LTC1164-6 Low Power 8Th Order Pin Selectable Elliptic Or Linear Phase Lowpass Filter

LTC1164-6 Low Power 8th Order Pin Selectable Elliptic or Linear Phase Lowpass Filter

FEATURES DESCRIPTIO U ■ 8th Order Pin Selectable Elliptic or Bessel Filter The LTC®1164-6 is a monolithic 8th order elliptic lowpass ■ 4mA Supply Current with ±5V Supplies filter featuring clock-tunable cutoff frequency and low ■ 64dB Attenuation at 1.44 fCUTOFF (Elliptic Response) power supply current. Low power operation is achieved ■ fCUTOFF Up to 30kHz (50:1 fCLK to fCUTOFF Ratio) without compromising noise or distortion performance. ■ 110µVRMS Wideband Noise with ±5V Supplies At ±5V supplies the LTC1164-6 uses only 4mA supply ■ Operates at Single 5V Supply with 1VRMS current while keeping wideband noise below 110µVRMS. Input Range With a single 5V supply, the LTC1164-6 can provide up to ■ Operates Up to ±8V Supplies 10kHz cutoff frequency and 80dB signal-to-noise ratio ■ TTL/CMOS Compatible Clock Input while consuming only 2.5mA. ■ No External Components The LTC1164-6 provides an elliptic lowpass rolloff with ■ Available in 14-Pin Dip and 16-Pin SO Wide Packages

stopband attenuation of 64dB at 1.44 fCUTOFF and an fCLK-

– U to-fCUTOFF ratio of 100:1 (Pin 10 to V ). For a ratio of 100:1, fCUTOFF can be clock-tuned up to 10kHz. For a fCLK-to- APPLICATIO S + fCUTOFF ratio of 50:1 (Pin 10 to V ), the LTC1164-6 ■ Antialiasing Filters provides an elliptic lowpass filter with fCUTOFF frequencies ■ Battery-Operated Instruments up to 20kHz. When Pin 10 is connected to ground, the ■ Telecommunication Filters LTC1164-6 approximates an 8th order linear phase response with 65dB attenuation at 4.5 f –3dB and fCLK /f–3dB ratio of 160:1. The LTC1164-6 is pin compatible with the LTC1064-1. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.

TYPICAL APPLICATIO U

10kHz Anti-Aliasing Elliptic Filter Frequency Response

1 14 NC 0 2 13 VIN NC –10 3 12 –8V –20 4 11 8V LTC1164-6 CLK = 1MHz –30 5 10 –8V –40 6 9 VOUT GAIN (dB) –50 7 8 –60

1164-6 TA01 –70 –80 WIDEBAND NOISE = 115µVRMS NOTE: THE CONNECTION FROM PIN 7 TO PIN 14 SHOULD BE MADE UNDER THE PACKAGE. THE POWER SUPPLIES SHOULD BE BYPASSED 1 10 100 BY A 0.1µF CAPACITOR AS CLOSE TO THE PACKAGE AS POSSIBLE. FREQUENCY (kHz)

1164-6 TA02 11646fa 1

LTC1164-6

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ABSOLUTEXIA U RA TI GU S (Note 1) Total Supply Voltage (V + to V –) ...... 16V Operating Temperature Range Input Voltage (Note 2) ...... (V ++ 0.3V) to (V – – 0.3V) LTC1164-6C ...... –40°C to 85°C Output Short-Circuit Duration ...... Indefinite LTC1164-6M (OBSOLETE) ...... – 55°C to 125°C Power Dissipation...... 400mW Storage Temperature Range ...... – 65°C to 150°C

Burn-In Voltage ...... 16V Lead Temperature (Soldering, 10 sec)...... 300°C WU

PACKAGE/ORDER I FOR ATIO U

TOP VIEW ORDER PART ORDER PART NC 1 14 CONNECT 2 NUMBER TOP VIEW NUMBER

VIN 2 13 NC NC 1 16 CONNECT 2 3 12 V– LTC1164-6CN LTC1164-6CSW GND VIN 2 15 NC + V 4 11 CLK GND 3 14 V– GND 5 10 ELL/BESS V+ 4 13 NC LP6 6 9 VOUT GND 5 12 CLK CONNECT 1 7 8 NC NC 6 11 ELL/BESS

N PACKAGE LP6 7 10 NC 14-LEAD PDIP CONNECT 1 8 9 VOUT TJMAX = 110°C, θJA = 65°C/W J PACKAGE 14-LEAD CERDIP SW PACKAGE 16-LEAD PLASTIC SO TJMAX = 150°C, θJA = 65°C/W LTC1164-6CJ OBSOLETE PACKAGE LTC1164-6MJ TJMAX = 110°C, θJA = 85°C/W Consider the N14 Package as an Alternate Source Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges.

