ADS1606IPAPT

ADS1605 ADS1606 SBAS274H − MARCH 2003 − REVISED MAY 2007 16-Bit, 5MSPS Analog-to-Digital Converter FEATURES DESCRIPTION D D D D D D D D D The ADS1605 and ADS1606 are high-speed, high-precision, delta-sigma analog-to-digital converters (ADCs) with 16-bit resolution. The data rate is 5 mega-samples per second (MSPS), the bandwidth (−3dB) is 2.45MHz, and passband ripple is less than ±0.0025dB (to 2.2MHz). Both devices offer the same outstanding performance at these speeds with a signal-to-noise ratio up to 88dB, total harmonic distortion down to −99dB, and a spurious-free dynamic range up to 101dB. For even higher-speed operation, the data rate can be doubled to 10MSPS in 2X mode. The ADS1606 includes an adjustable first-in first-out buffer (FIFO) for the output data. The input signal is measured against a voltage reference that can be generated on-chip or supplied externally. The digital output data are provided over a simple parallel interface that easily connects to digital signal processors (DSPs). An out-of-range monitor reports when the input range has been exceeded. The ADS1605/6 operate from a +5V analog supply (AVDD) and +3V digital supply (DVDD). The digital I/O supply (IOVDD) operates from +2.7 to +5.25V, enabling the digital interface to support a range of logic families. The analog power dissipation is set by an external resistor and can be reduced when operating at slower speeds. A power down mode, activated by a digital I/O pin, shuts down all circuitry. The ADS1605/6 are offered in a TQFP-64 package using TI PowerPAD technology. The ADS1605 and ADS1606, along with their 18-bit counterparts, the ADS1625 and ADS1626, are well suited for the demanding measurement requirements of scientific instrumentation, automated test equipment, data acquisition, and medical imaging. D D D Data Rate: 5MSPS (10MSPS in 2X Mode) Signal-to-Noise Ratio: 88dB Total Harmonic Distortion: −99dB Spurious-Free Dynamic Range: 101dB Linear Phase with 2.45MHz Bandwidth Passband Ripple: ±0.0025dB Selectable On-Chip Reference Directly Connects to TMS320C6000 DSPs Easily Upgradable to 18 Bits with the ADS1625 and ADS1626 Adjustable Power Dissipation: 315 to 570mW Power Down Mode Supplies: Analog +5V Digital +3V Digital I/O +2.7V to +5.25V APPLICATIONS D D D D D Scientific Instruments Automated Test Equipment Data Acquisition Medical Imaging Vibration Analysis VREFP VREFN VMID RBIAS VCAP AVDD DVDD IOVDD PD REFEN RESET CLK CS 2XMODE Reference and Bias Circuits AINP DS Modulator I/O Interface Digital Filter RD DRDY OTR AINN ADS1606 Only FIFO ADS1605 ADS1606 DOUT[15:0] FIFO_LEV[2:0] AGND DGND 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. PowerPAD is a trademark of Texas Instruments. All other trademarks are the property of their respective owners. Copyright  2003−2007, Texas Instruments Incorporated
          
             
 !     !    www.ti.com  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 ORDERING INFORMATION(1) PRODUCT PACKAGE−LEAD PACKAGE DESIGNATOR SPECIFIED TEMPERATURE RANGE PACKAGE MARKING ADS1605 HTQFP−64 PAP −40°C to +85°C ADS1605I ADS1606 HTQFP−64 PAP −40°C to +85°C ADS1606I ORDERING NUMBER TRANSPORT MEDIA, QUANTITY ADS1605IPAPT Tape and Reel, 250 ADS1605IPAPR Tape and Reel, 1000 ADS1606IPAPT Tape and Reel, 250 ADS1606IPAPR Tape and Reel, 1000 (1) For the most current package and ordering information, see the Package Option Addendum at the end of this data sheet, or see the TI web site at www.ti.com. PRODUCT FAMILY ABSOLUTE MAXIMUM RATINGS over operating free-air temperature range unless otherwise noted(1) ADS1605, ADS1606 UNIT AVDD to AGND −0.3 to +6 V DVDD to DGND −0.3 to +3.6 V IOVDD to DGND −0.3 to +6 V −0.3 to +0.3 V AGND to DGND Input Current 100mA, Momentary Input Current 10mA, Continuous Analog I/O to AGND −0.3 to AVDD + 0.3 Digital I/O to DGND −0.3 to IOVDD + 0.3 V +150 °C Operating Temperature Range −40 to +105 °C Storage Temperature Range −60 to +150 °C Maximum Junction Temperature V Lead Temperature (soldering, 10s) +260 °C (1) Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those specified is not implied. 2 PRODUCT RESOLUTION DATA RATE FIFO? ADS1605 16 Bits 5.0MSPS No ADS1606 16 Bits 5.0MSPS Yes ADS1625 18 Bits 1.25MSPS No ADS1626 18 Bits 1.25MSPS Yes 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.  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 ELECTRICAL CHARACTERISTICS All specifications at −40°C to +85°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 40MHz, External VREF = +3V, 2XMODE = low, VCM = 2.0V, FIFO disabled, and RBIAS = 37kΩ, unless otherwise noted. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT Analog Input 0dBFS Differential input voltage (VIN) (AINP − AINN) −2dBFS −6dBFS −20dBFS ±1.467VREF ±1.165VREF V ±0.735VREF ±0.147VREF V 2.0 V Common-mode input voltage (VCM) (AINP + AINN) / 2 Absolute input voltage (AINP or AINN with respect to AGND) V V 0dBFS −0.1 4.7 V −2dBFS input and smaller 0.1 4.2 V Dynamic Specifications Data rate 5.0 fIN = 100kHz, −2dBFS fIN = 100kHz, −6dBFS Total harmonic distortion (THD) Ǔ MSPS dB 84 dB 70 dB 86 dB fIN = 500kHz, −6dBFS fIN = 500kHz, −20dBFS 83 dB 69 dB fIN = 2MHz, −2dBFS fIN = 2MHz, −6dBFS 84 dB 82 dB fIN = 2MHz, −20dBFS fIN = 100kHz, −2dBFS 69 dB −93 dB 62 fIN = 100kHz, −6dBFS fIN = 100kHz, −20dBFS −99 fIN = 500kHz, −2dBFS fIN = 500kHz, −6dBFS −94 dB −97 dB fIN = 500kHz, −20dBFS fIN = 2MHz, −2dBFS −93 dB −98 dB fIN = 2MHz, −6dBFS fIN = 2MHz, −20dBFS −101 dB −92 dB fIN = 100kHz, −2dBFS fIN = 100kHz, −6dBFS 86 dB 84 dB 70 dB 86 dB fIN = 500kHz, −6dBFS fIN = 500kHz, −20dBFS 83 dB 69 dB fIN = 2MHz, −2dBFS fIN = 2MHz, −6dBFS 84 dB 82 dB fIN = 2MHz, −20dBFS 69 dB fIN = 100kHz, −20dBFS fIN = 500kHz, −2dBFS Signal-to-noise and distortion (SINAD) fCLK 40MHz 88 fIN = 100kHz, −20dBFS fIN = 500kHz, −2dBFS Signal-to-noise ratio (SNR) ǒ −94 62 dB −85 dB 3  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 ELECTRICAL CHARACTERISTICS (continued) All specifications at −40°C to +85°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 40MHz, External VREF = +3V, 2XMODE = low, VCM = 2.0V, FIFO disabled, and RBIAS = 37kΩ, unless otherwise noted. PARAMETER TEST CONDITIONS MIN TYP fIN = 100kHz, −2dBFS fIN = 100kHz, −6dBFS Intermodulation distortion (IMD) UNIT dB 101 dB 96 dB 95 dB fIN = 500kHz, −6dBFS fIN = 500kHz, −20dBFS 100 dB 95 dB fIN = 2MHz, −2dBFS fIN = 2MHz, −6dBFS 102 dB 105 dB fIN = 2MHz, −20dBFS 96 dB f1 = 1.99MHz, −6dBFS f2 = 2.00MHz, −6dBFS −94 dB 4 ns fIN = 100kHz, −20dBFS fIN = 500kHz, −2dBFS Spurious free dynamic range (SFDR) MAX 96 85 Aperture delay Digital Filter Characteristics Passband 0 2.2 Passband ripple 2.3 −3.0dB attenuation 2.45 Passband transition Stop band 2.8 Stop band attenuation ǒ fCLK 40MHz fCLK 40MHz fCLK Ǔ Ǔ Ǔ ±0.0025 MHz dB MHz MHz ǒ Ǔ 37.2 f CLK 40MHz Ǔ MHz dB 5.2 To ±0.001% fCLK 40MHz 40MHz 72 Group delay Settling time ǒ ǒ −0.1dB attenuation ǒ ǒ ǒ 9.4 40MHz fCLK Ǔ Ǔ 40MHz fCLK µs µs Static Specifications Resolution No missing codes Bits 1.0 LSB, rms ±0.75 LSB 16 Input-referred noise Integral nonlinearity 16 −1.5dBFS signal Bits Differential nonlinearity ±0.25 LSB Offset error 0.05 %FSR 1 ppmFSR/°C Offset error drift Gain error 0.25 % Gain error drift Excluding reference drift 10 ppm/°C Common-mode rejection At dc 75 dB Power-supply rejection At dc 65 dB 4  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 ELECTRICAL CHARACTERISTICS (continued) All specifications at −40°C to +85°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 40MHz, External VREF = +3V, 2XMODE = low, VCM = 2.0V, FIFO disabled, and RBIAS = 37kΩ, unless otherwise noted. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT Voltage Reference(1) VREF = (VREFP − VREFN) VREFP 2.5 3.0 3.2 V 3.75 4.0 4.25 V VREFN 0.75 1.0 1.25 V VMID 2.3 2.5 2.8 VREF drift Startup time V Internal reference (REFEN = low) 50 ppm/°C Internal reference (REFEN = low) 15 ms Clock Input Frequency (fCLK) 40 Duty Cycle fCLK = 40MHz 50 MHz 55 % 0.7 IOVDD IOVDD V DGND 0.3 IOVDD V 45 Digital Input/Output VIH VIL VOH VOL IOH = 50µA IOL = 50µA Input leakage DGND < VDIGIN < IOVDD IOVDD − 0.5 V DGND +0.5 V ±10 µA Power-Supply Requirements AVDD 4.75 5.25 V DVDD 2.7 3.3 V IOVDD 2.7 AVDD current (IAVDD) 5.25 V REFEN = low 110 135 mA REFEN = high 85 105 mA 45 55 mA 4 6 mA 570 710 mW DVDD current (IDVDD) IOVDD current (IIOVDD) IOVDD = 3V Power dissipation AVDD = 5V, DVDD = 3V, IOVDD = 3V, REFEN = high PD = low, CLK disabled 5 mW Temperature Range Specified −40 +85 °C Operating −40 +105 °C Storage −60 +150 °C Thermal Resistance, θJA θJC PowerPAD soldered to PCB with 2oz. PowerPAD trace and copper pad. 25 °C/W 0.5 °C/W (1) The specification limits for VREF, VREFP, VREFN, and VMID apply when using the internal or an external reference. The internal reference voltages are bounded by the limits shown. When using an external reference, the limits indicate the allowable voltages that can be applied to the reference pins. 5  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 DEFINITIONS Absolute Input Voltage Absolute input voltage, given in volts, is the voltage of each analog input (AINN or AINP) with respect to AGND. Aperture Delay Aperture delay is the delay between the rising edge of CLK and the sampling of the input signal. Common-Mode Input Voltage Common-mode input voltage (VCM) is the average voltage of the analog inputs: (AINP ) AINN) 2 Differential Input Voltage Differential input voltage (VIN) is the voltage difference between the analog inputs: (AINP−AINN). Differential Nonlinearity (DNL) DNL, given in least-significant bits of the output code (LSB), is the maximum deviation of the output code step sizes from the ideal value of 1LSB. Full-Scale Range (FSR) FSR is the difference between the maximum and minimum measurable input signals. FSR = 2 × 1.467VREF. Gain Error Gain error, given in %, is the error of the full-scale input signal with respect to the ideal value. Gain Error Drift Gain error drift, given in ppm/_C, is the drift over temperature of the gain error. The gain error is specified as the larger of the drift from ambient (T = 25_C) to the minimum or maximum operating temperatures. Integral Nonlinearity (INL) INL, given in least-significant bits of the output code (LSB), is the maximum deviation of the output codes from a best fit line. 6 Intermodulation Distortion (IMD) IMD, given in dB, is measured while applying two input signals of the same magnitude, but with slightly different frequencies. It is calculated as the difference between the rms amplitude of the input signal to the rms amplitude of the peak spurious signal. Offset Error Offset Error, given in % of FSR, is the output reading when the differential input is zero. Offset Error Drift Offset error drift, given in ppm of FSR/_C, is the drift over temperature of the offset error. The offset error is specified as the larger of the drift from ambient (T = 25_C) to the minimum or maximum operating temperatures. Signal-to-Noise Ratio (SNR) SNR, given in dB, is the ratio of the rms value of the input signal to the sum of all the frequency components below fCLK/2 (the Nyquist frequency) excluding the first six harmonics of the input signal and the dc component. Signal-to-Noise and Distortion (SINAD) SINAD, given in dB, is the ratio of the rms value of the input signal to the sum of all the frequency components below fCLK/2 (the Nyquist frequency) including the harmonics of the input signal but excluding the dc component. Spurious-Free Dynamic Range (SFDR) SFDR, given in dB, is the difference between the rms amplitude of the input signal to the rms amplitude of the peak spurious signal. Total Harmonic Distortion (THD) THD, given in dB, is the ratio of the sum of the rms value of the first six harmonics of the input signal to the rms value of the input signal.  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 VREFP VREFP VMID VREFN VREFN VCAP AVDD AGND CLK AGND DGND IOVDD DVDD DGND NC NC PIN ASSIGNMENTS 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 AGND 1 AVDD 2 AGND 3 46 FIFO_LEV[0] (ADS1606 Only) AINN 4 45 NC AINP 5 44 DOUT[15] AGND 6 43 DOUT[14] AVDD 7 RBIAS 8 AGND 9 40 DOUT[11] AVDD 10 39 DOUT[10] AGND 11 38 DOUT[9] AVDD 12 37 DOUT[8] REFEN 13 36 DOUT[7] NC 14 35 DOUT[6] 2XMODE 15 34 DOUT[5] TQFP PACKAGE (TOP VIEW) 48 FIFO_LEV[2] (ADS1606 Only) AD S1605 AD S1606 47 FIFO_LEV[1] (ADS1606 Only) 42 DOUT[13] Pow erPA D 41 DOUT[12] TM 23 24 25 26 27 28 29 30 31 32 DGND DVDD NC NC DOUT[0] DOUT[1] DOUT[2] DOUT[3] RESET 22 DRDY DGND 21 OTR 20 RD 19 CS 18 PD 33 DOUT[4] 17 DVDD NC 16 Terminal Functions TERMINAL NAME NO. TYPE AGND 1, 3, 6, 9, 11, 55, 57 Analog Analog ground AVDD 2, 7, 10, 12, 58 Analog Analog supply AINN 4 Analog input Negative analog input AINP 5 Analog input Positive analog input RBIAS 8 Analog REFEN NC 2XMODE PD DESCRIPTION Terminal for external analog bias setting resistor 13 Digital input: active low Internal reference enable. Internal pull-down resistor of 170kΩ to DGND. 14,16, 27, 28, 45, 50 Not connected These terminals are not connected within the ADS1605/6 and must be left unconnected. 15 Digital input Digital filter decimation rate. Internal pull-down resistor of 170kΩ to DGND. 17 Digital input: active low DVDD 18, 26, 52 Digital Digital supply DGND 19, 25, 51, 54 Digital Digital ground RESET 20 Digital input: active low Reset digital filter CS 21 Digital input: active low Chip select RD 22 Digital input: active low Read enable OTR 23 Digital output Analog inputs out of range DRDY 24 Digital output: active low Data ready on falling edge DOUT [15:0] 29−44 Digital output FIFO_LEV[2:0] 46−48 Digital input IOVDD 53 Digital CLK 56 Digital input VCAP VREFN VMID VREFP Power down all circuitry. Internal pull-up resistor of 170kΩ to DGND. Data output. DOUT[15] is the MSB and DOUT[0] is the LSB. FIFO level (for the ADS1606 only). FIFO_LEV[2] is MSB. NOTE: These terminals must be left disconnected on the ADS1605. Digital I/O supply Clock input 59 Analog Terminal for external bypass capacitor connection to internal bias voltage 60, 61 Analog Negative reference voltage 62 Analog Midpoint voltage 63, 64 Analog Positive reference voltage 7  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 PARAMETER MEASUREMENT INFORMATION t2 t1 CLK t2 t3 t4 DRDY t4 t6 t5 DOUT[15:0] Data N + 1 Data N Data N + 2 NOTE: CS and RD tied low. Figure 1. Data Retrieval Timing (ADS1605, ADS1606 with FIFO Disabled) RD, CS t7 t8 DOUT[15:0] Figure 2. DOUT Inactive/Active Timing (ADS1605, ADS1606 with FIFO Disabled) TIMING REQUIREMENTS FOR FIGURE 1 AND FIGURE 2 SYMBOL t1 1/t1 DESCRIPTION CLK period (1/fCLK) fCLK TYP MAX UNIT 20 25 1000 ns 1 40 50 10 MHz t2 CLK pulse width, high or low t3 Rising edge of CLK to DRDY low t4 DRDY pulse width high or low t5 Falling edge of DRDY to data invalid 10 ns t6 Falling edge of DRDY to data valid 15 ns t7 Rising edge of RD and/or CS inactive (high) to DOUT high impedance 15 ns t8 Falling edge of RD and/or CS active (low) to DOUT active. 