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| LTC1164-5 Low Power 8th Order Pin Selectable Butterworth or Bessel Lowpass Filter DESCRIPTIO The LTC(R)1164-5 is a monolithic 8th order filter; it approximates either a Butterworth or a Bessel lowpass response. The LTC1164-5 features clock-tunable cutoff frequency and low power consumption (4.5mA with 5V supplies and 2.5mA with single 5V supply). Low power operation is achieved without compromising noise or distortion performance. With 5V supplies and 10kHz cutoff frequency, the operating signal-to-noise ratio is 86dB and the THD throughout the passband is 0.015%. Under the same conditions, a 77dB signal-tonoise ratio and distortion is obtained with a single 5V supply while the clock feedthrough is kept below the noise level. The maximum signal-to-noise ratio is 92dB. The LTC1164-5 approximates an 8th order Butterworth response with a clock-to-cutoff frequency ratio of 100:1 (Pin 10 to V -) or 50:1 double-sampled (Pin 10 to V + and Pin 1 shorted to Pin 13). Double-sampling allows the input signal frequency to reach the clock frequency before any aliasing occurrence. An 8th order Bessel response can also be approximated with a clock-to-cutoff frequency ratio of 140:1 (Pin 10 to ground). With 7.5V supply, 5V supply and single 5V supply, the maximum clock frequency of the LTC1164-5 is 1.5MHz, 1MHz, and 1MHz respectively. The LTC1164-5 is pin-compatible with the LTC1064-2 and LTC-1064-3. , LTC and LT are registered trademarks of Linear Technology Corporation. FEATURES s s s s s s s s s s Pin Selectable Butterworth or Bessel Response 4mA Supply Current with 5V Supplies fCUTOFF up to 20kHz 100VRMS Wideband Noise THD < 0.02% (50:1, VS = 7.5V, VIN = 2VRMS) Operates with a Single 5V Supply (1VRMS Input Range) 60VRMS Clock Feedthrough (Single 5V Supply) Operates up to 8V Supplies TTL/CMOS-Compatible Clock Input No External Components APPLICATIO S s s s s Anti-Aliasing Filters Battery-Operated Instruments Telecommunications Filters Smoothing Filters TYPICAL APPLICATIO 1 VIN 2 3 8V 4 5 NC 6 7 LTC1164-5 14 Butterworth 20kHz Anti-Aliasing Filter 12 11 10 9 8 GAIN (dB) 13 -8V CLK = 1MHz TO V VOUT + 1164-5 TA01 WIDEBAND NOISE = 110VRMS THD IN PASSBAND < 0.02% AT VIN = 2VRMS NOTE: THE CONNECTION FROM PIN 7 TO PIN 14 SHOULD BE MADE UNDER THE PACKAGE. FOR 50:1 OPERATION CONNECT PIN 1 TO PIN 13 AS SHOWN. FOR 100:1 OR 150:1 OPERATION PINS 1 AND 13 SHOULD FLOAT. THE POWER SUPPLIES SHOULD BE BYPASSED BY A 0.1F CAPACITOR AS CLOSE TO THE PACKAGE AS POSSIBLE. U U U Frequency Response 0 -10 -20 -30 -40 -50 -60 -70 -80 1 10 FREQUENCY (kHz) 100 LTC1164-5 TA02 1 LTC1164-5 ABSOLUTE AXI U RATI GS + - Total Supply Voltage (V to V ) ............................. 16V Input Voltage (Note 2) ......... (V ++ 0.3V) to (V - - 0.3V) Output Short Circuit Duration ......................... Indefinite Power Dissipation ............................................. 400mW Burn-In Voltage ...................................................... 