AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 1-Bit, 10MHz, 2nd-Order, Isolated Delta-Sigma Modulator FEATURES DESCRIPTION • • • • • • • The AMC1203 is a 1-bit, 10MHz, isolated delta-sigma (ΔΣ) modulator with an output buffer separated from the input interface circuitry by a silicon dioxide (SiO2) isolation barrier. This barrier provides galvanic isolation of up to 4000VPEAK. Used in conjunction with isolated power supplies, these devices prevent noise currents on a data bus or other circuits from entering the local ground and interfering with or damaging sensitive circuitry. 1 2 • • 16-Bit Resolution SNR: 80.5dB min THD: –88dB max (AMC1203B) ±280mV Input Range with +5V Supply Internal 2.5V Reference Voltage: 1% Accuracy Gain Error: ±1% (AMC1203B) UL1577, IEC60747-5-2 (VDE0884, Rev. 2), and IEC61010-1 Approved – Isolation: 4000VPEAK, Working Voltage: 560V – Transient Immunity: 15kV/µs Typical 25-Year Life at Rated Working Voltage (see Application Report SLLA197) Operating Temperature Range: –40°C to +105°C The AMC1203 modulator operates from a +5V supply with a dynamic range of 95dB. The differential inputs are ideal for direct connection to shunt resistors or other low-level signal sources. With the appropriate digital filter and modulator rate, the device can be used to achieve 16-bit analog-to-digital (A/D) conversion with no missing codes. An effective resolution of 14 bits and an SNR of 85dB (typical) can be maintained with a sinc3 filter with a decimation ratio of 256. APPLICATIONS • The modulator output is translated to a balanced signal and then transferred by the capacitive isolation barrier. Across the isolation barrier, a differential comparator receives the logic transition information, and then sets or resets a flip-flop and the output circuit accordingly. Shunt Based Current Sensing in: – Motor Control – Uninterruptible Power Supplies – Power Inverters – Industrial Process Control The AMC1203 is available in an SO-8 gull-wing package. SO-8 and SO-16 packages are planned for release in 2008. The AMC1203 is characterized for operation over the ambient temperature range of –40°C to +105°C. Isolation Barrier + VIN+ 2nd-Order DS Modulator Output Buffer VREF MDAT + VIN- Interface Circuit - POR BIAS POR + Buffer 20MHz RC Oscillator 2.5V VREF Output Buffer VREF MCLK + - 1 2 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2008, Texas Instruments Incorporated AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. ORDERING INFORMATION (1) PRODUCT AMC1203 AMC1203B (1) (2) PACKAGE-LEAD PACKAGE DESIGNATOR SPECIFIED TEMPERATURE RANGE PACKAGE MARKING SO-8 Gull-Wing DUB –40°C to +105°C AMC1203 SO-8 (2) PSA –40°C to +105°C TBD SO-16 (2) DW –40°C to +105°C TBD SO-8 Gull-Wing DUB –40°C to +105°C AMC1203 SO-8 (2) PSA –40°C to +105°C TBD SO-16 (2) DW –40°C to +105°C TBD ORDERING NUMBER TRANSPORT MEDIA, QUANTITY AMC1203DUB Tube, 50 AMC1203DUBR Tape and Reel, 700 AMC1203PSA Tube, 80 AMC1203PSAR Tape and Reel, 2000 AMC1203DW Tube, 40 AMC1203DWR Tape and Reel, 2000 AMC1203BDUB Tube, 50 AMC1203BDUBR Tape and Reel, 700 AMC1203BPSA Tube, 80 AMC1203BPSAR Tape and Reel, 2000 AMC1203BDW Tube, 40 AMC1203BDWR Tape and Reel, 2000 For the most current package and ordering information see the Package Option Addendum at the end of this document, or see the TI web site at www.ti.com. SO-8 and SO-16 packages available in 2008. ABSOLUTE MAXIMUM RATINGS (1) Over operating free-air temperature range, unless otherwise noted. PARAMETER Supply voltage, VDD1 to GND1 or VDD2 to GND2 Analog input voltage at VIN+, VIN– Input current to any pin except supply pins Continuous total power dissipation (1) 2 UNIT –0.3 to +6 V GND1 – 0.3 to VDD1 + 0.3 V ±10 mA See Dissipation Ratings Table +150 °C Human body model (HBM) JEDEC standard 22, test method A114-C.01 ±3000 V Charged device Model (CDM) JEDEC standard 22, test method C101 ±1500 V Machine Model (MM) JEDEC standard 22, test method A115A ±200 V Maximum junction temperature, TJ Electrostatic discharge (ESD), all pins AMC1203 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 under the Recommended Operating Conditions is not implied. Exposure to absolute maximum rated conditions for extended periods may affect device reliability. Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 THERMAL CHARACTERISTICS (1) Over recommended operating conditions, unless otherwise noted. PARAMETER SO-8 GULL-WING SO-8 SO-16 UNIT Low-K 127 246 104 °C/W High-K 78 164 58 °C/W θJA Junction-to-air thermal resistance θJC Junction-to-case thermal resistance 61 32 25 °C/W PD Device power dissipation (max) 110 110 110 mW (1) Tested in accordance with the Low-K or High-K thermal metric definitions of EIA/JESD51-3 for leaded surface mount packages. RECOMMENDED OPERATING CONDITIONS Over operating free-air temperature range, unless otherwise noted. PARAMETER MIN NOM MAX Supply voltage, VDD1 to GND1 or VDD2 to GND2 4.5 5.0 5.5 Common-mode operating range, VCM Differential input voltage, (VIN+) – (VIN–) Operating junction temperature range, TJ (see the Thermal Characteristics table) UNIT V 0 VDD1 V –280 280 mV –40 +125 °C DISSIPATION RATINGS (1) PACKAGE DERATING FACTOR ABOVE TA = +25°C TA ≤ +25°C POWER RATING TA = +70°C POWER RATING TA = +85°C POWER RATING TA = +125°C POWER RATING SO-8 Gull-Wing 7.9mW/°C 984mW 629mW 511mW 354mW SO-8 4.1mW/°C 508mW 325mW 264mW 182mW SO-16 9.6mW/°C 1201mW 769mW 625mW 432mW (1) Based on Low-K thermal resisitance. REGULATORY INFORMATION VDE UL Certified according to IEC 60747-5-2 Recognized under 1577 Component Recognition Program File Number: 40014131 File Number: E181974 IEC 60747-5-2 ISOLATION CHARACTERISTICS Over recommended operating conditions, unless otherwise noted. PARAMETER VIORM VPD TEST CONDITIONS Maximum working insulation voltage Input to output test voltage VALUE UNIT 560 V Method A, after input or safety test (subgroup 2 or 3), VPD = VIORM × 1.2, t = 10s, partial discharge < 5pC 672 V Method A, after environmental test (subgroup 1), VPD = VIORM × 1.6, t = 10s, partial discharge < 5pC 896 V Method B1, routine and initial test, VPD = VIORM × 1.875, 100% production test with t = 1s, partial discharge < 5pC 1050 V VIOTM Transient overvoltage t = 60s 4000 V RS Isolation resistance VIO = 500V at TS > 109 Ω PD Pollution degree 2 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 3 AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 PACKAGE CHARACTERISTICS (1) Over recommended operating conditions, unless otherwise noted. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT L(I01) Minimum air gap (clearance) Shortest terminal to terminal distance through air L(I02) Minimum external tracking (creepage) Shortest terminal to terminal distance across the package surface CTI Tracking resistance (comparative tracking index) DIN IEC 60112 / VDE 0303 Part 1 ≥ 175 V Minimum internal gap (internal clearance) Distance through the insulation 0.008 mm RIO Isolation resistance 7.0 mm 7.0 mm Input to output, VIO = 500V, all pins on each side of the barrier tied together creating a two-terminal device, TA < +85°C > 1012 Ω Input to output, VIO = 500V, +100°C ≤ TA < TA max > 1011 Ω CIO Barrier capacitance input to output VI = 0.8VPP at 1MHz 1.2 pF CI Input capacitance to ground VI = 0.8VPP at 1MHz 3 pF (1) Creepage and clearance requirements should be applied according to the specific equipment isolation standards of an application. Care should be taken to maintain the creepage and clearance distance of the board design to ensure that the mounting pads of the isolator on the printed circuit board do not reduce this distance. Creepage and clearance on a printed circuit board become equal according to the measurement techniques shown in the Isolation Glossary. Techniques such as inserting grooves and/or ribs on a printed circuit board are used to help increase these specifications. IEC SAFETY LIMITING VALUES Safety limiting intends to prevent potential damage to the isolation barrier upon failure of input or output (I/O) circuitry. A failure of the I/O circuitry can allow low resistance to ground or the supply and, without current limiting, dissipate sufficient power to overheat the die and damage the isolation barrier, potentially leading to secondary system failures. The safety-limiting constraint is the operating virtual junction temperature range specified in the Absolute Maximum Ratings table. The power dissipation and junction-to-air thermal impedance of the device installed in