19-1071; Rev 2; 10/01
+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 oper-
ates 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 seri-
al-interface clock to perform successive-approximation
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 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 auto-
matically 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.
Portable Data Logging
Pin Configuration appears at end of data sheet.
SPI and QSPI are registered trademarks of Motorola, Inc.
MICROWIRE is a registered trademark of National
o 4-Channel Single-Ended or 2-Channel
o Single-Supply Operation:
+2.7V to +3.6V (MAX1246)
+2.7V to +5.25V (MAX1247)
o Internal 2.5V Reference (MAX1246)
o Low Power: 1.2mA (133ksps, 3V supply)
54µA (1ksps, 3V supply)
1µA (power-down mode)
4-Wire Serial Interface
o Software-Configurable Unipolar or Bipolar Inputs
o 16-Pin QSOP Package (same area as 8-pin SO)
MAX1246ACPE 0°C to +70°C 16 Plastic DIP
MAX1246BCPE 0°C to +70°C 16 Plastic DIP
MAX1246ACEE 0°C to +70°C 16 QSOP
MAX1246BCEE 0°C to +70°C 16 QSOP
Ordering Information continued at end of data sheet.
__________Typical Operating Circuit
________________________________________________________________ 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.