MAX1245 19-1066 Rev 1 11/09 +2.375V, Low-Power, 8-Channel, Serial 12-Bit ADC General Description Features The MAX1245 12-bit data-acquisition system combines Single +2.375V to +3.3V Operation an 8-channel multiplexer, high-bandwidth track/hold, and 8-Channel Single-Ended or 4-Channel serial interface with high conversion speed and ultra-low Differential Analog Inputs power consumption. It operates from a single +2.375V to +3.3V supply, and its analog inputs are software config- Low Power: 0.8mA (100ksps) urable for unipolar/bipolar and single-ended/differential 10A (1ksps) operation. 1A (power-down mode) The 4-wire serial interface directly connects to SPI, Internal Track/Hold, 100kHz Sampling Rate QSPI, and MICROWIRE devices without external SPI/QSPI/MICROWIRE/TMS320-Compatible logic. A serial strobe output allows direct connection to 4-Wire Serial Interface TMS320-family digital signal processors. The MAX1245 works with an external reference, and uses either the Software-Configurable Unipolar or Bipolar Inputs internal clock or an external serial-interface clock to 20-Pin DIP/SSOP Packages perform successive-approximation analog-to-digital conversions. Ordering Information This device provides a hard-wired SHDN pin and a INL software-selectable power-down, and can be pro- PART* TEMP RANGE PIN-PACKAGE (LSB) grammed to automatically shut down at the end of a conversion. Accessing the serial interface powers up MAX1245ACPP 0C to +70C 20 Plastic DIP 1/2 the MAX1245, and the quick turn-on time allows it to be MAX1245BCPP 0C to +70C 20 Plastic DIP 1 shut down between conversions. This technique can MAX1245ACAP 0C to +70C 20 SSOP 1/2 cut supply current to under 10A at reduced sampling MAX1245BCAP 0C to +70C 20 SSOP 1 rates. MAX1245AEPP -40C to +85C 20 Plastic DIP 1/2 The MAX1245 is available in a 20-pin DIP package and an SSOP that occupies 30% less area than an 8-pin DIP. MAX1245BEPP -40C to +85C 20 Plastic DIP 1 For supply voltages from +2.7V to +5.25V, use the pin- MAX1245AEAP -40C to +85C 20 SSOP 1/2 compatible MAX147. MAX1245BEAP -40C to +85C 20 SSOP 1 *Contact factory for availability of alternate surface-mount packages. Applications Portable Data Logging Medical Instruments Pin Configuration Battery-Powered Instruments Data Acquisition TOP VIEW Typical Operating Circuit 20 CH0 1 V DD +2.5V 2 19 CH1 SCLK 18 V CH2 3 CS V CH0 DD DD 0V to 0.1F +2.048V MAX1245 CH3 4 17 DIN DGND ANALOG AGND INPUTS CH4 5 16 SSTRB CH7 COM CPU CH5 6 15 DOUT MAX1245 CH6 7 14 DGND I/O CS CH7 8 13 AGND SCLK SCK (SK) +2.048V VREF DIN MOSI (SO) 12 V COM 9 DD DOUT MISO (SI) 0.1F SSTRB SHDN 10 11 VREF SHDN V SS DIP/SSOP SPI and QSPI are trademarks of Motorola, Inc. MICROWIRE is a trademark of National Semiconductor Corp. Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com.+2.375V, Low-Power, 8-Channel, Serial 12-Bit ADC ABSOLUTE MAXIMUM RATINGS V to AGND, DGND .............................................. -0.3V to +6V SSOP (derate 8.00mW/C above +70C) ................... 640mW DD AGND to DGND.................................................... -0.3V to +0.3V CERDIP (derate 11.11mW/C above +70C).............. 889mW CH0CH7, COM to AGND, DGND ............ -0.3V to (V + 0.3V) Operating Temperature Ranges DD VREF to AGND........................................... -0.3V to (V + 0.3V) MAX1245 C P ................................................... 0C to +70C DD Digital Inputs to DGND............................................ -0.3V to +6V MAX1245 E P ................................................ -40C to +85C Digital Outputs to DGND ........................... -0.3V to (V + 0.3V) Storage Temperature Range ............................ -60C to +150C DD Digital Output Sink Current .................................................25mA Lead Temperature (soldering, 10sec) ............................ +300C Continuous Power Dissipation (T = +70C) A Plastic DIP (derate 11.11mW/C above +70C) ......... 889mW Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (V = +2.375V to +3.3V, V = 0V, f = 1.5MHz, external clock (50% duty cycle), 15 clocks/conversion cycle (100ksps), COM DD CLK VREF = 2.048V applied to VREF pin, T = T to T , unless otherwise noted.) A MIN MAX PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DC ACCURACY (Note 1) Resolution 12 Bits MAX1245A 0.5 Relative Accuracy (Note 2) INL LSB MAX1245B 1.0 Differential Nonlinearity DNL No missing codes over temperature 1 LSB Offset Error 0.5 4 LSB Gain Error (Note 3) 0.5 4 LSB Gain Temperature Coefficient 0.25 ppm/C Channel-to-Channel Offset 0.2 LSB Matching DYNAMIC SPECIFICATIONS (10kHz sine-wave input, 0Vp-p to 2.048Vp-p, 100ksps, 1.5MHz external clock, bipolar input mode) Signal-to-Noise + Distortion Ratio SINAD 68 dB Total Harmonic Distortion THD Up to the 5th harmonic -76 dB Spurious-Free Dynamic Range SFDR 76 dB Channel-to-Channel Crosstalk 50kHz, 2V (Note 4) -85 dB p-p Small-Signal Bandwidth -3dB rolloff 2.25 MHz Full-Power Bandwidth 1.0 MHz CONVERSION RATE Internal clock, SHDN = open 5.5 7.5 Conversion Time (Note 5) t s Internal clock, SHDN = V 35 65 CONV DD External clock = 1.5MHz, 12 clocks/conversion 8 Track/Hold Acquisition Time t External clock = 1.5MHz 2.0 s ACQ Aperture Delay 40 ns Aperture Jitter <50 ps 1.5 SHDN = open Internal Clock Frequency MHz SHDN = V 0.225 DD 0.1 1.5 External Clock Frequency MHz Data transfer only 0 1.5 2 MAX1245