Datasheet LTC1062 Datasheet (LINEAR TECHNOLOGY)

FEATURES

■

Lowpass Filter with No DC Error

■

Low Passband Noise

■

Operates DC to 20kHz

■

Operates On a Single 5V Supply or Up to ±8V

■

5th Order Filter

■

Maximally Flat Response

■

Internal or External Clock

■

Cascadable for Faster Rolloff

■

Buffer Available

U

APPLICATIO S

■

60Hz Lowpass Filters

■

Antialiasing Filter

■

Low Level Filtering

■

Rolling Off AC Signals from High DC Voltages

■

Digital Voltmeters

■

Scales

■

Strain Gauges

LTC1062

5th Order Lowpass Filter

U

DESCRIPTIO

®

The LTC
lowpass filter with no DC error. Its unusual architecture
puts the filter outside the DC path so DC offset and low
frequency noise problems are eliminated. This makes the
LTC1062 very useful for lowpass filters where DC accuracy
is important.

The filter input and output are simultaneously taken across
an external resistor. The LTC1062 is coupled to the signal
through an external capacitor. This RC reacts with the
internal switched capacitor network to form a 5th order
rolloff at the output.

The filter cutoff frequency is set by an internal clock that
can be externally driven. The clock-to-cutoff frequency
ratio is typically 100:1, allowing the clock ripple to be
easily removed.

Two LTC1062s can be cascaded to form a 10th order quasi
max flat lowpass filter. The device can be operated with
single or dual supplies ranging from ±2.5V to ±9V.

1062 is a 5th order all pole maximally flat

TYPICAL APPLICATIO

10Hz 5th Order Butterworth Lowpass Filter Filter Amplitude Response and Noise

25.8k

V

V

–

= –5V

IN

1µF

1

FB

2

AGND

3

V

4

DIVIDER
RATIO

NOTE: TO ADJUST OSCILLATOR FREQUENCY,
USE A 6800pF CAPACITOR IN SERIES
WITH A 50k POT FROM PIN 5 TO GROUND

LTC 1062

–

B

C

OUT

OUT

OSC

+

V

The LTC1062 is manufactured using Linear Technology’s
enhanced LTCMOS

, LTC and LT are registered trademarks of Linear Technology Corporation.

LTCMOS is a trademark of Linear Technology Corporation.

TM

silicon gate process.

U

DC ACCURATE
OUTPUT

8

7

6

5

C

OSC=

3900pF

BUFFERED
OUTPUT

1062 TA01

+

= 5V

V

0

C

= 3900pF

OSC

–10

–20

–30

–40

–50

–60

–70

AMPLITUDE RESPONSE (dB)

–80

–90

–100

1

INPUT FREQUENCY (Hz)

10 100

1062 TA02

FILTER OUTPUT NOISE (µV/√Hz)

50

40

30

20

10

0

1062fd

1

LTC1062

WWWU

ABSOLUTE AXI U RATI GS

(Note 1)

Total Supply Voltage (V+ to V–) ............................... 18V

–

Input Voltage at Any Pin ..... V

– 0.3V ≤ VIN ≤ V+ + 0.3V

Operating Temperature Range

LTC1062M (OBSOLETE)............. –55°C ≤ T

LTC1062C ................................... – 40°C ≤ T

UU

W

≤ 125°C

A

≤ 85°C

A

PACKAGE/ORDER I FOR ATIO

TOP VIEW

FB

1

AGND

2

–

V

3

DIVIDER

4

RATIO

N8 PACKAGE
8-LEAD PDIP

T

= 100°C, θ

J MAX

J8 PACKAGE 8-LEAD CERDIP

T

= 150°C, θ

J MAX

Consider the N8 Package as an Alternate Source

B

8

OUT

OUT

7

+

V

6

C

5

OSC

= 130°C/W

JA

= 100°C/W

JA

OBSOLETE PACKAGE

ORDER PART

NUMBER

LTC1062CN8

LTC1062MJ8
LTC1062CJ8

Storage Temperature Range ................. –65°C to 150°C

Lead Temperature (Soldering, 10 sec)................. 300°C

ORDER PART

NUMBER

LTC1062CSW

NC

NC

AGND

DIVIDER

RATIO

NC

NC

1

2

3

FB

4

5

V–

6

7

8

SW PACKAGE

16-LEAD PLASTIC SO

T

= 150°C, θ

J MAX

TOP VIEW

JA

= 90°C/W

16

NC

15

NC

14

B

OUT

13

OUT

+

12

V

11

C

OSC

10

NC

9

NC

Consult LTC Marketing for parts specified with wider operating temperature ranges.

