NSC MF6CWMX-50, MF6CWM-50, MF6CWM-100 Datasheet

MF6 6th Order Switched Capacitor Butterworth Lowpass Filter

General Description

The MF6 is a versatile easy to use, precision 6th order Butterworth lowpass active filter. Switched capacitor techniques eliminate external component requirements and allow a clock tunable cutoff frequency. The ratio of the clock frequency to the lowpass cutoff frequency is internally set to 50 to 1 (MF6-50) or 100 to 1 (MF6-100). A Schmitt trigger clock input stage allows two clocking options, either self-clocking (via an external resistor and capacitor) for stand-alone applications, or an external TTL or CMOS logic compatible clock can be used for tighter cutoff frequency control. The maximally flat passband frequency response together with a DC gain of 1 V/V allows cascading MF6 sections for higher order

filtering. In addition to the filter, two independent CMOS op amps are included on the die and are useful for any general signal conditioning applications.

Features

n No external components n Cutoff frequency accuracy of

0.3%typical

n Cutoff frequency range of 0.1 Hz to 20 kHz n Two uncommitted op amps available n 5V to 14V total supply voltage n Cutoff frequency set by external or internal clock

Block and Connection Diagrams

TRI-STATE®is a registered trademark of National Semiconductor Corporation.

All Packages

DS005065-2

Top View

Order Number MF6CWM-50

or MF6CWM-100

See NS Package Number M14B

DS005065-1

June 1999

MF6 6th Order Switched Capacitor Butterworth Lowpass Filter

Absolute Maximum Ratings (Note 11)

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.

Supply Voltage 14V Voltage at Any Pin V

−

− 0.2V, V++ 0.2V Input Current at Any Pin (Note 13) 5 mA Package Input Current (Note 13) 20 mA Power Dissipation (Note 14) 500 mW Storage Temperature −65˚C to +150˚C ESD Susceptibility (Note 12) 800V

Soldering Information

Vapor Phase (60 sec.) 215˚C Infrared (15 sec.) 220˚C

See AN-450 “Surface Mounting Methods and Their Effect on Product Reliability” (Appendix D) for other methods of

soldering surface mount devices.

Operating Ratings (Note 11)

Temperature Range T

MIN

≤ TA≤ T

MAX

MF6CWM-50, MF6CWM-100 0˚C ≤ TA≤ +70˚C Supply Voltage (V

+−V−

) 5Vto14V

Filter Electrical Characteristics

The following specifications apply for f

CLK

≤ 250 kHz (Note 3) unless otherwise specified. Boldface limits apply for T

MIN

to T

MAX

; all other limits T

25˚C.

Parameter Conditions Typical Tested Design Units

(Note 8) Limit Limit

(Note 9) (Note 10)

+5V, V

−

−5V

, Cutoff MF6-50 Min 0.1 Frequency Max 20k Hz Range MF6-100 Min 0.1 (Note 1) Max 10k Total Supply Current f

CLK

250 kHz 4.0 6.0 8.5 mA Maximum Clock Filter Output 30 mV Feedthrough Op Amp 1 Out 25 (peak-to-

Op Amp 2 Out 20 peak)

source

0.0

0.30

0.30 dB

DC Gain ≤ 2kΩ f

CLK/fc

MF6-50 49.27±0.3

49.27±1

Clock to Cutoff MF6-100 98.97

0.3

98.97±1

Frequency Ratio DC MF6-50 −200 mV Offset Voltage MF6-100 −400 Minimum Output R

10 kΩ +4.0 +3.5 +3.5 V Voltage Swing −4.1 −3.8 −3.5 Maximum Output Source 50 Short Circuit Sink 1.5 mA Current (Note 6) Dynamic Range MF6-50 83 dB (Note 2) MF6-100 81 Additional MF6-50 f

CLK

250 kHz

Magnitude f=6000 Hz −9.47 −9.47

0.6 −9.47±0.75 dB

Response Test f=4500 Hz −0.92 −0.92

0.6 −0.92±0.4

Points (Note

MF6-100 f

CLK

250 kHz

f=3000 Hz −9.48 −9.48

0.3 −9.48±0.75 dB

f=2250 Hz −0.97 −0.97

0.3 −0.97±0.4

Attenuation Rate

MF6-50 f

CLK

250 kHz

dB/

6000 Hz −36 −36 octave

8000 Hz

MF6-100 f

CLK

250 kHz dB/

3000 Hz −36 −36 octave

4000 Hz

+2.5V, V

−

−2.5V

, Cutoff MF6-50 Min 0.1 Frequency Max 10k Hz Range MF6-100 Min 0.1 (Note 1) Max 5k

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Filter Electrical Characteristics (Continued)

The following specifications apply for f

CLK

≤ 250 kHz (Note 3) unless otherwise specified. Boldface limits apply for T

MIN

to T

MAX

; all other limits T

25˚C.

