19-0464; Rev 4; 1/10
+2.7V to +5.25V, Low-Power, 8-Channel,
Serial 10-Bit ADCs
Features
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.
S 8-Channel Single-Ended or 4-Channel Differential
The 4-wire serial interface connects directly to SPIK/
QSPIK and MICROWIREK 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 serial-interface clock to perform successive-approximation
analog-to-digital conversions.
The MAX149 has an internal 2.5V reference, while the
MAX148 requires an external reference. Both parts
have a reference-buffer amplifier with a Q1.5% 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
60FA at reduced sampling rates.
The MAX148/MAX149 are available in a 20-pin DIP and
a 20-pin SSOP.
Inputs
S Single-Supply Operation: +2.7V to +5.25V
S Internal 2.5V Reference (MAX149)
S Low Power: 1.2mA (133ksps, 3V Supply)
54µA (1ksps, 3V Supply)
1µA (Power-Down Mode)
S SPI/QSPI/MICROWIRE/TMS320-Compatible 4-Wire
Serial Interface
S Software-Configurable Unipolar or Bipolar Inputs
S 20-Pin DIP/SSOP Packages
Ordering Information
TEMP RANGE
PINPACKAGE
INL
(LSB)
MAX148ACPP
0°C to +70°C
20 Plastic DIP
±1/2
MAX148BCPP
0°C to +70°C
20 Plastic DIP
±1
MAX148ACAP
0°C to +70°C
20 SSOP
±1/2
MAX148BCAP
0°C to +70°C
20 SSOP
±1
PART†
Ordering Information continued at end of data sheet.
†Contact factory for availability of alternate surface-mount
package. Specify lead-free by placing + by the part number
when ordering.
*Contact factory for availability of CERDIP package, and for
processing to MIL-STD-883B. Not available in lead-free.
For 4-channel versions of these devices, see the
MAX1248/MAX1249 data sheet.
Typical Operating Circuit
+3V
Applications
Portable Data Logging
Data Acquisition
Medical Instruments
Process Control
DGND
MAX149
CH7
AGND
VREF
COM
CPU
CS
SCLK
DIN
DOUT
SSTRB
SHDN
I/O
SCK (SK)
MOSI (SO)
MISO (SI)
4.7FF
READJ
Pin Configuration appears at end of data sheet.
VDD
0.1FF
O TO
+2.5V
ANALOG
INPUTS
Battery-Powered Instruments
Pen Digitizers
VDD
CH0
0.01FF
VSS
SPI and QSPI are trademarks of Motorola, Inc. MICROWIRE is a trademark of National Semiconductor Corp.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX148/MAX149
General Description