ELECTRICAL CHARA C TERISTICS The ● denotes specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = ±7.5V, RL = 10k, TA = 25°C, fCLK = 400kHz, TTL or CMOS level (maximum clock rise or fall time ≤ 1µs) and all gain measurements are referenced to passband gain, unless otherwise specified. (fCLK/fCUTOFF) = 4kHz at 100:1 and 8kHz at 50:1. PARAMETER CONDITIONS MIN TYP MAX UNITS

Passband Gain 0.1Hz to 0.25 fCUTOFF (Note 4) fIN = 1kHz, (fCLK/fC) = 100:1 ● –0.50 – 0.15 0.25 dB Passband Ripple with VS = Single 5V 1Hz to 0.8 fC (Table 2) 0.1 to – 0.3 dB Gain at 0.50 fCUTOFF (Note 3) fIN = 2kHz, (fCLK/fC) = 100:1 ● –0.45 –0.10 0.10 dB Gain at 0.90 fCUTOFF (Note 3) fIN = 3.6kHz, (fCLK/fC) = 100:1 ● –0.75 – 0.30 0.10 dB Gain at 0.95 fCUTOFF (Note 3) fIN = 3.8kHz, (fCLK/fC) = 100:1 ● –1.40 – 0.70 – 0.40 dB Gain at fCUTOFF (Note 3) fIN = 4kHz, (fCLK/fC) = 100:1 ● –3.70 –2.70 –2.30 dB fIN = 8kHz, (fCLK/fC) = 50:1 ● –3.10 –2.10 –1.50 dB Gain at 1.44 fCUTOFF (Note 3) fIN = 5.76kHz, (fCLK/fC) = 100:1 ● –75 –64 –58 dB Gain at 2.0 fCUTOFF (Note 3) fIN = 8kHz, (fCLK/fC) = 100:1 ● –75 –64 –58 dB Gain with fCLK = 20kHz fIN = 200Hz, (fCLK/fC) = 100:1 –3.70 –2.70 –2.30 dB Gain with VS = ±2.375V fIN = 400kHz, fIN = 2kHz, (fCLK/fC) = 100:1 –0.50 –0.10 0.30 dB fIN = 400kHz, fIN = 4kHz, (fCLK/fC) = 100:1 –3.50 –2.50 –2.00 dB Input Frequency Range (Tables 3, 4) (fCLK/fC) = 100:1 0 –

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Maximum fCLK (Table 3) VS ≥ ±7.5V 1.5 MHz VS ≤ ±5V 1.0 MHz VS = Single 5V, AGND = 2V 1.0 MHz Clock Feedthrough Input at GND, f = fCLK, Square Wave VS = ±7.5V, (fCLK/fC) = 100:1 500 µVRMS VS = ±5V, (fCLK/fC) = 50:1 200 µVRMS Wideband Noise Input at GND, 1Hz ≤ f < fCLK VS = ±7.5V 115 ± 5% µVRMS VS = ±2.5V 100 ± 5% µVRMS Input Impedance 45 75 110 kΩ Output DC Voltage Swing VS = ±2.375V ● ±1.25 ±1.50 V VS = ±5V ● ±3.70 ±4.10 V VS = ±7.5V ● ±5.40 ±5.90 V Output DC Offset VS = ±5V, (fCLK/fC) = 100:1 ±100 ±160 mV Output DC Offset Tempco VS = ±5V, (fCLK/fC) = 100:1 ±100 µV/°C Power Supply Current VS = ±2.375V, TA > 25°C 2.5 4.0 mA ● 4.5 mA

VS = ±5V, TA > 25°C 4.5 7.0 mA ● 8.0 mA

VS = ±7.5V, TA > 25°C 7.0 11.0 mA ● 12.5 mA Power Supply Range ±2.375 ±8V Note 1: Stresses beyond those listed under Absolute Maximum Ratings Note 2: Connecting any pin to voltages greater than V+ or less than V – may cause permanent damage to the device. Exposure to any Absolute may cause latch-up. It is recommended that no sources operating from Maximum Rating condition for extended periods may affect device external supplies be applied prior to power-up of the LTC1164-6. reliability and lifetime. Note 3: All gains are measured relative to passband gain.

Note 4: The cutoff frequency of the filter is abbreviated as fCUTOFF or fC.

TYPICALPERFOR A CUW E CCHARA TERISTICS

Stopband Gain vs Frequency Stopband Gain vs Frequency (Elliptic Response) (Elliptic Response) 10 10 V = 5V V = ±5V 0 S ± 0 S fCLK = 500kHz fCLK = 250kHz –10 f = 5kHz –10 (fCLK/fC) = 50:1 C + (fCLK/fC) = 100:1 (PIN 10 AT V ) – –20 (PIN 10 AT V ) –20 TA = 25°C T = 25 C WITH EXTERNAL –30 A ° –30 SINGLE POLE LOW- –40 –40 PASS RC FILTER (f– 3dB = 10kHz) GAIN (dB) GAIN (dB) –50 –50 –60 –60 –70 –70 –80 –80 –90 –90 2184 6 8 10 12 14 16 20 22 2 4 6 8 10 12 14 1618 20 22 FREQUENCY (kHz) FREQUENCY (kHz)