Parameter Conditions Typical Tested Design Units

(Note 8) Limit Limit

(Note 9) (Note 10)

+2.5V, V

−

−2.5V

Total Supply Current f

CLK

250 kHz 2.5 4.0 4.0 mA

Maximum Clock

Filter Output 20 mV

Feedthrough Op Amp 1 Out 15 (peak-to-

Op Amp 2 Out 10 peak)

, DC Gain R

source

≤2kΩ 0.0

0.30

0.30 dB

CLK/fc

, Clock to

Cutoff Frequency

MF6-50 49.10

0.3

49.10±2

49.10±3

Ratio MF6-100 98.65

0.3

98.65±2

98.65±2.25

DC MF6-50 −200 mV Offset Voltage MF6-100 −400 Minimum Output R

10 kΩ +1.5 +1.0 +1.0 V Voltage Swing −2.2 −1.7 −1.5 Maximum

Output

Source

Short Circuit Sink 0.5 mA Current

(Note 6) Dynamic Range (Note 2) 77 dB Additional MF6-50 f

CLK

250 kHz

Magnitude f=6000 Hz −9.54 −9.54

0.6 −9.54±0.75 dB

Response Test f=4500 Hz −0.96 −0.96

0.3 −0.96±0.4

Points (Note

MF6-100 f

CLK

250 kHz

f=3000 Hz −9.67 −9.67

0.6 −9.67±0.75 dB

f=2250 Hz −1.01 −1.01

0.3 −1.01±0.4

Attenuation MF6-50 f

CLK

250 kHz dB/

Rate f

6000 Hz −36 −36 octave

8000 Hz

MF6-100 f

CLK

250 kHz dB/

3000 Hz −36 −36 octave

4000 Hz

Op Amp Electrical Characteristics

Boldface limits apply for T

MIN

to T

MAX

; all other limits T

25˚C.

Parameter Conditions Typical Tested Design Units

(Note 8) Limit Limit

(Note 9) (Note 10)

+5V, V

−

−5V

Input Offset Voltage

8.0

20 mV

Input Bias Current 10 pA CMRR (Op Amp

2 Only) V

CM1

1.8V, 60 55 dB

CM2

−2.2V

Output Voltage Swing R

10 kΩ +4.0 +3.8 +3.6 V

−4.5 −4.0 −4.0

Maximum Output Short Source 54 65 80

Circuit Current (Note 6) Sink 2.0 4.0 6.0 Slew Rate 7.0 V/µs DC Open Loop Gain 72 dB Gain Bandwidth Product 1.2 MHz

+2.5V, V

−

−2.5V

Input Offset Voltage

8.0

20 mV

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Op Amp Electrical Characteristics (Continued)

Boldface limits apply for T

MIN

to T

MAX

; all other limits T

25˚C.

Parameter Conditions Typical Tested Design Units

(Note 8) Limit Limit

(Note 9) (Note 10)

+2.5V, V

−

−2.5V

Input Bias Current 10 pA CMRR (Op-Amp

2 Only) V

CM1

+0.5V, 60 55 dB

CM2

−0.9V

Output Voltage Swing R

10 kΩ +1.5 +1.3 +1.1 V

−2.2 −1.7 −1.7 Maximum Output Short Source 24 mA Circuit Current (Note 6) Sink 1.0 Slew Rate 6.0 V/µs DC Open Loop Gain 67 dB Gain Bandwidth Product 1.2 MHz

Logic Input-Output Electrical Characteristics

(Note 5) The following specifications apply for V

−

0V unless otherwise specified. Boldface limits apply for T

MIN

MAX

; all other limits T

25˚C.

Parameter Conditions Typical Tested Design Units

(Note 8) Limit Limit

(Note 9) (Note 10) TTL CLOCK INPUT, CLK R PIN (Note 7) Maximum V

, Logical “0” 0.8 0.8 V Input Voltage Minimum V

, Logical “1” 2.0 2.0 V Input Voltage Maximum Leakage Current L Sh Pin at 2.0 2.0 µA at CLK R Pin Mid- Supply

SCHMITT TRIGGER

T+

, Positive Going Min V

10V 7.0 6.1 6.1 V

Threshold Voltage Max 8.9 8.9

Min V

5V 3.5 3.1 3.1 V

Max 4.4 4.4

T−

, Negative Going Min V

10V 3.0 1.3 1.3 V

Threshold Voltage Max 3.8 3.8

Min V

5V 1.5 0.6 0.6 V

Max 1.9 1.9

Hysteresis (V

T+−VT−

) Min V

10V 4.0 2.3 2.3 V Max 7.6 7.6 Min V

5V 2.0 1.2 1.2 V Max 3.8 3.8

Minimum Logical “1” Output

−10µA

10V 9.0 9.0 V

Voltage (Pin 11) V

5V 4.5 4.5

Maximum Logical “0” Output

10µA

10V 1.0 1.0 V

Voltage (Pin 11) V

5V 0.5 0.5

Minimum Output Source CLK R Tied V

10V 6.0 3.0 3.0 mA

Current (Pin 11) to Ground V

5V 1.5 0.75 0.75

Maximum Output Sink CLK R Tied V

10V 5.0 2.5 2.5 mA

Current (Pin 11) to V

5V 1.3 0.65 0.65

Note 1: The cutoff frequency of the filter is defined as the frequency where the magnitude response is 3.01 dB less than the DC gain of the filter. Note 2: For

