LTC2440 24-Bit High Speed Differential ADC with Selectable Speed/Resolution FEATURES DESCRIPTION TM n Up to 3.5kHz Output Rate (External f ) The LTC 2440 is a high speed 24-bit No Latency O n Selectable Speed/Resolution ADC with 5ppm INL and 5V offset. It uses a proprietary n 2V Noise at 880Hz Output Rate delta-sigma architecture enabling variable speed and reso- RMS n 200nV Noise at 6.9Hz Output Rate with lution with no latency. Ten speed/resolution combinations RMS Simultaneous 50/60Hz Rejection (6.9Hz/200nV to 3.5kHz/25V ) are programmed RMS RMS n 0.0005% INL, No Missing Codes through a simple serial interface. Alternatively, by tying a n Autosleep Enables 20A Operation at 6.9Hz single pin HIGH or LOW, a fast (880Hz/2V ) or ultralow RMS n <5V Offset (4.5V < V < 5.5V, 40C to 85C) noise (6.9Hz, 200nV , 50/60Hz rejection) speed/reso- CC RMS n Differential Input and Differential Reference with lution combination can be easily selected. The accuracy GND to V Common Mode Range (offset, full-scale, linearity, drift) and power dissipation CC n No Latency, Each Conversion is Accurate Even After are independent of the speed selected. Since there is no an Input Step latency, a speed/resolution change may be made between n Internal OscillatorNo External Components conversions with no degradation in performance. n Pin Compatible with the LTC2410 Following each conversion cycle, the LTC2440 automati- n 24-Bit ADC in Narrow 16-Lead SSOP Package cally enters a low power sleep state. Power dissipation may be reduced by increasing the duration of this sleep state. For example, running at the 3.5kHz conversion speed APPLICATIONS but reading data at a 100Hz rate draws 240A average n High Speed Multiplexing current (1.1mW) while reading data at a 7Hz output rate n Weight Scales draws only 25A (125W).The LTC2440 communicates n Auto Ranging 6-Digit DVMs through a flexible 3-wire or 4-wire digital interface that is n Direct Temperature Measurement compatible with the LTC2410 and is available in a narrow n High Speed Data Acquisition 16-lead SSOP package. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and No Latency and SoftSpan are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION RMS Noise vs Speed 100 Simple 24-Bit 2-Speed Acquisition System V = 5V CC V = 5V REF + 4.5V TO 5.5V V = V = 0V IN IN 10 V BUSY CC LTC2440 2V AT 880Hz + f REF O REFERENCE VOLTAGE 4 0.1V TO V CC 200nV AT 6.9Hz REF SCK V 1 CC (50/60Hz REJECTION) 3-WIRE + IN SDO ANALOG INPUT 6.9Hz, 200nV NOISE, SPI INTERFACE 0.5V TO 0.5V 50/60Hz REJECTION REF REF IN CS 10-SPEED SERIAL SDI PROGRAMMABLE 0.1 GND EXT 880Hz OUTPUT RATE, 1 10 100 1000 10000 2V NOISE CONVERSION RATE (Hz) 2440 TA01 2440 TA01 2440 TA02 2440fe 1 For more information www.linear.com/LTC2440 RMS NOISE (V)LTC2440 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Notes 1,2) TOP VIEW Supply Voltage (V ) to GND ....................... 0.3V to 6V CC Analog Input Pins Voltage 1 16 GND GND 2 15 to GND ......................................0.3V to (V + 0.3V) V BUSY CC CC + 3 14 REF f Reference Input Pins Voltage O 4 13 REF SCK to GND ......................................0.3V to (V + 0.3V) CC + 5 12 IN SDO Digital Input Voltage to GND .........0.3V to (V + 0.3V) CC 6 11 IN CS Digital Output Voltage to GND .......0.3V to (V + 0.3V) CC 7 10 SDI EXT Operating Temperature Range 8 9 GND GND LTC2440C ............................................... 0C to 70C GN PACKAGE LTC2440I ............................................40C to 85C 16-LEAD PLASTIC SSOP Storage Temperature Range .................. 65C to 150C T = 125C, = 110C/W JMAX JA Lead Temperature (Soldering, 10 sec) ...................300C