Document
19-0465; Rev 2; 10/01 EVAALVUAAILTAIOBNLEKIT
+2.7V, Low-Power, 8-Channel, Serial 12-Bit ADCs
MAX146/MAX147
General Description
The MAX146/MAX147 12-bit data-acquisition systems combine an 8-channel multiplexer, high-bandwidth track/hold, and serial interface with high conversion speed and low power consumption. The MAX146 operates from a single +2.7V to +3.6V supply; the MAX147 operates from a single +2.7V to +5.25V supply. 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 MAX146/MAX147 use either the internal clock or an external serial-interface clock to perform successive-approximation analog-to-digital conversions.
The MAX146 has an internal 2.5V reference, while the MAX147 requires an external reference. Both parts have a reference-buffer amplifier with a ±1.5% 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 MAX146/MAX147, and the quick turn-on time allows them to be shut down between all conversions. This technique can cut supply current to under 60µA at reduced sampling rates.
The MAX146/MAX147 are available in 20-pin DIP and SSOP packages.
For 4-channel versions of these devices, see the MAX1246/MAX1247 data sheet.
________________________Applications
____________________________Features
o 8-Channel Single-Ended or 4-Channel Differential Inputs
o Single-Supply Operation +2.7V to +3.6V (MAX146) +2.7V to +5.25V (MAX147)
o Internal 2.5V Reference (MAX146) 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
MAX146ACPP MAX146BCPP MAX146ACAP MAX146BCAP MAX146BC/D
TEMP RANGE
0°C to +70°C 0°C to +70°C 0°C to +70°C 0°C to +70°C 0°C to +70°C
PIN-PACKAGE
20 Plastic DIP 20 Plastic DIP 20 SSOP 20 SSOP Dice*
INL (LSB)
±1/2 ±1 ±1/2 ±1 ±1
Ordering Information continued at end of data sheet. *Dice are specified at TA = +25°C, DC parameters only.
Typical Operating Circuit
Portable Data Logging Data Acquisition
Medical Instruments Battery-Powered Instruments
Pen Digitizers
Process Control
Pin Configuration appears at end of data sheet.
SPI and QSPI are registered trademarks of Motorola, Inc. MICROWIRE is a registered trademark of National Semiconductor Corp.
0V TO +2.5V ANALOG INPUTS
4.7µF
0.047µF
CH0 VDD DGND
MAX146 AGND
CH7 VREF
REFADJ
COM CS
SCLK DIN
DOUT SSTRB SHDN
+3V VDD
0.1µF
CPU
I/O SCK (SK) MOSI (SO) MISO (SI)
VSS
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
+2.7V, Low-Power, 8-Channel, Serial 12-Bit ADCs
MAX146/MAX147
ABSOLUTE MAXIMUM RATINGS
VDD to AGND, DGND................................................. -0.3V to 6V AGND to DGND ...................................................... -0.3V to 0.3V
Continuous Power Dissipation (TA = +70°C) Plastic DIP (derate 11.11mW/°C above +70°C) ......... 889mW
CH0–CH7, COM to AGND, DGND ............ -0.3V to (VDD + 0.3V) VREF, REFADJ to AGND ........................... -0.3V to (VDD + 0.3V) Digital Inputs to DGND .............................................. -0.3V to 6V
SSOP (derate 8.00mW/°C above +70°C) ................... 640mW CERDIP (derate 11.11mW/°C above +70°C) .............. 889mW Operating Temperature Ranges
Digital Outputs to DGND ........................... -0.3V to (VDD + 0.3V) Digital Output Sink Current .................................................25mA
MAX146_C_P/MAX147_C_P .............................. 0°C to +70°C MAX146_E_P/MAX147_E_P............................ -40°C to +85°C
MAX146_MJP/MAX147_MJP ........................ -55°C to +125°C
Storage Temperature Range ............................ -60°C to +150°C
Lead Temperature (soldering, 10s) ................................ +300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VDD = +2.7V to +3.6V (MAX146); VDD = +2.7V to +5.25V (MAX147); COM = 0; fSCLK = 2.0MHz; external clock (50% duty cycle); 15 clocks/conversion cycle (133ksps); MAX146—4.7.