Rainbow Electronics MAX149 - Manual

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 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 ±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 MAX148/MAX149, 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 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.
________________________Applications
Portable Data Logging Data Acquisition
Medical Instruments Battery-Powered Instruments
Pen Digitizers Process Control
____________________________Features
♦ 8-Channel Single-Ended or 4-Channel
Differential Inputs
♦ Single-Supply Operation: +2.7V to +5.25V
♦ Internal 2.5V Reference (MAX149)
♦ Low Power: 1.2mA (133ksps, 3V supply)
54µA (1ksps, 3V supply)
1µA (power-down mode)
♦ SPI/QSPI/MICROWIRE/TMS320-Compatible
4-Wire Serial Interface
♦ Software-Configurable Unipolar or Bipolar Inputs
♦ 20-Pin DIP/SSOP Packages
MAX148/MAX149
+2.7V to +5.25V, Low-Power, 8-Channel,
Serial 10-Bit ADCs
________________________________________________________________ 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
CH7
4.7 µ F
0.1 µ F
CH0
0V TO
+2.5V
ANALOG
INPUTS MAX149
CPU
+3V
VREF
0.01 µ F
REFADJ
__________Typical Operating Circuit
19-0464; Rev 2; 5/98
PART †
MAX148 ACPP
MAX148BCPP
MAX148ACAP 0°C to +70°C
0°C to +70°C
0°C to +70°C
TEMP. RANGE PIN-PACKAGE
20 Plastic DIP
20 Plastic DIP
20 SSOP
EVALUATION KIT
AVAILABLE
Ordering Information
Ordering Information continued at end of data sheet.
† Contact factory for availability of alternate surface-mount
packages.
MAX148BCAP 0°C to +70°C 20 SSOP
INL
(LSB)
±1/2
±1
±1/2
±1
SPI and QSPI are trademarks of Motorola, Inc. MICROWIRE is a trademark of National Semiconductor Corp.
Pin Configuration appears at end of data sheet.
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.