LTC1850/LTC1851
8-Channel, 10-Bit/12-Bit,
1.25Msps Sampling ADCs
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FEATURES
DESCRIPTIO
The 10-bit LTC®1850 and 12-bit LTC1851 are complete
8-channel data acquisition systems. They include a flex-
ible8-channelmultiplexer,a1.25Mspssuccessiveapproxi-
mation analog-to-digital converter with sample-and-hold,
an internal 2.5V reference and reference buffer amplifier,
andaparalleloutputinterface. Themultiplexercanbecon-
figured for single-ended or differential inputs, two gain
ranges and unipolar or bipolar operation.
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Flexible 8-Channel Multiplexer
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Single-Ended or Differential Inputs
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Two Gain Ranges Plus Unipolar and Bipolar
Operation
1.25Msps Sampling Rate
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Single 5V Supply and 40mW Power Dissipation
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Scan Mode and Programmable Sequencer
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Pin Compatible 10-Bit LTC1850 and 12-Bit LTC1851
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True Differential Inputs Reject Common Mode Noise
The ADCs have a scan mode that will repeatedly cycle
through all 8 multiplexer channels and can also be
programmed with a sequence of up to 16 addresses and
configurations that can be scanned in succession. The
sequence memory can also be read back. The reference
and buffer amplifier provide pin strappable ranges of
4.096V, 2.5V and 2.048V. The parallel output includes
the 10-bit or 12-bit conversion result plus the 4-bit
multiplexer address. The digital outputs are powered
from a separate supply allowing for easy interface to 3V
digital logic. Typical power consumption is 40mW at
1.25Msps from a single 5V supply.
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Internal 2.5V Reference
Parallel Output Includes MUX Address
Easy Interface to 3V Logic
Nap and Sleep Shutdown Modes
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APPLICATIO S
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High Speed Data Acquisition
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Test and Measurement
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Imaging Systems
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Telecommunications
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Industrial Process Control
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, LTC and LT are registered trademarks of Linear Technology Corporation.
Spectrum Analysis
W
BLOCK DIAGRA
M1
SHDN
CS
LTC1851
CH0
CH1
CONVST
RD
CONTROL LOGIC
WR
CH2
CH3
CH4
CH5
CH6
CH7
COM
AND
DIFF
Integral Linearity, LTC1851
PROGRAMMABLE
SEQUENCER
A2
A1
1.00
0.50
A0
8-CHANNEL
INTERNAL
CLOCK
UNI/BIP
PGA
M0
MULTIPLEXER
OV
DD
BUSY
DIFF /S6
0.00
OUT
A2 /S5
OUT
A1 /S4
OUT
A0 /S3
OUT
D11/S2
D10/S1
D9/S0
D8
–0.50
2.5V
REFERENCE
12-BIT
1.25Msps ADC
DATA
LATCHES
OUTPUT
DRIVERS
REFOUT
D7
–1.00
D6
0
512 1024 1536 2048 2560 3072 3584 4096
CODE
D5
D4
LTC1850/51 G01
D3
REFIN
REF AMP
D2
D1
D0
OGND
1851 BD
REFCOMP
18501f
1