5
LTC1291
1291fa
CCHARA TERIST
ICS
UW
AT
Y
P
I
CA
LPER
F
O
R
C
E
D
OUT
Delay Time vs Temperature
Maximum Clock Rate vs Source
Resistance
Maximum Filter Resistor vs
Cycle Time
CYCLE TIME (µs)
10
MAXIMUM R
FILTER
** (Ω)
100
1k
10k
10
1k
10k
1291 G12
1
100
+
–
+V
IN
C
FILTER
≥1µF
R
FILTER
100
0.2
MAXIMUM CLK FREQUENCY* (MHz)
0.4
0.6
0.8
1.0
1k 10k 100k
1291 G11
0
V
CC
= 5V
CLK = 1MHz
R
SOURCE
–
(Ω)
+
–
+IN
–IN
+V
IN
R
SOURCE
–
AMBIENT TEMPERATURE (°C)
–50
0
INPUT CHANNEL LEAKAGE CURRENT (nA)
100
300
400
500
1000
700
–10
30
50 130
1291 G14
200
800
900
600
–30 10
70 90
110
ON CHANNEL
OFF CHANNEL
GUARANTEED
Input Channel Leakage Current
vs Temperature
Sample-and-Hold Acquisition
Time vs Source Resistance
* MAXIMUM CLK FREQUENCY REPRESENTS THE CLK
FREQUENCY AT WHICH A 0.1LSB SHIFT IN THE
ERROR AT ANY CODE TRANSITION FROM ITS 1MHz
VALUE IS FIRST DETECTED
**MAXIMUM R
FILTER
REPRESENTS THE FILTER RESISTOR
VALUE AT WHICH A 0.1LSB CHANGE IN FULL SCALE
ERROR FROM ITS VALUE AT R
FILTER
= 0Ω IS FIRST
DETECTED
PI FU CTIO S
U
UU
AMBIENT TEMPERATURE (°C)
–50
D
OUT
DELAY TIME FROM CLK↓ (ns)
150
200
250
50
1291 G10
100
0
–25
0
25
75
125100
V
CC
= 5V
50
MSB-FIRST DATA
LSB-FIRST DATA
R
SOURCE
+ (Ω)
100
1
S/H AQUISITION TIME TO 0.02% (µs)
10
100
1k 10k
1291 G13
+
–
V
IN
R
SOURCE
+
V
CC
= 5V
T
A
= 25°C
0V TO 5V INPUT STEP
CS (Pin 1): Chip Select Input. A logic low on this input
enables the LTC1291.
CH0, CH1 (Pins 2, 3): Analog Inputs. These inputs must
be free of noise with respect to GND.
GND (Pin 4): Analog Ground. GND should be tied directly
to an analog ground plane.
D
IN
(Pin 5): Digital Data Input. The multiplexer address is
shifted into this input.
D
OUT
(Pin 6): Digital Data Output. The A/D conversion
result is shifted out of this output.
CLK (Pin 7): Shift Clock. This clock synchronizes the serial
data transfer.
V
CC
(V
REF
) (Pin 8): Positive Supply and Reference Voltage.
This pin provides power and defines the span of the A/D
converter. This supply must be kept free of noise and
ripple by bypassing directly to the analog ground plane.