16V PACKAGE/ORDER I FOR ATIO TOP VIEW 50:1 MODE VIN GND V+ GND LP6 CONNECT 1 1 2 3 4 5 6 7 14 CONNECT 2 13 50:1 MODE 12 V- ORDER PART NUMBER LTC1164-5CN LTC1164-5CJ LTC1164-5MJ 11 CLK 10 BUTT/BESS 9 8 VOUT NC J PACKAGE 14-LEAD CERDIP N PACKAGE 14-LEAD PDIP TJMAX = 150C, JA = 65C/W (J) TJMAX = 110C, JA = 65C/W (N) Consult factory for Industrial grade parts. ELECTRICAL CHARACTERISTICS VS = 7.5V, RL = 10k, fCLK = 400kHz, TA = Operating Temperature Range, unless otherwise specified. PARAMETER Passband Gain 0.1Hz at 0.25fCUTOFF (Note 3) Gain at 0.50fCUTOFF (Note 3) Gain at 0.90fCUTOFF (Note 3) Gain at 0.95fCUTOFF (Note 3) Gain at fCUTOFF (Note 3) Gain at 1.44fCUTOFF (Note 3) Gain at 2.0fCUTOFF (Note 3) Gain with fCLK = 20kHz (Note 3) Gain with VS = 2.375V (Note 3) Input Frequency Range CONDITIONS fIN = 1kHz, (fCLK/fC) = 100:1 fIN = 1kHz, (fCLK/fC) = 50:1 fIN = 2kHz, (fCLK/fC) = 100:1 fIN = 4kHz, (fCLK/fC) = 50:1 fIN = 3.6kHz, (fCLK/fC) = 100:1 fIN = 3.8kHz, (fCLK/fC) = 100:1 fIN = 4kHz, (fCLK/fC) = 100:1 fIN = 8kHz, (fCLK/fC) = 50:1 fIN = 5.76kHz, (fCLK/fC) = 100:1 fIN = 8kHz, (fCLK/fC) = 100:1 fIN = 200Hz, (fCLK/fC) = 100:1 fIN = 400kHz, fIN = 2kHz, (fCLK/fC) = 100:1 fIN = 400kHz, fIN = 4kHz, (fCLK/fC) = 100:1 (fCLK/fC) = 100:1 (fCLK/fC) = 50:1 q q q q q q q q q q 2 U U W WW U W (Note 1) Operating Temperature Range LTC1164-5C ...................................... - 40C to 85C LTC1164-5M .................................... - 55C to 125C Storage Temperature Range ................ - 65C to 150C Lead Temperature (Soldering, 10 sec)................. 300C TOP VIEW 50:1 MODE 1 VIN 2 GND 3 V+ 4 GND 5 NC 6 LP6 7 CONNECT 1 8 S PACKAGE 16-LEAD PLASTIC SW TJMAX = 110C, JA = 85C/W 16 CONNECT 2 15 50:1 MODE 14 V - 13 NC 12 CLK 11 BUTT/BESS 10 NC 9 VOUT ORDER PART NUMBER LTC1164-5CS MIN - 0.5 - 0.5 - 0.45 - 0.35 - 2.50 - 4.10 - 4.20 - 20.5 - 45.0 - 4.50 - 0.50 - 4.20 LTC1164-5C TYP - 0.10 0.10 - 0.20 - 0.10 -1.90 - 2.60 - 3.40 - 3.80 -19.0 - 43.0 - 3.40 - 0.10 - 3.40 0 - UNITS dB dB dB dB dB dB dB dB dB dB dB dB dB kHz kHz LTC1164-5 ELECTRICAL CHARACTERISTICS VS = 7.5V, RL = 10k, fCLK = 400kHz, TA = Operating Temperature Range, unless otherwise specified. PARAMETER Maximum fCLK CONDITIONS VS 7.5V VS = 5.0V VS = Single 5V (GND = 2V) Input at GND, f = fCLK, Square Wave 5V, (fCLK/fC) = 100:1 5V, (fCLK/fC) = 50:1 Input at GND, 1Hz f < fCLK 5V, (fCLK/fC) = 100:1 5V, (fCLK/fC) = 50:1 70 VS = 2.375V VS = 5.0V VS = 7.5V VS = 5V, (fCLK/fC) = 100:1 VS = 5V, (fCLK/fC) = 100:1 VS = 2.375V, TA 25C q q q q MIN LTC1164-5C TYP 1.5 1.0 1.0 200 100 100 5% 115 5% 100 1.50 4.10 5.90 50 100 2.5 4.5 MAX UNITS MHz MHz MHz VRMS VRMS VRMS VRMS Clock Feedthrough Wideband Noise Input Impedance Output DC Voltage Swing 160 k V V V 1.25 3.70 5.40 Output DC Offset Output DC Offset TempCo Power Supply Current 160 4.0 4.5 7.0 8.0 11.0 12.5 8 mV V/C mA mA mA mA mA mA V VS = 5.0V, TA 25C q VS = 7.5V, TA 25C q 7.0 2.375 Power Supply Range The q denotes specifications which apply over the full operating temperature range. Note 1: Absolute Maximum Ratings are those values beyond which life of the device may be impaired. Note 2: Connecting any pin to voltages greater than V + or less than V - may cause latchup. It is recommended that no sources operating from external supplies be applied prior to power-up of the LTC1164-5. Note 3: All gains are measured relative to passband gain. The filter cutoff frequency is abbreviated as fCUTOFF or fC. TYPICAL PERFOR A CE CHARACTERISTICS Gain vs Frequency 0 -10 -20 A B C A. fCLK = 100kHz fCUTOFF = 1kHz (100:1, PIN 10 TO V -) B. fCLK = 375kHz fCUTOFF = 2.68kHz (140:1, PIN 10 GND) C. fCLK = 500kHz fCUTOFF = 10kHz (50:1, PIN 10 TO V +, PINS 1-13 SHORTED) GAIN (dB) -40 -50 -60 -70 -80 0.1 VS = 5V TA = 25C 1 10 FREQUENCY (kHz) 50 GAIN (dB) -30 UW Passband Gain and Phase vs Frequency 0 GAIN 0 PHASE (DEG) -5 -90 -10 -15 VS = 5V fCLK = 50kHz fCUTOFF = 1kHz (50:1, PIN 10 TO V +, PINS 1-13 SHORTED) TA = 25C 0.2 -180 PHASE -270 0.4 0.8 0.6 FREQUENCY (kHz) 1.0 LTC1164-5 * G02 LTC1164-5 * G01 3 LTC1164-5 TYPICAL PERFOR A CE CHARACTERISTICS Passband Gain and Phase vs Frequency Passband Gain and Phase vs Frequency 0 GAIN (dB) GAIN (dB) -5 -10 VS = 5V fCLK = 100kHz fCUTOFF = 1kHz (100:1, PIN 10 TO V -) TA = 25C 0.2 0.4 0.8 0.6 FREQUENCY (kHz) 1.0 LTC1164-5 * G03 -15 -20 Group Delay vs Frequency 500 450 400 VS = 7.5V TA = 25C A. fCLK = 500kHz (BUTTERWORTH 100:1) fCUTOFF = 5kHz B. fCLK = 750kHz (BESSEL 140:1) fCUTOFF = 5.36kHz 0.5 0 -0.5 GROUP DELAY (s) 350 300 250 200 150 100 50 0 0.5 1.5 2.5 3.5 4.5 5.5 FREQUENCY (kHz) 6.5 7.5 B A GAIN (dB) Maximum Passband over Temperature for VS = 7.5V, 50:1 0.5 0 -0.5 GAIN (dB) -1.0 -1.5 -2.0 -2.5 -3.0 -3.5 -4.0 1 10 FREQUENCY (kHz) 30 LTC1164-5 * G07 TA = 70C TA = -40C GAIN (dB) VS = 7.5V fCLK = 1.5MHz (50:1) fCUTOFF = 30kHz 4 UW 0 PHASE (DEG) 0 GAIN 0 PHASE (DEG) -90 -5 PHASE -10 VS = 5V fCLK = 150kHz fCUTOFF = 1.07kHz (140:1, PIN 10 TO GND) TA = 25C 0.2 0.4 0.8 0.6 FREQUENCY (kHz) 1.0 LTC1164-5 * G04 -90 -180 -180 -270 -15 -270 -360 -20 -360 Passband vs Frequency and fCLK A. fCLK = 200kHz fCUTOFF = 4kHz B. fCLK = 300kHz fCUTOFF = 6kHz C. fCLK = 500kHz fCUTOFF = 10kHz D. fCLK = 750kHz fCUTOFF = 15kHz E. fCLK = 1MHz fCUTOFF = 20kHz F. fCLK = 1.5MHz fCUTOFF = 30kHz AB C DE F -1.0 -1.5 -2.0 -2.5 -3.0 -3.5 -4.0 VS = 7.5V 50:1 TA = 25C 1 FREQUENCY (kHz) 10 30 0.1 LTC1164-5 * G05 LTC1164-5 * G06 Passband vs Frequency and fCLK 0.5 0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0 -3.5 VS = 7.5V 100:1 TA = 25C 1 FREQUENCY (kHz) 10 20 A B CD E A. fCLK = 200kHz fCUTOFF = 2kHz B. fCLK = 500kHz fCUTOFF = 5kHz C. fCLK = 750kHz fCUTOFF = 7.5kHz D. fCLK = 1MHz fCUTOFF = 10kHz E. fCLK = 1.5MHz fCUTOFF = 15kHz -4.0 0.1 LTC1164-5 * G08 LTC1164-5 TYPICAL PERFOR A CE CHARACTERISTICS Passband vs Frequency and fCLK 0.5 0 - 0.5 GAIN (dB) -1.5 -2.0 -2.5 - 3.0 - 3.5 A VS = 7.5V, 140:1 (BESSEL RESPONSE) TA = 25C 1 FREQUENCY (kHz) 10 LTC1164-5 * G09 GAIN (dB) -1.0 - 4.0 0.1 Maximum Passband over Temperature for VS = 5V, 50:1 0.5 0 -0.5 GAIN (dB) -1.5 -2.0 -2.5 -3.0 -3.5 -4.0 1 FREQUENCY (kHz) LTC1164-5 * G011 GAIN (dB) -1.0 VS = 5V fCLK = 1MHz fCUTOFF = 20kHz 10 20 Maximum Passband over Temperature for VS = 5V, 100:1 0.5 0 -0.5 GAIN (dB) GAIN (dB) -1.0 -1.5 -2.0 -2.5 -3.0 -3.5 -4.0 0.5 VS = 5V fCLK = 1MHz (100:1) fCUTOFF = 10kHz 1 FREQUENCY (kHz) LTC1164-5 * G13 UW B Passband vs Frequency and fCLK A. fCLK = 150kHz fCUTOFF = 1.07kHz B. fCLK = 450kHz fCUTOFF = 3.21kHz C. fCLK = 750kHz fCUTOFF = 5.36kHz D. fCLK = 1MHz fCUTOFF= 7.14kHz E. fCLK = 1.5MHz fCUTOFF = 10.71kHz 0.5 0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0 -3.5 -4.0 1 FREQUENCY (kHz) LTC1164-5 * G10 A B C D A. fCLK = 250kHz fCUTOFF = 5kHz B. fCLK = 500kHz fCUTOFF = 10kHz C. fCLK = 750kHz fCUTOFF = 15kHz D. fCLK = 1MHz fCUTOFF = 20kHz CD E VS = 5V 50:1 TA = 25C 10 20 Passband vs Frequency and fCLK 0.5 0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0 -3.5 VS = 5V 100:1 TA = 25C 1 FREQUENCY (kHz) 10 LTC1164-5 * G12 TA = 70C TA = -40C A B C DE A. fCLK = 200kHz fCUTOFF = 2kHz B. fCLK = 300kHz fCUTOFF = 3kHz C. fCLK = 500kHz fCUTOFF = 5kHz D. fCLK = 750kHz fCUTOFF = 7.5kHz E. fCLK = 1MHz fCUTOFF = 10kHz -4.0 0.1 Passband vs Frequency and fCLK 0.5 0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0 -3.5 -4.0 10 1 FREQUENCY (kHz) LTC1164-5 * G14 TA = 70C TA = -40C A B C D A. fCLK = 250kHz fCUTOFF = 5kHz B. fCLK = 500kHz fCUTOFF = 10kHz C. fCLK = 750kHz fCUTOFF = 15kHz D. fCLK = 1MHz fCUTOFF = 20kHz VS = SINGLE 5V 50:1 TA = 25C 10 20 5 LTC1164-5 TYPICAL PERFOR A CE CHARACTERISTICS Maximum Passband over Temperature for Single 5V, 50:1* -40 0.5 0 -0.5 TA = 70C -50 TA = -40C THD + NOISE (dB) THD + NOISE (dB) -60 -70 -80 -90 -100 0.1 7.5V SINGLE 5V 5V GAIN (dB) -1.0 -1.5 -2.0 -2.5 -3.0 -3.5 -4.0 1 FREQUENCY (kHz) LTC1164-5 * G015 VS = SINGLE 5V fCLK = 1MHz (50:1) fCUTOFF = 20kHz 10 THD + Noise vs Frequency -40 -50 THD + NOISE (dB) -40 THD + NOISE (dB) -60 -70 -80 -90 -60 -70 -80 -90 THD + NOISE (dB) VIN = 2VRMS 7.5V, 50:1 fCLK = 1MHz (5 REPRESENTATIVE UNITS) -100 1 FREQUENCY (kHz) LTC1164-5 * G18 10 THD + Noise vs Frequency -40 -50 VIN = 1VRMS 5V, 100:1 fCLK = 500kHz (5 REPRESENTATIVE UNITS) THD + NOISE (dB) THD + NOISE (dB) -60 -70 -80 -90 THD + NOISE (dB) -100 1 3 2 FREQUENCY (kHz) 4 5 * See also Passband vs Frequency and fCLK for Single 5V, 50:1; THD + Noise vs RMS Input for Single 5V, 50:1; and Maximum Passband for Single 5V, 50:1, for Two Ground Bias Levels. 6 UW 20 LTC1164-5 * G21 THD + Noise vs RMS Input, 50:1 -40 fIN = 1kHz fCLK = 500kHz THD + Noise vs RMS Input, 100:1 fIN = 1kHz fCLK = 500kHz SINGLE 5V -60 -70 -80 -90 -100 0.1 7.5V 5V -50 1 FREQUENCY (kHz) 5 LTC1164-5 * G16 1 FREQUENCY (kHz) 5 LTC1164-5 * G17 THD + Noise vs Frequency -40 VIN = 2VRMS 7.5V, 100:1 fCLK = 500kHz (5 REPRESENTATIVE UNITS) THD + Noise vs Frequency VIN = 1VRMS 5V, 50:1 fCLK = 500kHz (5 REPRESENTATIVE UNITS) -50 -50 -60 -70 -80 -90 -100 1 -100 1 3 2 FREQUENCY (kHz) 4 5 5 FREQUENCY (kHz) 10 LTC1164-5 * G20 LTC1164-5 * G19 THD + Noise vs Frequency -40 -50 -60 -70 -80 -90 -100 1 5 FREQUENCY (kHz) 10 LTC1164-5 * G22 THD + Noise vs Frequency -50 -54 -58 -62 -66 -70 -74 -78 -82 -86 -90 0.5 1 FREQUENCY (kHz) 5 LTC1164-5 * G23 VIN = 0.7VRMS SINGLE 5V SUPPLY 50:1, fCLK = 500kHz fC = 10kHz (5 REPRESENTATIVE UNITS) VIN = 2VRMS VS = 7.5V, 140:1 fCLK = 750kHz fC = 5.36kHz (5 REPRESENTATIVE UNITS) LTC1164-5 TYPICAL PERFOR A CE CHARACTERISTICS THD + Noise vs Input Voltage -50 -54 THD + WIDEBAND NOISE (dB) fIN = 1kHz, 140:1 fCLK = 750kHz -58 -62 -66 -70 -74 -78 -82 -86 -90 0.1 VS = 7.5V 1 INPUT VOLTAGE (VRMS) 5 LTC1164-5 * G24 VS = 5V 0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0 2 4 6 8 10 12 14 16 18 20 22 FREQUENCY (kHz) LTC1164-5 * TPC25 THD + NOISE (dB) PHASE (DEG) VS = 2.5V Phase Matching vs Frequency 10 TOTAL PHASE DIFFERENCE (DEG) MAXIMUM PHASE DIFFERENCE BETWEEN ANY TWO UNITS (SAMPLE OF 50 UNITS) VS 5V TA 70C fCLK 500KHz A. BUTTERWORTH (fCLK / fCUTOFF = 100:1 OR 50:1) B. BESSEL (fCLK /fCUTOFF = 140:1) 8 6 PSRR (dB) 4 A 2 B 0 0 1.0 0.4 0.6 0.8 0.2 FREQUENCY (FREQUENCY/fCUTOFF) Power Supply Current vs Power Supply Voltage 12 11 10 9 CURRENT (mA) 2V/DIV 7 6 5 4 3 2 1 0 0 1 234 5678 POWER SUPPLY (V + OR V -) 9 10 125C 8 -55C 500s/DIV BUTTERWORTH RATIO = 100:1 fCLK = 500kHz fC = 5kHz VS = 7.5V 1164-5 G30 2V/DIV UW 25C LTC1164-5 * G29 Maximum Passband for Single 5V, 50:1, for Two Ground Bias Levels 2.0 1.5 1.0 0.5 GND = 2.5V TA = 70C fCLK = 1MHz -40 -45 -50 -55 -60 -65 -70 -75 -80 -85 THD + Noise vs RMS Input for Single 5V, 50:1 fCLK = 1MHz TA =25C GND = 2V GND = 2V GND = 2.5V -90 0.50 0.75 1.00 1.25 INPUT (VRMS) 1.50 LTC1164-5 G26 Power Supply Rejection Ratio vs Frequency 10 0 -10 -20 -30 -40 -50 -60 -70 -80 1.2 fCUTOFF = 1kHz V+ V- -90 20 100 1k FREQUENCY (Hz) 10k 50k LTC1164-5 * G27 LTC1164-5 * G28 Transient Response VIN = 3V, 500Hz Square Wave Transient Response VIN = 3V, 500Hz Square Wave 500s/DIV BESSEL RATIO = 140:1 fCLK = 700kHz fC = 5kHz VS = 7.5V 1164-5 G31 7 LTC1164-5 PI FU CTIO S Power Supply (Pins 4, 12) The V + (Pin 4) and the V - (Pin 12) should be bypassed with a 0.1F capacitor to an adequate analog ground. The filter's power supplies should be isolated from other digital or high voltage analog supplies. A low noise linear supply is recommended. Using a switching power supply will lower the signal-to-noise ratio of the filter. The supply during power-up should have a slew rate less than 1V/s. When V + is applied before V -, and V - can be more positive than ground, a signal diode must be used to clamp V -. Figures 1 and 2 show typical connections for dual and single supply operation. V- 1 VIN V+ 2 3 4 5 0.1F 6 7 LTC1164-5 14 13 12 11 10 9 8 + GND DIGITAL SUPPLY 1k CLOCK SOURCE * OPTIONAL (SEE TEXT) Figure 1. Dual Supply Operation for fCLK/fCUTOFF = 100:1 VIN 5V V + 16V 0.1F 10k 10k + 1F VOUT 1164-5 F02 Figure 2. Single Supply Operation for fCLK/fCUTOFF = 100:1 8 U 1 2 3 4 5 6 7 U U Clock Input (Pin 11) Any TTL or CMOS clock source with a square-wave output and 50% duty cycle (10%) is an adequate clock source for the device. The power supply for the clock source should not be the filter's power supply. The analog ground for the filter should be connected to clock's ground at a single point only. Table 1 shows the clock's low and high level threshold value for a dual or single supply operation. A pulse generator can be used as a clock source provided the high level ON time is greater than 0.5s. Sine waves are not recommended for clock input frequencies less than 100kHz, since excessively slow clock rise or fall times generate internal clock jitter (maximum clock rise or fall time 1s). The clock signal should be routed from the right side of the IC package to avoid coupling into any input or output analog signal path. A 1k resistor between clock source and Pin 11 will slow down the rise and fall times of the clock to further reduce charge coupling, Figures 1 and 2. Table 1. Clock Source High and Low Threshold Levels POWER SUPPLY Dual Supply > 3.4V Dual Supply 3.4V Single Supply V+ > 6.8V, V - = 0V Single Supply V+ < 6.8V, V - = 0V HIGH LEVEL V +/3 V +/3 V +* 0.65 V +/3 LOW LEVEL 0.5V V - + 0.5V 0.5V + 1/2V + 0.5V * 0.1F VOUT 1164-5 F01 14 13 12 LTC1164-5 11 10 9 8 + GND DIGITAL SUPPLY 1k CLOCK SOURCE Analog Ground (Pins 3, 5) The filter performance depends on the quality of the analog signal ground. For either dual or single supply operation, an analog ground plane surrounding the package is recommended. The analog ground plane should be connected to any digital ground at a single point. For dual supply operation, Pins 3 and 5 should be connected to the analog ground plane. For single supply operation Pins 3 and 5 should be biased at 1/2 supply and they should be bypassed to the analog ground plane with at least a 1F capacitor (Figure 2). For single 5V operation