MAX149

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)
                      54A (1ksps, 3V supply
                      1A (power-down mode
SPI/QSPI/MICROWIRE/TMS320-Compatible  4-Wire Serial Interface
Software-Configurable Unipolar or Bipolar Inputs
20-Pin DIP/SSOP Packages

Portable Data Logging                     Data Acquisition
Medical Instruments                         Battery-Powered Instruments
Pen Digitizers                                   Process Control

V_DDto AGND, DGND................................................. .-0.3V to 6V
AGND to DGND...................................................... -0.3V to 0.3V
CH0(R)CCH7, COM to AGND, DGN.............. -0.3V to (V_DD+ 0.3V)
VREF, REFADJ to AGND.............................. -0.3V to (V_DD+ 0.3V)
Digital Inputs to DGND............................................. -0.3V to 6V
Digital Outputs to DGND........................... .-0.3V to (V_DD+ 0.3V)
Digital Output Sink Current................................................25mA
Continuous Power Dissipation (T_A= +70°C)
   Plastic DIP (derate 11.11mW/°C above +70°C) ...... 889mW
   SSOP (derate 8.00mW/°C above +70°C) ................. 640mW
   CERDIP (derate 11.11mW/°C above +70°C)............. 889mW
Operating Temperature Ranges
   MAX148_C_P/MAX149_C_P.............................. 0°C to +70°C
   MAX148_E_P/MAX149_E_P............................ -40°C to +85°C
   MAX148_MJP/MAX149_MJP........................ ...-55°C to +125°C
Storage Temperature Range........................... -60°C to +150°C
Lead Temperature (soldering, 10sec)............................. +300°C

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°O analog inputs are software configurable fo unipolar/bipolar and single-ended/differential operation.

The 4-wire serial interface connects directly to SPI^TM/ QSPI^TM and MICROWIRE^TM 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 60PAA 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.