Datasheet

8
LTC1448
TYPICAL APPLICATIONS
U
This circuit shows how to use one LTC1448 to make an
autoranging ADC. The microprocessor sets the reference
span and the Common pin for the analog input by loading
the appropriate digital code into the LTC1448. V
OUT A
controls the Common pin for the analog inputs to the
LTC1296 and V
OUT B
controls the reference span by setting
the REF
+
pin on the LTC1296. The LTC1296 has a Shut-
down pin that goes low in shutdown mode. This will turn
off the PNP transistor supplying power to the LTC1448.
The resistor and capacitor on the LTC1448 outputs act as
a lowpass filter for noise.
LTC1296
V
CC
50k
74HC04
5V
5V
CS
22µF
µP
CLK
8 ANALOG
INPUT CHANNELS
D
OUT
D
IN
CH0
COM
SSO REF
–
CH7
REF
+
50k
0.1µF
100Ω
100Ω
LTC1448
CS/LD
CLK
REF
D
IN
V
OUT B
GND
V
CC
1448 TA04
V
OUT A
0.1µF
0.1µF
+
An Autoranging 8-Channel ADC with Shutdown