LTC2381-16 16-Bit, 250ksps, Low Power SAR ADC with Serial Interface FEATURES DESCRIPTION n The LTC(R)2381-16 is a low noise, low power, high speed 16-bit successive approximation register (SAR) ADC. Operating from a 2.5V supply, the LTC2381-16 has a 2.5V fully differential input range. The LTC2381-16 consumes only 3.25mW and achieves 2LSB INL max, no missing codes at 16-bits and 92dB SNR. n n n n n n n n n n n n n n 250ksps Throughput Rate 2LSB INL (Max) Guaranteed 16-Bit No Missing Codes Low Power: 3.25mW at 250ksps, 13W at 1ksps 92dB SNR (typ) at fIN = 20kHz Extended Acquisition Time of 3.25s Allows Use of Lower Power Drivers Guaranteed Operation to 125C 2.5V Supply Fully Differential Input Range 2.5V External 2.5V Reference Input No Pipeline Delay, No Cycle Latency 1.8V to 5V I/O Voltages SPI-Compatible Serial I/O with Daisy-Chain Mode Internal Conversion Clock 16-pin MSOP and 4mm x 3mm DFN Packages APPLICATIONS n n n n n n The LTC2381-16 has a high speed SPI-compatible serial interface that supports 1.8V, 2.5V, 3.3V and 5V logic while also featuring a daisychain mode. The fast 250ksps throughput with no cycle latency makes the LTC2381-16 ideally suited for a wide variety of high speed applications. An internal oscillator sets the conversion time, easing external timing considerations. The LTC2381-16 automatically powers down between conversions, leading to reduced power dissipation that scales with the sampling rate. The LTC2381-16 features a proprietary sampling architecture that enables the ADC to begin acquiring the next sample during the current conversion. The resulting extended acquisition time of 3.25s allows the use of extremely low power ADC drivers. Medical Imaging High Speed Data Acquisition Portable or Compact Instrumentation Industrial Process Control Low Power Battery-Operated Instrumentation ATE L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION 32k Point FFT fS = 250ksps, fIN = 20kHz 2.5V 0 1.8V TO 5V SNR = 91.8dB THD = -106dB SINAD = 91.6dB SFDR = 107dB -20 50 LT6350 100 IN+ 0.1F VDD OVDD LTC2381-16 3300pF IN- 50 SINGLE-ENDEDTO-DIFFERENTIAL DRIVER 100 REF 2.5V GND CHAIN RDL/SDI SDO SCK BUSY CNV 238116 TA01 47F (X5R, 0805 SIZE) -40 SAMPLE CLOCK AMPLITUDE (dBFS) 10F ANALOG INPUT 0V TO 2.5V -60 -80 -100 -120 -140 -160 -180 0 25 50 75 FREQUENCY (kHz) 100 125 238116 TA02a 238116f 1 LTC2381-16 ABSOLUTE MAXIMUM RATINGS (Notes 1, 2) Supply Voltage (VDD) ...............................................2.8V Supply Voltage (OVDD) ................................................6V Reference Input (REF)..............................................2.8V Analog Input Voltage (Note 3) IN+, IN- ......................... (GND -0.3V) to (REF + 0.3V) Digital Input Voltage (Note 3)........................... (GND -0.3V) to (OVDD + 0.3V) Digital Output Voltage (Note 3)........................... (GND -0.3V) to (OVDD + 0.3V) Power Dissipation .............................................. 500mW Operating Temperature Range LTC2381C ................................................ 0C to 70C LTC2381I .............................................-40C to 85C LTC2381H .......................................... -40C to 125C Storage Temperature Range .................. -65C to 150C PIN CONFIGURATION TOP VIEW CHAIN 1 VDD 2 GND 3 + 4 IN- 5 GND 6 REF 7 REF 8 IN 16 GND 15 OVDD 17 GND TOP VIEW CHAIN VDD GND IN+ IN- GND REF REF 14 SDO 13 SCK 12 RDL/SDI 11 BUSY 10 GND 9 CNV 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 GND OVDD SDO SCK RDL/SDI BUSY GND CNV MS PACKAGE 16-LEAD (4mm s 5mm) PLASTIC MSOP DE PACKAGE 16-LEAD (4mm s 3mm) PLASTIC DFN TJMAX = 150C, JA = 110C/W TJMAX = 150C, JA = 43C/W EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2381CMS-16#PBF LTC2381CMS-16#TRPBF 238116 16-Lead Plastic MSOP 0C to 70C LTC2381IMS-16#PBF LTC2381IMS-16#TRPBF 238116 16-Lead Plastic MSOP -40C to 85C LTC2381HMS-16#PBF LTC2381HMS-16#TRPBF 238116 16-Lead Plastic MSOP -40C to 125C LTC2381CDE-16#PBF LTC2381CDE-16#TRPBF 23816 16-Lead (4mm x 3mm) Plastic DFN 0C to 70C LTC2381IDE-16#PBF LTC2381IDE-16#TRPBF 23816 16-Lead (4mm x 3mm) Plastic DFN -40C to 85C Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ 238116f 2 LTC2381-16 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 4) SYMBOL PARAMETER CONDITIONS VIN+ Absolute Input Range (IN+) MIN (Note 5) l VIN - Absolute Input Range (IN-) (Note 5) l VIN+ - VIN- Input Differential Voltage range VIN = VIN+ - VIN- l VCM Common-Mode Input Range l VREF/2- 0.05 IIN Analog Input Leakage Current l CIN Analog Input Capacitance CMRR Input Common Mode Rejection Ratio TYP MAX UNITS VREF V -0.05 VREF V -VREF +VREF V VREF/2+ 0.05 V 1 A -0.05 Sample Mode Hold Mode VREF/2 45 5 pF pF 70 dB CONVERTER CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 4) SYMBOL PARAMETER CONDITIONS MIN TYP MAX Resolution 16 Bits No Missing Codes l 16 Bits l -2 0.9 2 LSB LSB Transition Noise 0.6 (Note 6) LSBRMS INL Integral Linearity Error DNL Differential Linearity Error l -1 0.5 1 Bipolar Zero-Scale Error l -6 0.25 6 BZE (Note 7) Bipolar Zero-Scale Error Drift FSE UNITS l Bipolar Full-Scale Error 3 (Note 7) l -14 Bipolar Full-Scale Error Drift 3 LSB mLSB/C 14 0.1 LSB ppm/C DYNAMIC ACCURACY The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C and AIN = -1dBFS. (Notes 4, 8) SYMBOL PARAMETER CONDITIONS SINAD fIN = 20kHz Signal-to-(Noise + Distortion) Ratio MIN TYP l 88.5 92 89 SNR Signal-to-Noise