Micro Power Sampling A/D Converter

ADC121S625 12-Bit, 50 ksps to 200 ksps, Differential Input, Micro Power Sampling A/D Converter May 2005 ADC121S625 12-Bit, 50 ksps to 200 ksps, Differential Input, Micro Power Sampling A/D Converter General Description The ADC121S625 is a 12-bit, 50 ksps to 200 ksps sampling Analog-to-Digital (A/D) converter that features a fully differential, high impedance analog input and an external reference. While best performance is achieved with reference voltage between 500mV and 2.5V, the reference voltage can be varied from 100mV to 2.5V, with a corresponding resolution between 49µV and 1.22mV. The output serial data is binary 2’s complement, and is compatible with several standards, such as SPI™, QSPI™, MICROWIRE™, and with many common DSP serial interfaces. The differential input, low power, automatic power down, and small size make the ADC121S625 ideal for direct connection to transducers in battery operated systems or remote data acquisition applications. Operating from a single +5V supply, the normal power consumption is reduced to a few nanowatts in the power-down mode. The ADC121S625 is a pin-compatible superior replacement for the ADS7817 and is available in the MSOP-8 package. Operation is guaranteed over the industrial temperature range of −40˚C to +85˚C and clock rates of 800 kHz to 3.2 MHz. Features n n n n n True Differential Inputs Guaranteed performance from 50ksps to 200ksps External Reference High AC Common-Mode Rejection SPI™/QSPI™/MICROWIRE™/DSP compatible Serial Interface Key Specifications n n n n n n n Conversion Rate Offset Error Gain Error INL DNL CMRR Power Consumption — Active, 200ksps — Active, 50ksps — Power Down 50 to 200 ksps 0.4 LSB (typ) 0.05 LSB (typ) ± 1 LSB (max) ± 0.75 LSB (max) 82 dB (typ) 2.25 mW (typ) 1.33 mW (typ) 60 nW (typ) www.DataSheet4U.com Applications n n n n n n Automotive Navigation Portable Systems Medical Instruments Instrumentation and Control Systems Motor Control Direct Sensor Interface Connection Diagram 20132705 Ordering Information Order Code ADC121S625CIMM ADC121S625CIMMX ADC121S625EVAL TRI-STATE ® is a trademark of National Semiconductor Corporation. MICROWIRE™ is a trademark of National Semiconductor Corporation. QSPI™ and SPI™ are trademarks of Motorola, Inc. Temperature Range −40˚C to +85˚C −40˚C to +85˚C Description 8-Lead MSOP Package, 1000 Units Tape & Reel 8-Lead MSOP Package, 3500 Units Tape & Reel Evaluation Board Top Mark X0AC X0AC © 2005 National Semiconductor Corporation DS201327 www.national.com ADC121S625 Block Diagram 20132702 Pin Descriptions and Equivalent Circuits Pin No. 1 2 3 4 5 Symbol VREF +IN −IN GND CS Reference Voltage input. Non-inverting input. Inverting input. Ground pin. The ADC is in the active move when this pin is LOW and in the Power-Down Mode when this pin is HIGH. A conversion begins at the fall of CS. The serial output data word is comprised of 12 bits of data. In operation the data is valid on the falling edge of SCLK. The second clock pulse after the falling edge of CS enables the serial output. After one null bit the data is valid for the next 12 SCLK edges. Serial Clock used to control data transfer. Also serves as the conversion clock. Power Supply