MP3276
Fault Protected 16 Channel, 12-Bit
Data Acquisition Subsystem
FEATURES
•
Fault Protected 16-Channel 12-Bit A/D
Converter with Sample & Hold, Reference,
Clock and 3-state Outputs
•
Fast Conversion, less than 15µS
•
Microprocessor Bus Interface
•
2’s Complement Data Output
•
Parallel or Serial Data Output Modes
•
65 ns Bus Access Time
•
Remote Analog Ground Sensing
•
Overvoltage Protected Input (50 V over the Sup-
ply Voltages)
•
Precision Reference for Long Term Stability and
Low Gain T.C.
•
Guaranteed Linearity Over Temperature
•
Guaranteed Performance at +12/–5 V,
±12
&
±15
V
•
Low Power: 110 mW typ. (7 mW per Channel typ.)
•
32 Channel Version: MP3274
GENERAL DESCRIPTION
The MP3276 is a complete 16-channel, 12-bit Data Acquisi-
tion Subsystem with 3-state output buffers for direct interfacing
to 16-bit microprocessor buses. Implemented using an ad-
vanced BiCMOS process, the converter combines a 16-channel
passive overvoltage protected multiplexer instrumentation amp,
a sample & hold, a SAR, a 12-bit decoded D/A, a comparator, a
precision reference and the control logic to achieve an accurate
repeated conversion in less than 15µs, and a mux/instrumenta-
tion amp settling period of less than 10µs.
A unique input design provides input overvoltage protection
to
50
V over the supply voltages. The circuit design can allow
for an overvoltage condition on unselected channels without dis-
rupting the measured channel or operation of the MP3276! The
internal 4 V reference has sufficient output current to provide
other system reference needs. Precision thin film scaling and
offset resistors are laser trimmed to provide for less than 2 LSB
INL for +10 V inputs on all channels.
In addition, the MP3276 will output either full scale (0111 ....)
for overrange and – full scale (1000....) for underrange condi-
tions. This greatly simplifies microprocessor software develop-
ment.
SIMPLIFIED BLOCK DIAGRAM
GND REF.
GND
AB0-3
(4 pins)
AIN0-15
(16 pins)
16
AGND
2
V
REF
REF IN
VDAC
REF OUT
4V
REF
CLK
12
SAR
AGND
3
Control
Logic
12
Latch/
Shift Register
V
DD
V
CC
AGND
4
16 Ch.
MUX
–
+
Comp
REF IN /2
3-state
Drivers
PXS
DGND V
EE
AGND
WR RD
CS
ADEN
STL
STS
DB0-DB11
Rev. 4.00
1
EXAR [ EXAR CORPORATION ]