Ratio fIN = 20kHz l THD Total Harmonic Distortion fIN = 20kHz, First 5 Harmonics l Spurious Free Dynamic Range fIN = 20kHz SFDR MAX dB 92 -106 UNITS dB -99 dB 107 dB -3dB Input Bandwidth 30 MHz Aperture Delay 2 ns 30 ps 250 ns Aperture Jitter Transient Response Full-Scale Step 238116f 3 LTC2381-16 REFERENCE INPUT The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 4) SYMBOL PARAMETER CONDITIONS VREF Reference Voltage (Note 5) l MIN IREF Load Current (Note 9) l TYP 2.4 MAX UNITS 2.6 V 285 A DIGITAL INPUTS AND DIGITAL OUTPUTS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 4) SYMBOL PARAMETER CONDITIONS MIN VIH High Level Input Voltage l VIL Low Level Input Voltage l IIN Digital Input Current TYP MAX UNITS 0.8 * OVDD VIN = 0V to OVDD l -10 OVDD - 0.2 V 0.2 * OVDD V 10 A CIN Digital Input Capacitance VOH High Level Output Voltage IO = -500 A l 5 pF VOL Low Level Output Voltage IO = 500 A l IOZ Hi-Z Output Leakage Current VOUT = 0V to OVDD l ISOURCE Output Source Current VOUT = 0V -10 mA ISINK Output Sink Current VOUT = OVDD 10 mA V -10 0.2 V 10 A POWER REQUIREMENTS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 4) SYMBOL PARAMETER VDD Supply Voltage CONDITIONS l OVDD Supply Voltage IDD Supply Current Power Down Mode Power Down Mode 250ksps Sample Rate Conversion Done Conversion Done (H-Grade) PD Power Dissipation Power Down Mode Power Down Mode 250ksps Sample Rate Conversion Done Conversion Done (H-Grade) MIN TYP MAX UNITS 2.375 2.5 2.625 V 1.71 l l l 5.25 V 1.3 0.5 0.5 1.7 40 110 mA A A 3.25 1.25 1.25 4.25 100 275 mW W W ADC TIMING CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 4) SYMBOL PARAMETER fSMPL Maximum Sampling Frequency l l 2 l 3.25 tCONV Conversion Time tACQ Acquisition Time CONDITIONS tACQ = tCYC - tHOLD (Note 10) MIN TYP MAX UNITS 250 ksps 3 s s tHOLD Maximum Time Between Acquisitions l tCYC Time Between Conversions l 4 us tCNVH CNV High Time l 20 ns tBUSYLH CNV to BUSY Delay CL = 20pF (Note 11) l tCNVL Minimum Low Time for CNV (Note 11) l 200 ns tSCK SCK Period (Notes 11, 12) l 10 ns 750 20 ns ns 238116f 4 LTC2381-16 ADC TIMING CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 4) SYMBOL PARAMETER tSCKH SCK High Time CONDITIONS l MIN 4 TYP MAX ns tSCKL SCK Low Time l 4 ns tSSDISCK SDI Setup Time From SCK (Note 11) l 4 ns tHSDISCK SDI Hold Time From SCK (Note 11) l 1 ns tSCKCH SCK Period in Chain Mode tSCKCH = tSSDISCK + tDSDO (Note 11) l 13.5 ns tDSDO SDO Data Valid Delay from SCK CL = 20pF (Note 11) l 9.5 UNITS ns tHSDO SDO Data Remains Valid Delay from SCK CL = 20pF (Note 10) l tDSDOBUSYL SDO Data Valid Delay from BUSY CL = 20pF (Note 10) l 5 ns tEN Bus Enable Time After RDL (Note 11) l 16 ns tDIS 1 ns Bus Relinquish Time After RDL (Note 11) l tSSCKRDL SCK Setup Time from RDL/SDI (Note 10) l 1 ns tHSCKRDL SCK Hold Time from RDL/SDI (Note 10) l 16 ns Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: All voltage values are with respect to ground. Note 3: When these pin voltages are taken below ground or above REF or OVDD, they will be clamped by internal diodes. This product can handle input currents up to 100mA below ground or above REF or OVDD without latch-up. Note 4: VDD = 2.5V, OVDD = 2.5V, REF = 2.5V, fSMPL = 250kHz. Note 5: Recommended operating conditions. Note 6: Integral nonlinearity is defined as the deviation of a code from a straight line passing through the actual endpoints of the transfer curve. The deviation is measured from the center of the quantization band. 13 ns Note 7: Bipolar zero-scale error is the offset voltage measured from -0.5LSB when the output code flickers between 0000 0000 0000 0000 and 1111 1111 1111 1111. Full-scale bipolar error is the worst-case of -FS or +FS untrimmed deviation from ideal first and last code transitions and includes the effect of offset error. Note 8: All specifications in dB are referred to a full-scale 2.5V input with a 2.5V reference voltage. Note 9: fSMPL = 250kHz, IREF varies proportionately with sample rate. Note 10: Guaranteed by design, not subject to test. Note 11: Parameter tested and guaranteed at OVDD = 1.71V, OVDD = 2.5V and OVDD = 5.25V. Note 12: tSCK of 10ns maximum allows a shift clock frequency up to 100MHz for rising capture. 0.8*OVDD tWIDTH 0.2*OVDD tDELAY tDELAY 0.8*OVDD 0.8*OVDD 0.2*OVDD 0.2*OVDD 50% 50% 238216 F01 Figure 1. Voltage Levels for Timing Specifications 238116f 5 LTC2381-16 TYPICAL PERFORMANCE CHARACTERISTICS fSMPL = 250ksps, unless otherwise noted. Integral Nonlinearity vs Output Code TA = 25C, VDD = 2.5V, OVDD = 2.5V, REF = 2.5V, Differential Nonlinearity vs Output Code DC Histogram 1600000 1.0 2.0 1400000 1.5 DNL ERROR (LSB) 0.5 0.0 -0.5 1000000 COUNTS INL ERROR (LSB) 1200000 0.5 1.0 0.0 600000 400000 -1.0 -0.5 200000 -1.5 -2.0 -1.0 16384 32768 49152 OUTPUT CODE 65536 0 16384 32768 49152 OUTPUT CODE 238116 G01 -80 -100 -120 -95 92 SNR 91.5 SINAD 91 -140 90.5 -160 -180 25 50 75 FREQUENCY (kHz) 100 90 125 32769 -90 92.5 -60 0 32768 THD, Harmonics vs Input Frequency 93 SNR, SINAD (dBFS) -40 32767 CODE 238116 G03 SNR, SINAD vs Input Frequency SNR = 91.8dB THD = -106dB SINAD = 91.6dB SFDR = 107dB -20 32765 238116 G02 32k Point FFT fS = 250Ksps, fIN = 20kHz 0 0 32764 65536 HARMONICS, THD (dBFS) 0 AMPLITUDE (dBFS) 800000 -100 3RD THD -105 -110 2ND -115 -120 -125 0 25 50 75 FREQUENCY (kHz) -130 100 0 25 50 75 FREQUENCY (kHz) 238116 G05 100 238116 G06 238116 G04 SNR, SINAD vs