15 ns NOTE: DOUT[15:0] and DRDY load = 10pF. 8 MIN ns 10 ns 4 t1 ns  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 CLK t11 RESET t9 t12 t 10 DRDY t3 Settled Data DOUT[15:0] NOTE: CS and RD tied low. Figure 3. Reset TIming (ADS1605, ADS1606 with FIFO Disabled) TIMING REQUIREMENTS FOR FIGURE 3 SYMBOL DESCRIPTION t3 Rising edge of CLK to DRDY low t9 RESET pulse width t10 Delay from RESET active (low) to DRDY forced high and DOUT forced low t11 RESET rising edge to falling edge of CLK t12 Delay from DOUT active to valid DOUT (settling to 0.001%) MIN TYP MAX 10 UNIT ns 50 ns 9 −5 ns 10 47 ns DRDY Cycles NOTE: DOUT[15:0] and DRDY load = 10pF. 9  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 t1 t2 CLK t2 t 13 t14 DRDY t15 t16 CS(1) t21 t 17 RD t20 t18 DOUT[15:0] t19 D1 DL(2) D2 (1) CS may be tied low. (2) The number of data readings (DL) is set by the FIFO level. Figure 4. Data Retrieval Timing (ADS1606 with FIFO Enabled) RD, CS t7 t8 DOUT[15:0] Figure 5. DOUT Inactive/Active Timing (ADS1606 with FIFO Enabled) TIMING REQUIREMENTS FOR FIGURE 4 AND FIGURE 5 SYMBOL DESCRIPTION TYP MAX UNIT 25 1000 ns t1 CLK period (1/fCLK) 20 t2 CLK pulse width, high or low 10 t7 Rising edge of RD and/or CS inactive (high) to DOUT high impedance 7 15 ns t8 Falling edge of RD and/or CS active (low) to DOUT active. 7 15 ns t13 Rising edge of CLK to DRDY high t14 DRDY period t15 DRDY positive pulse width t16 RD high hold time after DRDY goes low t17 CS low before RD goes low ns 12 8 × FIFO Level(1) 1 ns CLK Cycles CLK Cycles 0 ns 0 ns RD negative pulse width 10 ns t19 RD positive pulse width 10 ns t20 RD high before DRDY toggles 2 CLK Cycles t21 RD high before CS goes high 0 ns t18 NOTE: DOUT[15:0] and DRDY load = 10pF. (1) See FIFO section for more details. 10 MIN  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 CLK t11 RESET t9 t26 t25 DRDY t23 RD t24 Figure 6. Reset Timing (ADS1606 with FIFO Enabled) TIMING REQUIREMENTS FOR FIGURE 6 SYMBOL DESCRIPTION MIN t9 RESET pulse width 50 t11 RESET rising edge to falling edge of CLK −5 TYP MAX UNIT ns 10 ns t23 RD pulse low after RESET goes high 8 CLK Cycles t24 RD pulse high before first DRDY pulse after RESET goes high 8 CLK Cycles t25 DRDY low after RESET goes low t26 Delay from RESET high to valid DOUT (settling to 0.001%) 8 × (FIFO level + 1) CLK Cycles See Table 4 DRDY Cycles 11  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 TYPICAL CHARACTERISTICS All specifications at TA = 25°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 40MHz, External VREF = +3V, 2XMODE = low, VCM = 2.0V, and RBIAS = 37kΩ, unless otherwise noted. SPECTRAL RESPONSE SPECTRAL RESPONSE 0 0 Amplitude (dB) −40 −60 −80 −100 fIN = 100kHz, −6dBFS SNR = 84dB THD = −99dB SFDR = 101dB −20 −40 Amplitude (dB) fIN = 100kHz, −2dBFS SNR = 88dB THD = −93dB SFDR = 96dB −20 −60 −80 −100 −120 −120 −140 −140 −160 −160 0 0.5 1.0 1.5 2.0 2.5 0 0.5 Frequency (MHz) SPECTRAL RESPONSE 0 Amplitude (dB) −40 −60 −80 −100 −40 2.5 −60 −80 −100 −120 −120 −140 −140 −160 −160 0 0.5 1.0 1.5 2.0 2.5 0 0.5 Frequency (MHz) 2.0 2.5 2.0 2.5 f IN = 2MHz, −6dBFS SNR = 82dB THD = −101dB SFDR = 105dB −20 −40 Amplitude (dB) −40 1.5 SPECTRAL RESPONSE 0 fIN = 2MHz, −2dBFS SNR = 84dB THD = −98dB SFDR = 102dB −20 1.0 Frequency (MHz) SPECTRAL RESPONSE 0 Amplitude (dB) 2.0 fIN = 500kHz, −6dBFS SNR = 83dB THD = −103dB SFDR = 106dB −20 Amplitude (dB) fIN = 500kHz, −2dBFS SNR = 86dB THD = −97dB SFDR = 97dB −20 1.5 SPECTRAL RESPONSE 0 −60 −80 −100 −60 −80 −100 −120 −120 −140 −140 −160 −160 0 0.5 1.0 1.5 Frequency (MHz) 12 1.0 Frequency (MHz) 2.0 2.5 0 0.5 1.0 1.5 Frequency (MHz)  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 TYPICAL CHARACTERISTICS (continued) All specifications at TA = 25°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 40MHz, External VREF = +3V, 2XMODE = low, VCM = 2.0V, and RBIAS = 37kΩ, unless otherwise noted. INTERMODULATION RESPONSE NOISE HISTOGRAM 0 18k VIN = 0V Power Spectral Density (dB) 16k Occurrences 14k 12k 10k 8k 6k 4k 2k −4 −3 −2 −1 0 1 2 3 4 −40 −60 −80 −100 −120 −140 −160 1.95 1.96 1.97 1.98 1.99 2.00 2.01 2.02 2.03 2.04 2.05 0 −5 fIN1 = 1.99MHz fIN2 = 2.00MHz IMD = −94dB −20 5 Output Code (LSB) Frequency (MHz) SIGNAL−TO−NOISE RATIO, TOTAL HARMONIC DISTORTION, AND SPURIOUS−FREE DYNAMIC RANGE vs INPUT SIGNAL AMPLITUDE SIGNAL−TO−NOISE RATIO vs INPUT FREQUENCY 110 90 VIN = −2dBFS 85 90 80 70 60 50 THD 40 VIN = −6dBFS 80 SFDR SNR (dB) SNR, THD, and SFDR (dB) 100 75 VIN = −20dBFS 70 SNR 30 65 fIN = 100kHz 20 10 −70 −60 −50 −40 −30 −20 −10 60 0.001 0 0.01 0.1 1 Input Signal Amplitude, VIN (dB) Input Frequency, fIN (MHz) TOTAL HARMONIC DISTORTION vs INPUT FREQUENCY SPURIOUS−FREE DYNAMIC RANGE vs INPUT FREQUENCY −85 10 110 108 106 VIN = −20dBFS VIN = −6dBFS 104 SFDR (dB) THD (dB) −90 −95 VIN = −2dBFS −100 100 98 96 VIN = −6dBFS −105 102 VIN = −2dBFS VIN = −20dBFS 94 92 −110 0.001 0.01 0.1 Input Frequency, fIN (MHz) 1 10 90 0.001 0.01 0.1 1 10 Input Frequency, fIN (MHz) 13  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 TYPICAL CHARACTERISTICS (continued) All specifications at TA = 25°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 40MHz, External VREF = +3V, 2XMODE = low, VCM = 2.0V, and RBIAS = 37kΩ, unless otherwise noted. SIGNAL−TO−NOISE RATIO vs INPUT COMMON−MODE VOLTAGE TOTAL HARMONIC DISTORTION vs INPUT COMMON−MODE VOLTAGE −65 89 87 −75 VIN = −2dBFS −85 83 THD (dB) SNR (dB) 85 VIN = −6dBFS 81 VIN = −2dBFS −95 VIN = −6dBFS −105 −115 79 −125 77 fIN = 100kHz fIN = 100kHz −135 75 1.5 1.7 1.9 2.1 2.3 2.5 1.5 2.3 SIGNAL−TO−NOISE RATIO vs CLK FREQUENCY 90 VIN = −6dBFS 2.5 RBIAS = 30kΩ 85 80 95 VIN = −2dBFS 75 SNR (dB) 90 85 80 RBIAS = 37kΩ 70 R BIAS = 45kΩ 65 RBIAS = 50kΩ 60 55 75 RBIAS = 60kΩ 50 70 f IN = 100kHz, − 6dBFS 45 fIN = 100kHz 40 65 1.5 1.7 1.9 2.1 2.3 2.5 10 20 Input Common−Mode Voltage, VCM (V) −65 fIN = 100kHz, −6dBFS RBIAS = 30kΩ 100 SFDR (dB) RBIAS = 45kΩ −85 60 105 RBIAS = 50kΩ −80 50 110 RBIAS = 60kΩ −75 40 SPURIOUS−FREE DYNAMIC RANGE vs CLK FREQUENCY fIN = 100kHz, −6dBFS −70 30 CLK Frequency, fCLK (MHz) TOTAL HARMONIC DISTORTION vs CLK FREQUENCY THD (dB) 2.1 SPURIOUS−FREE DYNAMIC RANGE vs INPUT COMMON−MODE VOLTAGE 100 −90 RBIAS = 37kΩ 95 RBIAS = 45kΩ 90 RBIAS = 50kΩ 85 −95 RBIAS = 60kΩ RBIAS = 37kΩ 80 −100 RBIAS = 30kΩ −105 75 10 20 30 40 CLK