1164-6 G01 1164-6 G02 11646fa 3 LTC1164-6

TYPICALPERFOR A CUW E CCHARA TERISTICS

Stopband Gain vs Frequency Passband Gain and Phase (Linear Phase Response) vs Frequency 2.0 0 10 A. RESPONSE WITHOUT V = 5V 0 S ± EXTERNAL RC FILTER 1.5 –45 f = 800kHz CLK B. RESPONSE WITH AN f = 5kHz 1.0 –90 –10 C EXTERNAL SINGLE (f /f ) = 160:1 CLK C POLE LOWPASS RC –20 (PIN 10 AT GND) 0.5 –135 FILTER (f AT 10kHz) PHASE (DEG) T = 25 C – 3dB –30 A ° 0 –180 –40 –0.5 –225

GAIN (dB) –50 GAIN (dB) –1.0 –270 VS = ±5V –60 –1.5 fCLK = 500kHz –315 A fC = 5kHz –70 –2.0 (fCLK/fC) = 100:1 –360 (PIN 10 AT V–) –80 B –2.5 –405 TA = 25°C –90 –3.0 –450 2 6 10 14 18 22 26 3034 38 42 1 2 3 4 5 FREQUENCY (kHz) FREQUENCY (kHz)

1164-6 G03 1164-6 G04

Passband Gain and Phase vs Maximum Passband over Passband Gain vs Frequency Frequency (Linear Phase Response) Temperature 3 0 0.4 0.8 A 2 –30 0.2 0.4 B 1 –60 0 C 0 PHASE 0 –90 –0.2

–0.4 PHASE (DEG) –1 –120 –0.4 A. TA = 125°C –0.8 GAIN B. TA = 85°C –2 –150 –0.6 VS = ±5V D. TA = –40°C –1.2 f = 500kHz GAIN (dB)

CLK GAIN (dB) GAIN (dB) –3 V = 5V –180 –0.8 –1.6 fC = 5kHz S ± V = ±5V (fCLK/fC) = 100:1 –4 fCLK = 800kHz –210 –1.0 S – –2.0 (PIN 10 AT V ) fC = 5kHz fCLK = 1MHz –1.2 f = 10kHz TA = 25°C –5 (fCLK/fC) = 160:1 –240 C –2.4 (10 REPRESENTA- (PIN 10 AT GND) (fCLK/fC) = 100:1 –6 –270 –1.4 (PIN 10 AT V–) –2.8 TIVE UNITS) TA = 25°C –7 –300 –1.6 0.4 1.0 1.6 2.2 2.8 3.4 4.0 1 2 3 4 5 1 5 10 FREQUENCY (kHz) FREQUENCY (kHz) FREQUENCY (kHz) 1164-6 G07 1164-6 G05 1164-6 G11

Passband Gain and Phase vs Passband vs Frequency and fCLK Frequency and fCLK 2.0 3 0 A. fCLK = 400kHz A. RESPONSE WITHOUT VS = ±5V –45 EXTERNAL SINGLE 1.5 fCUTOFF = 4kHz 2 (fCLK/fC) = 100:1 POLE RC FILTER (PIN 10 AT V–) B. fCLK = 600kHz 1 A –90 1.0 B. RESPONSE WITH AN T = 25 C fCUTOFF = 6kHz –135 A ° 0 EXTERNAL SINGLE 0.5 C. fCLK = 800kHz B –1 –180 PHASE (DEG) POLE LOWPASS RC fCUTOFF = 8kHz PHASE 0 –2 A –225 FILTER (f– 3dB AT 10kHz) D. fCLK = 1MHz –0.5 fCUTOFF = 10kHz –3 –270 B –315 GAIN (dB) –4 GAIN (dB) –1.0 V = ±5V –5 S –360 –1.5 fCLK = 250kHz –6 fC = 5kHz –405 –2.0 –7 (fCLK/fC) = 50:1 –450 A B CD (PIN 10 AT V–) –2.5 –8 –495 TA = 25°C –3.0 –9 –540 1 5 10 12345 INPUT FREQUENCY (kHz) FREQUENCY (kHz)

1164-6 G06 1164-6 G08

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TYPICALPERFOR A CUW E CCHARA TERISTICS

Maximum Passband over Passband vs Frequency and fCLK Temperature 2.0 2.0 A. fCLK = 250kHz 1.5 fCUTOFF = 5kHz 1.5 B. fCLK = 500kHz 1.0 fCUTOFF = 10kHz 1.0 0.5 C. fCLK = 1MHz 0.5 TA = 70°C fCUTOFF = 20kHz 0 0 TA = –40°C –0.5 –0.5 A B C GAIN (dB) –1.0 GAIN (dB) –1.0 VS = SINGLE 5V –1.5 –1.5 (fCLK/fC) = 50:1 VS = ±8V GND = 2V WITH –2.0 (fCLK/fC) = 50:1 –2.0 EXTERNAL RC (PIN 10 AT V+) LOWPASS FILTER –2.5 –2.5 TA = 25°C (f– 3dB = 40kHz) –3.0 –3.0 1 10 30 2184 6 8 10 12 14 16 20 22 FREQUENCY (kHz) FREQUENCY (kHz)