Input level, fIN = 20kHz SNR, SINAD vs Temperature 93.0 HARMONICS, THD (dBFS) -100 92.50 SNR SNR, SINAD (dBFS) SNR, SINAD (dBFS) 92.5 SINAD 92.0 91.5 91.0 -40 THD, Harmonics vs Temperature 93.00 SNR 92.00 SINAD 91.50 -30 -20 -10 INPUT LEVEL (dB) 0 238116 G07 91.00 -55 -35 -15 5 25 45 65 85 105 125 TEMPERATURE (C) -105 -110 THD 2ND -115 -120 -55 -35 -15 3RD 5 25 45 65 85 105 125 TEMPERATURE (C) 238116 G08 238116 G09 238116f 6 LTC2381-16 TYPICAL PERFORMANCE CHARACTERISTICS fSMPL = 250ksps, unless otherwise noted. INL/DNL vs Temperature Full-Scale Error vs Temperature Offset Error vs Temperature 0 1 0 -FS 0.5 MAX DNL 0 MIN DNL -0.5 -0.5 -0.25 OFFSET ERROR (LSB) FULL-SCALE ERROR (LSB) MAX INL INL/DNL ERROR (LSB) TA = 25C, VDD = 2.5V, OVDD = 2.5V, REF = 2.5V, -1 +FS -1.5 -0.5 -0.75 MIN INL -1 -55 -35 -15 -2 -55 -35 -15 5 25 45 65 85 105 125 TEMPERATURE (C) Supply Current vs Temperature Supply Current vs Sampling Rate 1.4 IVDD + IOVDD + IREF 25 POWER SUPPLY CURRENT (mA) IVDD POWER-DOWN CURRENT (A) POWER SUPPLY CURRENT (mA) 30 IREF 238116 G12 Shutdown Current vs Temperature 1.5 0.5 5 25 45 65 85 105 125 TEMPERATURE (C) 238116 G11 238116 G10 1 -1 -55 -35 -15 5 25 45 65 85 105 125 TEMPERATURE (C) 20 15 10 5 1.2 1 0.8 0.6 0.4 0.2 IOVDD 0 -55 -35 -15 5 25 45 65 85 105 125 TEMPERATURE (C) 238116 G13 0 -55 -35 -15 0 5 25 45 65 85 105 125 TEMPERATURE (C) 0 50 100 150 200 SAMPLING RATE (kHz) 250 238116 G14 238116 G15 238116f 7 LTC2381-16 PIN FUNCTIONS CHAIN (Pin 1): Chain Mode Selector Pin. When low, the LTC2381-16 operates in Normal Mode and the RDL/SDI input pin functions to enable or disable SDO. When high, the LTC2381-16 operates in Chain Mode and the RDL/SDI pin functions as SDI, the daisychain serial data input. RDL/SDI (Pin 12): When CHAIN is low, the part is in Normal Mode and the pin is treated as a bus enabling input. When CHAIN is high, the part is in chain mode and the pin is treated as a serial data input pin where data from another ADC in the daisychain is input. VDD (Pin 2): 2.5V Digital Power Supply. The range of VDD is 2.375V to 2.625V. Bypass VDD to GND with a 10F ceramic capacitor. SCK (Pin 13): Serial Data Clock Input. When SDO is enabled, the conversion result or daisychain data from another ADC is shifted out on the rising edges of this clock MSB first. GND (Pins 3, 6, 10 and 16): Ground. SDO (Pin 14): Serial Data Output. The conversion result or daisychain data is output on this pin on each rising edge of SCK MSB first. The output data is in 2's complement format. IN+, IN- (Pins 4, 5): Positive and Negative Differential Analog Inputs. REF (Pins 7, 8): Reference Input. The range of REF is 2.4V to 2.6V. This pin is referred to the GND pin and should be decoupled closely to the pin with a 47F ceramic capacitor (X5R, 0805 size). OVDD (Pin 15): I/O Interface Digital Power. The range of OVDD is 1.71V to 5.25V. This supply is nominally set to the same supply as the host interface (1.8V, 2.5V, 3.3V, or 5V). Bypass OVDD to GND with a 0.1F capacitor. CNV (Pin 9): Convert Input. A rising edge on this input initiates a new conversion. When the conversion is done, the part powers down as long as CNV is held high. When CNV is returned low, the part powers up in preparation for the next conversion. GND (Exposed Pad Pin 17 - DFN Package Only): Ground. Exposed pad must be soldered directly to the ground plane. BUSY (Pin 11): BUSY indicator. Goes high at the start of a new conversion and returns low when the conversion has finished. FUNCTIONAL BLOCK DIAGRAM VDD = 2.5V REF = 2.5V OVDD = 1.8V to 5V LTC2381-16 IN+ + 16-BIT SAMPLING ADC IN- SPI PORT - CONTROL LOGIC CHAIN SDO RDL/SDI SCK CNV BUSY GND 238116 BD01 238116f 8 LTC2381-16 TIMING DIAGRAM Conversion Timing Using the Serial Interface CHAIN, RDL/SDI = 0 POWER-UP CNV POWER-DOWN CONVERT BUSY HOLD ACQUIRE SCK D15 D14 D13 D2 D1 D0 SDO 238116 TD01 APPLICATIONS INFORMATION OVERVIEW CONVERTER OPERATION The LTC2381-16 is a low noise, low power, high speed 16-bit successive approximation register (SAR) ADC. Operating from a single 2.5V supply, the LTC2381-16 supports a large 2.5V fully differential input range, making it ideal for high performance applications which require a wide dynamic range. The LTC2381-16 achieves 2LSB INL max, no missing codes at 16-bits and 92dB SNR. A rising edge on the CNV pin initiates a conversion. During the conversion phase, the 16-bit CDAC is sequenced through a successive approximation algorithm, effectively comparing the sampled input with binary-weighted fractions of the reference voltage (e.g. VREF/2, VREF/4 ... VREF/65536) using the differential comparator. At the end of conversion, the CDAC output approximates the sampled analog input. The ADC control logic then prepares the 16-bit digital output code for serial transfer. Fast 250ksps throughput with no cycle latency makes the LTC2381-16 ideally suited for a wide variety of high speed applications. An internal oscillator sets the conversion time, easing external timing considerations. The LTC2381-16 dissipates only 3.25mW at 250ksps, while an auto power-down feature is provided to further reduce power dissipation during inactive periods. The LTC2381-16 features a proprietary sampling architecture that enables the ADC to begin acquiring the next sample during the current conversion. The resulting extended acquisition time of 3.25s allows the use of extremely low power ADC drivers. TRANSFER