at the highest fCLK of 1MHz, Pins 3 and 5 should be biased at 2V. This minimizes passband gain and phase variations (see Typical Performance Characteristics curves: Maximum Passband for Single 5V, 50:1; and THD + Noise vs RMS Input for Single 5V, 50:1). LTC1164-5 PI FU CTIO S Butterworth/Bessel (Pin 10) The DC level at Pin 10 determines the ratio of the clock frequency to the cutoff frequency of the filter. Pin 10 at V + gives a 50:1 ratio and a Butterworth response (pins 1 to 13 are shorted for 50:1 only). Pin 10 at V - gives a 100:1 Butterworth response. Pin 10 at ground gives a Bessel response and a ratio of 140:1. For single supply operation the ratio is 50:1 when Pin 10 is at V + (pins 1 to 13 shorted), 100:1 when Pin 10 is at ground, and 140:1 when at 1/2 supply. When Pin 10 is not tied to ground, it should be bypassed to analog ground with a 0.1F capacitor. If the DC level at Pin 10 is switched mechanically or electrically at slew rates greater than 1V/s while the device is operating, a 10k resistor should be connected between Pin 10 and the DC source. Filter Input (Pin 2) The input pin is connected internally through a 100k resistor tied to the inverting input of an op amp. Filter Output (Pins 9, 6) Pin 9 is the specified output of the filter; it can typically source or sink 1mA. Driving coaxial cables or resistive loads less than 20k will degrade the total harmonic distortion of the filter. When evaluating the device's distortion an output buffer is required. A noninverting buffer, Figure 3, can be used provided that its input common mode range is well within the filter's output swing. Pin 6 is an intermediate filter output providing an unspecified 6th order lowpass filter. Pin 6 should not be loaded. Figure 3. Buffer for Filter Output External Connection (Pins 7, 14 and 1, 13) Pins 7 and 14 should be connected together. In a printed circuit board the connection should be done under the IC package through a short trace surrounded by the analog ground plane. When the clock to cutoff frequency ratio is set at 50:1, Pin 1 should be shorted to Pin 13; if not, the passband will exhibit 1dB of gain peaking and it will deviate from a Butterworth response. Pin 1 is the inverting input of an internal op amp and it should preferably be 0.2 inches away from any other circuit trace. NC (Pin 8) Pin 8 is not connected to any internal circuit point on the device and should be preferably tied to analog ground. APPLICATIO S I FOR ATIO Clock Feedthrough Table 2. Output Clock Feedthrough VS 2.5V 5V 7.5V 50:1 60VRMS 100VRMS 150VRMS 100:1 60VRMS 200VRMS 500VRMS Clock feedthrough is defined as, the RMS value of the clock frequency and its harmonics that are present at the filter's output pin (Pin 9). The clock feedthrough is tested with the input pin (Pin 2) grounded and, it depends on PC board layout and on the value of the power supplies. With proper layout techniques the values of the clock feedthrough are shown in Table 2. Note: The clock feedthrough at 2.5V supplies is imbedded in the wideband noise of the filter. The clock waveform is a square wave. + 1k - U W U U U U U LT1056 1164-5 F03 9 LTC1164-5 APPLICATIO S I FOR ATIO Any parasitic switching transients during the rise and fall edges of the incoming clock are not part of the clock feedthrough specifications. Switching transients have frequency contents much higher