24-Bit High Speed Differential delta-sigma ADC

www.DataSheet4U.com LTC2440 24-Bit High Speed Differential ∆Σ ADC with Selectable Speed/Resolution FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO Up to 3.5kHz Output Rate Selectable Speed/Resolution 2µVRMS Noise at 880Hz Output Rate 200nVRMS Noise at 6.9Hz Output Rate with Simultaneous 50/60Hz Rejection 0.0005% INL, No Missing Codes Autosleep Enables 20µA Operation at 6.9Hz < 5µV Offset (4.5V < VCC < 5.5V, – 40°C to 85°C) Differential Input and Differential Reference with GND to VCC Common Mode Range No Latency, Each Conversion is Accurate Even After an Input Step Internal Oscillator—No External Components Pin Compatible with the LTC2410 24-Bit ADC in Narrow 16-Lead SSOP Package The LTC®2440 is a high speed 24-bit No Latency ∆ΣTM ADC with 5ppm INL and 5µV offset. It uses proprietary deltasigma architecture enabling variable speed and resolution with no latency. Ten speed/resolution combinations (6.9Hz/ 200nVRMS to 3.5kHz/25µVRMS) are programmed through a simple serial interface. Alternatively, by tying a single pin HIGH or LOW, a fast (880Hz/2µVRMS) or ultralow noise (6.9Hz, 200nVRMS, 50/60Hz rejection) speed/resolution combination can be easily selected. The accuracy (offset, full-scale, linearity, drift) and power dissipation are independent of the speed selected. Since there is no latency, a speed/resolution change may be made between conversions with no degradation in performance. Following each conversion cycle, the LTC2440 automatically 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 but reading data at a 100Hz rate draws 240µA average current (1.1mW) while reading data at a 7Hz output rate draws only 25µA (125µW).The LTC2440 communicates through a flexible 3-wire or 4-wire digital interface that is compatible with the LTC2410 and is available in a narrow 16-lead SSOP package. , LTC and LT are registered trademarks of Linear Technology Corporation. No Latency ∆Σ is a trademark of Linear Technology Corporation. APPLICATIO S ■ ■ ■ ■ ■ High Speed Multiplexing Weight Scales Auto Ranging 6-Digit DVMs Direct Temperature Measurement High Speed Data Acquisition TYPICAL APPLICATIO 4.5V TO 5.5V Simple 24-Bit 2-Speed Acquisition System 100 VCC = 5V VREF = 5V VIN+ = VIN– = 0V VCC BUSY RMS NOISE (µV) 2 3 REFERENCE VOLTAGE 0.1V TO VCC ANALOG INPUT –0.5VREF TO 0.5VREF 4 5 6 15 10 2µV AT 880Hz 200nV AT 6.9Hz 1 (50/60Hz REJECTION) 1, 8, 9, 16 LTC2440 14 FO REF + 13 REF – SCK 12 IN + SDO 11 IN – CS 7 SDI 10 EXT GND 3-WIRE SPI INTERFACE VCC 6.9Hz, 200nV NOISE, 50/60Hz REJECTION 10-SPEED SERIAL PROGRAMMABLE 880Hz OUTPUT RATE, 2µV NOISE 0.1 1 10 100 1000 CONVERSION RATE (Hz) 10000 2440 TA02 2440 TA01 2440 TA01 U Speed vs RMS Noise sn2440, 2440fas U U 1 LTC2440 ABSOLUTE (Notes 1, 2) AXI U RATI GS PACKAGE/ORDER I FOR ATIO TOP VIEW GND VCC REF + REF – IN + IN – SDI GND 1 2 3 4 5 6 7 8 16 GND 15 BUSY 14 FO 13 SCK 12 SDO 11 CS 10 EXT 9 GND Supply Voltage (VCC) to GND .......................