FUNCTION The LTC2381-16 digitizes the full-scale voltage of 2 x REF into 216 levels, resulting in an LSB size of 76V with REF = 2.5V. The ideal transfer function is shown in Figure 2. The output data is in 2's complement format. ANALOG INPUT The analog inputs of the LTC2381-16 are fully differential in order to maximize the signal swing that can be digitized. The analog inputs can be modeled by the equivalent 238116f 9 LTC2381-16 APPLICATIONS INFORMATION OUTPUT CODE (TWO'S COMPLEMENT) circuit shown in Figure 3. The diodes at the input provide ESD protection. In the acquisition phase, each input sees approximately 45pF (CIN) from the sampling CDAC in series with 40 (RON) from the on-resistance of the sampling switch. Any unwanted signal that is common to both inputs will be reduced by the common mode rejection of the ADC. The inputs draw a current spike while charging the CIN capacitors during acquisition. When the LTC2381-16 is not acquiring the input, the analog inputs draw only a small leakage current. For best performance, a buffer amplifier should be used to drive the analog inputs of the LTC2381-16. The amplifier provides low output impedance which produces fast settling of the analog signal during the acquisition phase. It also provides isolation between the signal source and the current spike the ADC inputs draw. Input Filtering The noise and distortion of the buffer amplifier and signal source must be considered since they add to the ADC noise and distortion. Noisy input signals should be filtered prior to the buffer amplifier input with an appropriate filter to minimize noise. The simple 1-pole RC lowpass filter (LPF1) shown in Figure 4 is sufficient for many applications. 011...111 BIPOLAR ZERO 011...110 time is important even for DC inputs, because the ADC inputs draw a current spike when entering acquisition. 000...001 000...000 111...111 111...110 100...001 FSR = +FS - -FS 1LSB = FSR/65536 100...000 -1 0V 1 FSR/2 - 1LSB LSB LSB INPUT VOLTAGE (V) -FSR/2 238116 F02 Figure 2. LTC2381-16 Transfer Function REF RON CIN IN+ BIAS VOLTAGE REF IN- RON CIN 238116 F03 Figure 3. The Equivalent Circuit for the Differential Analog Input of the LTC2381-16 INPUT DRIVE CIRCUITS A low impedance source can directly drive the high impedance inputs of the LTC2381-16 without gain error. A high impedance source should be buffered to minimize settling time during acquisition and to optimize the distortion performance of the ADC. Minimizing settling Another filter network consisting of LPF2 and the 100 series input resistors should be used between the buffer and ADC inputs to both minimize the noise contribution of the buffer and to help minimize disturbances reflected into the buffer from sampling transients. Long RC time constants at the analog inputs will slow down the settling of the analog inputs. Therefore, LPF2 requires a wider bandwidth than LPF1. A buffer amplifier with a low noise density must be selected to minimize degradation of the SNR. With the 482kHz lowpass filter shown in Figure 4, the LT6350 provides the full data sheet performance of the LTC2381-16. High quality capacitors and resistors should be used in the RC filters since these components can add distortion. NPO and silver mica type dielectric capacitors have excellent linearity. Carbon surface mount resistors can generate distortion from self heating and from damage that may occur during soldering. Metal film surface mount resistors are much less susceptible to both problems. LPF2 50 SINGLE-ENDEDINPUT SIGNAL LPF1 500 LT6350 100 IN+ 3300pF LTC2381-16 6600pF 50 100 SINGLE-ENDED- BW = 482kHz BW = 48kHz TO-DIFFERENTIAL DRIVER IN- 238116 F04 Figure 4. Input Signal Chain 238116f 10 LTC2381-16 APPLICATIONS INFORMATION For single-ended input signals, a single-ended to differential conversion circuit must be used to produce a differential signal at the inputs of the LTC2381-16. The LT6350 ADC driver is recommended for performing single-ended-todifferential conversions.The LT6350 is flexible and may be configured to convert single-ended signals of various amplitudes to the 2.5V differential input range of the LTC2381-16. The LT6350 is also available in H-grade to complement the extended temperature operation of the LTC2381-16 up to 125C. Figure 5 shows the LT6350 being used to convert a 0V to 2.5V single-ended input signal. In this case, the first amplifier is configured as a unity gain buffer and the singleended input signal directly drives the high-impedance input of the amplifier. As shown in the FFT of Figure 5a, the LT6350 drives the LTC2381-16 to full datasheet performance without degrading the SNR or THD . The LT6350 can also be used to buffer and convert single-ended signals larger than the input range of the LTC2381-16 in order to maximize the signal swing that can be digitized. Figure 6 shows the LT6350 converting a 0V-5V single-ended input signal to the 2.5V differential input range of the LTC2381-16. In this case, the first amplifier in the LT6350 is configured as an inverting amplifier stage, which acts to attenuate the input signal down to the 0V-2.5V input range of the LTC2381-16. In the inverting amplifier configuration, the single-ended input signal source no longer directly drives a high impedance input of the first amplifier. The input impedance is instead set by resistor RIN. RIN must be chosen carefully based on the source