than the applied clock; their amplitude strongly depends on scope probing techniques as well as grounding and power supply bypassing. The clock feedthrough, if bothersome, can be greatly reduced by adding a simple R/C lowpass network at the output of the filter pin (Pin 9). This R/C will completely eliminate any switching transient. Wideband Noise The wideband noise of the filter is the total RMS value of the device's noise spectral density and it is used to determine the operating signal-to-noise ratio. Most of its frequency contents lie within the filter passband and it cannot be reduced with post filtering. For instance, the LTC1164-5 wideband noise at 2.5V supply is 100VRMS, 95VRMS of which have frequency contents from DC up to the filter's cutoff frequency. The total wideband noise (RMS) is nearly independent of the value of the clock. The clock feedthrough specifications are not part of the wideband noise. Speed Limitations The LTC1164-5 optimizes AC performance versus power consumption. To avoid op amp slew rate limiting at maximum clock frequencies, the signal amplitude should be kept below a specified level as shown in Table 3. Table 3. Maximum VIN vs VS and fCLK POWER SUPPLY VS = 7.5V VS = 7.5V VS = 5.0V Single 5V MAXIMUM fCLK 1.5MHz 1.0MHz 1.0MHz 1.0MHz MAXIMUM VIN 1VRMS (fIN > 35kHz) 0.5VRMS (fIN > 250kHz) 3VRMS (fIN > 25kHz) 0.7VRMS (fIN > 250kHz) 2.5VRMS (fIN > 25kHz) 0.5VRMS (fIN > 100kHz) 0.7VRMS (fIN > 25kHz) 0.5VRMS (fIN > 100kHz) LOWPASS FILTER LTC1064-3 Bessel LTC1164-5 Bessel LTC1164-6 Bessel LTC1264-7 Linear Phase LTC1164-7 Linear Phase LTC1064-7 Linear Phase LTC1164-5 Butterworth LTC1164-6 Elliptic LTC1064-4 Elliptic LTC1064-1 Elliptic 10 U Aliasing Aliasing is an inherent phenomenon of sampled data systems and it occurs when input frequencies close to the sampling frequency are applied. For the LTC1164-5 case at 100:1, an input signal whose frequency is in the range of fCLK 2.5% will be aliased back into the filter's passband. If, for instance, an LTC1164-5 operating with a 100kHz clock and 1kHz cutoff frequency receives a 98kHz 10mV input signal, a 2kHz 56V alias signal will appear at its output. When the LTC1164-5 operates with a clock-tocutoff frequency of 50:1, aliasing occurs at twice the clock frequency. Table 4 shows details. Table 4. Aliasing Data (fCLK = 100kHz, VS = 5V) INPUT FREQUENCY (VIN = 1VRMS) 97.0kHz 97.5kHz 98.0kHz 98.5kHz 99.0kHz 99.5kHz 197.0kHz 197.5kHz 198.0kHz 198.5kHz 199.0kHz 199.5kHz OUTPUT LEVEL (Relative to Input) -102.0dB - 65.0dB - 45.0dB - 23.0dB - 4.0dB - 0.3dB - 23.0dB -12.0dB - 5.0dB -1.8dB -1.0dB - 0.8dB OUTPUT FREQUENCY (Aliased Frequency) 3.0kHz 2.5kHz 2.0kHz 1.5kHz 1.0kHz 0.5kHz 3.0kHz 2.5kHz 2.0kHz 1.5kHz 1.0kHz 0.5kHz (fCLK/fC) = 100:1, fCUTOFF = 1kHz (fCLK/fC) = 50:1, fCUTOFF = 2kHz W U U Table 5. Transient Response of LTC Lowpass Filters DELAY TIME* (SEC) 0.50/fC 0.43/fC 0.43/fC 1.15/fC 1.20/fC 1.20/fC 0.80/fC 0.85/fC 0.90/fC 0.85/fC RISE TIME** (SEC) 0.34/fC 0.34/fC 0.34/fC 0.36/fC 0.39/fC 0.39/fC 0.48/fC 0.54/fC 0.54/fC 0.54/fC SETTLING TIME*** (SEC) 0.80/fC 0.85/fC 1.15/fC 2.05/fC 2.20/fC 2.20/fC 2.40/fC 4.30/fC 4.50/fC 6.50/fC OVERSHOOT (%) 0.5 0 1 5 5 5 11 18 20 20 * To 50% 5%, ** 10% to 90% 5%, *** To 1% 0.5% LTC1164-5 TYPICAL APPLICATIO S Single 5V, IS = 5.2mA, 16th Order Clock-Tunable Lowpass Filter, fCLK/fCUTOFF = 60:1, -75dB Attenuation at 