input. Description 6 DOUT 7 8 SCLK VA www.national.com 2 ADC121S625 Absolute Maximum Ratings (Notes 1, 2) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Analog Supply Voltage VA Voltage on Any Pin to GND Input Current at Any Pin (Note 3) Package Input Current (Note 3) Power Consumption at TA = 25˚C ESD Susceptibility (Note 5) Human Body Model Machine Model Charge Device Modeling (CDM) Soldering Temperature, Infrared, 10 seconds (Note 6) Junction Temperature Storage Temperature −0.3V to 6.5V −0.3V to (VA +0.3V) Operating Ratings (Notes 1, 2) Operating Temperature Range Supply Voltage, VA Reference Voltage, VREF Input Common-Mode Voltage, VCM Digital Input Pins Voltage Range Clock Frequency Differential Analog Input Voltage −40˚C ≤ TA ≤ +85˚C +4.5V to +5.5V +0.1V to 2.5V See Figure 1 (Sect 2.3) 0 to VA 0.8 MHz to 3.2 MHz −VREF to +VREF ±10 mA ±50 mA See (Note 4) 2500V 250V 750V 260˚C +150˚C −65˚C to +150˚C Package Thermal Resistance Package 8-lead MSOP θJA 20˚C / W (Note 8) The following specifications apply for VA = +4.5V to 5.5V, VREF = 2.5V, fSCLK = 0.8 to 3.2 MHz, fIN = 20 kHz, CL = 100 pF, unless otherwise noted. Boldface limits apply for TA = TMIN to TMAX: all other limits TA = 25˚C. Symbol Parameter Conditions Typical Limits Units (Note 7) Bits LSB (max) LSB (min) LSB (max) LSB (max) LSB LSB ADC121S625 Converter Electrical Characteristics STATIC CONVERTER CHARACTERISTICS Resolution with No Missing Codes INL DNL OE FSE GE SINAD SNR THD SFDR ENOB Integral Non-Linearity Differential Non-Linearity Offset Error Positive Full-Scale Error Negative Full-Scale Error Gain Error Signal-to-Noise Plus Distortion Ratio Signal-to-Noise Ratio Total Harmonic Distortion Spurious-Free Dynamic Range Effective Number of Bits fIN = 20 kHz, −0.1 dBFS fIN = 20 kHz, −0.1 dBFS fIN = 20 kHz, −0.1 dBFS fIN = 20 kHz, −0.1 dBFS fIN = 20 kHz, −0.1 dBFS Output at 70.7%FS with FS Input Differential Input Single-Ended Input +0.5 −0.3 12 +1.0 -1.0 ±0.4 0.4 +0.2 +0.2 -0.05 72.6 72.9 −84 85.2 11.8 26 22 ±0.75 ±4 ±4 68.5 70 −74 74 11.1 LSB dBc (min) dBc (min) dBc (max) dBc (min) bits (min) MHz MHz DYNAMIC CONVERTER CHARACTERISTICS FPBW −3 dB Full Power Bandwidth ANALOG INPUT CHARACTERISTICS VIN IDCL CINA CMRR VREF Differential Input Range DC Leakage Current Input Capacitance Common Mode Rejection Ratio Reference Voltage Range In Track Mode In Hold Mode −VREF +VREF V (min) V (max) µA (max) pF pF dB 0.1 2.5 V (min) V (max) ±0.04 17 3 82 ±2 3 www.national.com ADC121S625 ADC121S625 Converter Electrical Characteristics (Note 8) (Continued) The following specifications apply for VA = +4.5V to 5.5V, VREF = 2.5V, fSCLK = 0.8 to 3.2 MHz, fIN = 20 kHz, CL = 100 pF, unless otherwise noted. Boldface limits apply for TA = TMIN to TMAX: all other limits TA = 25˚C. Parameter Conditions Typical Limits Units (Note 7) Symbol ANALOG INPUT CHARACTERISTICS CS low, fSCLK = 3.2 MHz, fS = 200 ksps, output = FF8h IREF Reference Current CS low, fSCLK = 3.2 MHz, fS = 50 ksps, output = FF8h CS low, fSCLK = 3.2 MHz, 12.5 ksps, output = FF8h CS high, fSCLK = 0 DIGITAL INPUT CHARACTERISTICS VIH VIL IIN CIND Input High Voltage Input Low Voltage Input Current Input Capacitance VA = 4.5V to 5.5V, ISOURCE = 250 µA VA = 4.5V to 5.5V, ISOURCE = 2 mA