supply Current CS High ● 612 mA
CS High Power Shutdown CLK Off ● 510 µA
LTC1291B/LTC1291C/LTC1291D
E
LECTR
IC
AL C CHARA TER ST
ICS
DIGITAL
A
D
U
I
DC
Note 7: Two on-chip diodes are tied to each analog input which will
conduct for analog voltages one diode drop below GND or one diode drop
above V
CC
. Be careful during testing at low V
CC
levels (4.5V), as high level
analog inputs (5V) can cause this input diode to conduct, especially at
elevated temperature, and cause errors for inputs near full scale. This spec
allows 50mV forward bias of either diode. This means that as long as the
analog input does not exceed the supply voltage by more than 50mV, the
output code will be correct.
Note 8: Channel leakage current is measured after the channel selection.
Note 9: Increased leakage currents at elevated temperatures cause the
S/H to droop, therefore it is recommended that f
CLK
≥ 125kHz at 125°C,
f
CLK
≥ 30kHz at 85°C and f
CLK
≥ 3kHz at 25°C.
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 ground (unless otherwise
noted).
Note 3: V
CC
= 5V, CLK = 1.0MHz unless otherwise specified.
Note 4: One LSB is equal to V
CC
divided by 4096. For example, when V
CC
=
5V, 1LSB = 5V/4096 = 1.22mV.
Note 5: Linearity error is specified between the actual end points of the
A/D transfer curve. The deviation is measured from the center of the
quantization band.
Note 6: Recommended operating conditions.
The ● denotes the specifications which
apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
The ● denotes the specifications which apply over the full operating temperature range,
otherwise specifications are at T
A
= 25°C. (Note 3)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
t
dis
Delay Time, CS↑ to D
OUT
Hi-Z See Test Circuits ● 80 150 ns
t
en
Delay Time, CLK↓ to D
OUT
Enabled See Test Circuits ● 80 200 ns
t
hDI
Hold Time, D
IN
after CLK↑ V
CC
= 5V (Note 6) 50 ns
t
hDO
Time Output Data Remains Valid after CLK↓ 130 ns
t
WHCLK
CLK High Time V
CC
= 5V (Note 6) 300 ns
t
WLCLK
CLK Low Time V
CC
= 5V (Note 6) 400 ns
t
f
D
OUT
Fall Time See Test Circuits ● 65 130 ns
t
r
D
OUT
Rise Time See Test Circuits ● 25 50 ns
t
suDI
Setup Time, D
IN
Stable before CLK↑ V
CC
= 5V (Note 6) 50 ns
t
suCS
Setup Time, CS↓ before CLK↑ V
CC
= 5V (Note 6) 50 ns
t
WHCS
CS High Time During Conversion V
CC
= 5V (Note 6) 500 ns
t
WLCS
CS Low Time During Data Transfer V
CC
= 5V (Note 6) 18 CLK Cycles
C
IN
Input Capacitance Analog Inputs On Channel 100 pF
Analog Inputs Off Channel 5 pF
Digital Inputs 5 pF
LTC1291B/LTC1291C/LTC1291D