the application hardware determines the junction temperature. The assumed junction-to-air thermal resistance in the Thermal Characteristics table is that of a device installed in the JESD51-3, Low Effective Thermal Conductivity Test Board for Leaded Surface Mount Packages and is conservative. The power is the recommended maximum input voltage times the current. The junction temperature is then the ambient temperature plus the power times the junction-to-air thermal resistance. PARAMETER IS Safety input, output, or supply current TC Maximum case temperature TEST CONDITIONS MIN TYP MAX θJA = 246°C/W, VI = 5.5V, TJ = +150°C, TA = +25°C UNIT 90 mA +150 °C IEC 61000-4-5 RATINGS PARAMETER Surge immunity TEST CONDITIONS 1.2/50µs voltage surge and 8/20µs current surge VALUE UNIT ±6000 V IEC 60664-1 RATINGS PARAMETER TEST CONDITIONS SPECIFICATION Basic isolation group Material group IIIa Rated mains voltage ≤ 150 VRMS I-IV Rated mains voltage < 300 VRMS I-III Installation classification 4 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 ELECTRICAL CHARACTERISTICS At TA = –40°C to +105°C, VDD1 = 4.5V to 5.5V, VDD2 = 4.5V to 5.5V, VIN+ = –280mV to +280mV, VIN– = 0V, and sinc3 filter with OSR = 256, unless otherwise noted. AMC1203 PARAMETER TEST CONDITIONS RESOLUTION MIN TYP (1) MAX UNIT 16 Bits DC ACCURACY AMC1203 ±3 ±9 LSB AMC1203B ±2 ±6 LSB +1 LSB INL Integral linearity error (2) DNL Differential nonlinearity (3) –1 VOS Offset error (4) –1 TCVOS Offset error thermal drift GERR Gain error TCGERR Gain error thermal drift PSRR Power-supply rejection ratio ±0.1 1 mV ±1.5 ±5 µV/°C % AMC1203 –2 ±0.2 2 AMC1203B –1 ±0.2 1 % ±20 ppm/°C 80 dB ANALOG INPUTS FSR Full-scale differential voltage input range VCM Operating common-mode signal (3) CI Input capacitance to GND1 CID Differential input capacitance RID Differential input resistance IIL Input leakage current CMTI Common-mode transient immunity CMRR Common-mode rejection ratio (VIN+) – (VIN–) –320 320 –0.1 5 VIN+ or VIN– 3 6 pF kΩ 5 15 VIN from 0V to 5V at 50kHz V pF 28 –5 VIN from 0V to 5V at 0Hz mV nA kV/µs 92 dB 105 dB INTERNAL CLOCK tCLK Clock period See Figure 2 83.33 100 125 ns fCLK Clock frequency See Figure 2 8 10 12 MHz tH Clock high-time See Figure 2 (tCLK/2) – 8 50 (tCLK/2) + 8 ns tD1 Data valid time after falling edge of clock See Figure 2 –2 0 2 ns 85 AC ACCURACY SINAD Signal-to-noise + distortion fIN = 1kHz 80 SNR Signal-to-noise ratio fIN = 1kHz 80.5 THD Total harmonic distortion SFDR Spurious-free dynamic range (1) (2) (3) (4) dB 85 dB AMC1203, fIN = 1kHz –92 –84.5 AMC1203B, fIN = 1kHz –95 –88 AMC1203, fIN = 1kHz 86 92 AMC1203B, fIN = 1kHz 89 95 dB dB All typical values are at TA = +25°C Integral nonlinearity is defined as the maximum deviation of the line through the inputs of the specified input range of the transfer curve of the specified VIN expressed either as number of LSBs, or as a percent of the specified 560mV input range. Ensured by design. Maximum values, including temperature drift, are ensured over the full specified temperature range. Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 5 AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 ELECTRICAL CHARACTERISTICS (continued) At TA = –40°C to +105°C, VDD1 = 4.5V to 5.5V, VDD2 = 4.5V to 5.5V, VIN+ = –280mV to +280mV, VIN– = 0V, and sinc3 filter with OSR = 256, unless otherwise noted. AMC1203 MIN TYP (1) IOH = –8mA VDD2 – 0.8 4.6 V IOH = –4mA VDD2 – 0.4 4.8 V PARAMETER TEST CONDITIONS MAX UNIT DIGITAL OUTPUTS VOH High-level output voltage VOL Low-level output voltage IOL = 8mA 0.3 0.8 V IOL = 4mA 0.2 0.4 V 5.0 5.5 V POWER SUPPLY VDD Supply voltage VDD1 and VDD2 4.5 IDD1 Analog supply current 6 8 IDD2 Digital supply current 10 12 mA PD Power dissipation 80 110 mW mA EQUIVALENT INPUT CIRCUIT RSW 350W (typ) AIN+ CINT 7pF (typ) 1.5pF Switching Frequency = CLK High Impedance >1GW VCM 1.5pF R SW 350W (typ) CINT 7pF (typ) AIN- High Impedance >1GW Figure 1. Equivalent Analog Input Circuit 6 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 PIN ASSIGNMENTS DUB or PSA(1) PACKAGE SO-8 Gull-Wing or SO-8 (TOP VIEW) VDD1 1 VIN+ 2 DW PACKAGE(1) SO-16 (TOP VIEW) 8 VDD2 VDD1 1 16 GND2 7 MCLK VIN+ 2 15 NC 14 VDD2 AMC1203 VIN- 3 6 MDAT VIN- 3 GND1 