2.7V, Low-Power, 4-Channel, Serial 12-Bit ADCs in QSOP-16

The MAX1246/MAX1247 12-bit data-acquisition systems combine a 4-channel multiplexer, high-bandwidth track/hold, and serial interface with high conversion speed and low power consumption. The MAX1246 operates from a single +2.7V to +3.6V supply; the MAX1247 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 MAX1246/MAX1247 use either the internal clock or an external serial-interface clock to perform successive-approximation analog-to-digital conversions.

The MAX1246 has an internal 2.5V reference, while the MAX1247 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-bar 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 MAX1246/MAX1247, 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 MAX1246/MAX1247 are available in a 16-pin DIP and a small QSOP that occupies the same board area as an 8-pin SO.

For 8-channel versions of these devices, see the MAX146/MAX147 data sheet.

Applications

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

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

* Single-Supply Operation:

* +2.7V to +3.6V (MAX1246)

* +2.7V to +5.25V (MAX1247)

* Internal 2.5V Reference (MAX1246)

* 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)