– 0.3V to 6V Analog Input Pins Voltage to GND .................................... – 0.3V to (VCC + 0.3V) Reference Input Pins Voltage to GND .................................... – 0.3V to (VCC + 0.3V) Digital Input Voltage to GND ........ – 0.3V to (VCC + 0.3V) Digital Output Voltage to GND ..... – 0.3V to (VCC + 0.3V) Operating Temperature Range LTC2440C ............................................... 0°C to 70°C LTC2440I ............................................ – 40°C to 85°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C ORDER PART NUMBER LTC2440CGN LTC2440IGN GN PART MARKING 2440 2440I GN PACKAGE 16-LEAD PLASTIC SSOP TJMAX = 125°C, θJA = 110°C/W Consult LTC Marketing for parts specified with wider operating temperature ranges. The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Notes 3, 4) PARAMETER Resolution (No Missing Codes) Integral Nonlinearity Offset Error Offset Error Drift Positive Full-Scale Error Positive Full-Scale Error Drift Negative Full-Scale Error Negative Full-Scale Error Drift Total Unadjusted Error CONDITIONS 0.1V ≤ VREF ≤ VCC, –0.5 • VREF ≤ VIN ≤ 0.5 • VREF, (Note 5) VCC = 5V, REF+ = 5V, REF– = GND, VINCM = 2.5V, (Note 6) REF+ = 2.5V, REF– = GND, VINCM = 1.25V, (Note 6) 2.5V ≤ REF+ ≤ VCC, REF– = GND, GND ≤ IN+ = IN– ≤ VCC (Note 12) 2.5V ≤ REF+ ≤ VCC, REF– = GND, GND ≤ IN+ = IN– ≤ VCC REF + = 5V, REF – = GND, IN + = 3.75V, IN – = 1.25V REF + = 2.5V, REF – = GND, IN + = 1.875V, IN – = 0.625V 2.5V ≤ REF+ ≤ VCC, REF– = GND, IN+ = 0.75REF+, IN– = 0.25 • REF+ REF + = 5V, REF – = GND, IN + = 1.25V, IN – = 3.75V REF + = 2.5V, REF – = GND, IN + = 0.625V, IN – = 1.875V 2.5V ≤ REF+ ≤ VCC, REF– = GND, IN+ = 0.25 • REF+, IN– = 0.75 • REF+ 5V ≤ VCC ≤ 5.5V, REF+ = 2.5V, REF– = GND, VINCM = 1.25V 5V ≤ VCC ≤ 5.5V, REF+ = 5V, REF– = GND, VINCM = 2.5V REF+ = 2.5V, REF– = GND, VINCM = 1.25V, (Note 6) 2.5V ≤ REF+ ≤ VCC, REF– = GND, GND ≤ IN– = IN+ ≤ VCC ● ● ● ● ● ● ● ELECTRICAL CHARACTERISTICS MIN 24 TYP 5 3 2.5 20 10 10 0.2 10 10 0.2 15 15 15 120 MAX 15 5 UNITS Bits ppm of VREF ppm of VREF µV nV/°C 30 50 ppm of VREF ppm of VREF ppm of VREF/°C 30 50 ppm of VREF ppm of VREF ppm of VREF/°C ppm of VREF ppm of VREF ppm of VREF dB Input Common Mode Rejection DC sn2440, 2440fas 2 U W U U WW W LTC2440 A ALOG I PUT A D REFERE CE The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 3) SYMBOL IN+ IN– VIN REF+ REF– VREF CS(IN+) CS(IN–) CS(REF+) CS(REF–) IDC_LEAK(IN+, IN–, REF+, REF–) PARAMETER Absolute/Common Mode IN+ Voltage Absolute/Common Mode IN– Voltage Input Differential Voltage Range (IN+ – IN–) Absolute/Common Mode REF+ Voltage Absolute/Common Mode REF– Voltage Reference Differential Voltage Range (REF+ – REF–) IN+ Sampling Capacitance IN– Sampling Capacitance REF+ Sampling Capacitance REF– Sampling Capacitance Leakage Current, Inputs and Reference Average Input/Reference Current During Sampling ISAMPLE(IN+, IN–, REF+, REF–) DIGITAL I PUTS A D DIGITAL OUTPUTS SYMBOL VIH VIL VIH VIL IIN IIN CIN