1164-6 G09 1164-6 G10

Group Delay vs Frequency Group Delay vs Frequency THD + Noise vs Frequency (Linear Phase Response) (Elliptic Response) (Elliptic Response) 250 700 –40 A. f = 250kHz, (f /f ) = 50:1 V = ±5V, V = 1V fCLK = 800kHz CLK CLK C –45 S IN RMS WITH EXTERNAL RC LOWPASS (20k RESISTOR PIN 14 TO V–) (fCLK/fC) = 160:1 600 FILTER (f = 10kHz) –50 f = 500kHz, f = 5kHz 200 fC = 5kHz C CLK C B. fCLK = 500kHz A (fCLK/fC) = 100:1, TA = 25°C 500 –55 (5 REPRESENTATIVE UNITS)

s) (f /f ) = 100:1 s) CLK C µ µ B 150 –60 400 –65

100 300 –70 THD + NOISE (dB) GROUP DELAY ( GROUP DELAY ( –75 200 50 VS = ±5V –80 100 f = 5kHz C –85 TA = 25°C 0 0 –90 1 2 3 4 5 6 7 8109 11 1 2 3 4 5 1 2534 FREQUENCY (kHz) FREQUENCY (kHz) FREQUENCY (kHz) 1164-6 G13 1164-6 G22 1164-6 G12

THD + Noise vs Frequency THD + Noise vs Frequency THD + Noise vs Frequency (Elliptic Response) (Elliptic Response) (Linear Phase Response) –40 –40 –40 V = SINGLE 5V, V = 0.7V V = ±5V –45 VS = ±5V, VIN = 1VRMS, –45 S IN RMS –45 S fCLK = 500kHz, fC = 10kHz, fCLK = 500kHz, fC = 5kHz, VIN = 1VRMS –50 (fCLK/fC) = 50:1, TA = 25°C, –50 (fCLK/fC) = 100:1, TA = 25°C –50 fCLK = 800kHz WITH EXTERNAL RC LOWPASS (5 REPRESENTATIVE UNITS) fC = 5kHz –55 –55 –55 FILTER (f– 3dB = 20kHz) (fCLK/fC) = 160:1 T = 25 C –60 (5 REPRESENTATIVE UNITS) –60 –60 A ° –65 –65 –65 –70 –70 –70 THD + NOISE (dB) THD + NOISE (dB) –75 THD + NOISE (dB) –75 –75 –80 –80 –80 –85 –85 –85 –90 –90 –90 1 5 10 0.5 1 5 1 2534 FREQUENCY (kHz) FREQUENCY (kHz) FREQUENCY (kHz)

1164-6 G14 1164-6 G16 1164-6 G23

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TYPICALPERFOR A CUW E CCHARA TERISTICS THD + Noise vs RMS Input THD + Noise vs RMS Input for Power Supply Current vs Power (Elliptic Response) Single 5V (Elliptic Response) Supply Voltage –40 –40 12 (fCLK/fC) = 100:1 OR 50:1 –45 –45 (fCLK/fC) = 100:1 OR 50:1 11 fIN = 1kHz, TA = 25°C –55°C fIN = 1kHz, TA = 25°C 10 –50 –50 A B 9 –55 –55 8 25°C –60 –60 7 125°C VS = ±5V –65 –65 6 5 –70 –70

CURRENT (mA) 4 THD + NOISE (dB) –75 THD + NOISE (dB) –75 3 –80 –80 VS = ±7.5V 2 –85 –85 A. GND = 2.5V 1 B. GND = 2V –90 –90 0 0.1 150.1 1 2 0 1324579 6810 + – INPUT (VRMS) INPUT (VRMS) POWER SUPPLY (V OR V )

1164-6 G17 1164-6 G18 1164-6 G19

Transient Response Transient Response

2V/DIV

1ms/DIV 1164-6 G20 1ms/DIV 1164-6 G21

VS = ±7.5V, VIN = ±3V 100Hz SQUARE WAVE VS = ±7.5V, VIN = ±3V 100Hz SQUARE WAVE

fCLK = 500kHz, (fCLK/fC) = 100:1, fCUTOFF = 5kHz fCLK = 800kHz, (fCLK/fC) = 160:1, fCUTOFF = 5kHz

ELLIPTIC RESPONSE LINEAR PHASE RESPONSE U

PI FU CTIO SUU (14-Lead Dual-In-Line Package) NC (Pins 1, 8, 13): Pins 1, 8, and 13 are not connected to at least a 1µF capacitor (Figure 2). For single 5V operation any internal circuit point on the device and should prefer- at the highest fCLK of 1MHz, Pins 3 and 5 should be biased ably be tied to analog ground. at 2V. This minimizes passband gain and phase variations (see Typical Performance Characteristics curves: Maxi- V (Pin 2): The input pin is connected internally through IN mum Passband for Single 5V, 50:1; and THD + Noise vs a 50k resistor tied to the inverting input of an op amp. RMS Input for Single 5V, 50:1). GND (Pins 3, 5): The filter performance depends on the V+ (Pins 4, 12):The V+ (Pin 4) and the V – (Pin 12) should quality of the analog signal ground. For either dual or be bypassed with a 0.1 F capacitor to an adequate analog single supply operation, an analog ground plane sur- µ ground. The filter’s power supplies should be isolated rounding the package is recommended. The analog ground from other digital or high voltage analog supplies. A low plane should be connected to any digital ground at a single noise linear supply is recommended. Using a switching point. For dual supply operation, Pins 3 and 5 should be power supply will lower the signal-to-noise ratio of the connected to the analog ground plane. For single supply filter. The supply during power-up should have a slew rate operation Pins 3 and 5 should be biased at 1/2 supply and less than 1V/ s. When V+ is applied before V – and V – they should be bypassed to the analog ground plane with µ

