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_______________General Desc ription
The MAX1246/MAX1247 12-bit data-acquisition systems
combine a 4-channel multiplexer, high-bandwidth
track/hold, and serial interface with high conversion
speed and low power consumption. The MAX1246 oper-
ates from a single +2.7V to +3.6V supply; the MAX1247
operates from a single +2.7V to +5.25V supply. Both
devices’ analog inputs are software configurable for
unipolar/bipolar and single-ended/differential operation.
The 4-wire serial interface connects directly to SPI /
QSPI and Microwire devices without external logic. A
serial strobe output allows direct connection to TMS320-
family digital signal processors. The MAX1246/MAX1247
use either the internal clock or an external serial-interface
clock to perform successive-approximation analog-to-
digital conversions.
The MAX1246 has an internal 2.5V reference, while the
MAX1247 requires an external reference. Both parts have
a reference-buffer amplifier with a ±1.5% voltage-
adjustment range.
These devices provide a hard-wired
SHDN
pin and a
software-selectable power-down, and can be pro-
grammed to automatically shut down at the end of a con-
version. Accessing the serial interface automatically
powers up the MAX1246/MAX1247, and the quick turn-on
time allows them to be shut down between all conver-
sions. This technique can cut supply current to under
60μA at reduced sampling rates.
The MAX1246/MAX1247 are available in a 16-pin DIP and
a small QSOP that occupies the same board area as an
8-pin SO.
For 8-channel versions of these devices, see the
MAX146/MAX147 data sheet.
________________________Applic ations
Portable Data Logging
Data Acquisition
Medical Instruments
Battery-Powered Instruments
Pen Digitizers
Process Control
____________________________Features
o
4-Channel Single-Ended or 2-Channel
Differential Inputs
o
Single-Supply Operation:
+2.7V to +3.6V (MAX1246)
+2.7V to +5.25V (MAX1247)
o
Internal 2.5V Reference (MAX1246)
o
Low Power: 1.2mA (133ksps, 3V supply)
54μA (1ksps, 3V supply)
1μA (power-down mode)
o
SPI/QSPI/Microwire/TMS320-Compatible
4-Wire Serial Interface
o
Software-Configurable Unipolar or Bipolar Inputs
o
16-Pin QSOP Package (same area as 8-pin SO)
M
+2.7V, Low-Power, 4-Channel,
S erial 12-Bit ADCs in QS OP-16
________________________________________________________________ Maxim Integrated Products
1
V
DD
I/O
SCK (SK)
MOSI (SO)
MISO(SI)
V
SS
SHDN
SSTRB
DOUT
DIN
SCLK
CS
COM
AGND
DGND
V
DD
CH3
4.7
μ
F
0.1
μ
F
CH0
0V TO
+2.5V
ANALOG
INPUTS
MAX1246
CPU
+3V
VREF
0.047
μ
F
REFADJ
__________Typic al Operating Circ uit
19-1071; Rev 1; 3/97
EVALUATION KIT
AVAILABLE
PART
MAX1246
ACPE
MAX1246BCPE
MAX1246ACEE
MAX1246BCEE
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
TEMP. RANGE
PIN-PACKAGE
16 Plastic DIP
16 Plastic DIP
16 QSOP
16 QSOP
______________Ordering Information
Ordering Information continued at end of data sheet.
Contact factory for availability of alternate surface-mount
packages.
INL
(LSB)
±1/2
±1
±1/2
±1
SPI and QSPI are registered trademarks of Motorola, Inc. Microwire is a registered trademark of National Semiconductor Corp.
Pin Configuration appears at end of data sheet.