Simplified Block Diagram
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- 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)
- Battery-Powered Applications
- Data Acquisition
- Medical Instruments
- Pen Digitizers
- Portable Data Logging
- System Supervision
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.