impedance of the signal source. Higher values of RIN tend to degrade both the noise and distortion of the LT6350 and LTC2381-16 as a system. R1, R2 and R3 must be selected in relation to RIN to achieve the desired attenuation and to maintain a balanced input impedance in the first amplifier. Table 1 shows the resulting SNR and THD for several values of RIN , R1, R2 and R3 in this configuration. Figure 6a shows the resulting FFT when using the LT6350 as shown in Figure 6. The LT6350 can also be used to buffer and convert large, true bipolar signals which swing below ground to the 2.5V differential input range of the LTC2381-16. Figure 7 shows the LT6350 being used to convert a 10V true bipolar signal for use by the LTC2381-16. The input impedance is again set by resistor RIN. Table 2 shows the resulting SNR and THD for several values of RIN. Figure 7a shows the resulting FFT when using the LT6350 as shown in Figure 7. LT6350 + - 8 1 0V to 2.5V RINT 4 OUT1 0V to 2.5V 5 OUT2 2.5V to 0V RINT 2 + - - + VCM = VREF/2 238116 F05 Figure 5. LT6350 Converting a 0V-2.5V Single-Ended Signal to a 2.5V Differential Input Signal 0 SNR = 91.8dB THD = -106dB SINAD = 91.6dB SFDR = 107dB -20 -40 AMPLITUDE (dBFS) Single-Ended-to-Differential Conversion -60 -80 -100 -120 -140 -160 -180 0 25 50 75 FREQUENCY (kHz) 100 125 238116 F05a Figure 5a. 32k Point FFT Plot for Circuit Shown in Figure 5 238116f 11 LTC2381-16 APPLICATIONS INFORMATION VCM VREF R2 = 1.24k 200pF R2 = 1k 150pF LT6350 4 10F + - 8 R4 = 680 R3 = 2k RINT 1 RIN = 2k RINT 2 R1 = 1k OUT1 + - LT6350 2.5V to 0V 10F R4 = 1.1k R3 = 10k - + 5 OUT2 0V to 2.5V 8 + - 1 RIN = 10k VCM = VREF/2 75pF 0V to 5V 238116 F06 Figure 6. LT6350 Converting a 0V-5V Single-Ended Signal to a 2.5V Differential Input Signal 0 OUT1 2.5V to 0V 5 OUT2 0V to 2.5V + - VCM = VREF/2 220pF 238116 F07 Figure 7. LT6350 Converting a 10V Single-Ended Signal to a 2.5V Differential Input Signal 0 SNR = 91.8dB THD = -95.5dB SINAD = 91.4dB SFDR = 96.9dB -20 -40 AMPLITUDE (dBFS) -40 AMPLITUDE (dBFS) 10V SNR = 91.7dB THD = -100dB SINAD = 91.2dB SFDR = 103.5dB -20 - + 2 R1 = 1.24k 4 RINT RINT -60 -80 -100 -120 -60 -80 -100 -120 -140 -140 -160 -160 -180 -180 0 25 50 75 FREQUENCY (kHz) 100 125 0 25 50 75 FREQUENCY (kHz) 238116 F06a 100 125 238116 F07a Figure 6a. 32k Point FFT Plot for Circuit Shown in Figure 6 Figure 7a. 32k Point FFT Plot for Circuit Shown in Figure 7 Table 1. SNR, THD vs RIN for 0-5V Single-Ended Input Signal Table 2. SNR, THD vs RIN for 10V Single-Ended Input Signal RIN () R1 () R2 () R3 () R4 () SNR (dB) THD (dB) RIN () R1 () R2 () R3 () R4 () SNR (dB) THD (dB) 2k 1k 1k 2k 680 92 -100 10k 1.24k 1.24k 10k 1.1k 92 -96 10k 5k 5k 10k 3.3k 91 -100 50k 6.19k 6.19k 50k 5.49k 91 -96 50k 25k 25k 50k 16k 91 -97 100k 12.4k 12.4k 100k 11k 91 -97 ADC REFERENCE The LTC2381-16 requires an external reference to define its input range. A low noise, low temperature drift reference is critical to achieving the full datasheet performance of the ADC. Linear Technology offers a portfolio of high performance references designed to meet the needs of many applications. With its small size, low power and high accuracy, the LTC6652-2.5 is particularly well suited for use with the LTC2381-16. The LTC6652-2.5 offers 0.05% (max) initial accuracy and 5ppm/C (max) temperature coefficient for high precision applications. The LTC6652-2.5 is fully specified over the H-grade temperature range and complements the extended temperature operation of the LTC2381-16 up to 125C. We recommend bypassing the LTC6652-2.5 with a 47F ceramic capacitor (X5R, 0805 size) close to the REF pin. All performance curves shown in this datasheet were obtained using the LTC6652-2.5. 238116f 12 LTC2381-16 APPLICATIONS INFORMATION When idling, the REF pin on the LTC2381-16 draws only a small leakage current(< 1A). In applications where a burst of samples is taken after idling for long periods as shown in Figure 8, IREF quickly goes from approximately 0A to a maximum of 285A at 250ksps. This step in DC current draw triggers a transient response in the reference that must be considered since any deviation in the reference output voltage will affect the accuracy of the output code. In applications where the transient response of the reference is important, the fast settling LTC6655-2.5 reference is recommended. Inserting a 1 resistor between the 47F bypass capacitor and reference output as shown in Figure 9 helps to improve the transient settling time and minimize the reference voltage deviation. VOUT_S LTC6655-2.5 VOUT_F 1 REF 47F LTC2381-16 238116 F09 Figure 9. LTC6655-2.5 Driving REF of LTC2381-16 0 SNR = 91.8dB THD = -106dB SINAD = 91.6dB SFDR = 107dB -20 -40 AMPLITUDE (dBFS) The REF pin of the LTC2381-16 draws charge (QCONV) from the 47F bypass capacitor during each conversion cycle. The reference replenishes this charge with a DC current, IREF = QCONV/tCYC. The DC current draw of the REF pin, IREF , depends on the sampling rate and output code. If the LTC2381-16 is used to continuously sample a signal at a constant rate, the LTC6652-2.5 will keep the deviation of the reference voltage over the entire code span to less than 0.5LSBs. -60 -80 -100 -120 -140 -160 -180 0 25 50 75 FREQUENCY (kHz) 100 125 238116 F10 Figure 10. 