LTC2442IG#PBF Linear Technology, LTC2442IG#PBF Datasheet - Page 29

• Manufacturer Part Number: LTC2442IG#PBF
• Description: IC ADC 24BIT 4CH 36-SSOP
• Manufacturer: Linear Technology

Specifications of LTC2442IG#PBF

• Number Of Bits: 24
• Sampling Rate (per Second): 8k
• Data Interface: MICROWIRE™, Serial, SPI™
• Number Of Converters: 1
• Power Dissipation (max): 50mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 36-SSOP (0.200", 5.30mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIO S I FOR ATIO
Details of the Conversion and Autozero Process
The LTC2442 performs automatic offset cancellation for
each conversion. This is accomplished by taking the aver-
age of two “half-conversions” with the inputs applied in
opposite polarity. Figure 21 shows a conversion on CH0 to
CH1 differential at OSR of 32768, in 1x mode. This chan-
nel is selected by sending the appropriate confi guration
word to the LTC2442 through the SPI interface. On the
13
through the multiplexer and CH1 is connected to +INB.
The outputs of the amplifi ers slew during the remainder
of the data I/O state and the conversion begins on the
th
falling clock edge, the CH0 input is applied to +INA
U
U
Figure 21. Amplifi er Outputs and CS, SCK, BUSY During a Conversion
OUTB
BUSY
OUTA
SCK
W
CS
on CH0-1, OSR32768. V
U
20ms/DIV
INDIFF
32
(approximately 73ms later) the multiplexer switches the
CH0 input to +INB and the CH1 input to +INA. The digital
fi lter subtracts the two half-conversions, which removes
the offset of the amplifi ers and converter.
At the end of a conversion, the multiplexer assumes that
the next conversion will be on the same channel and
switches back to the opposite polarity on the channel just
converted. This gives extra settling time when convert-
ing on one channel continuously. If a different channel is
programmed, the multiplexer will switch again on the 13
falling clock edge.
nd
= 2.5V, V
falling clock edge. Halfway through the conversion
CM
= 2.5V
2V/DIV
5V/DIV
LTC2442
29
2442f
th