Frequency, fCLK (MHz) 14 1.9 Input Common−Mode Voltage, VCM (V) 105 SFDR (dB) 1.7 Input Common−Mode Voltage, VCM (V) 50 60 10 20 30 40 CLK Frequency, fCLK (MHz) 50 60  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 TYPICAL CHARACTERISTICS (continued) All specifications at TA = 25°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 40MHz, External VREF = +3V, 2XMODE = low, VCM = 2.0V, and RBIAS = 37kΩ, unless otherwise noted. SIGNAL−TO−NOISE RATIO vs TEMPERATURE TOTAL HARMONIC DISTORTION vs TEMPERATURE −85 100 VIN = −2dBFS 90 −90 VIN = −6dBFS 80 THD (dB) SNR (dB) VIN = −20dBFS 70 −95 VIN = −2dBFS −100 VIN = −6dBFS VIN = −20dBFS −105 60 fIN = 100kHz 50 −40 fIN = 100kHz −15 10 35 60 85 −110 −40 −15 10 SPURIOUS−FREE DYNAMIC RANGE vs TEMPERATURE POWER−SUPPLY CURRENT vs TEMPERATURE 85 130 I AVDD (REFEN = low) 120 105 110 Current (mA) VIN = −6dBFS SFDR (dB) 60 Temperature (_C) 110 100 VIN = −20dBFS 95 100 IAVDD (REFEN = high) 90 80 70 60 VIN = −2dBFS 90 IDVDD + IIOVDD 50 40 fIN = 100kHz 85 −40 −15 10 35 60 30 −40 85 DVDD = IOVDD = 3V RBIAS = 37kΩ, fCLK = 40MHz −15 10 Temperature (_ C) 35 60 85 Temperature (_ C) ANALOG SUPPLY CURRENT vs RBIAS SUPPLY CURRENT vs CLK FREQUENCY 140 100 130 Analog Current, IAVDD (mA) IAVDD (RBIAS = 37kΩ) 80 Supply Current (mA) 35 Temperature (_C) IAVDD (RBIAS = 60kΩ) 60 40 IDVDD + IIOVDD 20 AVDD = 5V, DVDD = IOVDD = 3V, REFEN = High 120 110 100 REFEN = low 90 80 70 REFEN = high 60 50 0 10 20 30 CLK Frequency, fCLK (MHz) 40 50 30 35 40 45 50 55 60 RBIAS (kΩ) 15  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 TYPICAL CHARACTERISTICS (continued) All specifications at TA = 25°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 40MHz, External VREF = +3V, 2XMODE = low, VCM = 2.0V, and RBIAS = 37kΩ, unless otherwise noted. INTEGRAL NONLINEARITY 1.0 f IN = 100Hz, −1.5dBFS 0.4 0.6 0.3 0.4 0.2 DNL (LSB) INL (LSB) 0.8 DIFFERENTIAL NONLINEARITY 0.5 0.2 0 −0.2 0.1 0 −0.1 −0.4 −0.2 −0.6 −0.3 −0.8 −0.4 −0.5 −1.0 −25k −20k −15k −10k −5k 0 5k Output Code (LSB) 16 f IN = 100Hz, −1.5dBFS 10k 15k 20k 25k −25k −20k −15k −10k −5k 0 5k Output Code (LSB) 10k 15k 20k 25k  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 OVERVIEW The ADS1605 and ADS1606 are high-performance deltasigma ADCs with a default oversampling ratio of 8. The modulator uses an inherently stable 2-1-1 pipelined deltasigma modulator architecture incorporating proprietary circuitry that allows for very linear high-speed operation. The modulator samples the input signal at 40MSPS (when fCLK = 40MHz). A low-ripple linear phase digital filter decimates the modulator output to provide data output word rates of 5MSPS with a signal passband out to 2.45MHz. The 2X mode, enabled by a digital I/O pin, doubles the data rate to 10MSPS by reducing the oversampling ratio to 4. See the 2X Mode section for more details. Conceptually, the modulator and digital filter measure the differential input signal, VIN = (AINP – AINN), against the scaled differential reference, VREF = (VREFP – VREFN), as shown in Figure 7. The voltage reference can either be generated internally or supplied externally. An 16-bit parallel data bus, designed for direct connection to DSPs, outputs the data. A separate power supply for the I/O allows flexibility for interfacing to different logic families. Out-ofrange conditions are indicated with a dedicated digital output pin. Analog power dissipation is controlled using an external resistor. This allows reduced dissipation when operating at slower speeds. When not in use, power consumption can be dramatically reduced using the PD pin. The ADS1606 incorporates an adjustable FIFO buffer for the output data. The level of the FIFO is set by the FIFO_LEV[2:0] pins. Other than the FIFO buffer, the ADS1605 and ADS1606 are identical, and are referred to together in this data sheet as the ADS1605/6. ANALOG INPUTS (AINP, AINN) The ADS1605/6 measures the differential signal, VIN = (AINP − AINN), against the differential reference, VREF = (VREFP – VREFN). The reference is scaled internally so that the full-scale differential input voltage is 1.467VREF. That is, the most positive measurable differential input is 1.467VREF, which produces the most posiVREFP VREFN tive digital output code of 7FFFh. Likewise, the most negative measurable differential input is –1.467VREF, which produces the most negative digital output code of 8000h. The ADS1605/6 supports a very wide range of input signals. For VREF = 3V, the full-scale input voltages are ±4.4V. Having such a wide input range makes out-ofrange signals unlikely. However, should an out-of-range signal occur, the digital output OTR will go high. To achieve the highest analog performance, it is recommended that the inputs be limited to ±1.165VREF (−2dBFS). For VREF = 3V, the corresponding recommended input range is ±3.78V. The analog inputs must be driven with a differential signal to achieve optimum performance. The recommended common-mode voltage of the input signal, V CM + AINP ) AINN, is 2.0V. For signals larger than 2 −2dBFS, the input common-mode voltage needs to be raised in order to meet the absolute input voltage specifications. The Typical Characteristics show how performance varies with input common-mode voltage. In addition to the differential and common-mode input voltages, the absolute input voltage is also important. This is the voltage on either input (AINP or AINN) with respect to AGND. The range for this voltage is: * 0.1V t (AINN or AINP) t 4.6V If either input is taken below –0.1V, ESD protection diodes on the inputs will turn on. Exceeding 4.6V on either input will result in degradation in the linearity performance. ESD protection diodes will also turn on if the inputs are taken above AVDD (+5V). For signals below –2dBFS, the recommended absolute input voltage is: * 0.1V t (AINN or AINP) t 4.2V Keeping the inputs within this range provides for optimum performance. IOVDD Σ VREF 1.467 OTR 1.467VREF AINP AINN Σ VIN Σ∆ Modulator Digital Filter Parallel Interface ADS1606 Only FIFO DOUT[15:0] FIFO_LEV[2:0] 2XMODE Figure 7. Conceptual Block Diagram 17  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 INPUT CIRCUITRY The ADS1605/6 uses switched-capacitor circuitry to measure the input voltage. Internal capacitors are charged by the inputs and then discharged internally with this cycle repeating at the frequency of CLK. Figure 8 shows a conceptual diagram of these circuits. Switches S2 represent the net effect of the modulator circuitry in discharging the sampling capacitors; the actual implementation is different. The timing for switches S1 and S2 is shown in Figure 9. S1 ADS1605 ADS1606 AINP AGND, improve linearity and should be placed as close to the pins as possible. Place the drivers close to the inputs and use good capacitor bypass techniques on their supplies; usually a smaller high-quality ceramic capacitor in parallel with a larger capacitor. Keep the resistances used in the driver circuits low—thermal noise in the driver circuits degrades the overall noise performance. When the signal can be ac-coupled to the