MAX148 Datasheet, PDF (1/24 Pages) Maxim Integrated Products – +2.7V to +5.25V, Low-Power, 8-Channel, Serial 10-Bit ADCs

19-0464; Rev 2; 5/98
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+2.7V to +5.25V, Low-Power, 8-Channel,
Serial 10-Bit ADCs
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
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
Ordering Information
PART^†
TEMP. RANGE
PIN-PACKAGE
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
Ordering Information continued at end of data sheet.
† _{Contact factory for availability of alternate surface-mount}
packages.
__________Typical Operating Circuit
0V TO
+2.5V
ANALOG
INPUTS
4.7µF
0.01µF
CH0
V_DD
DGND
MAX149 _AGND
CH7
COM
VREF
REFADJ
CS
SCLK
DIN
DOUT
SSTRB
SHDN
+3V
V_DD
0.1µF
CPU
I/O
SCK (SK)
MOSI (SO)
MISO (SI)
V_SS
Pin Configuration appears at end of data sheet.
SPI and QSPI are trademarks of Motorola, Inc. MICROWIRE is a trademark of National Semiconductor Corp.
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