ELECTRICAL CHARACTERISTICS

The

● denotes specifications which apply over the full operating tempera-

ture range, otherwise specifications are at TA = 25°C. V+ = 5V, V– = – 5V, unless otherwise specified. AC output measured at Pin 7,
Figure 1.

PARAMETER CONDITIONS MIN TYP MAX UNITS

Power Supply Current C

Input Frequency Range 0 to 20 kHz

Filter Gain at fIN = 0 f

= 0.5fC (Note 2) C = 0.01µF, R = 25.78k –0.02 –0.3 dB

f

IN

f

= f

IN

C

= 2f

f

IN

C

= 4f

f

IN

C

Clock-to-Cutoff Frequency Ratio, f

CLK/fC

Filter Gain at fIN = 16kHz f

f

Tempco f

CLK/fC

Filter Output (Pin 7, Pin 13 in SW16) DC Swing Pin 7/Pin13 (SW16) Buffered with an External Op Amp ● ±3.5 ±3.8 V

Clock Feedthrough 1mV

(Pin 5 to V–, Pin 11 in SW16) = 100pF 4.5 7 mA

OSC

= 100kHz, Pin 4 (Pin 6 in SW16) at V+, 0.00 dB

CLK

f

= 100kHz, Pin 4 (Pin 6 in SW16) at V+,100 ±1%

CLK

● 10 mA

● –2 –3.00 dB

● –28–30.00 dB

● –52–60.00 dB

C = 0.01µF, R = 25.78k

= 400kHz, Pin 4 at V+, C = 0.01µF, R = 6.5k ● –43 –52 dB

CLK

= 400kHz, Pin 4 at V+, C = 0.01µF, R = 6.5k 10 ppm/°C

CLK

P-P

2

1062fd

LTC1062

ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full operating tempera-

ture range, otherwise specifications are at TA = 25°C. V+ = 5V, V– = – 5V, unless otherwise specified, AC output measured at Pin 7,
Figure 1.

PARAMETER CONDITIONS MIN TYP MAX UNITS

Internal Buffer

Bias Current 250 pA

● 170 1000 pA

Offset Voltage 220 mV

Voltage Swing R

Short-Circuit Current Source/Sink 40/3 mA

Clock (Note 3)

Internal Oscillator Frequency C

Max Clock Frequency 4 MHz
Pin 5 (Pin 11 in SW16) Source or Sink Current ● 40 80 µA

Note 1: Absolute Maximum Ratings are those values beyond which the life of
a device may be impaired.

Note 2: f

is the frequency where the gain is –3dB with respect to the input

C

signal.

= 20k ● ±3.5 ±3.8 V

LOAD

(Pin 5 to V–, Pin 11 in SW16) = 100pF 25 32 50 kHz

OSC

● 15 65 kHz

Note 3: The external or driven clock frequency is divided by either 1, 2 or 4
depending upon the voltage at Pin 4. For the N8 package, when Pin 4 = V
ratio = 1; when Pin 4 = GND, ratio = 2; when Pin 4 = V

–

, ratio = 4.

+

,

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Amplitude Response Normalized
to the Cutoff Frequency

0

= ±2.5V

V

S

= 25°C

T

–10

A

f

1

C

0.1

2πRC

=

1.62

f

CLK

f

CLK

= 500kHz, fC = 5kHz
= 250kHz, fC = 2.5kHz

f

= 100kHz, fC = 1kHz

CLK

f

= 10kHz, fC = 100Hz

CLK

f

= 1kHz, fC = 10Hz

CLK

110

fIN/f

C

–20

–30

–40

–50

–60

RESPONSE (dB)

–70

–80

–90

–100

1062 G01

Amplitude Response Normalized
to the Cutoff Frequency

0

V

= ±2.5V

S

= 25°C

T

–10

A

f

1

C

0.1

2πRC

f

=

f

CLK

1.62

CLK

= 500kHz, fC = 5kHz
= 250kHz, fC = 2.5kHz

f

= 100kHz, fC = 1kHz

CLK

f

= 10kHz, fC = 100Hz

CLK

f

= 1kHz, fC = 10Hz

CLK

110

fIN/f

C

–20

–30

–40

–50

–60

RESPONSE (dB)

