TL H 9294
LMF60
High
Performance
6th-Order
Switched
Capacitor
Butterworth
Lowpass
Filter
May 1996
LMF60 High Performance
6th-Order Switched Capacitor
Butterworth Lowpass Filter
General Description
The LMF60 is a high performance precision 6th-order But-
terworth lowpass active filter It is fabricated using Nation-
al's LMCMOS process an improved silicon-gate CMOS pro-
cess specifically designed for analog products Switched-
capacitor techniques eliminate external component require-
ments and allow a clock-tunable cutoff frequency The ratio
of the clock frequency to the low-pass cutoff frequency is
internally set to 50 1 (LMF60-50) or 100 1 (LMF60-100) A
Schmitt trigger clock input stage allows two clocking op-
tions either self-clocking (via an external resistor and ca-
pacitor) for stand-alone applications or for tighter cutoff fre-
quency control a TTL or CMOS logic compatible clock can
be directly applied The maximally flat passband frequency
response together with a DC gain of 1V V allows cascading
LMF60 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 appli-
cations The LMF60 is pin- and functionally-compatible with
the MF6 but provides improved performance
Features
Y
Cutoff frequency range of 0 1 Hz to 30 kHz
Y
Cutoff frequency accuracy of
g
1 0% maximum
Y
Low offset voltage
g
100 mV maximum
g
5V supply
Y
Low clock feedthrough of 10 mV
p p
typical
Y
Dynamic range of 88 dB typical
Y
Two uncommitted op amps available
Y
No external components required
Y
14-pin DIP or 14-pin wide-body S O package
Y
Single Dual Supply Operation
a
4V to
a
14V (
g
2V to
g
7V)
Y
Cutoff frequency set by external or internal clock
Y
Pin-compatible with the MF6
Applications
Y
Communication systems
Y
Audio filtering
Y
Anti-alias filtering
Y
Data acquisition noise filtering
Y
Instrumentation
Y
High-order tracking filters
Block and Connection Diagrams
TL H 9294 1
All Packages
TL H 9294 2
Top View
Order Number LMF60CMJ-50
(5962-9096 701MCA or
LMF60CMJ50 883)
LMF60CMJ-100 or
(5962-9096 702MCA
or LMF60CMJ100 883)
See NS Package Number J14A
Order Number LMF60CIWM-50
or LMF60CIWM-100
See NS Package Number M14B
Order Number LMF60CIN-50
or LMF60CIN-100
See NS Package Number N14A
TRI-STATE
is a registered trademark of National Semiconductor Corporation
C1996 National Semiconductor Corporation
RRD-B30M56 Printed in U S A
Absolute Maximum Ratings
(Note 1)
If Military Aerospace specified devices are required
please contact the National Semiconductor Sales
Office Distributors for availability and specifications
Supply Voltage (V
a
b
V
b
) (Note 2)
15V
Voltage at Any Pin
V
a
a
0 2V
V
b
b
0 2V
Input Current at Any Pin (Note 3)
5 mA
Package Input Current (Note 3)
20 mA
Power Dissipation (Note 4)
500 mW
Storage Temperature
b
65 C to
a
150 C
ESD Susceptibility (Note 5)
2000V
CLK IN Pin
1700V
Soldering Information
N Package 10 sec
260 C
J Package 10 sec
300 C
SO Package Vapor Phase (60 sec )
215 C
Infrared (15 sec ) (Note 6)
220 C
Operating Ratings
(Note 1)
Temperature Range
T
Min
s
T
A
s
T
Max
LMF60CIN-50 LMF60CIN-100
LMF60CIJ-50 LMF60CIJ-100
LMF60CIWM-50
LMF60CIWM-100
b
40 C
s
T
A
s
a
85 C
LMF60CMJ-50 LMF60CMJ-100
LMF60CMJ50 883
LMF60CMJ100 883
b
55 C
s
T
A
s
a
125 C
Supply Voltage (V
a
b
V
b
)
4V to 14V
Filter Electrical Characteristics
The following specifications apply for f
CLK
e
500 kHz (Note 7) unless otherwise specified Boldface limits apply for T
A
e
T
J
e
T
MIN
to T
MAX
all other limits T
A
e
T
J
e
25 C
Symbol
Parameter
Conditions
Typical
Limits
Units
(Note 8)
(Note 9)
(Limits)
V
a
e a
5V V
b
e b
5V
f
CLK
Clock Frequency Range
5
Hz (Min)
(Note 16)
1 5
MHz (Max)
I
S
Total Supply Current
7 0
12 0
mA (Max)
Clock Feedthrough
V
IN
e
0V
Filter
10
mVp-p
Opamp
5
mVp-p
H
o
DC Gain
R
Source
s
2 kX
0 10
0 10
dB (Max)
b
0 26
b
0 30
dB (Min)
f
CLK
f
C
Clock to
LMF60-50
49 00
g
0 8%
49 00
g
1 0%
(Max)
Cutoff
Frequency
LMF60-100
98 10
g
0 8%
98 10
g
1 0%
(Max)
Ratio (Note 10)
Temperature Coefficient
4
ppm C
of f
CLK
f
C
A
MIN
Stopband Attenuation
At 2
c
f
C
36
dB (Min)
V
OS
DC Offset
LMF60-50
g
100
mV (Max)
Voltage
LMF60-100
g
150
mV (Max)
V
OUT
Output Voltage
a
3 9
a
3 7
V (Min)
Swing (Note 2)
b
4 2
b
4 0
V (Max)
I
SC
Output Short Circuit
Source
90
mA
Current (Note 11)
Sink
2 2
mA
Dynamic Range
88
dB
(Note 12)
Additional
LMF60-50
f
IN
e
12 kHz
b
9 45
g
0 46
b
9 45
g
0 50
dB
Magnitude
