19-1066; Rev 1; 11/09
+2.375V, Low-Power, 8-Channel,
Serial 12-Bit ADC
________________General Description
The MAX1245 12-bit data-acquisition system combines
an 8-channel multiplexer, high-bandwidth track/hold, and
serial interface with high conversion speed and ultra-low
power consumption. It operates from a single +2.375V to
+3.3V supply, and its analog inputs are software config-
urable for unipolar/bipolar and single-ended/differential
operation.
The 4-wire serial interface directly connects to SPI™,
QSPI™, and MICROWIRE™ devices without external
logic. A serial strobe output allows direct connection to
TMS320-family digital signal processors. The MAX1245
works with an external reference, and uses either the
internal clock or an external serial-interface clock to
perform successive-approximation analog-to-digital
conversions.
This device provides 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
conversion. Accessing the serial interface powers up
the MAX1245, and the quick turn-on time allows it to be
shut down between conversions. This technique can
cut supply current to under 10µA at reduced sampling
rates.
The MAX1245 is available in a 20-pin DIP package and
an SSOP that occupies 30% less area than an 8-pin DIP.
For supply voltages from +2.7V to +5.25V, use the pin-
compatible MAX147.
____________________________Features
♦
Single +2.375V to +3.3V Operation
♦
8-Channel Single-Ended or 4-Channel
Differential Analog Inputs
♦
Low Power: 0.8mA (100ksps)
10µA (1ksps)
1µA (power-down mode)
♦
Internal Track/Hold, 100kHz Sampling Rate
♦
SPI/QSPI/MICROWIRE/TMS320-Compatible
4-Wire Serial Interface
♦
Software-Configurable Unipolar or Bipolar Inputs
♦
20-Pin DIP/SSOP Packages
MAX1245
________________Ordering Information
PART*
MAX1245ACPP
MAX1245BCPP
MAX1245ACAP
MAX1245BCAP
MAX1245AEPP
MAX1245BEPP
MAX1245AEAP
MAX1245BEAP
TEMP RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
20 Plastic DIP
20 Plastic DIP
20 SSOP
20 SSOP
20 Plastic DIP
20 Plastic DIP
20 SSOP
20 SSOP
INL
(LSB)
±1/2
±1
±1/2
±1
±1/2
±1
±1/2
±1
________________________Applications
Portable Data Logging
Battery-Powered Instruments
Medical Instruments
Data Acquisition
*Contact
factory for availability of alternate surface-mount packages.
___________________Pin Configuration
TOP VIEW
CH0 1
20 V
DD
19 SCLK
18 CS
___________Typical Operating Circuit
+2.5V
0V to
+2.048V
ANALOG
INPUTS
CH0
V
DD
0.1μF
DGND
AGND
COM
V
DD
CH1 2
CH2 3
CH3 4
CH4 5
MAX1245
17 DIN
16 SSTRB
15 DOUT
14 DGND
13 AGND
12 V
DD
11 VREF
CH7
CPU
MAX1245
CS
SCLK
DIN
DOUT
SSTRB
SHDN
I/O
SCK (SK)*
MOSI (SO)
MISO (SI)
V
SS
CH5 6
CH6 7
CH7 8
COM 9
SHDN 10
+2.048V
0.1μF
VREF
DIP/SSOP
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.
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
