19-0464; Rev 2; 5/98
KIT
ATION
EVALU
E
BL
AVAILA
+2.7V to +5.25V, Low-Power, 8-Channel,
Serial 10-Bit ADCs
General Description
____________________________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)
54碌A (1ksps, 3V supply)
1碌A (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
MAX148/MAX149
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鈥?analog inputs are software configurable for
unipolar/bipolar and single-ended/differential operation.
The 4-wire serial interface connects directly to SPI鈩?
QSPI鈩?and MICROWIRE鈩?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 鹵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
60碌A 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
鈥?/div>
MAX148ACPP
TEMP. RANGE
0擄C to +70擄C
PIN-PACKAGE
20 Plastic DIP
INL
(LSB)
鹵1/2
鹵1
MAX148BCPP
0擄C to +70擄C
20 Plastic DIP
鹵1/2
MAX148ACAP
0擄C to +70擄C
20 SSOP
MAX148BCAP
0擄C to +70擄C
20 SSOP
鹵1
Ordering Information continued at end of data sheet.
鈥?/div>
Contact factory for availability of alternate surface-mount
packages.
__________Typical Operating Circuit
+3V
CH0
0V TO
+2.5V
ANALOG
INPUTS
V
DD
DGND
V
DD
0.1碌F
________________________Applications
Portable Data Logging
Medical Instruments
Pen Digitizers
Data Acquisition
Battery-Powered Instruments
Process Control
MAX149
AGND
CH7
VREF
COM
CS
SCLK
DIN
REFADJ
DOUT
SSTRB
SHDN
V
SS
I/O
SCK (SK)
MOSI (SO)
MISO (SI)
CPU
4.7碌F
0.01碌F
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.
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