4 5 GND2 GND1 4 13 MCLK AMC1203 (1) PSA package available in late 2008. Table 1. SO-8 PIN CONFIGURATION PIN NO. VDD1 Analog power supply 2 VIN+ Noninverting analog input 3 VIN– Inverting analog input 4 GND1 Analog ground 5 GND2 Digital ground 7 8 5 12 NC NC 6 11 MDAT NC 7 10 NC GND1 8 9 GND2 NAME DESCRIPTION 1 6 NC (1) DW package available in 2008. Table 2. SO-16 PIN CONFIGURATION PIN NO. NAME DESCRIPTION MDAT Modulator data output 1 VDD1 Analog power supply MCLK Modulator clock output 2 VIN+ Noninverting analog input VIN– Inverting analog input VDD2 3 Digital power supply 4, 8 (1) 5, 6, 7, 10, 12, 15 9, 16 (1) (1) GND1 Analog ground NC No internal connection—can be tied to any potential or left unconnected GND2 Digital ground 11 MDAT Modulator data output 13 MCLK Modulator clock output 14 VDD2 Digital power supply Both pins are connected internally via a low-impedance path; thus only one of the pins must be tied to the ground plane. Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 7 AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 TIMING INFORMATION tCLK tHIGH MCLK tD tS tH MDAT Figure 2. Modulator Output Mode Timing TIMING CHARACTERISTICS FOR MODULATOR OUTPUT MODE Over recommended operating free-air temperature range at –40°C to +105°C, VDD1 = +5V, and VDD2 = +5V, unless otherwise noted. PARAMETER MIN TYP MAX UNIT 83.33 100 125 ns (tCLK/2) – 8 tP/2 (tCLK/2) + 8 ns –2 0 2 ns tCLK MCLK clock period tHIGH MCLK clock high time tD Data delay after falling edge of MCLK tS Data setup time prior to rising edge of MCLK 31.5 ns tH Data hold time after rising edge of MCLK 31.5 ns 8 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 TYPICAL CHARACTERISTICS At VDD1 = VDD2 = 5V, VIN+ = –280mV to +280mV, VIN– = 0V, and sinc3 filter with OSR = 256, unless otherwise noted. INTEGRAL NONLINEARITY vs INPUT SIGNAL AMPLITUDE INTEGRAL NONLINEARITY vs TEMPERATURE 6 3 5 4 2 3 1 INL (LSB) INL (LSB) 2 1 0 -1 0 -1 -2 -3 -2 -4 -5 -6 -300 -3 -200 -100 0 VIN (mV) 100 200 300 20 35 50 65 Temperature (°C) 80 Figure 3. Figure 4. OFFSET ERROR vs SUPPLY VOLTAGE OFFSET ERROR vs TEMPERATURE 0.20 0.5 0.15 0.4 95 110 125 0.3 0.10 0.2 0.05 VOS (mV) VOS (mV) 5 -40 -25 -10 0 -0.05 0.1 0 -0.1 -0.2 -0.10 -0.3 -0.15 -0.4 -0.5 4.75 5.00 VDD1 (V) 5.25 5.50 5 -40 -25 -10 20 35 50 65 Temperature (°C) 80 95 Figure 5. Figure 6. GAIN ERROR vs TEMPERATURE EFFECTIVE NUMBER OF BITS vs OVERSAMPLING RATIO 0 18 -0.1 16 -0.2 14 -0.3 12 ENOB (Bits) Gain (%) -0.20 4.50 -0.4 -0.5 110 125 Sinc3 Filter Sinc2 Filter 10 8 -0.6 6 -0.7 4 -0.8 2 Sinc Filter 0 -0.9 -40 -25 -10 5 20 35 50 65 Temperature (°C) 80 95 110 125 1 Figure 7. 10 100 OSR 1000 10000 Figure 8. Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 9 AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 TYPICAL CHARACTERISTICS (continued) At VDD1 = VDD2 = 5V, VIN+ = –280mV to +280mV, VIN– = 0V, and sinc3 filter with OSR = 256, unless otherwise noted. SIGNAL-TO-NOISE RATIO vs INPUT SIGNAL AMPLITUDE SIGNAL-TO-NOISE RATIO vs TEMPERATURE 100 90 fIN = 500Hz 89 90 87 70 86 SNR (dB) SNR (dB) 88 80 60 85 84 83 50 82 40 81 30 80 1 10 100 1000 -40 -25 -10 5 VIN (mVPP) Figure 10. SIGNAL-TO-NOISE RATIO vs INPUT SIGNAL FREQUENCY SIGNAL-TO-NOISE RATIO vs TEMPERATURE 110 90 105 89 110 125 fIN = 1kHz 87 95 SNR (dB) SNR (dB) 95 88 90 85 86 85 84 83 80 82 75 81 70 80 100 1k fIN (Hz) 10k -40 -25 -10 5 20 35 50 65 Temperature (°C) 80 95 Figure 11. Figure 12. TOTAL HARMONIC DISTORTION vs INPUT SIGNAL FREQUENCY TOTAL HARMONIC DISTORTION vs TEMPERATURE -80 -80 -85 -85 -90 -90 THD (dB) THD (dB) 80 Figure 9. 100 -95 110 125 -95 -100 -100 -105 -105 -110 -110 100 1k fIN (Hz) 10k -40 -25 -10 Figure 13. 10 20 35 50 65 Temperature (°C) 5 20 35 50 65 Temperature (°C) 80 95 110 125 Figure 14. Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 TYPICAL CHARACTERISTICS (continued) At VDD1 = VDD2 = 5V, VIN+ = –280mV to +280mV, VIN– = 0V, and sinc3 filter with OSR = 256, unless otherwise noted. FREQUENCY SPECTRUM (4096 Point FFT, fIN = 1kHz, 0.56VPP) 0 0 -20 -20 -40 -40 Magnitude (dB) Magnitude (dB) FREQUENCY SPECTRUM (4096 Point FFT, fIN = 500Hz, 0.56VPP) -60 -80 -80 -100 -100 -120 -120 -140 -140 0 2 4 6 8 10 12 Frequency (kHz) 14 16 18 20 0 2 4 6 8 10 12 Frequency (kHz) 14 16 Figure 15. Figure 16. COMMON-MODE REJECTION RATIO vs INPUT SIGNAL FREQUENCY POWER-SUPPLY REJECTION RATIO vs FREQUENCY 120 18 20 110 With Sinc3 Filter 100 110 90 PSRR (dB) CMRR (dB) -60 100 Without Filter 80 70 60 90 50 80 40 100 1k 10k fIN (Hz) 100k 1M 100 1k 10k 100k Frequency (Hz) Figure 17. Figure 18. INTERNAL CLOCK FREQUENCY vs SUPPLY VOLTAGE INTERNAL CLOCK FREQUENCY vs TEMPERATURE 10.40 10.5 10.35 10.4 10.25 fCLK (MHz) fCLK (MHz) 10.30 10.20 10.15 10.10 10.3 10.2 10.1 10.05 10.00 4.50 10.0 4.75 5.00 VDD1 (V) 5.25 5.50 -40 -25 -10 Figure 19. 5 20 35 50 65 Temperature (°C) 80 95 110 125 Figure 20. Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 11 AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 TYPICAL CHARACTERISTICS (continued) At VDD1 = VDD2 = 5V, VIN+ = –280mV to +280mV, VIN– = 0V, and sinc3 filter with OSR = 256, unless otherwise noted. ANALOG SUPPLY CURRENT vs TEMPERATURE DIGITAL SUPPLY CURRENT vs TEMPERATURE 6.5 10.0 9.5 6.0 IDD2 (mA) IDD1 (mA) 9.0 5.5 5.0 8.5 8.0 4.5 7.5 4.0 7.0 -40 -25 -10 5 20 35 50 65 Temperature (°C) 80 95 110 125 -40 -25 -10 Figure 21. 12 5 20 35 50 65 Temperature (°C) 80 95 110 125 Figure 22. Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 GENERAL DESCRIPTION The AMC1203 is a single-channel, 2nd-order, CMOS, delta-sigma modulator, designed for medium- to high-resolution A/D conversions from dc to 39kHz with an oversampling ratio (OSR) of 256. The isolated output of the converter (MDAT) provides a stream of digital ones and zeros. The time average of this serial output is proportional to the analog input voltage. The modulator shifts the quantization noise to high frequencies; therefore, a low-pass digital filter should be used at the output of the device to increase the overall performance. This filter is also used to convert from the 1-bit data stream at a high sampling rate into a higher-bit data word at a lower rate (decimation). A digital signal processor (DSP), microcontroller (µC) or field programmable gate array (FPGA) can be used to implement the filter. Another option is using a suitable application-specific device, such as the AMC1210, a four-channel digital sinc-filter. Figure 23 shows two AMC1203s and one ADS1205 (dual-channel, non-isolated modulator) connected to an AMC1210, building the entire analog front-end of a resolver-based motor-control application. For detailed information on the ADS1205 and AMC1210, please visit our home page at www.ti.com. The overall performance (speed and accuracy) depends on the selection of an appropriate OSR and filter type. A higher OSR results in higher accuracy while operating at lower refresh rate. Alternatively, a lower OSR results in lower accuracy, but provides data at a higher refresh rate. This system allows flexibility with the digital filter design and is capable of A/D conversion results that have a dynamic range exceeding 95dB with OSR = 256. Resolver Control Module AMC1210 PWM1 Signal Generator PWM2 Filter Module 1 Comparator Filter IN1 ADS1205 CLK1 IN2 Sinc Filter/ Integrator Input Control Filter Module 2 CLK2 Current Shunt Resistor IN3 AMC1203 CLK3 IN4 AMC1203 RST INT ACK Time Measurement ADS1205 Current Shunt Resistor CLK Interrupt Unit CLK4 Register Map Interface Module Filter Module 3 CS ALE RD WR M0 M1 AD0 AD7 Filter Module 4 Figure 23. Example of a Resolver-Based Motor-Control Application Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 13 AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 THEORY OF OPERATION The differential analog input of the AMC1203 is implemented with a switched-capacitor circuit. This switched-capacitor circuit implements a 2nd-order modulator stage that digitizes the input signal into a 1-bit output stream. The internally-generated clock signal (sourcing the capacitor circuit and the modulator) is available as an output signal on the MCLK pin. The analog input signal is continuously sampled by the modulator and compared to an internal voltage reference. A digital stream, accurately representing the analog input voltage over time, appears at the output of the converter. ANALOG INPUT The input design topology of the AMC1203 is based on a fully-differential, switched-capacitor architecture with a dynamic input