19-0464; Rev 2; 5/98
KIT
ATION
EVALU
ABLE
AVAIL
+2.7V to +5.25V, Low-Power, 8-Channel,
Serial 10-Bit ADCs
____________________________Features
o 8-Channel Single-Ended or 4-Channel
Differential Inputs
o Single-Supply Operation: +2.7V to +5.25V
o Internal 2.5V Reference (MAX149)
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 20-Pin DIP/SSOP Packages
The MAX149 has an internal 2.5V reference, while the
MAX148 requires an external reference. Both parts have
a reference-buffer amplifier with a ±1.5% voltageadjustment range.
These devices provide a hard-wired SHDN pin and a
software-selectable power-down, and can be programmed to automatically shut down at the end of a conversion. Accessing the serial interface automatically
powers up the MAX148/MAX149, and the quick 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.
The MAX148/MAX149 are available in a 20-pin DIP and a
20-pin SSOP.
For 4-channel versions of these devices, see the
MAX1248/MAX1249 data sheet.
Ordering Information
PART†
TEMP. RANGE
MAX148ACPP
0°C to +70°C
PIN-PACKAGE
20 Plastic DIP
INL
(LSB)
±1/2
±1
MAX148BCPP
0°C to +70°C
20 Plastic DIP
±1/2
MAX148ACAP
0°C to +70°C
20 SSOP
MAX148BCAP
0°C to +70°C
20 SSOP
±1
Ordering Information continued at end of data sheet.
† Contact factory for availability of alternate surface-mount
packages.
__________Typical Operating Circuit
________________________Applications
+3V
Portable Data Logging
Data Acquisition
Medical Instruments
Battery-Powered Instruments
Pen Digitizers
Process Control
CH0
0V TO
+2.5V
ANALOG
INPUTS
VDD
DGND
MAX149 AGND
CH7
VREF
4.7µF
CPU
COM
CS
SCLK
DIN
REFADJ
0.01µF
VDD
0.1µF
DOUT
I/O
SCK (SK)
MOSI (SO)
MISO (SI)
SSTRB
SHDN
VSS
Pin Configuration appears at end of data sheet.
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.
MAX148/MAX149
General Description
The MAX148/MAX149 10-bit data-acquisition systems
combine an 8-channel multiplexer, high-bandwidth
track/hold, and serial interface with high conversion
speed and low power consumption. They operate from a
single +2.7V to +5.25V supply, and sample to 133ksps.
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 MAX148/
MAX149 use either the internal clock or an external serialinterface clock to perform successive-approximation
analog-to-digital conversions.
