MAX1245BCAP

19-1066; Rev 1; 11/09 +2.375V, Low-Power, 8-Channel, Serial 12-Bit ADC ________________General Description The MAX1245 12-bit data-acquisition system combines an 8-channel multiplexer, high-bandwidth track/hold, and serial interface with high conversion speed and ultra-low power consumption. It operates from a single +2.375V to +3.3V supply, and its analog inputs are software configurable for unipolar/bipolar and single-ended/differential operation. The 4-wire serial interface directly connects to SPI™, QSPI™, and MICROWIRE™ devices without external logic. A serial strobe output allows direct connection to TMS320-family digital signal processors. The MAX1245 works with an external reference, and uses either the internal clock or an external serial-interface clock to perform successive-approximation analog-to-digital conversions. This device provides 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 powers up the MAX1245, and the quick turn-on time allows it to be shut down between conversions. This technique can cut supply current to under 10µA at reduced sampling rates. The MAX1245 is available in a 20-pin DIP package and an SSOP that occupies 30% less area than an 8-pin DIP. For supply voltages from +2.7V to +5.25V, use the pincompatible MAX147. ____________________________Features ♦ Single +2.375V to +3.3V Operation ♦ 8-Channel Single-Ended or 4-Channel Differential Analog Inputs ♦ Low Power: 0.8mA (100ksps) 10µA (1ksps) 1µA (power-down mode) ♦ Internal Track/Hold, 100kHz Sampling Rate ♦ SPI/QSPI/MICROWIRE/TMS320-Compatible 4-Wire Serial Interface ♦ Software-Configurable Unipolar or Bipolar Inputs ♦ 20-Pin DIP/SSOP Packages MAX1245 ________________Ordering Information PART* MAX1245ACPP MAX1245BCPP MAX1245ACAP MAX1245BCAP MAX1245AEPP MAX1245BEPP MAX1245AEAP MAX1245BEAP TEMP RANGE 0°C to +70°C 0°C to +70°C 0°C to +70°C 0°C to +70°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C PIN-PACKAGE 20 Plastic DIP 20 Plastic DIP 20 SSOP 20 SSOP 20 Plastic DIP 20 Plastic DIP 20 SSOP 20 SSOP INL (LSB) ±1/2 ±1 ±1/2 ±1 ±1/2 ±1 ±1/2 ±1 ________________________Applications Portable Data Logging Battery-Powered Instruments Medical Instruments Data Acquisition *Contact factory for availability of alternate surface-mount packages. ___________________Pin Configuration TOP VIEW CH0 1 20 VDD 19 SCLK 18 CS ___________Typical Operating Circuit +2.5V 0V to +2.048V ANALOG INPUTS CH0 VDD DGND AGND COM VDD 0.1μF CH1 2 CH2 3 CH3 4 CH4 5 MAX1245 17 DIN 16 SSTRB 15 DOUT 14 DGND 13 AGND 12 VDD 11 VREF CH7 CPU MAX1245 CS SCLK DIN DOUT SSTRB SHDN I/O SCK (SK)* MOSI (SO) MISO (SI) VSS CH5 6 CH6 7 CH7 8 COM 9 SHDN 10 +2.048V 0.1μF VREF 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 Maxim’s website at www.maxim-ic.com. +2.375V, Low-Power, 8-Channel, Serial 12-Bit ADC MAX1245 ABSOLUTE MAXIMUM RATINGS VDD to AGND, DGND .............................................. -0.3V to +6V AGND to DGND.................................................... -0.3V to +0.3V CH0–CH7, COM to AGND, DGND ............ -0.3V to (VDD + 0.3V) VREF to AGND........................................... -0.3V to (VDD + 0.3V) Digital Inputs to DGND............................................ -0.3V to +6V Digital Outputs to DGND ........................... -0.3V to (VDD + 0.3V) Digital Output Sink Current .................................................25mA Continuous Power Dissipation (TA = +70°C) Plastic DIP (derate 11.11mW/°C above +70°C) ......... 889mW SSOP (derate 8.00mW/°C above +70°C) ................... 640mW CERDIP (derate 11.11mW/°C above +70°C) .............. 889mW Operating Temperature Ranges MAX1245_C_P ................................................... 0°C to +70°C MAX1245_E_P ................................................ -40°C to +85°C Storage Temperature Range ............................ -60°C to +150°C Lead Temperature (soldering, 10sec) ............................ +300°C 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 (VDD = +2.375V to +3.3V, COM = 0V, fCLK = 1.5MHz, external clock (50% duty cycle), 15 clocks/conversion cycle (100ksps), VREF = 2.048V applied to VREF pin, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER DC ACCURACY (Note 1) Resolution Relative Accuracy (Note 2) Differential Nonlinearity Offset Error Gain Error (Note 3) Gain Temperature Coefficient Channel-to-Channel Offset Matching INL DNL MAX1245A MAX1245B No missing codes over temperature ±0.5 ±0.5 ±0.25 ±0.2 SYMBOL CONDITIONS MIN 12 ±0.5 ±1.0 ±1 ±4 ±4 TYP MAX UNITS Bits LSB LSB LSB LSB ppm/°C LSB 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 Spurious-Free Dynamic Range Channel-to-Channel Crosstalk Small-Signal Bandwidth Full-Power Bandwidth CONVERSION RATE Internal clock, SHDN = FLOAT Conversion Time (Note 5) Track/Hold Acquisition Time Aperture Delay Aperture Jitter Internal Clock Frequency External Clock Frequency SHDN = FLOAT SHDN = VDD 0.1 Data transfer only 0 tCONV tACQ Internal clock, SHDN = VDD External clock = 1.5MHz, 12 clocks/conversion External clock = 1.5MHz 40