CIN VOH VOL VOH VOL IOZ PARAMETER High Level Input Voltage CS, FO Low Level Input Voltage CS, FO High Level Input Voltage SCK Low Level Input Voltage SCK Digital Input Current CS, FO Digital Input Current SCK Digital Input Capacitance CS, FO Digital Input Capacitance SCK High Level Output Voltage SDO, BUSY Low Level Output Voltage SDO, BUSY High Level Output Voltage SCK Low Level Output Voltage SCK Hi-Z Output Leakage SDO (Note 8) IO = –800µA IO = 1.6mA IO = –800µA (Note 9) IO = 1.6mA (Note 9) CONDITIONS 4.5V ≤ VCC ≤ 5.5V 4.5V ≤ VCC ≤ 5.5V The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 3) MIN ● ● ● ● ● ● 4.5V ≤ VCC ≤ 5.5V (Note 8) 4.5V ≤ VCC ≤ 5.5V (Note 8) 0V ≤ VIN ≤ VCC 0V ≤ VIN ≤ VCC (Note 8) U U U U U U CONDITIONS ● ● ● ● ● ● MIN GND – 0.3V GND – 0.3V –VREF/2 0.1 GND 0.1 TYP MAX VCC + 0.3V VCC + 0.3V VREF/2 VCC VCC – 0.1V VCC UNITS V V V V V V pF pF pF pF 3.5 3.5 3.5 3.5 CS = VCC, IN+ = GND, IN– REF+ = 5V, REF– = GND = GND, ● –100 10 100 nA Varies, See Applications Section TYP MAX UNITS V 2.5 0.8 2.5 0.8 –10 –10 10 10 10 10 V V V µA µA pF pF V ● ● ● ● ● VCC – 0.5V 0.4V VCC – 0.5V 0.4V –10 10 V V V µA sn2440, 2440fas 3 LTC2440 POWER REQUIRE E TS SYMBOL VCC ICC PARAMETER Supply Voltage Supply Current Conversion Mode Sleep Mode CS = 0V (Note 7) CS = VCC (Note 7) The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 3) CONDITIONS ● ● ● TI I G CHARACTERISTICS SYMBOL fEOSC tHEO tLEO tCONV PARAMETER External Oscillator Frequency Range External Oscillator High Period External Oscillator Low Period Conversion Time The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 3) CONDITIONS ● ● ● fISCK DISCK fESCK tLESCK tHESCK tDOUT_ISCK tDOUT_ESCK t1 t2 t3 t4 tKQMAX tKQMIN t5 t7 t8 Internal SCK Frequency Internal SCK Duty Cycle External SCK Frequency Range External SCK Low Period External SCK High Period Internal SCK 32-Bit Data Output Time External SCK 32-Bit Data Output Time CS ↓ to SDO Low Z CS ↑ to SDO High Z CS ↓ to SCK ↓ CS ↓ to SCK ↑ SCK ↓ to SDO Valid SDO Hold After SCK ↓ SCK Set-Up Before CS ↓ SDI Setup Before SCK ↑ SDI Hold After SCK ↑ Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: All voltage values are with respect to GND. Note 3: VCC = 4.5 to 5.5V unless otherwise specified. VREF = REF + – REF –, VREFCM = (REF + + REF –)/2; VIN = IN + – IN –, VINCM = (IN + + IN –)/2. Note 4: FO pin tied to GND or to external conversion clock source with fEOSC = 10MHz unless otherwise specified. Note 5: Guaranteed by design, not subject to test. Note 6: Integral nonlinearity is defined as the deviation of a code from a straight line passing through the actual endpoints of the transfer curve. The deviation is measured from the center of the quantization band. 4 UW MIN 4.5 TYP MAX 5.5 UNITS V mA µA 8 8 11 30 UW MIN 0.1 25 25 0.99 126 TYP MAX 20 10000 10000 UNITS MHz ns ns ms ms ms OSR = 256 (SDI = 0) OSR = 32768 (SDI = 1) External Oscillator (Note 10, 13) Internal Oscillator (Note 9) External Oscillator (Notes 9, 10) (Note