19-1072; Rev 2; 5/98
+2 .7 V t o +5 .2 5 V, Lo w -P o w e r, 4 -Ch a n n e l,
S e ria l 1 0 -Bit ADCs in QS OP -1 6
8/MAX1249
_______________Ge n e ra l De s c rip t io n
____________________________Fe a t u re s
The MAX1248/MAX1249 10-bit data-acquisition sys-
tems combine a 4-channel multiplexer, high-bandwidth
track/hold, and serial interface with high conversion
speed and low power consumption. They operate from
a s ing le +2.7V to +5.25V s up p ly, a nd the ir a na log
inputs are software configurable for unipolar/bipolar
and single-ended/differential operation.
♦ 4-Channel Single-Ended or 2-Channel
Differential Inputs
♦ Single +2.7V to +5.25V Operation
♦ Internal 2.5V Reference (MAX1248)
♦ 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-fa mily d ig ita l s ig na l p roc e s s ors . The
MAX1248/MAX1249 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 MAX1248 has an internal 2.5V reference, while the
MAX1249 requires an external reference. Both parts
have a reference-buffer amplifier with a ±1.5% voltage
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
conversion. Accessing the serial interface automatically
p owe rs up the MAX1248/MAX1249, a nd the q uic k
turn-on time allows them to be shut down between all
conversions. This technique can cut supply current to
under 60µA at reduced sampling rates.
INL
(LSB)
PART†
TEMP. RANGE PIN-PACKAGE
MAX1248ACPE 0°C to +70°C
16 Plastic DIP
16 Plastic DIP
16 QSOP
±1/2
±1
MAX1248BCPE
MAX1248ACEE
MAX1248BCEE
0°C to +70°C
0°C to +70°C
0°C to +70°C
±1/2
±1
16 QSOP
The MAX1248/MAX1249 are available in a 16-pin DIP
and a very small QSOP that occupies the same board
area as an 8-pin SO.
Ordering Information continued at end of data sheet.
†
Contact factory for availability of alternate surface-mount
packages.
For 8-c ha nne l ve rs ions of the s e d e vic e s , s e e the
MAX148/MAX149 data sheet.
________________________Ap p lic a t io n s
__________Typ ic a l Op e ra t in g Circ u it
Portable Data Logging
Medical Instruments
Pen Digitizers
Data Acquisition
+3V
Battery-Powered Instruments
System Supervision
V
DD
V
CH0
DD
C3
0.1µF
0V TO
+2.5V
ANALOG
INPUTS
DGND
MAX1248
CH3
AGND
COM
CPU
I/O
CS
Pin Configuration appears at end of data sheet.
SCLK
SCK (SK)
MOSI (SO)
MISO (SI)
VREF
DIN
C1
4.7µF
DOUT
SSTRB
SHDN
REFADJ
V
SS
C2
0.01µF
SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.