impedance of 28kΩ at 10MHz, as Figure 1 shows. This input stage provides the mechanism to achieve low system noise, high common-mode rejection (92dB), and excellent power-supply rejection. The input impedance becomes a consideration in designs with high input-signal source impedance. This high-impedance may cause degradation in gain, linearity, and THD. The importance of this effect, however, depends on the desired system performance. There are two restrictions on the analog input signals, VIN+ and VIN–. If the input voltage exceeds the range GND – 0.3V to VDD + 0.3V, the input current must be limited to 10mA, because the input protection diodes on the front end of the converter begin to turn on. In addition, the linearity and the noise performance of the device is ensured only when the differential analog voltage resides within ±280mV. MODULATOR The modulator topology of the AMC1203 is fundamentally a 2nd-order, switched-capacitor, delta-sigma modulator, such as the one conceptualized in Figure 24. The analog input voltage (X(t)) and the output of the 1-bit digital-to-analog converter (DAC) are differentiated, providing an analog voltage (X2) at the input of the first integrator or modulator stage. The output of the first integrator is further differentiated with the DAC output, and the resulting voltage (X3) feeds the input of the second integrator stage. When the value of the integrated signal (X4) at the output of the second stage equals the comparator reference voltage, the output of the comparator switches from high to low, or vice versa, depending on its previous state. In this case, the 1-bit DAC responds on the next clock pulse by changing its analog output voltage (X6), causing the integrators to progress in the opposite direction, while forcing the value of the integrator output to track the average of the input. fCLK X(t) X2 Integrator 1 X3 Integrator 2 X4 DATA fS VREF Comparator X6 DAC Figure 24. Block Diagram of the 2nd-Order Modulator 14 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 DIGITAL OUTPUT 0 The system clock of the AMC1203 is 20 MHz by default, and is generated internally using an RC circuit. The system clock is divided by two for the modulator clock; thus, the default clock frequency of the modulator is 10MHz. This clock is also available on the output terminal MCLK, whereas the data are provided at the MDAT output pin. The data are changing at the falling edge of MCLK, so data can safely be latched with the rising edge; see the Timing Characteristics. fDATA = 10MHz/32 = 312.5kHz -3dB: 81.9kHz OSR = 32 -10 -20 Gain (dB) A differential input signal of 0V ideally produces a stream of ones and zeros that are high 50% of the time and low 50% of the time. A differential input of +280mV produces a stream of ones and zeros that are high 87.5% of the time. A differential input of –280mV produces a stream of ones and zeros that are high 12.5% of the time. The input voltage versus the output modulator signal is shown in Figure 27. -30 -40 -50 -60 -70 -80 0 400 600 800 1000 Frequency (kHz) 1200 1400 1600 Figure 25. Frequency Response of the Sinc3 Filter 30k fMOD = 10MHz OSR = 32 FSR = 32768 ENOB = 9.9 Bits Settling Time = 3 ´ 1/fDATA = 9.6ms 25k Output Code FILTER USAGE The modulator generates a bit stream that is processed by a digital filter to get a digital word similar to the conversion result of a conventional analog-to-digital converter (ADC). A very simple filter, built with minimal effort and hardware, is a sinc3 filter: 200 20k 15k 10k 3 H(z) = 5k 1 - z-OSR 1 - z-1 (1) This filter provides the best output performance at the lowest hardware size (count of digital gates). For an OSR in the range of 16 to 256, this filter is a good choice. All the characterizations in this document are also done with a sinc3 filter with OSR=256 and an output word width of 16 bits. 3 In a sinc filter response (shown in Figure 25 and Figure 26), the location of the first notch occurs at the frequency of output data rate fDATA = fCLK/OSR. The –3dB point is located at half the Nyquist frequency or fDATA/4. 