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LTC1164-6 U

PI FU CTIO SUU (14-Lead Dual-In-Line Package) could go above ground, a signal diode must be used to buffer, Figure 3,can be used provided that its input common clamp V. Figures 1 and 2 show typical connections for dual mode range is well within the filter’s output swing. Pin 6 is and single supply operation. an intermediate filter output providing an unspecified 6th order lowpass filter. Pin 6 should not be loaded. V– 1 14 * ELLIPTIC/LINEAR PHASE (Pin 10): The DC level at this pin 2 13 VIN 0.1µF selects the desired filter response, elliptic or linear phase 3 12 and determines the ratio of the clock frequency to the 4 11 1k V+ LTC1164-6 CLOCK SOURCE cutoff frequency of the filter. Pin 10 connected to V – 5 10 6 9 provides an elliptic lowpass filter with clock-to-fCUTOFF 0.1µF 7 8 GND + ratio of 100:1. Pin 10 connected to analog ground pro- DIGITAL SUPPLY vides a linear phase lowpass filter with a clock- to-f–3dB * OPTIONAL ratio of 160:1 and a transient response overshoot of 1%. VOUT 1164-6 F01 + When Pin 10 is connected to V the clock-to-fCUTOFF ratio Figure 1. Dual Supply Operation for fCLK/fCUTOFF = 100:1 is 50:1 and the filter response is elliptic. Bypassing Pin 10 to analog ground reduces the output DC offsets. If the DC 1 14 level at Pin 10 is switched mechanically or electrically at 2 13 VIN slew rates greater than 1V/µs while the device is operating, 3 12 1k a 10k resistor should be connected between Pin 10 and the + 4 11 V LTC1164-6 CLOCK SOURCE DC source. 0.1µF 5 10 6 9 CLK (Pin 11): Any TTL or CMOS clock source with a 10k 7 8 GND + DIGITAL SUPPLY square-wave output and 50% duty cycle (±10%) is an + adequate clock source for the device. The power supply for 10k 1µF the clock source should not be the filter’s power supply. VOUT The analog ground for the filter should be connected to 1164-6 F02 clock’s ground at a single point only. Table 1 shows the Figure 2. Single Supply Operation for fCLK/fCUTOFF = 100:1 clock’s low and high level threshold value for a dual or single supply operation. A pulse generator can be used as Table 1. Clock Source High and Low Threshold Levels a clock source provided the high level ON time is greater POWER SUPPLY HIGH LEVEL LOW LEVEL than 0.5µs. Sine waves are not recommended for clock Dual Supply = ±7.5V ≥ 2.18V ≤ 0.5V input frequencies less than 100kHz, since excessively Dual Supply = ±5V ≥ 1.45V ≤ 0.5V slow clock rise or fall times generate internal clock jitter Dual Supply = ±2.5V ≥ 0.73V ≤ – 2.0V (maximum clock rise or fall time ≤ 1µs). The clock signal Single Supply = 12V ≥ 7.80V ≤ 6.5V should be routed from the right side of the IC package to Single Supply = 5V ≥ 1.45V ≤ 0.5V avoid coupling into any input or output analog signal path. V– (Pins 7, 14): Pins 7 and 14 should be connected A 1k resistor between clock source and Pin 11 will slow together. In a printed circuit board the connection should down the rise and fall times of the clock to further reduce be done under the IC package through a short trace charge coupling, Figures 1 and 2.

surrounded by the analog ground plane. –

VOUT (Pins 9, 6): Pin 9 is the specified output of the filter; it can typically source or sink 1mA. Driving coaxial cables 1k + or resistive loads less than 20k will degrade the total LT1006, fC < 5kHz harmonic distortion of the filter. When evaluating the device’s LT1200, fC > 5kHz 1164-6 F03 distortion an output buffer is required. A noninverting Figure 3. Buffer for Filter Output 11646fa 7

