Datasheet

9
LTC1854/LTC1855/LTC1856
185456fa
UU
U
PI FU CTIO S
COM (Pin 1): Common Input. This is the negative refer-
ence point for all single-ended inputs. It must be free of
noise and is usually connected to the analog ground plane.
CH0 (Pin 2): Analog MUX Input.
CH1 (Pin 3): Analog MUX Input.
CH2 (Pin 4): Analog MUX Input.
CH3 (Pin 5): Analog MUX Input.
CH4 (Pin 6): Analog MUX Input.
CH5 (Pin 7): Analog MUX Input.
CH6 (Pin 8): Analog MUX Input.
CH7 (Pin 9): Analog MUX Input.
MUXOUT
+
(Pin 10): Positive MUX Output. Output of the
analog multiplexer. Connect to ADC
+
for normal operation.
MUXOUT
–
(Pin 11): Negative MUX Output. Output of the
analog multiplexer. Connect to ADC
–
for normal operation.
ADC
+
(Pin 12): Positive Analog Input to the Analog-to-
Digital Converter.
ADC
–
(Pin 13): Negative Analog Input to the Analog-to-
Digital Converter.
AGND1 (Pin 14): Analog Ground.
V
REF
(Pin 15): 2.5V Reference Output. Bypass to analog
ground with a 1mF tantalum capacitor.
REFCOMP (Pin 16): Reference Buffer Output. Bypass to
analog ground with a 10mF tantalum and a 0.1mF ceramic
capacitor. Nominal output voltage is 4.096V.
AGND2 (Pin 17): Analog Ground.
AGND3 (Pin 18): Analog Ground. This is the substrate
connection.
AV
DD
(Pin 19): 5V Analog Supply. Bypass to analog ground
with a 0.1mF ceramic and a 10mF tantalum capacitor.
DV
DD
(Pin 20): 5V Digital Supply. Bypass to digital ground
with a 0.1mF ceramic and a 10mF tantalum capacitor.
OV
DD
(Pin 21): Positive Supply for the Digital Output
Buffers (3V to 5V). Bypass to digital ground with a 0.1mF
ceramic and a 10mF tantalum capacitor.
BUSY (Pin 22): Output shows converter status. It is low
when a conversion is in progress.
SDO (Pin 23): Serial Data Output.