32k Point FFT of the LTC2381-16 DYNAMIC PERFORMANCE Fast Fourier Transform (FFT) techniques are used to test the ADC's frequency response, distortion and noise at the rated throughput. By applying a low distortion sine wave and analyzing the digital output using an FFT algorithm, the ADC's spectral content can be examined for frequencies outside the fundamental. The LTC2381-16 provides guaranteed tested limits for both AC distortion and noise measurements. Signal-to-Noise and Distortion Ratio (SINAD) The signal-to-noise and distortion ratio (SINAD) is the ratio between the RMS amplitude of the fundamental input frequency and the RMS amplitude of all other frequency components at the A/D output. The output is band-limited to frequencies from above DC and below half the sampling frequency. Figure 10 shows that the LTC2381-16 achieves a typical SINAD of 92dB at a 250kHz sampling rate with a 20kHz input. CNV IDLE PERIOD IDLE PERIOD 238116 F08 Figure 8. CNV Waveform Showing Burst Sampling 238116f 13 LTC2381-16 APPLICATIONS INFORMATION Signal-to-Noise Ratio (SNR) TIMING AND CONTROL The signal-to-noise ratio (SNR) is the ratio between the RMS amplitude of the fundamental input frequency and the RMS amplitude of all other frequency components except the first five harmonics and DC. Figure 10 shows that the LTC2381-16 achieves a typical SNR of 92dB at a 250kHz sampling rate with a 20kHz input. CNV Timing Total Harmonic Distortion (THD) Total Harmonic Distortion (THD) is the ratio of the RMS sum of all harmonics of the input signal to the fundamental itself. The out-of-band harmonics alias into the frequency band between DC and half the sampling frequency (fSMPL/2). THD is expressed as: The LTC2381-16 conversion is controlled by CNV. A rising edge on CNV will start a conversion. Once a conversion has been initiated, it cannot be restarted until the conversion is complete. For optimum performance, CNV should be driven by a clean low jitter signal. Converter status is indicated by the BUSY output which remains high while the conversion is in progress. To ensure that no errors occur in the digitized results, any additional transitions on CNV should occur within 40ns from the start of the conversion or after the conversion has been completed. ACQUISITION 2 THD = 20 log 2 2 V 2 + V 3 + V 4 + ...+ VN 2 V1 where V1 is the RMS amplitude of the fundamental frequency and V2 through VN are the amplitudes of the second through Nth harmonics. A proprietary sampling architecture allows the LTC2381-16 to begin acquiring the input signal for the next conversion 750ns after the start of the current conversion. This extends the acquisition time to 3.25s, easing settling requirements and allowing the use of extremely low power ADC drivers. (Refer to the Timing Diagram.) 1.4 The LTC2381-16 provides two power supply pins: the 2.5V power supply (VDD), and the digital input/output interface power supply (OVDD). The flexible OVDD supply allows the LTC2381-16 to communicate with any digital logic operating between 1.8V and 5V, including 2.5V and 3.3V systems. Power Supply Sequencing The LTC2381-16 does not have any specific power supply sequencing requirements. Care should be taken to adhere to the maximum voltage relationships described in the Absolute Maximum Ratings section. The LTC2381-16 has a power-on-reset (POR) circuit that will reset the LTC2381-16 at initial power-up or whenever the power supply voltage drops below 1V. Once the supply voltage reenters the nominal supply voltage range, the POR will reinitialize the ADC. No conversions should be initiated until 20s after a POR event to ensure the reinitialization period has ended. Any conversions initiated before this time will produce invalid results. POWER SUPPLY CURRENT (mA) POWER CONSIDERATIONS 1.2 1 0.8 0.6 0.4 0.2 0 0 50 100 150 200 SAMPLING RATE (kHz) 250 238116 F11 Figure 11. Power Supply Current of the LTC2381-16 Versus Sampling Rate Internal Conversion Clock The LTC2381-16 has an internal clock that is trimmed to achieve a maximum conversion time of 2.5s. 238116f 14 LTC2381-16 APPLICATIONS INFORMATION Auto Power-Down DIGITAL INTERFACE The LTC2381-16 automatically powers down after a conversion has been completed as long as CNV remains high. During power-down, the data from the last conversion can be clocked out. To minimize power dissipation during power-down, disable SDO and turn off SCK. To power up the part, bring CNV low at least 200ns (tCONVL) before the initiation of the next conversion. The auto power-down feature will reduce the power dissipation of the LTC238116 as the sampling frequency is reduced. Since the time required to power up the part does not change at lower sample rates, the LTC2381-16 can remain powered-down for a larger fraction of the conversion cycle (tCYC), thereby reducing the average power dissipation which scales linearly with sampling rate as shown in Figure 11. The LTC2381-16 has a serial digital interface. The flexible OVDD supply allows the LTC2381-16 to communicate with any digital logic operating between 1.8V and 5V, including 2.5V and 3.3V systems. The serial output data is clocked out on the SDO pin when an external clock is applied to the SCK pin if SDO is enabled. Clocking out the data after the conversion will yield the best performance. With a shift clock frequency of at least 15MHz, a 250ksps throughput is still achieved. The serial output data changes state on the rising edge of SCK and can be captured on the falling edge or next rising edge of SCK. D15 remains valid till the first rising edge of SCK. The serial interface on the LTC2381-16 is simple and straightforward to use. The following sections describe the operation of the LTC2381-16. Several modes are provided depending on whether a single or multiple ADCs share the SPI bus or are daisy-chained. 