Datasheet

6
LTC1292/LTC1297
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CCHARA TERIST
ICS
UW
AT
Y
P
I
CA
LPER
F
O
R
C
E
100
0.2
MAXIMUM CLK FREQUENCY* (MHz)
0.4
0.6
0.8
1.0
1k 10k 100k
LTC1292/7G13
0
V
CC
= 5V
V
REF
= 5V
CLK = 1MHz
R
SOURCE
– (Ω)
+
–
+IN
–IN
+V
IN
R
SOURCE
Maximum Filter Resistor vs
Cycle Time
PI FU CTIO S
U
UU
* 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.
CYCLE TIME (µs)
10
MAXIMUM R
FILTER
** (Ω)
100
1k
10k
10
1k
10k
LTC1292/7 G14
1
100
+
–
+V
IN
C
FILTER
≥1µF
R
FILTER
Maximum Clock Rate vs
Source Resistance
R
SOURCE
+ (Ω)
100
1
S & H AQUISITION TIME TO 0.02% (µs)
10
100
1000 10000
LTC1292/7 G15
+
–
+V
IN
R
SOURCE
V
REF
= 5V
V
CC
= 5V
T
A
= 25°C
0V TO 5V INPUT STEP
Sample-and-Hold Acquisition
Time vs Source Resistance
Input Channel Leakage Current vs
Temperature
AMBIENT TEMPERATURE (°C)
–50
0
INPUT CHANNEL LEAKAGE CURRENT (nA)
100
300
400
500
1000
700
–10
30
50 130
LTC1292/7 G16
200
800
900
600
–30 10
70 90
110
ON CHANNEL
OFF CHANNEL
GUARANTEED
Noise Error vs Reference Voltage
REFERENCE VOLTAGE (V)
0
0
PEAK-TO-PEAK NOISE ERROR (LSB)
0.25
0.75
1.00
1.25
2
4
5
2.25
0.50
13
1.50
1.75
2.00
LTC1292/7 G17
LTC1292/LTC1297
NOISE = 200µV
P-P
CS (Pin 1): Chip Select Input. A logic low on this input
enables the LTC1292/LTC1297. Power shutdown is acti-
vated on the LTC1297 when CS is brought high.
+IN, –IN (Pin 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.
V
REF
(Pin 5): Reference Input. The reference input defines
the span of the A/D converter and must be kept free of
noise with respect to GND.
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
(Pin 8): Positive Supply. This supply must be kept free
of noise and ripple by bypassing directly to the analog
ground plane.