0 0 5 10 15 20 25 30 Number of Output Clocks 35 40 Figure 26. Pole Response of the Sinc3 Filter Performance can be improved, for example, by using a cascaded filter structure. The first decimation stage could be built using a sinc3 filter with a low OSR and the second stage using a high-order filter. Modulator Output +FS (Analog Input) -FS (Analog Input) Analog Input Figure 27. Analog Input vs Modulator Output Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 15 AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 In motor-control applications, a very fast response time for the over-current detection is required. The time for full settling of the filter depends on its order (that is, a sinc3 filter requires three data clocks for full settling (with fDATA = fMOD/OSR). Therefore, for over-current protection, filter types other than sinc3 might be a better choice; an alternative is the sinc2 filter. Figure 29 compares the settling times of different filter orders (sincfast is a modified sinc2 filter): 16 sinc3 14 sincfast 12 ENOB (Bits) The effective number of bits (ENOB) is often used to compare the performance of ADCs and delta-sigma modulators. Figure 28 shows the ENOB of the AMC1203 with different oversampling ratios. In this data sheet, this number is calculated from the SNR using following formula: SNR = 1.76dB + 6.02dB ´ ENOB (2) sinc2 10 8 6 sinc 4 2 0 1 10 100 1000 OSR Figure 28. Measured Effective Number of Bits vs Oversampling Ratio 2 1 - z-OSR (1 + z-2OSR) 1 - z-1 10 (3) For more information, see application note SBAA094, Combining the ADS1202 with an FPGA Digital Filter for Current Measurement in Motor Control Applications, available for download at www.ti.com. sinc3 9 8 sincfast 7 ENOB (Bits) H(z) = sinc2 6 5 4 sinc 3 2 1 0 0 1 2 3 4 5 6 Settling Time (ms) 7 8 9 10 Figure 29. Measured Effective Number of Bits vs Settling Time 16 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 APPLICATION INFORMATION A typical operation of the AMC1203 in a motor-control application is shown in Figure 30. Measurement of the motor phase current is done via the shunt resistor (RSHUNT; in this case, a 2-terminal shunt). For better performance, the differential signal is filtered using RC filters (components R2, R3 and C2). Optionally, C3 and C4 can be used to reduce charge dumping from the inputs. In this case, care should be taken when choosing the quality of these capacitors—mismatch in values of these capacitors will lead to a common-mode error at the input of the modulator. The high-side power supply for the AMC1203 (VDD1) is derived from the power supply of the upper gate driver. For lowest cost, a Zener diode can be used to limit the voltage to 5V ±10%. A decoupling capacitor HV+ of 0.1µF is recommended for filtering this power-supply path. This capacitor (C1 in Figure 30) should be placed as close as possible to the VDD1 pin for best performance. If better filtering is required, an additional 1µF to 10µF capacitor can be used. The floating ground reference (GND1) is derived from the end of the shunt resistor, which is connected to the negative input of the AMC1203 (VIN–). If a 4-terminal shunt is used, the inputs of the AMC1203 are connected to the inner leads, while GND1 is connected to one of the outer leads of the shunt. Both digital outputs, MCLK and MDAT, can be directly connected to a digital filter (that is, the AMC1210); see Figure 23. Floating Power Supply Gated Drive Circuit Isolation Barrier R1 AMC1203 D1 5.1V R3 12W RSHUNT To Load Power Supply Gated Drive Circuit VDD1 VDD2 VIN+ MDAT VIN- MCLK GND1 GND2 C1(1) 0.1mF R2 12W C2 330pF C3 10pF (optional) C4 10pF (optional) NOTE: (1) Place C1 close to AMC1203. HV- Figure 30. Typical Application Diagram Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 17 AMC1203 www.ti.com SBAS427 – FEBRUARY 2008 ISOLATION GLOSSARY Creepage Distance: The shortest path between two conductive input to output leads measured along the surface of the insulation. The shortest distance path is found around the end of the package body. the leakage current produces an overvoltage at the site of the discontinuity, and an electric spark is generated. These sparks often cause carbonization on insulation material and lead to a carbon track between points of different potential. This process is known as tracking. Insulation: Operational insulation—Insulation