LTC1292_15 Datasheet, PDF (6/24 Pages) Linear Technology – Single Chip 12-Bit Data Acquisition Systems

LTC1292/LTC1297
TYPICAL PERFOR A CE CHARACTERISTICS
Maximum Clock Rate vs
Source Resistance
1.0
V_CC = 5V
V_REF = 5V
0.8
CLK = 1MHz
+V_IN + +IN
0.6
R_{SOURCE – –IN}
0.4
0.2
0
100
1k
10k
R_SOURCE– (Ω)
100k
LTC1292/7G13
Input Channel Leakage Current vs
Temperature
1000
900
GUARANTEED
800
700
600
500
400
300
200
ON CHANNEL
100
OFF CHANNEL
0
–50 –30 –10 10 30 50 70 90 110 130
AMBIENT TEMPERATURE (°C)
LTC1292/7 G16
Maximum Filter Resistor vs
Cycle Time
10k
R_FILTER
+V_IN
+
1k
C_FILTER ≥1µF
–
100
10
Sample-and-Hold Acquisition
Time vs Source Resistance
100
V_REF = 5V
V_CC = 5V
T_A = 25°C
0V TO 5V INPUT STEP
10
+ ^RSOURCE
+V_IN
–
1
10
100
1k
10k
CYCLE TIME (µs)
LTC1292/7 G14
Noise Error vs Reference Voltage
2.25
LTC1292/LTC1297
2.00 _{NOISE = 200µVP-P}
1.75
1.50
1.25
1.00
0.75
0.50
0.25
0
0
1
2
3
4
5
REFERENCE VOLTAGE (V)
LTC1292/7 G17
1
100
1000
R_SOURCE+ (Ω)
10000
LTC1292/7 G15
* 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
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.
6
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.
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