VA = 4.5V to 5.5V, ISINK = 250 µA VA = 4.5V to 5.5V, ISOURCE = 2 mA VA = 4.5V to 5.5V VA = 4.5V to 5.5V VIN = 0V or VA 2.4 0.8 V (min) V (max) µA (max) pF (max) V (min) V 0.4 V (max) V 12 3 0.7 0.3 µA µA µA µA ±0.03 2 VA − 0.05 VA − 0.1 0.02 0.1 1 4 VA − 0.2 DIGITAL OUTPUT CHARACTERISTICS VOH VOL IOZH, IOZL COUT Output High Voltage Output Low Voltage TRI-STATE Leakage Current TRI-STATE Output Capacitance Output Coding POWER SUPPLY CHARACTERISTICS VA Analog Supply Voltage fSCLK = 3.2 MHz, fSMPL = 200 ksps, fIN = 20 kHz, CL = 15pF fSCLK = 3.2 MHz, fSMPL = 12.5 ksps, CL = 15pF, Power Down between conversions fSCLK = 0.8 MHz, fSMPL = 50 ksps, CL = 15pF fSCLK = 0.2 MHz, fSMPL = 12.5 ksps, CL = 15pF (Note 10) IA Supply Current, Shutdown (CS high) Shutdown fSCLK = 0 fSCLK = 3.2 MHz fSCLK = 3.2 MHz, fSMPL = 200 ksps, fIN = 20 kHz, CL = 15pF fSCLK = 3.2 MHz, fSMPL = 12.5 ksps, CL = 15pF, Power Down between conversions fSCLK = 0.8 MHz, fSMPL = 50 ksps, CL = 15pF fSCLK = 0.2 MHz, fSMPL = 12.5 ksps, CL = 15pF (Note 10) PWR Power Consumption, Shutdown (CS Shutdown high) fSCLK = 0 fSCLK = 3.2 MHz 410 4.5 5.5 510 V (min) V (max) µA (max) ±0.03 2 ±1 4 µA (max) pF (max) Binary 2’S Complement IA Active Supply Current, Normal Mode (Operational) 31 µA 242 200 0.01 6 2.25 2.8 2 µA µA µA (max) µA mW (max) PWR Active Power Consumption, Normal Mode (Operational) 0.18 mW 1.33 1.1 0.06 33 11 mW mW µW (max) µW www.national.com 4 ADC121S625 ADC121S625 Converter Electrical Characteristics (Note 8) (Continued) The following specifications apply for VA = +4.5V to 5.5V, VREF = 2.5V, fSCLK = 0.8 to 3.2 MHz, fIN = 20 kHz, CL = 100 pF, unless otherwise noted. Boldface limits apply for TA = TMIN to TMAX: all other limits TA = 25˚C. Parameter Conditions Typical Limits Units (Note 7) Symbol POWER SUPPLY CHARACTERISTICS Offset Change with 1.0V change in VA Gain Error Change with 1.0V change in VA 71 83 dB dB PSRR Power Supply Rejection Ratio AC ELECTRICAL CHARACTERISTICS fSCLK fSCLK fS Maximum Clock Frequency Minimum Clock Frequency Maximum Sample Rate 4.8 200 300 3.2 800 200 1.5 tACQ Track/Hold Acquisition Time 2.0 tCONV tCYC fRATE tAD Conversion Time Normal Operation Throughput Time Throughput Rate Aperture Delay 6 Short Cycled 12 12 16 14 200 MHz (min) kHz (max) ksps (min) SCLK cycles (min) SCLK cycles (max) SCLK cycles SCLK cycles SCLK cycles (min) ksps (max) ns (Note 8) The following specifications apply for VA = +4.5V to 5.5V, VREF = 2.5V, fSCLK = 0.8 MHz to 3.2 MHz, CL = 100 pF, Boldface limits apply for TA = TMIN to TMAX: all other limits TA = 25˚C. Symbol tCFCS tCSCR tCHLD tCDV tDIS tEN tCH tCL tr tf Parameter SCLK Fall toCS Fall CS Fall to SCLK Rise SCLK Fall to Data Change Hold Time SCLK Fall to Next DOUT Valid Rising Edge of CS To DOUT Disabled 2nd SCLK Fall after CS Fall to DOUT Enabled SCLK High Time SCLK Low Time DOUT Rise Time DOUT Fall Time (Note 9) (Note 9) 38 38 6 42 42 5 13 Conditions Typical Limits 0 0 10 100 50 50 60 60 50 50 Units ns (min) ns (min) ns (min) ns (max) ns (max) ns (max) ns (min) ns (min) ns (max) ns (max) ADC121S625 Timing Specifications Note 1: Absolute maximum ratings are limiting values which indicate limits beyond which damage to the device may occur. Operating Ratings indicate