ADS1605/6 inputs, a simple RC filter can set the input common mode voltage. The ADS1605/6 is a high-speed, highperformance ADC. Special care must be taken when selecting the test equipment and setup used with this device. Pay particular attention to the signal sources to ensure they do not limit performance when measuring the ADS1605/6. S2 10pF 8pF 392 Ω VMID − S1 AINN V IN 392Ω 40pF 392 Ω O P A 2 8 22 2 0.01 µ F S2 10pF 8pF V CM(1) AINP (2) 100pF 392 Ω VMID 49.9Ω 1µ F AGND 1kΩ (2) 392Ω 100pF (3) V CM(1) Figure 8. Conceptual Diagram of Internal Circuitry Connected to the Analog Inputs V IN 392 Ω 40pF 392Ω O P A 2 8 22 A D S 1 6 06 (2) 1kΩ 2 0.01 µ F 49.9Ω AINN (2) V CM(1) t SAMPLE = 1/f CLK A D S 1 6 05 100pF 392Ω 1µ F AGND On S1 Off On S2 Off (1) Recommended VCM = 2.0V. (2) Optional ac−coupling circuit provides common−mode input voltage. (3) Increase to 390pF when fIN ≤ 100kHz for improved SNR and THD. Figure 10. Recommended Driver Circuit Using the OPA2822 Figure 9. Timing for the Switches in Figure 2 22pF 24.9Ω DRIVING THE INPUTS The external circuits driving the ADS1605/6 inputs must be able to handle the load presented by the switching capacitors within the ADS1605/6. The input switches S1 in Figure 8 are closed approximately one half of the sampling period, tsample, allowing only ≈12ns for the internal capacitors to be charged by the inputs, when fCLK = 40MHz. Figure 10 and Figure 11 show the recommended circuits when using single-ended or differential op amps, respectively. The analog inputs must be driven differentially to achieve optimum performance. The external capacitors, between the inputs and from each input to 18 AINP 392Ω 392Ω 100pF −VIN VCM ADS1605 THS4503 100pF +VIN 392Ω 392Ω ADS1606 24.9Ω AINN 100pF 22pF Figure 11. Recommended Driver Circuits Using the THS4503 Differential Amplifier  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 REFERENCE INPUTS (VREFN, VREFP, VMID) The ADS1605/6 can operate from an internal or external voltage reference. In either case, the reference voltage VREF is set by the differential voltage between VREFN and VREFP: VREF = (VREFP – VREFN). VREFP and VREFN each use two pins, which should be shorted together. VMID equals approximately 2.5V and is used by the modulator. VCAP connects to an internal node and must also be bypassed with an external capacitor. For the best analog performance, it is recommended that an external reference voltage (VREF) of 3.0V be used. INTERNAL REFERENCE (REFEN = LOW) To use the internal reference, set the REFEN pin low. This activates the internal circuitry that generates the reference voltages. The internal reference voltages are applied to the pins. Good bypassing of the reference pins is critical to achieve optimum performance and is done by placing the bypass capacitors as close to the pins as possible. Figure 12 shows the recommended bypass capacitor values. Use high quality ceramic capacitors for the smaller values. Avoid loading the internal reference with external circuitry. If the ADS1605/6 internal reference is to be used by other circuitry, buffer the reference voltages to prevent directly loading the reference pins. ADS1605 ADS1606 10µF 0.1µF VREFP VREFP in the Electrical Characteristics table. Typically VREFP = 4V, VMID = 2.5V and VREFN = 1V. The external circuitry must be capable of providing both a dc and a transient current. Figure 13 shows a simplified diagram of the internal circuitry of the reference when the internal reference is disabled. As with the input circuitry, switches S1 and S2 open and close as shown in Figure 9. ADS1605 ADS1606 S1 VREFP VREFP S2 300Ω VREFN VREFN 50pF S1 Figure 13. Conceptual Internal Circuitry for the Reference When REFEN = High Figure 14 shows the recommended circuitry for driving these reference inputs. Keep the resistances used in the buffer circuits low to prevent excessive thermal noise from degrading performance. Layout of these circuits is critical, make sure to follow good high-speed layout practices. Place the buffers and especially the bypass capacitors as close to the pins as possible. VCAP is unaffected by the setting on REFEN and must be bypassed when using the internal or an external reference. 392Ω 0.001µF 22µF 22µF ADS1605 ADS1606 VMID 0.1µF 10µF 0.1µF VREFP VREFP OPA2822 10µF 4V 0.1µF 392Ω 22µF 0.1µF VREFN VREFN 10µF 0.001µF 22µF 22µF 0.1µF VMID OPA2822 VCAP 10µF 2.5V 0.1µF 0.1µF 392Ω 0.001µF AGND Figure 12. Reference Bypassing When Using the Internal Reference EXTERNAL REFERENCE (REFEN = HIGH) To use an external reference, set the REFEN pin high. This deactivates the internal generators for VREFP, VREFN and VMID, and saves approximately 25mA of current on the analog supply (AVDD). The voltages applied to these pins must be within the values specified 22µF VREFN VREFN OPA2822 1V 10µF 0.1µF VCAP 0.1µF AGND Figure 14. Recommended Buffer Circuit When Using an External Reference 19  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 CLOCK INPUT (CLK) The ADS1605/6 requires an external clock signal to be applied to the CLK input pin. The sampling of the modulator is controlled by this clock signal. As with any highspeed data converter, a high quality clock is essential for optimum performance. Crystal clock oscillators are the recommended CLK source; other sources such as frequency synthesizers are usually not adequate. Make sure to avoid excess ringing on the CLK input; keeping the trace as short as possible will help. Measuring high frequency, large amplitude signals requires tight control of clock jitter. The uncertainty during sampling of the input from clock jitter limits the maximum achievable SNR. This effect becomes more pronounced with higher frequency and larger magnitude inputs. Fortunately, the ADS1605/6 oversampling topology reduces clock jitter sensitivity over that of Nyquist rate converters like pipeline and successive approximation converters by a factor of Ǹ8. In order to not limit the ADS1605/6 SNR performance, keep the jitter on the clock source below the values shown in Table 1. When measuring lower frequency and lower amplitude inputs, more CLK jitter can be tolerated. In determining the allowable clock source jitter, select the worst-case input (highest frequency, largest amplitude) that will be seen in the application. Table 1. Maximum Allowable Clock Source Jitter for Different Input Signal Frequencies and Amplitude MAXIMUM AMPLITUDE MAXIMUM ALLOWABLE CLOCK SOURCE JITTER 2MHz −2dB 1.9ps 2MHz −20dB 14ps 1MHz −2dB 3.8ps 1MHz −20dB 28ps 500kHz −2dB 7.6ps 500kHz −20dB 57ps 100kHz −2dB 38ps 100kHz −20dB 285ps INPUT SIGNAL MAXIMUM FREQUENCY Likewise, when the input is negative out-of-range by going below the negative full-scale value of –1.467VREF, the output clips to 8000h and the OTR output goes high. The OTR remains high while the input signal is out-ofrange. Table 2. Output Code Versus Input Signal INPUT SIGNAL (INP – INN) IDEAL OUTPUT CODE(1) OTR ≥+1.467VREF (> 0dB) 7FFFH 1 1.467VREF (0dB) 7FFFH 0 +1.467V REF 0001H 0 2 15 * 1 0 0000H 0 −1.467V REF FFFFH 0 8000H 0 8000H 1 2 15 *1 ǒ2 2 * 1 Ǔ 15 −1.467V REF 15 ǒ2 2 * 1 Ǔ v −1.467V REF 15 15 (1) Excludes effects of noise, INL, offset and gain errors. OUT-OF-RANGE INDICATION (OTR) If the output code on DOUT[15:0] exceeds the positive or negative full-scale, the out-of-range digital output OTR will go high on the falling edge of DRDY. When the output code returns within the full-scale range, OTR returns low on the falling edge of DRDY. DATA RETRIEVAL Data retrieval is controlled through a simple parallel interface. The falling edge of the DRDY output indicates new data are available. To activate the output bus, both CS and RD must be low, as shown in Table 3. Make sure the DOUT bus does not drive heavy loads (> 20pF), as this will degrade performance. Use an external buffer when driving an edge connector or cables. Table 3. Truth Table for CS and RD CS RD 0 0 Active 0 1 High impedance DATA FORMAT 1 0 High impedance The 16-bit output data are in binary two’s complement format as shown in Table 2. When the input is positive out-of-range, exceeding the positive full-scale value of 1.467VREF, the output clips to all 7FFFh and the OTR output goes high. 1 1 High impedance 20 DOUT[15:0]  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 RESETTING THE ADS1605 RESETTING THE ADS1606 The ADS1605 and ADS1606 (with FIFO disabled) are asynchronously reset when the RESET pin is taken low. During reset, all of the digital circuits are cleared, DOUT[15:0] are forced low, and DRDY forced high. It is recommended that the RESET pin be released on the falling edge of CLK. Afterwards, DRDY goes low on the second rising edge of CLK. Allow 47 DRDY cycles for the digital filter to settle before retrieving data. See Figure 3 for the timing specifications. The ADS1606 with the FIFO enabled requires a different reset sequence than the ADS1605, as shown in Figure 16. Ignore any DRDY toggles that occur while RESET is low. Release RESET on the rising edge of CLK, then afterwards toggle RD to complete the reset sequence. Reset can be used to synchronize multiple ADS1605s. All devices to be synchronized must use a common CLK input. With the CLK inputs running, pulse RESET on the falling edge of CLK, as shown in Figure 15. Afterwards, the converters will be converting synchronously with the DRDY outputs updating simultaneously. After synchronization, allow 47 DRDY cycles (t12) for output data to fully settle. CLK RESET Ignore t26 DRDY RD Toggle RD to complete reset sequence ADS16051 RESET Clock RESET CLK DRDY DOUT[15:0] DRDY1 DOUT[15:0]1 ADS16052 RESET CLK DRDY DOUT[15:0] DRDY2 DOUT[15:0]2 Figure 16. Resetting the ADS1606 with the FIFO Enabled After resetting, the settling time for the ADS1606 is 47 CLK cycles, regardless of the FIFO level. Therefore, for higher FIFO levels, it takes fewer DRDY cycles to settle because the DRDY period is longer. Table 4 shows the number of DRDY cycles required to settle for each FIFO level. CLK Table 4. ADS1606 Reset Settling RESET t12 DRDY1 Settled Data DOUT[15:0]1 DRDY2 FIFO LEVEL FILTER SETTLING TIME AFTER RESET (t26 in units of DRDY cycles ) 2 24 4 12 6 8 8 6 10 5 12 4 14 4 Settled Data DOUT[15:0]2 Synchronized Figure 15. Synchronizing Multiple Converters 21  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 SETTLING TIME IMPULSE RESPONSE The settling time is an important consideration when measuring signals with large steps or when using a multiplexer in front of the analog inputs. The ADS1605/6 digital filter requires time for an instantaneous change in signal level to propagate to the output. Figure 18 plots the normalized response for an input applied at t = 0 with 2XMODE = low. The X-axis units of time are DRDY cycles (for the ADS1605 or the ADS1606 with FIFO disabled). As shown in Figure 18, the peak of the impulse takes 26 DRDY cycles to propagate to the output. For fCLK = 40MHz, a DRDY cycle is 0.2µs in duration and the propagation time (or group delay) is 26 × 0.2µs = 5.2µs. Figure 17 shows the settling error as a function of time for a full-scale signal step applied at t = 0 with 2XMODE = low. This figure uses DRDY cycles (for the ADS1605 or the ADS1606 with FIFO disabled) for the time scale (X-axis). After 47 DRDY cycles, the settling error drops below 0.001%. For fCLK = 40MHz, this corresponds to a settling time of 9.4µs. 101 Settling Error (%) 0.8 0.6 0.4 0.2 0 −0.2 −0.4 100 0 5 10 15 20 25 30 35 40 Time (DRDY cycles) 10−1 10−2 Figure 18. Impulse Response 10−3 10−4 25 30 35 40 Settling Time (DRDY cycles) Figure 17. Settling Time 22 1.0 Normalized Responce Be sure to allow the filter time to settle after applying a large step in the input signal, switching the channel on a multiplexer placed in front of the inputs, resetting the ADS1605/6, or exiting the power-down mode, 45 50 45 50  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 FREQUENCY RESPONSE 0.0025 0.0015 0.0010 0.0005 0 −0.0005 −0.0010 −0.0015 −0.0020 Figure 20 shows the passband ripple from dc to 2.2MHz (fCLK = 40MHz). Figure 21 shows a closer view of the passband transition by plotting the response from 2.0MHz to 2.5MHz (fCLK = 40MHz). 0 0.5 1.0 1.5 2.0 2.5 Frequency (MHz) Figure 20. Passband Ripple 1 0 −1 Magnitude (dB) The overall frequency response repeats at multiples of the CLK frequency. To help illustrate this, Figure 22 shows the response out to 120MHz (fCLK = 40MHz). Notice how the passband response repeats at 40MHz, 80MHz and 120MHz; it is important to consider this when there is high-frequency noise present with the signal. The modulator bandwidth extends to 100MHz. High-frequency noise around 40MHz and 80MHz will not be attenuated by either the modulator or the digital filter. This noise will alias back in-band and reduce the overall SNR performance unless it is filtered out prior to the ADS1605/6. To prevent this, place an anti-alias filter in front of the ADS1605/6 that rolls off before 37MHz. fC LK = 40MHz 0.0020 Magnitude (dB) The linear phase FIR digital filter sets the overall frequency response. The decimation rate is set to 8 (2XMODE = low) for all the figures shown in this section. Figure 19 shows the frequency response from dc to 20MHz for fCLK = 40MHz. The frequency response of the ADS1605/6 filter scales directly with CLK frequency. For example, if the CLK frequency is decreased by half (to 20MHz), the values on the X-axis in Figure 19 would need to be scaled by half, with the span becoming dc to 10MHz. −2 −3 −4 −5 fCL K = 40MHz −6 20 −7 fCL K = 40MHz 2.0 2.05 0 2.1 2.15 2.2 2.25 2.3 2.35 2.4 2.45 2.5 Magnitude (dB) Frequency (MHz) −20 Figure 21. Passband Transition −40 −60 −80 20 −100 fCL K = 40MHz 0 0 2 4 6 8 10 12 14 16 Frequency (MHz) Figure 19. Frequency Response 18 20 Magnitude (dB) −120 −20 −40 −60 −80 −100 0 20 40 60 80 100 120 Frequency (MHz) Figure 22. Frequency Response Out to 120MHz 23  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 FIFO (ADS1606 ONLY) The ADS1606 includes an adjustable level first-in firstout buffer (FIFO) for the output data. The FIFO allows data to be temporarily stored within the ADS1606 to provide more flexibility for the host controller when retrieving data. Pins FIFO_LEV[2:0] set the level or depth of the FIFO. Note that these pins must be left unconnected on the ADS1605. The FIFO is enabled by setting at least one of the FIFO_LEV inputs high. Table 5 shows the corresponding FIFO level and DRDY period for the different combinations of FIFO_LEV[2:0] settings. For the best performance when using the FIFO, it is recommended to: 1. Set IOVDD = 3V. 2. Synchronize data retrieval with CLK. 3. Minimize loading on outputs DOUT[15:0]. 