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APPLICATI S I FOR ATIO U Passband Response Table 3. Clock Feedthrough V 50:1 100:1 The passband response of the LTC1164-6 is optimized for S ±2.5V 60µV 60µV a f /f ratio of 100:1. Minimum passband ripple RMS RMS CLK CUTOFF ±5V 100µVRMS 200µVRMS occurs from 1Hz to 80% of f . Athough the passband CUTOFF ±7.5V 150µVRMS 500µVRMS of the LTC1164-6 is optimized for ratio fCLK /fCUTOFF of Note: The clock feedthrough at ±2.5V supplies is imbedded in the wideband noise of the filter. (The 100:1, if a ratio of 50:1 is desired, connect a single pole clock signal is a square wave.) lowpass RC (f –3dB = 2 fCUTOFF) at the output of the filter. Any parasitic switching transients during the rise and fall The RC will make the passband gain response as flat as the edges of the incoming clock are not part of the clock 100:1 case. If the RC is omitted, and clock frequencies are feedthrough specifications. Switching transients have fre- below 500kHz the passband gain will peak by 0.4dB at quency contents much higher than the applied clock; their 90% fCUTOFF. amplitude strongly depends on scope probing techniques as well as grounding and power supply bypassing. The Table 2. Typical Passband Ripple with Single 5V Supply (fCLK/fC) = 100:1, GND = 2V, 30kHz, Fixed Single Pole, Lowpass clock feedthrough, if bothersome, can be greatly reduced RC Filter at Pin 9 (See Typical Applications) by adding a simple R/C lowpass network at the output of PASSBAND PASSBAND GAIN the filter (Pin 9). This R/C will completely eliminate any FREQUENCY (REFERENCED TO 0dB) switching transient. fCUTOFF = 1kHz fCUTOFF = 10kHz TA = 25°CTA = 0°CTA = 25°CTA = 70°C Wideband Noise % of fCUTOFF (dB) (dB) (dB) (dB) 10 0.00 0.00 0.00 0.00 The wideband noise of the filter is the total RMS value of 20 – 0.02 0.00 0.01 0.01 the device’s noise spectral density and it is used to 30 – 0.05 – 0.01 – 0.01 0.01 determine the operating signal-to-noise ratio. Most of its 40 – 0.10 – 0.02 – 0.02 0.02 50 – 0.13 – 0.03 – 0.01 0.03 frequency contents lie within the filter passband and it 60 – 0.15 – 0.01 0.01 0.05 cannot be reduced with post filtering. For instance, the 70 – 0.18 – 0.01 0.01 0.07 LTC1164-6 wideband noise at ±2.5V supply is 100µVRMS, 80 – 0.25 – 0.08 – 0.05 0.02 90 – 0.39 – 0.23 – 0.18 – 0.05 90µVRMS of which have frequency contents from DC up to fCUTOFF – 2.68 – 2.79 – 2.74 – 2.68 the filter’s cutoff frequency. The total wideband noise (µVRMS) is nearly independent of the value of the clock. The gain peaking can approximate a sin χ/χ correction for The clock feedthrough specifications are not part of the some applications. (See Typical Performance Characteristics wideband noise. curve, Passband vs Frequency and fCLK at fCLK/fC = 50:1.) When the LTC1164-6 operates with a single 5V supply and its Speed Limitations cutoff frequency is clock-tuned to 10kHz, an output single The LTC1164-6 optimizes AC performance versus power pole RC filter can also help maintain outstanding passband consumption. To avoid op amp slew rate limiting at flatness from 0°C to 70°C. Table 2 shows details. maximum clock frequencies, the signal amplitude should be kept below a specified level as shown on Table 4. Clock Feedthrough Clock feedthrough is defined as, the RMS value of the Aliasing clock frequency and its harmonics that are present at the Aliasing is an inherent phenomenon of sampled data filter’s output (Pin 9). The clock feedthrough is tested with systems and it occurs when input frequencies close to the the input (Pin 2) grounded and, it depends on PC board sampling frequency are applied. For the LTC1164-6 case, layout and on the value of the power supplies. With proper an input signal whose frequency is in the range of fCLK layout techniques the values of the clock feedthrough are ±4%, will be aliased back into the filter’s passband. If, for shown in Table 3. instance, an LTC1164-6 operating with a 100kHz clock

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LTC1164-6

U WU O

APPLICATI S I FOR ATIO U and 1kHz cutoff frequency receives a 98.5kHz, 10mVRMS Table 6. Transient Response of LTC Lowpass Filters input signal, a 1.5kHz, 10µVRMS alias signal will appear at DELAY RISE SETTLING OVER- its output. When the LTC1164-6 operates with a clock-to- TIME* TIME** TIME*** SHOOT LOWPASS FILTER (SEC) (SEC) (SEC) (%) cutoff frequency of 50:1, aliasing occurs at twice the clock frequency. Table 5 shows details. LTC1064-3 Bessel 0.50/fC 0.34/fC 0.80/fC 0.5 LTC1164-5 Linear Phase 0.43/fC 0.34/fC 0.85/fC 0 Table 4. Maximum VIN vs VS and fCLK LTC1164-6 Linear Phase 0.43/fC 0.34/fC 1.15/fC 1 POWER SUPPLY MAXIMUM f MAXIMUM V CLK IN LTC1264-7 Linear Phase 1.15/fC 0.36/fC 2.05/fC 5 7.5V 1.5MHz 1V (f > 35kHz) ± RMS IN LTC1164-7 Linear Phase 1.20/fC 0.39/fC 2.20/fC 5 1MHz 3VRMS (fIN > 25kHz) LTC1064-7 Linear Phase 1.20/fC 0.39/fC 2.20/fC 5 ≥1MHz 0.7VRMS (fIN > 250kHz) LTC1164-5 Butterworth 0.80/fC 0.48/fC 2.40/fC 11 ±5V 1MHz 2.5VRMS (fIN > 25kHz) 1MHz 0.5VRMS (fIN > 100kHz) LTC1164-6 Elliptic 0.85/fC 0.54/fC 4.30/fC 18 Single 5V 1MHz 0.7VRMS (fIN > 25kHz) LTC1064-4 Elliptic 0.90/fC 0.54/fC 4.50/fC 20 1MHz 0.5VRMS (fIN > 100kHz) LTC1064-1 Elliptic 0.85/fC 0.54/fC 6.50/fC 20 * To 50% ±5%, ** 10% to 90% ±5%, *** To 1% ±0.5% Table 5. Aliasing (fCLK = 100kHz) INPUT FREQUENCY OUTPUT LEVEL OUTPUT FREQUENCY