238116f 15 LTC2381-16 TIMING DIAGRAM Normal Mode, Single Device Figure 12 shows a single LTC2381-16 operated in Normal Mode with CHAIN and RDL/SDI tied to ground. With RDL/ SDI grounded, SDO is enabled and the MSB(D15) of the new conversion data is available at the falling edge of BUSY. This is the simplest way to operate the LTC2381-16. When CHAIN = 0, the LTC2381-16 operates in Normal mode. In Normal mode, RDL/SDI enables or disables the serial data output pin SDO. If RDL/SDI is high, SDO is in high-impedance. If RDL/SDI is low, SDO is driven. CONVERT DIGITAL HOST CNV BUSY CHAIN IRQ LTC2381-16 RDL/SDI SDO DATA IN SCK CLK 238116 F10 CONVERT POWER-DOWN POWER-UP ACQUIRE CONVERT ACQUIRE CHAIN = 0 tCYC tCNVH tCNVL CNV tHOLD BUSY tACQ tACQ = tCYC - tHOLD tCONV tSCK tBUSYLH SCK tSCKH 1 2 3 SDO 15 16 tSCKL tHSDO tDSDOBUSYL 14 tDSDO D15 D14 D13 D1 D0 238116 F10a (RDL/SDI = 0) Figure 12. Using a Single LTC2381-16 in Normal Mode 238116f 16 LTC2381-16 TIMING DIAGRAM Normal Mode, Multiple Devices time in order to avoid bus conflicts. As shown in Figure 13, the RDL/SDI inputs idle high and are individually brought low to read data out of each device between conversions. When RDL/SDI is brought low, the MSB of the selected device is output onto SDO. To ensure the MSB is properly output and captured, SCK must be held low at least 1ns before and 16ns after bringing RDL/SDI low. Figure 13 shows multiple LTC2381-16 devices operating in Normal Mode(CHAIN = 0) sharing CNV, SCK and SDO. By sharing CNV, SCK and SDO, the number of required signals to operate multiple ADCs in parallel is reduced. Since SDO is shared, the RDL/SDI input of each ADC must be used to allow only one LTC2381-16 to drive SDO at a RDL2 RDL1 CONVERT CNV CNV CHAIN CHAIN BUSY IRQ LTC2381-16 LTC2381-16 SDO B A DIGITAL HOST SDO RDL/SDI RDL/SDI SCK SCK DATA IN CLK 238116 F11 POWER-DOWN CONVERT ACQUIRE CONVERT POWER-UP ACQUIRE CHAIN = 0 CNV BUSY tCNVL tHOLD tCONV tBUSYLH RDL/SDIA RDL/SDIB tSCK tHSCKRDL tSCKH 1 SCK 2 tSSCKRDL 3 Hi-Z 15 tHSDO D15A D14A D13A 16 17 D1A D0A 18 19 30 31 32 tSCKL tDIS tDSDO tEN SDO 14 Hi-Z D15B D14B D13B D1B D0B Hi-Z 238116 F11a Figure 13. Normal Mode with Multiple Devices Sharing CNV, SCK and SDO 238116f 17 LTC2381-16 TIMING DIAGRAM When CHAIN = OVDD, the LTC2381-16 operates in Chain Mode. In Chain Mode, SDO is always enabled and RDL/SDI serves as the serial data input pin (SDI) where daisychain data output from another ADC can be input. This is useful for applications where hardware constraints may limit the number of lines needed to interface to a large number of converters. Figure 14 shows an example with two daisy chained devices. The MSB of converter A will appear at SDO of converter B after 16 SCK cycles. The MSB of converter A is clocked in at the SDI/RDL pin of converter B on the rising edge of the first SCK. CONVERT OVDD OVDD CNV CHAIN RDL/SDI CNV CHAIN RDL/SDI SDO A DIGITAL HOST LTC2381-16 LTC2381-16 BUSY B IRQ DATA IN SDO SCK SCK CLK 238116 F12 POWER-DOWN CONVERT POWER-UP CONVERT ACQUIRE ACQUIRE CHAIN = OVDD RDL/SDIA = 0 tCYC tCNVL CNV tHOLD BUSY tCONV tBUSYLH tSCKCH SCK 1 2 3 14 tSCKH 15 tSSDISCK 16 18 30 31 32 tSCKL tHSDO tHSDISCK SDOA = RDL/SDIB 17 tDSDO D15A D14A D13A D1A D0A D15B D14B D13B D1B D0B tDSDOBUSYL SDOB D15A D14A D1A D0A 238116 F14 Figure 14. Chain Mode Timing Diagram 238116f 18 LTC2381-16 BOARD LAYOUT To obtain the best performance from the LTC2381-16 a printed circuit board is recommended. Layout for the printed circuit board (PCB) should ensure the digital and analog signal lines are separated as much as possible. In particular, care should be taken not to run any digital clocks or signals alongside analog signals or underneath the ADC. Recommended Layout The following is an example of a recommended PCB layout. A single solid ground plane is used. Bypass capacitors to the supplies are placed as close as possible to the supply pins. Low impedance common returns for these bypass capacitors are essential to the low noise operation of the ADC. The analog input traces are screened by ground. For more details and information refer to DC1571A, the evaluation kit for the LTC2381-16. Partial Top Silkscreen 238116 F13 238116f 19 LTC2381-16 BOARD LAYOUT Partial Layer 1 Component Side 238116 BL01 Partial Layer 2 Ground Plane 238116 BL02 238116f 20 LTC2381-16 BOARD LAYOUT Partial Layer 3 PWR Plane 238116 BL03 Partial Layer 4 Bottom Layer 238116 BL04 238116f 21 AIN - E7 VREF/2 EXT R39 O JP5 HD1X3-100 EXT_CM AIN+ R14 O +2.5V 3 2 1 COUPLING AC DC C46 1F COUPLING AC DC C8 1F C47 OPT C48 10F 6.3V 4 2 5 4 +3.3V C2 0.1F R3 CLK 33 TO CPLD R41 OPT R40 1k R18 1k R9 1k C49 OPT C63 10F 6.3V 3 V+ C43 1F C55 1F 6 C45 V - 10F 2 +IN2 8 +IN1 V- C62 10F R37 1k R34 O C61 10F 6.3V C42 15pF R32 O V+ C44 1F C57 0.1F V+ C59 1F OUT2 5 -IN1 OUT1 4 U15 7 LT6350CMS8 SHDN U2 R6 3 U8 3 NC7SZ04P5X NC7SVU04P5X 1k R15 1k HD1X3-100 JP2 CM C18 OPT C17 10F JP1 HD1X3-100 R5 49.9 1206 2 5 +3.3V C1 0.1F R2 1k +3.3V 2 CLKIN 1 3 C5 0.1F 2 C60 1F C58 OPT R35 OPT R36 49.9 R45 O R32 49.9 R31 OPT SDO C10 OPT 1 3 5 7 9 11 13 9V TO 10V R1 100 IN- IN+ C10 0.1F C6 