4. Ensure rise and fall times on CLK and RD are 1ns or longer. Table 5. FIFO Buffer Level Settings for the ADS1606 FIFO_LEV[2:0] FIFO BUFFER LEVEL DRDY PERIOD 000 0: disabled, operates like ADS1605 8/fCLK 001 2 010 4 16/fCLK 32/fCLK 011 6 48/fCLK 64/fCLK 100 8 101 10 110 12 80/fCLK 96/fCLK 111 14 112/fCLK FIFO Operation The ADS1606 FIFO collects the number of output readings set by the level corresponding to the FIFO_LEV[2:0] setting. When the specified level is reached, DRDY is pulsed high, indicating the data in the FIFO are ready to be read. The DRDY period is a function of the FIFO level, as shown in Table 5. To read the data, make sure CS is low (it is acceptable to tie it low) and then take RD low. The first, or oldest, data will be presented on the data output pins. After reading this data, advance to the next data reading by toggling RD. On the next falling edge of RD, the second data are present on the data output pins. Continue this way until all the data have been read from the FIFO, making sure to take RD high when complete. Afterwards, wait until DRDY toggles and repeat the readback cycle. Figure 23 shows an example readback when FIFO_LEV[2:0] = 010 (level = 4). Readback considerations The exact number of data readings set by the FIFO level must be read back each time DRDY toggles. The one exception is that readback can be skipped entirely. In this case, the DRDY period increases to 128 CLK period. Figure 24 shows an example when readback is skipped with the FIFO level = 4. Do not read back more or less readings from the FIFO than set by the level. This interrupts the FIFO operation and can cause DRDY to stay low indefinitely. If this occurs, the RESET pin must be toggled followed by a RD pulse. This resets the ADS1606 FIFO and also the digital filter, which then must settle afterwards before valid data is ready. See the section, Resetting the ADS1606, for more details. Also note that the RD signal is independent of the CS signal. Therefore, when multiple devices are used, the RD signal should not be shared. Alternatively, individual RD signals can be generated by performing an OR operation with the CS signal. Setting the FIFO Level The FIFO level setting is usually a static selection that is set when power is first applied to the ADS1606. If the FIFO level needs to be changed after powerup, there are two options. One is to asynchronously set the new value on pin FIFO_LEV[2:0] then toggle RESET. Remember that the ADS1606 will need to settle after resetting. See the section, Resetting the ADS1606, for more details. The other option avoids requiring a reset, but needs synchronization of the FIFO level change with the readback. The FIFO_LEV[2:0] pins have to be changed after RD goes high after reading the first data, but before RD goes low to read the last data from the FIFO. The new FIFO level becomes active immediately and the DRDY period adjusts accordingly. When decreasing the FIFO level this way, make sure to give adequate time for readback of the data before setting the new, smaller level. Figure 25 shows an example of a synchronized FIFO level change from 4 to 8. DRDY CS(1) RD DOUT[15:0] Data1(2) Data2 Data3 Data4 (1) CS can be tied low. (2) Data1 is the oldest data and Data4 is the most recent. Figure 23. Example of FIFO Readback when FIFO Level = 4 24  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 32/fCLK 128/fCLK DRDY RD Figure 24. Example of Skipping Readback when FIFO Level = 4 32/fCLK 64/fCLK DRDY RD FIFO_LEV[2:0] 010 (Level = 4) 100 (Level = 8) Change FIFO_LEV[2:0] here Figure 25. Example of Synchronized Change of FIFO Level from 4 to 8 ANALOG POWER DISSIPATION An external resistor connected between the RBIAS pin and the analog ground sets the analog current level, as shown in Figure 26. The current is inversely proportional to the resistor value. Table 6 shows the recommended values of RBIAS for different CLK frequencies. Notice that the analog current can be reduced when using a slower frequency CLK input because the modulator has more time to settle. Avoid adding any capacitance in parallel to RBIAS , since this will interfere with the internal circuitry used to set the biasing. Table 6. Recommended RBIAS Resistor Values for Different CLK Frequencies fCLK DATA RATE RBIAS TYPICAL POWER DISSIPATION WITH REFEN HIGH 16MHz 2MHz 60kΩ 315mW 24MHz 3MHz 50kΩ 400mW 32MHz 4MHz 45kΩ 475mW 40MHz 5MHz 37kΩ 570mW POWER DOWN (PD) ADS1605 ADS1606 RBIAS RBIAS AGND Figure 26. External Resistor Used to Set Analog Power Dissipation When not in use, the ADS1605/6 can be powered down by taking the PD pin low. All circuitry will be shutdown, including the voltage reference. To minimize the digital current during power down, stop the clock signal supplied to the CLK input. There is an internal pull-up resistor of 170kΩ on the PD pin, but it is recommended that this pin be connected to IOVDD if not used. If using the ADS1606 with the FIFO enabled, issue a reset after exiting power-down mode. Make sure to allow time for the reference to start up after exiting power-down mode. The internal reference typically requires 15ms. After the reference has stabilized, allow at least 100 DRDY cycles for the modulator and digital filter to settle before retrieving data. 25  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 POWER SUPPLIES main supply bus should also be bypassed with a bank of capacitors from 47µF to 0.1µF, as shown. Three supplies are used on the ADS1605/6: analog (AVDD), digital (DVDD) and digital I/O (IOVDD). Each supply must be suitably bypassed to achieve the best performance. It is recommended that a 1µF and 0.1µF ceramic capacitor be placed as close to each supply pin as possible. Connect each supply-pin bypass capacitor to the associated ground, as shown in Figure 27. Each The IO and digital supplies (IOVDD and DVDD) can be connected together when using the same voltage. In this case, only one bank of 47µF to 0.1µF capacitors is needed on the main supply bus, though each supply pin must still be bypassed with a 1µF and 0.1µF ceramic capacitor. DVDD 47µF 4.7µF 1µF 0.1µF 47µF 4.7µF 1µF 0.1µF IOVDD CP AVDD CP AVDD 54 53 52 51 DGND 2 55 DVDD AGND 57 DGND 1 58 IOVDD 0.1µF AGND 1µF AGND 4.7µF AVDD 47µF CP CP If using separate analog and digital ground planes, connect together on the ADS1605/6 PCB. 3 6 AGND 7 AVDD 9 AGND CP DGND AGND NOTE: CP = 1µF  0.1µF ADS1605 ADS1606 CP 10 AVDD 11 AGND 19 25 CP Figure 27. Recommended Power-Supply Bypassing 26 DVDD DGND 18 DGND 12 AVDD DVDD CP 26 CP  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 2X MODE The 2XMODE digital input