2.3 fCUTOFF 1 VIN 2 3 5V 0.1F 15k 4 5 6 IC1 LTC1164-5 14 13 12 11 10 9 8 5V 5V 0.1F 1 2 3 4 5 6 7 IC2 LTC1164-5 14 13 12 11 10 9 8 5V VOUT + 1F 10k Gain vs Frequency 10 0 -10 GAIN (dB) -30 -40 -50 -60 -70 -80 -90 1 10 FREQUENCY (kHz) 30 LTC1164-5 * TA03 THD + NOISE (dB) -20 VS = SINGLE 5V fCLK = 600kHz fCUTOFF = 10kHz PACKAGE DESCRIPTIO CORNER LEADS OPTION (4 PLCS) 0.045 - 0.068 (1.143 - 1.727) FULL LEAD OPTION 0.300 BSC (0.762 BSC) 0.008 - 0.018 (0.203 - 0.457) 0 - 15 NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE OR TIN PLATE LEADS 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. U U 7 fCLK 1k 1164-5 F04 THD + Noise vs Frequency -40 -45 -50 -55 -60 -65 -70 -75 -80 -85 -90 1 5 FREQUENCY (kHz) 10 LTC1164-5 * TA04 VS = SINGLE 5V VIN = 0.5VRMS fCLK = 600kHz fC = 10kHz Dimensions in inches (millimeters) unless otherwise noted. J Package 14-Lead CERDIP (Narrow 0.300, Hermetic) (LTC DWG # 05-08-1110) 0.005 (0.127) MIN 0.840 (21.336) MAX 16 15 14 13 12 11 10 9 0.023 - 0.045 (0.584 - 1.143) HALF LEAD OPTION 0.025 (0.635) RAD TYP 1 2 3 4 5 6 7 8 0.220 - 0.310 (5.588 - 7.874) 0.200 (5.080) MAX 0.015 - 0.060 (0.380 - 1.520) 0.125 (3.175) MIN 0.045 - 0.068 (1.143 - 1.727) 0.014 - 0.026 (0.360 - 0.660) 0.100 0.010 (2.540 0.254) J16 1197 11 LTC1164-5 TYPICAL APPLICATIO S 8th Order Butterworth Lowpass Filter fCLK/fC = 50:1 1 VIN V+ 0.1F 2 3 4 14 13 12 LTC1164-5 11 10 9 8 1164-5 TA06 V- fCLK V+ VOUT 0.1F + 5 6 7 1164-5 TA05 PACKAGE DESCRIPTIO 0.300 - 0.325 (7.620 - 8.255) 0.130 0.005 (3.302 0.127) 0.020 (0.508) MIN 0.009 - 0.015 (0.229 - 0.381) 0.005 (0.125) MIN 0.100 0.010 (2.540 0.254) *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm) +0.035 0.325 -0.015 8.255 +0.889 -0.381 ( ) 0.125 (3.175) MIN 0.291 - 0.299** (7.391 - 7.595) 0.010 - 0.029 x 45 (0.254 - 0.737) 0.093 - 0.104 (2.362 - 2.642) 0.037 - 0.045 (0.940 - 1.143) 16 15 0 - 8 TYP 0.009 - 0.013 (0.229 - 0.330) NOTE 1 0.016 - 0.050 (0.406 - 1.270) NOTE: 1. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS. THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 1 2 3 4 5 6 7 8 S16 (WIDE) 0396 RELATED PARTS PART NUMBER LTC1069-1 LTC1069-6 DESCRIPTION Low Power, 8th Order Elliptic Lowpass Filter Very Low Power, 8th Order Elliptic Lowpass Filter COMMENTS Operates from a Single 3.3V to 5V Supply Optimized for 3V/5V Single Supply Operation, Consumes 1mA at 3V 11645as, sn11645 LT/TP 1098 2K REV A * PRINTED IN USA 12 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com U U 8th Order Butterworth Lowpass Filter fCLK/fC = 100:1 1 VIN + 8th Order Linear Phase Lowpass Filter fCLK/fC = 140:1 1 VIN 2 3 V+ 0.1F 4 5 LTC1164-5 14 13 12 11 10 9 8 VOUT fCLK V- 0.1F 14 13 12 LTC1164-5 11 10 9 8 VOUT fCLK V- 0.1F 2 3 V 4 + 5 6 7 0.1F 6 7 1164-5 TA07 Dimensions in inches (millimeters) unless otherwise noted. N Package 14-Lead PDIP (Narrow 0.300) (LTC DWG # 05-08-1510) 0.045 - 0.065 (1.143 - 1.651) 0.770* (19.558) MAX 14 13 12 11 10 9 8 0.065 (1.651) TYP 0.018 0.003 (0.457 0.076) 0.255 0.015* (6.477 0.381) 1 2 3 4 5 6 7 N14 1197 SW Package 16-Lead Plastic Small Outline (Wide 0.300) (LTC DWG # 05-08-1620) 0.398 - 0.413* (10.109 - 10.490) 14 13 12 11 10 9 0.050 (1.270) TYP 0.004 - 0.012 (0.102 - 0.305) NOTE 1 0.394 - 0.419 (10.007 - 10.643) 0.014 - 0.019 (0.356 - 0.482) TYP (c) LINEAR TECHNOLOGY CORPORATION 1993 |
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