(VIN = 1VRMS) (Relative to Input) (Aliased Frequency) ts (kHz) (dB) (kHz) INPUT OUTPUT 90% fCLK/fC = 100:1, fCUTOFF = 1kHz 96 (or 104) –75.0 4.0 97 (or 103) – 68.0 3.0 98 (or 102) – 65.0 2.0 50% td 98.5 (or 101.5) – 60.0 1.5 99 (or 101) – 3.2 1.0 99.5 (or 100.5) – 0.5 0.5 10% tr fCLK/fC = 50:1, fCUTOFF = 2kHz 192 (or 208) –76.0 8.0 194 (or 206) – 68.0 6.0 0.54 RISE TIME (tr) = ±5% 196 (or 204) – 63.0 4.0 fCUTOFF 4.3 SETTLING TIME (t ) = ±5% 198 (or 202) – 3.4 2.0 s f (TO 1% of OUTPUT) CUTOFF 199 (or 201) – 1.3 1.0 0.85 TIME DELAY (td) = GROUP DELAY ≈ f 1164-6 F04 199.5(or 200.5) – 0.9 0.5 (TO 50% OF OUTPUT) CUTOFF

Figure 4 U

TYPICAL APPLICATI O S 8th Order Elliptic Lowpass Filter (fCLK/fC) = 50:1 1 14 2 13 V + IN V NOTES: 3 12 V – 1. OPTIONAL OUTPUT BUFFER + 4 11 1/2πRC = (2)(fCUTOFF) V LTC1164-6 fCLK 0.1µF – 2. PINS 1, 8, 13 CAN BE GROUNDED 5 10 0.1µF V+ LT®1006 OR LEFT FLOATING R 6 9 + VOUT 7 8 C 1164-6 TA06 V –

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LTC1164-6 U

TYPICAL APPLICATI O S

8th Order Elliptic Lowpass Filter (fCLK/fC) = 100:1 8th Order Linear Phase Lowpass Filter (fCLK/fC) = 160:1 1 14 1 14 2 13 2 13 VIN VIN 3 12 3 12 V – V – + 4 11 + 4 11 V LTC1164-6 fCLK 0.1µF V LTC1164-6 fCLK 0.1µF 5 10 5 10 0.1µF 0.1µF 6 9 6 9 VOUT VOUT 7 8 7 8

1164-6 TA07 1164-6 TA08

8th Order 20kHz Cutoff, Elliptic Filter Operating with a Single 5V Supply and Driving 1k, 1000pF Load 1 14 5V 5V 2 13 VIN NOTES: 3 12 1. TOTAL SUPPLY CURRENT IS = 4mA (EXCLUDING OUTPUT LOAD CURRENT) 4 11 1k f 2 7 5V LTC1164-6 CLK 51.1k = 1MHz – 2. FLAT PASSBAND UP TO 18kHz, 0.1 F 5 10 f = 20kHz µ 5V LT1200 VOUT –3dB 10k 10k 3. THD + NOISE ≤ –70dB, 6 9 3 + 1VP-P ≤ VIN ≤ 3VP-P, fIN = 1kHz 7 8 4 1k 1000pF 510pF 1164-6 TA09 0.1µF 6.65k

Single 5V, 16th Order Lowpass Filter fCUTOFF = 10kHz R1 789 1 14 1 14 Ω VS = SINGLE 5V, IS = 5mA TYP VIN 16TH ORDER LOWPASS FILTER C1 2 13 2 13 FIXED fCUTOFF, fCLK = 540kHz 0.01µF 3 12 3 12 fCUTOFF = 10kHz (f /f ) = 54:1 4 LTC1164-6 11 4 LTC1164-6 11 CLK C 5V 5V 1/2πR1C1 = 1/2πR2C2 = 2fCUTOFF IC1 IC2 5 10 5 10 0.1µF 15k 5V 0.1µF 5V 6 9 6 9 VOUT + 7 8 7 8 R2 C2 1µF 10k 7.89k 0.001µF

1k fCLK 1164-6 TA03

Gain vs Frequency THD + Noise vs Frequency 10 –40 0 –45 VS = SINGLE 5V IS = 5mA, 16TH ORDER –10 –50 ELLIPTIC LOWPASS VIN = 0.5VRMS –20 –55 fCLK = 540kHz –30 –60 fC = 10kHz –40 –65