f
IN
e
9 kHz
b
0 87
g
0 16
b
0 87
g
0 20
dB
Response
LMF60-100
f
IN
e
6 kHz
b
9 30
g
0 46
b
9 30
g
0 50
dB
Test Points
(Note 13)
f
IN
e
4 5 kHz
b
0 87
g
0 16
b
0 87
g
0 20
dB
http
www national com
2
Logic Input-Output Characteristics
(Continued)
The following specifications apply for V
b
e
0V (Note 15) L Sh
e
0V unless otherwise specified Boldface limits apply for T
A
e
T
J
e
T
MIN
to T
MAX
all other limits T
A
e
T
J
e
25 C
Symbol
Parameter
Conditions
Typical
Limits
Units
(Note 8)
(Note 9)
(Limits)
SCHMITT TRIGGER
V
Ta
Positive Going Input
V
a
e
10V
6 1
6 0
V (Min)
Threshold Voltage
8 8
8 9
V (Max)
V
a
e
5V
3 0
2 9
V (Min)
4 3
4 4
V (Max)
V
Tb
Negative Going Input
V
a
e
10V
1 4
1 3
V (Min)
Threshold Voltage
3 8
3 9
V (Max)
V
a
e
5V
0 7
0 6
V (Min)
1 9
2 0
V (Max)
V
Ta
b
V
Tb
Hysteresis
V
a
e
10V
2 3
2 1
V (Min)
7 4
7 6
V (Max)
V
a
e
5V
1 1
0 9
V (Min)
3 6
3 8
V (Max)
V
OH
Logical ``1'' Voltage
V
a
e a
10V
9 1
9 0
V (Min)
I
O
e b
10 mA Pin 11
V
a
e a
5V
4 6
4 5
V (Min)
V
OL
Logical ``0'' Voltage
V
a
e a
10V
0 9
1 0
V (Max)
I
O
e b
10 mA Pin 11
V
a
e a
5V
0 4
0 5
V (Max)
I
SOURCE
Output Source
CLK R to V
b
Current Pin 11
V
a
e a
10V
4 9
3 7
mA (Min)
V
a
e a
5V
1 6
1 2
mA (Min)
I
SINK
Output Sink
CLK R to V
a
Current Pin 11
V
a
e a
10V
4 9
3 7
mA (Min)
V
a
e a
5V
1 6
1 2
mA (Min)
Note 1
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur Operating Ratings indicate conditions for which the device is
functional Specified Electrical Characteristics do not apply when operating the device outside its specified conditions
Note 2
All voltages are measured with respect to AGND unless otherwise specified
Note 3
When the input voltage (V
IN
) at any pin exceeds the power supply rails (V
IN
k
V
b
or V
IN
l
V
a
) 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 with 5 mA to four
Note 4
The Maximum power dissipation must be derated at elevated temperatures and is dictated by T
J Max
i
JA
and the ambient temperature T
A
The maximum
allowable power dissipation is PD
e
(T
J Max
b
T
A
) i
JA
or the number given in the absolute ratings whichever is lower For this device T
J Max
e
125 C and the
typical junction-to-ambient thermal resistance of the LMF60CCN when board mounted is 67 C W For the LMF60CIJ this number decreases to 62 C W For the
LMF60CIWM i
JA
e
78 C W
Note 5
Human body model 100 pF discharged through a 1 5 kX resistor
Note 6
See AN450 ``Surface Mounting Methods and Their Effect on Product Reliability'' or the section titled ``Surface Mount'' found in any current Linear Databook
for other methods of soldering surface mount devices
Note 7
The specifications given are for a clock frequency (f
CLK
) of 500 kHz at
a
5V and 250 kHz at
g
2 5V Above this frequency the cutoff frequency begins to
deviate from the specified error band over the temperature range but the filter still maintains its amplitude characteristics See application hints
Note 8
Typicals are at 25 C and represent the most likely parametric norm
Note 9
Guaranteed to National's Average Outgoing Quality Level (AOQL)
Note 10
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 11
The short circuit source current is measured by forcing the output to its maximum positive swing and then shorting that output to the negative supply The
short circuit sink current is measured by forcing the output being tested to its maximum negative voltage and then shorting that output to the positive supply These
are worst case conditions
Note 12
For
g
5V supplies the dynamic range is referenced to 2 62 V
rms
(3 7V peak) where the wideband noise over a 20 kHz bandwidth is typically 100 mV For
g
2 5V supplies the dynamic range is referenced to 0 849 V
rms
(1 2V peak) where the wideband noise over a 20 kHz bandwidth is typically 75 mV
rms
Note 13
The filter's magnitude response is tested at the cutoff frequency f
C
at f
IN
e
2 f
C
and at these two additional frequencies
Note 14
The LMF60 is operated with symmetrical supplies and L Sh is tied to GND
Note 15
For simplicity all the logic levels (except for the TTL input logic levels) have been referenced to V
b
e
0V The logic levels will scale accordingly for
g
5V
and
g
2 5V supplies
Note 16
The nominal ratio of the clock frequency to the low-pass cutoff frequency is internally set to 50-to-1 (LMF60-50) or 100-to-1 (LMF60-100)
http
www national com
5
PDF 
ZIP