determines the performance (16-bit or 14-bit) by setting the oversampling ratio. When 2XMODE = low, the oversampling ratio = 8 for 16-bit performance. When 2XMODE = high, the oversampling ratio = 4 for 14-bit performance. Note that when 2XMODE is high, all 16 bits of DOUT remain active. Decreasing the oversampling ratio from 8 to 4 doubles the data rate in 2X mode. For fCLK = 40MHz, the data rate then becomes 10MSPS. In addition, the group delay decreases to 0.9µs and the settling time becomes 1.3µs or 13 DRDY cycles. With the reduced oversampling in 2X mode, the noise increases. Typical SNR performance degrades by 14dB. THD remains approximately the same. There is an internal pull-down resistor of 170kΩ on the 2XMODE; however, it is recommended this pin be forced either high or low. For more information on the performance of the 2X mode, see application note Operating the ADS1605 and ADS1606 in 2X Mode: 10MSPS (SLAA180), available for download at www.ti.com. LAYOUT ISSUES The ADS1605/6 is a very high-speed, high-resolution data converter. In order to achieve the maximum performance, careful attention must be given to the printed circuit board (PCB) layout. Use good high-speed techniques for all circuitry. Critical capacitors should be placed close to pins as possible. These include capacitors directly connected to the analog and reference inputs and the power supplies. Make sure to also properly bypass all circuitry driving the inputs and references. Two approaches can be used for the ground planes: either a single common plane; or two separate planes, one for the analog grounds and one for the digital grounds. When using only one common plane, isolate the flow of current on pin 57 from pin 1; use breaks on the ground plane to accomplish this. Pin 57 carries the switching current from the analog clocking for the modulator and can corrupt the quiet analog ground on pin 1. When using two planes, it is recommended that they be tied together right at the PCB. Do not try to connect the ground planes together after running separately through edge connectors or cables as this reduces performance and increases the likelihood of latchup. In general, keep the resistances used in the driving circuits for the inputs and reference low to prevent excess thermal noise from degrading overall performance. Avoid having the ADS1605/6 digital outputs drive heavy loads. Buffers on the outputs are recommended unless the ADS1605/6 is connected directly to a DSP or controller situated nearby. Additionally, make sure the digital inputs are driven with clean signals as ringing on the inputs can introduce noise. The ADS1605/6 uses TI PowerPAD technology. The PowerPAD is physically connected to the substrate of the silicon inside the package and must be soldered to the analog ground plane on the PCB using the exposed metal pad underneath the package for proper heat dissipation. Please refer to application report SLMA002, located at www.ti.com, for more details on the PowerPAD package. 27  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 APPLICATIONS INFORMATION INTERFACING THE ADS1605 TO THE TMS320C6000 Figure 28 illustrates how to directly connect the ADS1605 to the TMS320C6000 DSP. The processor controls reading using output ARE. The ADS1605 is selected using the DSP control output, CE2. The ADS1605 16-bit data output bus is directly connected to the TMS320C6000 data bus. The data ready output from the ADS1605, DRDY, drives interrupt EXT_INT7 on the TMS320C6000. INTERFACING THE ADS1606 TO THE TMS320C6000 Figure 29 illustrates how to directly connect the ADS1606 to the TMS320C6000 DSP. The processor controls reading using output ARE. The ADS1606 is permanently selected by grounding the CS pin. The ADS1606 16-bit data output bus is directly connected to the TMS320C6000 data bus. The data ready output from the ADS1606, DRDY, drives interrupt EXT_INT7 on the TMS320C6000. ADS1606 ADS1605 16 DOUT[15:0] TMS320C6000 16 DOUT[15:0] XD[15:0] DRDY DRDY TMS320C6000 XD[15:0] EXT_INT7 EXT_INT7 CS CS CE2 RD RD ARE Figure 28. ADS1605—TMS320C6000 Interface Connection 28 ARE Figure 29. ADS1606—TMS320C6000 Interface Connection  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 INTERFACING THE ADS1605 TO THE TMS320C5400 INTERFACING THE ADS1606 TO THE TMS320C5400 Figure 30 illustrates how to connect the ADS1605 to the TMS320C5400 DSP. The processor controls the reading using the outputs R/W and IS. The I/O space select signal (IS) is optional and is used to prevent the ADS1605 RD input from being strobed when the DSP is accessing other external memory spaces (address or data). This can help reduce the possibility of digital noise coupling into the ADS1605. When not using this signal, replace NAND gate U1 with an inverter between R/W and RD. Two signals, IOSTRB and A15, combine using NAND gate U2 to select the ADS1605. If there are no additional devices connected to the TMS320C5400 I/O space, U2 can be eliminated. Simply connect IOSTRB directly to CS. The ADS1605 16-bit data output bus is directly connected to the TMS320C5400 data bus. The data ready output from the ADS1605, DRDY, drives interrupt INT3 on the TMS320C5400. Figure 31 illustrates how to directly connect the ADS1606 to the TMS320C5400 DSP. The processor controls reading using outputs R/W and IS. The ADS1606 is permanently selected by grounding the CS pin. If there are any additional devices connected to theTMS320C5400 I/O space, address decode logic will be required between the ADC and the DSP to prevent data bus contention and ensure only one device at a time is selected. The ADS1606 16-bit data output bus is directly connected to the TMS320C5400 data bus. The data ready output from the ADS1606, DRDY, drives interrupt INT3 on the TMS320C5400. ADS1606 16 DOUT[15:0] D[15:0] DRDY ADS1605 16 DOUT[15:0] INT3 CS U2 RD U1 INT3 TMS320C5400 D[15:0] DRDY TMS320C5400 CS RD U1 R/W IS IOSTRB A15 R/W IS Figure 30. ADS1605—TMS320C5400 Interface Connection Figure 31. ADS1606—TMS320C5400 Interface Connection Code Composer Studio, available from TI, provides support for interfacing TI DSPs through a collection of data converter plugins. Check the TI website, located at www.ti.com/sc/dcplug−in, for the latest information on ADS1605/6 support. 29  "#$%& "#$%$ www.ti.com SBAS274H − MARCH 2003 − REVISED MAY 2007 Revision History DATE REV PAGE SECTION 5/15/07 H 24 Readback Considerations DESCRIPTION Added last three sentences. NOTE: Page numbers for previous revisions may differ from page numbers in the current version. 30 PACKAGE OPTION ADDENDUM www.ti.com 14-Oct-2022 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) Samples (4/5) (6) ADS1605IPAPR ACTIVE HTQFP PAP 64 1000 RoHS & Green NIPDAU Level-3-260C-168 HR -40 to 85 ADS1605I Samples ADS1605IPAPT ACTIVE HTQFP PAP 64 250 RoHS & Green NIPDAU Level-3-260C-168 HR -40 to 85 ADS1605I Samples ADS1606IPAPT ACTIVE HTQFP PAP 64 250 RoHS & Green NIPDAU Level-3-260C-168 HR -40 to 85 ADS1606I Samples (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) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of