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Software Programmable Features:
Unipolar/Bipolar Conversions
4 Differential/8 Single Ended Inputs
MSB or LSB First Data Sequence
Variable Data Word Length
Built-In Sample and Hold
Single Supply 5V, 10V or
鹵5V
Operation
Direct 4 Wire Interface to Most MPU Serial Ports and
All MPU Parallel Ports
30kHz Maximum Throughput Rate
The LTC
廬
1090 is a data acquisition component which
contains a serial I/O successive approximation A/D con-
verter. It uses LTCMOS
TM
switched capacitor technology
to perform either 10-bit unipolar, or 9-bit plus sign bipolar
A/D conversions. The 8-channel input multiplexer can be
configured for either single ended or differential inputs (or
combinations thereof). An on-chip sample and hold is
included for all single ended input channels.
The serial I/O is designed to be compatible with industry
standard full duplex serial interfaces. It allows either
MSB or LSB first data and automatically provides 2鈥檚
complement output coding in the bipolar mode. The
output data word can be programmed for a length of 8, 10,
12 or 16 bits. This allows easy interface to shift registers
and a variety of processors.
The LTC1090A is specified with total unadjusted error
(including the effects of offset, linearity and gain errors)
less than
鹵0.5LSB.
The LTC1090 is specified with offset and linearity less than
鹵0.5LSB
but with a gain error limit of
鹵2LSB
for
applications where gain is adjustable or less critical.
KEY SPECIFICATIO S
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Resolution: 10 Bits
Total Unadjusted Error (LTC1090A):
鹵1/2LSB
Max
Conversion Time: 22碌s
Supply Current: 2.5mA Max, 1.0mA Typ
, LTC and LT are registered trademarks of Linear Technology Corporation.
LTCMOS is a trademark of Linear Technology Corp.
TYPICAL APPLICATIO
LTC1090
DIFFERENTIAL
INPUT
5V
BIPOLAR INPUT
5V
鈥?V
D
OUT
D
IN
T
UNIPOLAR
INPUTS
SCLK
CS
FOR 8051 CODE SEE
APPLICATIONS INFORMATION
SECTION
MPU
(e.g., 8051)
1.0
0.5
ERROR (LSBs)
P1.1
P1.2
P1.3
P1.4
SERIAL DATA
LINK
0.0
鈥?0.5
鈥?.0
0
512
OUTPUT CODE
LTC1090 鈥?TA02
(+)
(鈥?
鈥?UNIPOLAR
INPUT
LTC1090 鈥?TA01
鈥?V
U
Linearity Plot
1024
1090fc
U
U
1
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