GAIN (dB) –50 –70

V = SINGLE 5V THD + NOISE (dB) –60 S –75 IS = 5mA, 16TH ORDER –70 ELLIPTIC LOWPASS –80 fCLK = 540kHz –85 –80 fCUTOFF = 10kHz –90 –90 1 10 30 1 5 10 FREQUENCY (kHz) FREQUENCY (kHz)

1164-6 TA04 1164-6 TA05 11646fa 10 LTC1164-6

PACKAGE DESCRIPTIONU

J Package 14-Lead CERDIP (Narrow .300 Inch, Hermetic) (Reference LTC DWG # 05-08-1110)

.840 (21.336) CORNER LEADS OPTION .005 MAX (4 PLCS) (0.127) MIN 16 15 14 13 12 11 10 9

.023 – .045 (0.584 – 1.143) .025 .220 – .310 HALF LEAD (5.588 – 7.874) OPTION (0.635) .045 – .065 RAD TYP (1.143 – 1.65) FULL LEAD 1 234 5 6 78 OPTION .200 .300 BSC (5.080) (7.62 BSC) MAX .015 – .060 (0.380 – 1.520)

.008 – .018 0° – 15° (0.203 – 0.457)

.045 – .065 .125 .100 (1.143 – 1.651) (3.175) (2.54) NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE MIN .014 – .026 BSC

OR TIN PLATE LEADS (0.360 – 0.660) J16 0801 OBSOLETE PACKAGE

N Package 14-Lead PDIP (Narrow .300 Inch) (Reference LTC DWG # 05-08-1510)

.770* (19.558) MAX 14 13 12 11 10 9 8

.255 ± .015* (6.477 ± 0.381)

1 2 3 4 5 6 7

.300 – .325 .130 ± .005 .045 – .065 (7.620 – 8.255) (3.302 ± 0.127) (1.143 – 1.651)

.020 (0.508) MIN .065 .008 – .015 (1.651) (0.203 – 0.381) TYP

+.035 .325 .005 –.015 .120 .018 ± .003 +0.889 (0.127) .100 8.255 (3.048) (0.457 ± 0.076) –0.381 MIN (2.54) () MIN N14 1103 BSC NOTE: INCHES 1. DIMENSIONS ARE MILLIMETERS *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)

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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. 11 LTC1164-6

TYPICAL APPLICATIONU 8th Order Low Power, Clock-Tunable Elliptic Filter with Active RC Input Antialiasing Filter and Output Smoothing Filter C2 0.022µF

R1 R2 R3 1.15k 76.8k 5.62k 1 14 VIN + 1/2 2 13 C1 C3 LT1013 0.1µF 0.001µF 3 12 – V– + 4 11 0.1µF V LTC1164-6 fCLK – f = 1kHz 1/2 C 0.1µF 5 10 – ATTENUATION AT 10kHz = –48dB V LT1013 VOUT 6 9 + NOTES: 7 8 R1 R2 C2 1. CLOCK-TUNABLE OVER ONE DECADE 16.9k 97.6k 0.001µF C1 OF CUTOFF FREQUENCY 0.0047µF 2. BOTH INPUT AND OUTPUT RC ACTIVE FILTERS ARE 0.1dB CHEBYSHEV FILTERS 100Hz ≤ fC ≤ 1kHz WITH 1kHz RIPPLE BANDWIDTH 10kHz ≤ fCLK ≤ 100kHz fC = 1kHz ATTENUATION AT 10kHz = –30dB 1164-6 TA10

PACKAGE DESCRIPTIONU SW Package 16-Lead Plastic Small Outline (Wide .300 Inch) (Reference LTC DWG # 05-08-1620)

.030 ±.005 .050 BSC .045 ±.005 .398 – .413 TYP (10.109 – 10.490) NOTE 4 N 16 15 14 13 12 11 10 9

.420 .325 ±.005 MIN NOTE 3 .394 – .419 (10.007 – 10.643)

123 N/2 N/2

RECOMMENDED SOLDER PAD LAYOUT 1 234 5 6 78 .291 – .299 (7.391 – 7.595) NOTE 4 .093 – .104 .037 – .045 .010 – .029 × 45° (2.362 – 2.642) (0.940 – 1.143) (0.254 – 0.737) .005 (0.127) RAD MIN 0° – 8° TYP

.050 .009 – .013 (1.270) .004 – .012 (0.229 – 0.330) NOTE 3 BSC (0.102 – 0.305) .014 – .019 .016 – .050 (0.356 – 0.482) (0.406 – 1.270) TYP NOTE: INCHES 1. DIMENSIONS IN S16 (WIDE) 0502 (MILLIMETERS) 2. DRAWING NOT TO SCALE 3. 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 4. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)

RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1069-1 Low Power, 8th Order Elliptic Lowpass Operates from a Single 3.3V to ±5V Supply LTC1069-6 Very Low Power 8th Order Elliptic Lowpass Optimized for 3V/5V Single Supply Operation, Consumes 1mA at 3V

11646fa Linear Technology Corporation LT 0207 REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 12 ● ● (408) 432-1900 FAX: (408) 434-0507 www.linear.com © LINEAR TECHNOLOGY CORPORATION 1993