10F 6.3V C39 OPT R1 NPO 100 C9 10F 6.3V C19 3300pF 1206 NPO +2.5V +3.3V U10 LTC6652AHMS8-2.5 8 1 DNC GND 2 7 VIN GND 3 6 V SHDN OUT 5 4 GND GND R38 OPT C11 0.1F 9V TO 10V C7 0.1F C12 1F 1 2 3 E6 EXT_REF J3 DC590 2 4 6 8 10 12 14 CNV SCK SDO BUSY R1 O R7 1k 3 2 1 C56 0.1F JP6 FS EXT 6652 3 3 R17 R13 2k 1k U9 NC7SZ04P5X 2 4 VSS 6 5 7 3 2 1 C15 0.1F U7 C14 0.1F 8 24LC025-I/ST VCC SCL SCK SDA WP CNV ARRAY A2 EEPROM A1 A0 4 5 +3.3V R10 4.99k R11 4.99k CLKOUT C16 1 0.1F DB0 DB1 DB2 DB3 DB4 DB5 DB6 DB7 DB8 DB9 DB10 DB11 DB12 DB13 DB14 DB15 DB16 DB17 3 5 2 CNVST_33 FROM CPLD U4 NC7SVU04P5X +3.3V C4 0.1F R12 4.99k 39 37 35 33 31 29 27 25 23 21 19 17 15 13 11 9 7 5 3 1 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 J2 CON-EDGE 40-100 R4 7 33 4 8 +3.3V C3 0.1F R8 33 DC590 DETECT TO CPLD PR\ Q CLR\ Q\ 5 2 D VCC 1 CP GND +3.3V C13 0.8VREF 0.1F VREF 6 U3 NL17SZ74 +3.3V 4 HD1X3-100 U6 OPT NC7SZ66P5X 5 CNV VCC 9 2 B A 1 13 SCK OE 4 14 SDO GND 11 BUSY 3 12 RD C20 47F 6.3V 0805 RDL/SDI LTC2381-16 JP4 REF HD1X3-100 VDD 2 OVDD 15 7 8 1 3 REF REF1 GND GND GND GND + - - + 22 3 6 10 16 1 R1 33 LTC2381-16 BOARD LAYOUT Partial Schematic of Demoboard 238116f LTC2381-16 PACKAGE DESCRIPTION DE Package 16-Lead Plastic DFN (4mm x 3mm) (Reference LTC DWG # 05-08-1732 Rev O) R = 0.115 TYP 4.00 0.10 (2 SIDES) 0.70 0.05 2.20 0.05 3.30 0.10 3.00 0.10 (2 SIDES) PACKAGE OUTLINE PIN 1 TOP MARK (SEE NOTE 6) 1.70 0.05 16 R = 0.05 TYP 3.30 0.05 3.60 0.05 0.40 0.10 9 1.70 0.10 PIN 1 NOTCH R = 0.20 OR 0.35 s 45 CHAMFER (DE16) DFN 0806 REV O 8 0.75 0.05 0.200 REF 0.25 0.05 0.45 BSC 3.15 REF 0.00 - 0.05 BOTTOM VIEW--EXPOSED PAD 3.15 REF RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 1 0.23 0.05 0.45 BSC NOTE: 1. DRAWING PROPOSED TO BE MADE VARIATION OF VERSION (WGED-3) IN JEDEC PACKAGE OUTLINE MO-229 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE MS Package 16-Lead Plastic MSOP (Reference LTC DWG # 05-08-1669 Rev O) 4.039 p 0.102 (.159 p .004) (NOTE 3) 0.889 p 0.127 (.035 p .005) 5.23 (.206) MIN 16151413121110 9 3.20 - 3.45 (.126 - .136) 0.254 (.010) DETAIL "A" 0o - 6o TYP 0.280 p 0.076 (.011 p .003) REF 3.00 p 0.102 (.118 p .004) (NOTE 4) 4.90 p 0.152 (.193 p .006) GAUGE PLANE 0.305 p 0.038 (.0120 p .0015) TYP 0.53 p 0.152 (.021 p .006) 0.50 (.0197) BSC RECOMMENDED SOLDER PAD LAYOUT DETAIL "A" 0.18 (.007) SEATING NOTE: PLANE 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX 1234567 8 1.10 (.043) MAX 0.17 - 0.27 (.007 - .011) TYP 0.50 (.0197) BSC 0.86 (.034) REF 0.1016 p 0.0508 (.004 p .002) MSOP (MS16) 1107 REV O 238116f Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 23 LTC2381-16 TYPICAL APPLICATION ADC Driver: Single-Ended Input to Differential Output with Filter 0 SNR = 91.8dB THD = -106dB SINAD = 91.6dB SFDR = 107dB -20 LPF1 LT6350 4 500 8 6600pF 1 + - RINT RINT 2 BW = 48kHz LPF2 50 + - 100 -40 IN+ 3300pF + - 5 LTC2381-16 50 100 BW = 482kHz IN- 238116 TA03 AMPLITUDE (dBFS) SINGLE-ENDED INPUT SIGNAL -60 -80 -100 -120 -140 VCM = VREF/2 -160 -180 0 25 50 75 FREQUENCY (kHz) 100 125 238116 TA04 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT2383/LTC2382 16-Bit, 1Msps/500ksps Serial ADC 2.5V Supply, Differential Input, 92dB SNR, 2.5V Input Range,16-Pin MSOP and 4mmx3mm16-Pin DFN Packages,Pin Compatible with the LTC2382-16 LTC2393-16 16-Bit, 1Msps Parallel/Serial ADC 5V Supply, Differential Input, 94dB SNR, 4.096V Input Range, 48-Pin LQFP Package, Pin Compatible with the LTC2392-16, LTC2391-16 LTC2392-16 16-Bit, 500Ksps Parallel/Serial ADC 5V Supply, Differential Input, 94dB SNR, 4.096V Input Range, 48-Pin LQFP Package, Pin Compatible with the LTC2393-16, LTC2391-16 LTC2391-16 16-Bit, 250Ksps Parallel/Serial ADC 5V Supply, Differential Input, 94dB SNR, 4.096V Input Range, 48-Pin LQFP Package, Pin Compatible with the LTC2393-16, LTC2392-16 LTC1864/LTC1864L 16-bit, 250ksps/150ksps 1-channel Power, ADC 5V/3V Supply, 1-Channel, 4.3mW/1.3mW, MSOP-8 Package LTC1865/LTC1865L 16-bit, 250ksps 2-channel Power ADC 5V/3V Supply, 1-Channel, 4.3mW/1.3mW, MSOP-8 Package LTC2302/LTC2306 12-Bit, 500ksps, 1-/2-Channel, Low Noise, ADC ADCs LTC2355-14/LTC2356-14 14-Bit, 3.5Msps Serial ADC 5V Supply, 14mW at 500ksps, 10-Pin DFN Package 3.3V Supply, 1-Channel, Unipolar/Bipolar, 18mW, MSOP-10 Package DACs LTC2641 16-Bit Single Serial VOUT DACs 1LSB INL, 1LSB DNL, MSOP-8 Package, 0V to 5V Output LTC2630 12-/10-/8-Bit Single VOUT DACs SC70 6-Pin Package, Internal Reference, 1LSB INL (12Bits) REFERENCES LTC6652 Precision Low Drift Low Noise Buffered Reference 2.5V, 5ppm/C Max Tempco, 2.1ppm Peak-to-Peak Noise, MSOP-8 Package LTC6655 Precision Low Drift Low Noise Buffered Reference 2.5V, 5ppm/C Max Tempco, 0.25ppm Peak-to-Peak Noise, MSOP-8 Package AMPLIFIERS LT6350 Low Noise Single-Ended-To-Differential ADC Driver Rai-to-Rail Input and Outputs, 240ns 0.01% Settling Time, DFN-8 or MSOP-8 Packages LT6200/LT6200-5/ LT6200-10 165MHz/800MHz/1.6GHz Op Amp with Unity Gain/AV = 5/AV = 10 Low Noise Voltage: 0.95nV/Hz (100kHz), Low Distortion: -80dB at 1MHz, TSOT23-6 Package LT6202/LT6203 Single/Dual 100MHz Rail-to-Rail Input/Output Noise Low Power Amplifiers 1.9nVHz, 3mA Maximum, 100MHz Gain Bandwidth LTC1992 Low Power, Fully Differential Input/Output Amplifier/Driver Family 1mA Supply Current 238116f 24 Linear Technology Corporation LT 0810 * PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear.com (c) LINEAR TECHNOLOGY CORPORATION 2010