needed for the correct operation of the equipment. Clearance: The shortest distance between two conductive input to output leads measured through air (line of sight). Basic insulation—Insulation to protection against electric shock. provide basic Supplementary insulation—Independent insulation applied in addition to basic insulation in order to ensure protection against electric shock in the event of a failure of the basic insulation. Double insulation—Insulation comprising both basic and supplementary insulation. Reinforced insulation—A single insulation system that provides a degree of protection against electric shock equivalent to double insulation. Input-to Output Barrier Capacitance: The total capacitance between all input terminals connected together, and all output terminals connected together. Input-to Output Barrier Resistance: The total resistance between all input terminals connected together, and all output terminals connected together. Primary Circuit: An internal circuit directly connected to an external supply mains or other equivalent source that supplies the primary circuit electric power. Secondary Circuit: A circuit with no direct connection to primary power that derives its power from a separate isolated source. Comparative Tracking Index (CTI): CTI is an index used for electrical insulating materials. It is defined as the numerical value of the voltage that causes failure by tracking during standard testing. Tracking is the process that produces a partially conducting path of localized deterioration on or through the surface of an insulating material as a result of the action of electric discharges on or close to an insulation surface. The higher CTI value of the insulating material, the smaller the minimum creepage distance. Generally, insulation breakdown occurs either through the material, over its surface, or both. Surface failure may arise from flashover or from the progressive degradation of the insulation surface by small localized sparks. Such sparks are the result of the breaking of a surface film of conducting contaminant on the insulation. The resulting break in 18 Pollution Degree: Pollution Degree 1—No pollution, or only dry, nonconductive pollution occurs. The pollution has no influence on device performance. Pollution Degree 2—Normally, only nonconductive pollution occurs. However, a temporary conductivity caused by condensation is to be expected. Pollution Degree 3—Conductive pollution, or dry nonconductive pollution that becomes conductive because of condensation, occurs. Condensation is to be expected. Pollution Degree 4 – Continuous conductivity occurs as a result of conductive dust, rain, or other wet conditions. Installation Category: Overvoltage Category—This section is directed at insulation coordination by identifying the transient overvoltages that may occur, and by assigning four different levels as indicated in IEC 60664. I: Signal Level: Special equipment or parts of equipment. II: Local Level: Portable equipment, etc. III: Distribution Level: Fixed installation. IV: Primary Supply Level: Overhead lines, cable systems. Each category should be subject to smaller transients than the previous category. Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated Product Folder Link(s): AMC1203 PACKAGE OPTION ADDENDUM www.ti.com 20-Mar-2008 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty AMC1203BDUB ACTIVE SOP DUB 8 50 Green (RoHS & no Sb/Br) CU NIPDAU Level-4-260C-72 HR AMC1203BDUBG4 ACTIVE SOP DUB 8 50 Green (RoHS & no Sb/Br) CU NIPDAU Level-4-260C-72 HR AMC1203BDUBR ACTIVE SOP DUB 8 700 Green (RoHS & no Sb/Br) CU NIPDAU Level-4-260C-72 HR AMC1203BDUBRG4 ACTIVE SOP DUB 8 700 Green (RoHS & no Sb/Br) CU NIPDAU Level-4-260C-72 HR AMC1203DUB ACTIVE SOP DUB 8 50 Green (RoHS & no Sb/Br) CU NIPDAU Level-4-260C-72 HR AMC1203DUBG4 ACTIVE SOP DUB 8 50 Green (RoHS & no Sb/Br) CU NIPDAU Level-4-260C-72 HR AMC1203DUBR ACTIVE SOP DUB 8 700 Green (RoHS & no Sb/Br) CU NIPDAU Level-4-260C-72 HR AMC1203DUBRG4 ACTIVE SOP DUB 8 700 Green (RoHS & no Sb/Br) CU NIPDAU Level-4-260C-72 HR Lead/Ball Finish MSL Peak Temp (3) (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. 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