2.7V to +5.25V, Low-Power, 4-Channel, Serial, 10-Bit ADCs in QSOP-16

The MAX1248/MAX1249 10-bit data-acquisition systems combine a 4-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 their 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 MAX1248/MAX1249 use either the internal clock or an external serial-interface clock to perform successive-approximation analog-to-digital conversions.

The MAX1248 has an internal 2.5V reference, while the MAX1249 requires an external reference. Both parts have a reference-buffer amplifier with a ±1.5% voltage adjustment range.

These devices provide a hard-wired active-low 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 MAX1248/MAX1249, 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 MAX1248/MAX1249 are available in a 16-pin DIP and a very small QSOP that occupies the same board area as an 8-pin SO.

For 8-channel versions of these devices, see the MAX148/MAX149 datasheet.

Applications

* Battery-Powered Applications * Data Acquisition * Medical Instruments * Pen Digitizers * Portable Data Logging * System Supervision

* 4-Channel Single-Ended or 2-Channel Differential Inputs

* Single +2.7V to +5.25V Operation

* Internal 2.5V Reference (MAX1248)

* Low Power:

* 1.2mA (133ksps, +3V supply)

* 54µA (1ksps, +3V supply)

* 1µA (power-down mode)

* SPI/QSPI/MICROWIRE/TMS320-Compatible 4-Wire Serial Interface

* Software-Configurable Unipolar or Bipolar Inputs

* 16-Pin QSOP Package (same area as 8-pin SO)