5V supplies the dynamic range is referenced to 2.82 Vrms (4V peak) where the wideband noise over a 20 kHz bandwidth is typically 200 µVrms for

the MF6-50 and 250 µVrmsfortheMF6-100.For

2.5V supplies the dynamic range isreferencedto1.06Vrms (1.5V peak) where the widebandnoiseovera20kHz

bandwidth is typically 140 µVrms for both the MF6-50 and the MF6-100. Note 3: The specifications for the MF6 have been given for a clock frequency (f

CLK

) of 250 kHz and less. Above this clock frequency the cutoff frequency begins to

deviate from the specified error band of

1.0%but the filter still maintains its magnitude characteristics. See Application Hints, Section 1.5.

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Logic Input-Output Electrical Characteristics (Continued)

Note 4: Besides checking the cutoff frequency (fc) and the stopband attenuation at 2 fc, two additional frequencies are used to check the magnitude response of the

filter. The magnitudes are referenced to a DC gain of 0.0 dB. Note 5: For simplicity all the logic levels have been referenced to V

−

0V and will scale accordingly for

5V and±2.5V supplies (except for the TTL input logic lev-

els). Note 6: The short circuit source current is measured by forcing the output that is being tested to its maximum positive voltage swing and then shorting that output

to the negative supply. The short circuit sink current is measured by forcing the output that is being tested to its maximum negative voltage swing and then shorting that output to the positive supply. These are the worst-case conditions.

Note 7: The MF6 is operating with symmetrical split supplies and L.Sh is tied to ground. Note 8: Typicals are at 25˚C and represent most likely parametric norm. Note 9: Tested limits are guaranteed to National’s AOQL (Average Outgoing Quality Level). Note 10: Design limits are guaranteed, but not 100%tested. These limits are not used to calculate outgoing quality levels. Note 11: Absolute Maximum Ratings indicate limits beyond which damage to the device mayoccur. DC andACelectricalspecifications do not apply when operating

the device beyond its specified conditions.

Note 12: Human body model, 100 pF discharged through a 1.5k Ω resistor. Note 13: When the input voltage (V

) at any pin exceeds the power supply rails (V

V−or V

V+) the absolute value of current at that pin should be limited

to 5 mA or less. The 20 mA package input current limits the number of pins that can exceed the power supply boundaries witha5mAcurrent limit to four. Note 14: The maximum power dissipation must be derated at elevated temperatures and is dictated by T

JMAX

, θJA, and the ambient temperature, TA. The maximum

allowable power dissipation at any temperature is P

JMAX−TA

)/θJAor the number given in the Absolute Maximum Ratings, whichever is lower. For this device,

JMAX

125˚C, and the typical junction-to-ambient thermal resistance is 78˚C/W. For the MF6CJ this number decreases to 62˚C/W. For MF6CWM, θ

78˚C/W.

Typical Performance Characteristics

Schmitt Trigger Threshold Voltage vs Power Supply Voltage

DS005065-40

Crosstalk from Filter to Op-Amps (MF6-100)

DS005065-41

Crosstalk from Either Op-Amp to Filter Output (MF6-50)

DS005065-42

Crosstalk from Filter to Op-Amps (MF6-50)

DS005065-43

Crosstalk from Either Op-Amp to Filter Output (MF6-100)

DS005065-44

Equivalent Input Noise Voltage of Op-Amps

DS005065-45

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Typical Performance Characteristics (Continued)

Positive Voltage Swing vs Power Supply Voltage (Op Amp Output)

DS005065-46

Positive Voltage Swing vs Power Supply Voltage (Filter Output)

DS005065-47

Positive Voltage Swing vs Temperature (Filter and Op Amp Outputs)

DS005065-48

Negative Voltage Swing vs Power Supply Voltage (Filter and Op Amp Outputs)

DS005065-49

Negative Voltage Swing vs Temperature (Filter and Op Amp Outputs)

DS005065-50

Power Supply Current vs Clock Frequency

DS005065-51

Power Supply Current vs Temperature

DS005065-52

Power Supply Current vs Power Supply Voltage

DS005065-53

CLK/fc

Deviation

vs Clock Frequency

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