–70

–80

–90

–100

1062 G01

Passband Gain
vs Input Frequency

0.4
VS = ±5V

= 25°C

T

A

0.2

= 100kHz

f

CLK

0

–0.2

–0.4

–0.6

PASSBAND GAIN (dB)

–0.8

–1.0

0.1 0.2 0.4 0.6 0.8

1

2πRC

=

2πRC

f

1.62

C

1

fIN/f

f

C

=

1.6

1

2πRC

C

f

C

=

1.64

1

1062 G03

1062fd

3

LTC1062

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Passband Gain
vs Input Frequency and Temperature

0.4
VS = ±5V

f

= 100kHz

CLK

0.2

0

–0.2

–0.4

–0.6

PASSBAND GAIN (dB)

–0.8

–1.0

0.1 0.2 0.4 0.6 0.8

1

2πRC

f

C

=

1.62

TA = 125°C

TA = –55°C

fIN/f

C

Normalized Oscillator Frequency,
f

vs Supply Voltage

OSC

1.6

1.5

1.4

1.3

1.2

AT 5V SUPPLY

1.1

OSC

1.0

TO f

0.9

0.8

OSCILLATOR FREQUENCY NORMALIZED

0.7
4

8

6

10

V

12

SUPPLY

14

(V)

Passband Phase Shift
vs Input Frequency Filter Noise Spectral Density

80

VS = ±5V

= 25°C

T

A

70

60

50

40

30

20

FILTER OUTPUT NOISE (µV/√Hz)

10

0

0.1 10 100 10k

fC = 10Hz

fC = 100Hz

fC = 1kHz

1

CUTOFF FREQUENCY (Hz)

Power Supply Current
vs Power Supply Voltage

16

14

12

10

8

6

SUPPLY CURRENT (mA)

4

2

0

6

4

8

POWER SUPPLY VOLTAGE (V)

10

TA = –55°C

12

14

TA = 125°C

16

1k

1062 G06

TA = 25°C

18

1062 G09

20

1062 G04

1

0

–30

–60

–90

–120

PHASE SHIFT (DEG)

–150

–180

–210

0.1 0.2 0.4 0.6 0.8
fIN/f

Oscillator Frequency, f

VS = ±5V

= 100kHz

f

CLK

f

1

C

=

1.62

2πRC
TA = 25°C

1

C

1062 G05

OSC

vs Ambient Temperature

260

C

= 0pF

OSC

240

220

200

180

160

140

120

100

OSCILLATOR FREQUENCY (kHz)

80

18

16

20

1062 G07

60

–50

–25

V+ = 10V

–

= 0V

V

V+ = 5V

–

= 0V

V

50

25

0

AMBIENT TEMPERATURE (°C)

75

100

125

1062 G08

4

1062fd

BLOCK DIAGRA

LTC1062

W

For Adjusting Oscillator Frequency, Insert a 50k Pot in Series with C

FB

1

AGND

2

–

V

3

4

÷

AC TEST CIRCUIT

V

R = 25.8k

IN

C = 0.01µF

50Ω

V

–

= –5V

1

2

3

4

FB

AGND

–

V

DIVIDER
RATIO

SWITCHED

CAPACITOR

NETWORK

f

CLK

CLOCK GEN

÷ 1, 2, 4 OSC

8

B

OUT

7

OUT

LTC1062

6

+

V

5

C

OSC

R′

1062 F01

–5V

. Use Two Times Calculated C

OSC

BY CONNECTING PIN 4 TO V+, AGND OR V–, THE

B

8

OUT

×1

5V

f

= 100kHz

CLK

5V

7

6

5

1062 BD

0.1µF

OUT

V

C

3

2

+

OSC

+

LTC1052

–

1

–5V

OUTPUT FREQUENCY OF THE INTERNAL CLOCK
GENERATOR IS THE OSCILLATOR FREQUENCY DI­VIDED BY 1, 2, 4. THE (f
WITH RESPECT TO THE INTERNAL CLOCK GENERA­TOR OUTPUT FREQUENCY. PIN 5 CAN BE DRIVEN
WITH AN EXTERNAL CMOS LEVEL CLOCK. THE
LTC1062 CAN ALSO BE SELF-CLOCKED BY CON­NECTING AN EXTERNAL CAPACITOR (C
GROUND (OR TO V
THIS CONDITION AND WITH ±5V SUPPLIES, THE
INTERNAL OSCILLATOR FREQUENCY IS:

f

≅ 140kHz [33pF/(33pF + C

OSC

5V

7

6

MEASURED
OUTPUT

8

4

0.1µF

CLK/fC

–

IF C

IS POLARIZED). UNDER

OSC

FOR BEST MAX FLAT APPROXIMATION,
THE INPUT RC SHOULD BE SUCH AS:

1

2πRC

A 0.5k RESISTOR, R′, SHOULD BE USED IF
THE BIPOLAR EXTERNAL CLOCK IS APPLIED
BEFORE THE POWER SUPPLIES TURN ON

) RATIO OF 100:1 IS

)]

OSC

f

CLK

=

100

OSC

) TO

OSC

1

•

1.63

Figure 1

1062fd

5

LTC1062

WUUU

APPLICATIO S I FOR ATIO

Filter Input Voltage Range

Every node of the LTC1062 typically swings within 1V of
either voltage supply, positive or negative. With the appro­priate external (RC) values, the amplitude response of all
the internal or external nodes does not exceed a gain of
0dB with the exception of Pin 1. The amplitude response
of the feedback node (Pin 1) is shown in Figure 2. For an
input frequency around 0.8 • f

, the gain is 1.7V/V and, with

C

±5V supplies, the peak-to-peak input voltage should not
exceed 4.7V. If the input voltage goes beyond this value,
clipping and distortion of the output waveform occur, but
the filter will not get damaged nor will it oscillate. Also, the
absolute maximum input voltage should not exceed the
power supplies.

6

4

2

0

–2

(dB)

IN

–4

/V

–6

PIN1

V

–8

–10

–12

–14

0.1

Figure 2. Amplitude Response of Pin 1

110

fIN/f

VS = ±5V

f

1

C

=

1.62

2πRC

C

1062 F02

Internal Buffer

The internal buffer out (Pin 8) and Pin 1 are part of the
signal AC path. Excessive capacitive loading will cause
gain errors in the passband, especially around the cutoff
frequency. The internal buffer gain at DC is typically

0.006dB. The internal buffer output can be used as a filter
output, however, it has a few millivolts of DC offset. The
temperature coefficient of the internal buffer is typically
1µV/°C.

Filter Attenuation

The LTC1062 rolloff is typically 30dB/octave. When the
clock and the cutoff frequencies increase, the filter’s
maximum attenuation decreases. This is shown in the

Typical Performance Characteristics. The decrease of the
maximum attenuation is due to the rolloff at higher
frequencies of the loop gains of the various internal
feedback paths and not to the increase of the noise floor.
For instance, for a 100kHz clock and 1kHz cutoff fre­quency, the maximum attenuation is about 64dB. A 4kHz,
1V
at the output. A 6kHz, 1V

input signal will be predictably attenuated by 60dB

RMS

input signal will be attenu-

RMS

ated by 64dB and not by 77dB as an ideal 5th order
maximum flat filter would have dictated. The LTC1062
output at 6kHz will be about 630µV
RMS noise from DC to 17kHz was 100µV

. The measured

RMS

which is

RMS

16dB below the filter output.

C

, Pin 5

OSC

The C
C

OSC

, Pin 5, can be used with an external capacitor,

OSC

, connected from Pin 5 to ground. If C

is polarized

OSC

it should be connected from Pin 5 to the negative supply,
Pin 3. C

lowers the internal oscillator frequency. If

OSC

Pin 5 is floating, an internal 33pF capacitor plus the
external interpin capacitance set the oscillator frequency
around 140kHz with ±5V supply. An external C

OSC

will
bring the oscillator frequency down by the ratio (33pF)/
(33pF + C

). The Typical Performance Characteristics

OSC

curves provide the necessary information to get the inter­nal oscillator frequency for various power supply ranges.
Pin 5 can also be driven with an external CMOS clock to
override the internal oscillator. Although standard 7400
series CMOS gates do not guarantee CMOS levels with the
current source and sink requirements of Pin 5, they will, in
reality, drive the C

pin. CMOS gates conforming to

OSC

standard B series output drive have the appropriate volt­age levels and more than enough output current to
simultaneously drive several LTC1062 C

pins. The

OSC

typical trip levels of the internal Schmitt trigger which
input is Pin 5, are given in Table 1.

