7
LTC1285/LTC1288
LTC1285
V
REF
(Pin 1): Reference Input. The reference input defines
the span of the A/D converter.
IN
+
(Pin 2): Positive Analog Input.
IN
–
(Pin 3): Negative Analog Input.
GND (Pin 4): Analog Ground. GND should be tied directly
to an analog ground plane.
CS/SHDN (Pin 5): Chip Select Input. A logic low on this
input enables the LTC1285. A logic high on this input
disables and powers down the LTC1285.
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 and determines conversion speed.
V
CC
(Pin 8): Power Supply Voltage. This pin provides
power to the A/D converter. It must be kept free of noise
and ripple by bypassing directly to the analog ground
plane.
TYPICAL PERFORMANCE CHARACTERISTICS
U
W
Minimum Clock Frequency
for 0.1 LSB Error vs Temperature
TEMPERATURE (°C)
0
CLOCK FREQUENCY (kHz)
80
100
120
40
LTC1285/88 • TPC22
60
40
0
10
20 30
60 70
50
20
2
V
CC
= 2.7V
V
REF
= 2.5V
TEMPERATURE (°C)
–55
LEAKAGE CURRENT (nA)
10
100
1000
105
LTC1285/88 • TPC24
1
0.1
0.01
–15
25
65
–35 125
5
45
85
V
CC
= 2.7V
V
REF
= 2.5V
ON CHANNEL
OFF CHANNEL
Input Channel Leakage Current
vs Temperature
Digital Input Logic Threshold
vs Supply Voltage
SUPPLY VOLTAGE (V)
2.5
DIGITAL INPUT LOGIC THRESHOLD VOLTAGE (V)
2.0
2.5
3.0
4.0 5.0
LTC1285/88 • TPC23
1.5
1.0
3.0 3.5
4.5 5.5 6.0
0.5
0
T
A
= 25°C
PIN FUNCTIONS
UUU
LTC1288
CS/SHDN (Pin 1): Chip Select Input. A logic low on this
input enables the LTC1288. A logic high on this input
disables and powers down the LTC1288.
CH0 (Pin 2): Analog Input.
CH1 (Pin 3): Analog Input.
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 and determines conversion speed.
V
CC
/V
REF
(Pin 8): Power Supply and Reference Voltage.
This pin provides power and defines the span of the A/D
converter. It must be kept free of noise and ripple by
bypassing directly to the analog ground plane.
