MAX1400 19-1430 Rev 1 7/02 +5V, 18-Bit, Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC General Description Features The MAX1400 18-bit, low-power, multichannel, serial- 18-Bit Resolution, Sigma-Delta ADC output ADC uses a sigma-delta modulator with a digital 16-Bit Performance with No Missing Codes decimation filter to achieve true 16-bit accuracy. The to 480sps user-selectable decimation factor of the digital filter allows the conversion resolution to be reduced in Low Quiescent Current exchange for a higher output data rate. The device 250A (operating mode) achieves true 16-bit performance at an output data rate of 2A (power-down mode) up to 480sps. In addition, the modulator sampling 3 Fully Differential or 5 Pseudo-Differential Signal frequency may be optimized for either lowest power Input Channels dissipation or highest throughput rate. The MAX1400 operates from +5V. 2 Additional Fully Differential Calibration This device offers three fully differential input channels Channels/Auxiliary Input Channels that can be independently programmed with a gain Access to the Mux Output/ADC Input between +1V/V and +128V/V. Furthermore, it can com- pensate an input-referred DC offset (such as system off- Programmable Gain and Offset set) up to 117% of the selected full-scale range. These Fully Differential Reference Inputs three differential channels may also be configured to Converts Continuously or On Command operate as five pseudo-differential input channels. Two additional, fully differential system-calibration channels Automatic Channel Scanning and Continuous are provided for gain and offset error correction. External Data Output Mode access is provided to the multiplexer (mux) output to Operates with +5V Analog Supply and facilitate additional signal processing. +3V or +5V Digital Supply The MAX1400 can be configured to scan all signal inputs sequentially and provide the results through the serial SPI/QSPI-Compatible 3-Wire Serial Interface interface with minimum communications overhead. When 28-Pin SSOP Package used with a 2.4576MHz or 1.024MHz master clock, the digital decimation filter can be programmed to produce Pin Configuration zeros in its frequency response at the line fre- quency and associated harmonics, ensuring excellent TOP VIEW line rejection without the need for further post-filtering. The MAX1400 comes in a 28-pin SSOP package. CLKIN 1 28 SCLK CLKOUT 2 27 DIN Applications CS 3 26 DOUT Portable Industrial Instruments RESET 4 25 INT Portable Weigh Scales MUXOUT+ 5 24 V DD Loop-Powered Systems MAX1400 MUXOUT- 6 23 DGND Pressure Transducers ADCIN+ 7 22 CALOFF+ ADCIN- 8 21 CALOFF- Ordering Information AGND 9 20 REFIN+ V+ 10 19 REFIN- PART TEMP RANGE PIN-PACKAGE AIN1 11 18 CALGAIN+ MAX1400CAI 0C to +70C 28 SSOP MAX1400EAI -40C to +85C 28 SSOP AIN2 12 17 CALGAIN- AIN3 13 16 AIN6 AIN4 14 15 AIN5 SSOP SPI and QSPI are trademarks of Motorola, Inc. Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com.+5V, 18-Bit, Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC ABSOLUTE MAXIMUM RATINGS V+ to AGND, DGND.................................................-0.3V to +6V Maximum Current Input into Any Pin ..................................50mA V to AGND, DGND...............................................-0.3V to +6V Continuous Power Dissipation (T = +70C) DD A AGND to DGND.....................................................-0.3V to +0.3V 28-Pin SSOP (derate 9.52mW/C above +70C) ........524mW Analog Inputs to AGND................................-0.3V to (V+ + 0.3V) Operating Temperature Ranges Analog Outputs to AGND.............................-0.3V to (V+ + 0.3V) MAX1400CAI .....................................................0C to +70C Reference Inputs to AGND...........................-0.3V to (V+ + 0.3V) MAX1400EAI...................................................-40C to +85C CLKIN and CLKOUT to DGND...................-0.3V to (V + 0.3V) Storage Temperature Range .............................-60C to +150C DD All Other Digital Inputs to DGND..............................-0.3V to +6V Lead Temperature (soldering, 10s) .................................+300C All Digital Outputs to DGND.......................-0.3V to (V + 0.3V) DD 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+ = +5V 5%, V = +2.7V to +5.25V, V = +2.50V, REFIN- = AGND, f = 2.4576MHz, T = T to T , unless other- DD REFIN+ CLKIN A MIN MAX wise noted. Typical values are at T = +25C.) A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS STATIC PERFORMANCE No missing codes guaranteed by design Noise-Free Resolution 16 Bits for filter settings with FS1 = 0 Output Noise Depends on filter setting and selected gain Table 16 Integral Nonlinearity INL Bipolar mode, filter settings with FS1 = 0 -0.0015 0.0015 %FSR Nominal Gain (Note 1) 0.98 Unipolar Offset Error Relative to nominal offset of 1% FSR -1 +2 %FSR For gains of 1, 2, 4 0.5 Unipolar Offset Drift V/C For gains of 8, 16, 32, 64, 128 0.3 Bipolar Zero Error -2.0 +2.0 %FSR For gains of 1, 2, 4 0.8 Bipolar Zero Drift V/C For gains of 8, 16, 32, 64, 128 0.3 For gains of 1, 2, 4, 8, 16, 32, 64 -2.5 +2.5 Positive Full-Scale Error %FSR (Note 2) For gain of 128 -3.5 +3.5 For gains of 1, 2, 4 0.8 Full-Scale Drift (Note 3) V/C For gains of 8, 16, 32, 64, 128 0.3 For gains of 1, 2, 4, 8, 16, 32, 64 -2 +2 Gain Error (Note 4) %FSR For gain of 128 -3 +3 For gains of 1, 2, 4, 8, 16, 32, 64 1 Gain-Error Drift (Note 5) ppm/C For gain of 128 5 For gains of 1, 2, 4, 8, 16, 32, 64 -2.5 +2.5 Bipolar Negative Full-Scale Error %FSR For gain of 128 -3.5 +3.5 For gains of 1, 2, 4 0.8 Bipolar Negative Full-Scale Drift V/C For gains of 8, 16, 32, 64, 128 0.3 2 MAX1400