19-1071; Rev 1; 3/97
+2 .7 V, Lo w -P o w e r, 4 -Ch a n n e l,
S e ria l 1 2 -Bit ADCs in QS OP -1 6
6/MAX1247
_______________Ge n e ra l De s c rip t io n
____________________________Fe a t u re s
The MAX1246/MAX1247 12-bit data-acquisition systems
c omb ine a 4-c ha nne l multip le xe r, hig h-b a nd wid th
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.
♦ 4-Channel Single-Ended or 2-Channel
Differential Inputs
♦ Single-Supply Operation:
+2.7V to +3.6V (MAX1246)
+2.7V to +5.25V (MAX1247)
♦ Internal 2.5V Reference (MAX1246)
♦ Low Power: 1.2mA (133ksps, 3V supply)
54µA (1ksps, 3V supply)
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.
1µA (power-down mode)
♦ SPI/QSPI/Microwire/TMS320-Compatible
4-Wire Serial Interface
♦ Software-Configurable Unipolar or Bipolar Inputs
♦ 16-Pin QSOP Package (same area as 8-pin SO)
The MAX1246 has an internal 2.5V reference, while the
MAX1247 requires an external reference. Both parts have
a re fe re nc e -b uffe r a mp lifie r with a ± 1.5% volta g e -
adjustment range.
______________Ord e rin g In fo rm a t io n
These devices provide a hard-wired SHDN pin and a
s oftwa re -s e le c ta b le p owe r-d own, a nd c a n b e p ro-
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.
INL
(LSB)
PART†
TEMP. RANGE PIN-PACKAGE
MAX1246ACPE 0°C to +70°C
16 Plastic DIP
16 Plastic DIP
16 QSOP
±1/2
±1
MAX1246BCPE
MAX1246ACEE
MAX1246BCEE
0°C to +70°C
0°C to +70°C
0°C to +70°C
±1/2
±1
16 QSOP
Ordering Information continued at end of data sheet.
Contact factory for availability of alternate surface-mount
packages.
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-c ha nne l ve rs ions of the s e d e vic e s , s e e the
MAX146/MAX147 data sheet.
__________Typ ic a l Op e ra t in g Circ u it
________________________Ap p lic a t io n s
+3V
Portable Data Logging
Medical Instruments
Pen Digitizers
Data Acquisition
V
DD
V
CH0
DD
0.1µF
Battery-Powered Instruments
Process Control
0V TO
+2.5V
ANALOG
INPUTS
DGND
MAX1246
CH3
AGND
COM
CPU
I/O
VREF
CS
4.7µF
SCLK
SCK (SK)
MOSI (SO)
MISO (SI)
DIN
DOUT
REFADJ
0.047µF
SSTRB
SHDN
V
SS
Pin Configuration appears at end of data sheet.
SPI and QSPI are registered trademarks of Motorola, Inc. Microwire is a registered trademark of National Semiconductor Corp.
________________________________________________________________ Maxim Integrated Products
1
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