Table 1

V

SUPPLY

±2.5V 0.9V –1V

±5V 1.3V –2.1V

±6V 1.7V –2.5V

±7V 1.75V –2.9V

+

V

TH

–

V

TH

1062fd

6

WUUU

APPLICATIO S I FOR ATIO

LTC1062

Divide By 1, 2, 4 (Pin 4)

+

By connecting Pin 4 to V

, to mid supplies or to V–, the
clock frequency driving the internal switched capacitor
network is the oscillator frequency divided by 1, 2, 4
respectively. Note that the f

ratio of 100:1 is with

CLK/fC

respect to the internal clock generator output frequency.
The internal divider is useful for applications where octave
tuning is required. The ÷2 threshold is typically ±1V from
the mid supply voltage.

Transient Response

Figure 3 shows the LTC1062 response to a 1V input step.

200mV/VERT DIV
50ms/HORIZ DIV, f
5ms/HORIZ DIV, f

0.5ms/HORIZ DIV, f

f

1

C

=

1.62

2πRC

Filter Noise

The filter wideband RMS noise is typically 100µV

RMS

for
±5V supply and it is nearly independent from the value of
the cutoff frequency. For single 5V supply the RMS noise
is 80µV
the passband, that is from DC to f

. Sixty-two percent of the wideband noise is in

RMS

. The noise spectral

C

density, unlike conventional active filters, is nearly zero for
frequencies below 0.1 • f

. This is shown in the Typical

C

Performance Characteristics section. Table 2 shows the
LTC1062 RMS noise for different noise bandwidths.

f

1

= 10Hz

C

= 100Hz

C

= 1kHz

C

2πRC

C

=

1.94

Table 2

1

2πRC

Figure 3. Step Response to a 1V Peak Input Step

NOISE BW RMS NOISE (VS = ±5V)

DC – 0.1 • f

DC – 0.25 • f

DC – 0.5 • f

DC – 1 • f

DC – 2 • f

C

C

C

C

C

2µV

8µV

20µV

62µV

100µV

f

C

=

2.11

1062fd

7

LTC1062

TYPICAL APPLICATIO S

U

AC Coupling an External CMOS Clock Powered

from a Single Positive Supply, V

V

IN

C

1

FB

2

AGND

LTC1062

3

–

–

V

V

4

DIVIDER
RATIO

B

C

OUT

OUT

OSC

8

7

6

+

V

5

V

OUT

+

V

0.01µF

100k

1062 TA03

+

+

V

0

Adding an External (R1, C1) to Eliminate the Clock Feedthrough and

to Improve the High Frequency Attenuation Floor

–

C1

0.01C

EXTERNAL

BUFFER

+

V

OUT

R

V

IN

C

1

FB

2

AGND

3

–

V

V

4

DIVIDER
RATIO

LTC1062

–

B

OUT

C

OUT

OSC

+

V

R1

10R

8

7

6

5

1062 TA04

+

V

f

CLK

Filtering AC Signals from High DC Voltages

HIGH DC INPUT = 100V

–

= –5V

V

8

R

25.8k

V

IN

EXAMPLE:

= 100KHz, fC = 1kHz. THE FILTER ACCURATELY PASSES

f

CLK

THE HIGH DC INPUT AND ACTS AS 5TH ORDER LP FILTER
FOR THE AC SIGNALS RIDING ON THE DC

V+ = 5V

C

0.01µF

1

2

3

4

FB

AGND

LTC1062

–

V

DIVIDER
RATIO

B

C

OUT

OUT

V

OSC

+

1062 TA05

C

0.01µF

8

12R

309.6k

7

6

5

CLK IN = f

DC OUTPUT

• 100

C

Passband Amplitude Response for the

High DC Accurate 5th Order Filter

0.2

0

–0.2

–0.4

–0.6

–0.8

PASSBAND GAIN (dB)

–1.0

–1.2

VS = ±5V

= 100kHz

f

CLK

–1.4

0.01

0.1 1

fIN/f

C

1062 TA06

1062fd

TYPICAL APPLICATIO S

LTC1062

U

Cascading Two LTC1062s to Form a Very

Selective Clock Sweepable Bandpass Filter

R1

10k

V

IN

R2

10k

1

FB

2

AGND

LTC1062

3

4

–

V

DIVIDER
RATIO

–5V 5V

B

C

OUT

OUT

OSC

8

7

6

+

V

5

R′1
10k

R′2

12.5k

–5V

1

2

3

4

FB

AGND

LTC1062

–

V

DIVIDER
RATIO

B

C

OUT

OUT

V

OSC

8

V

OUT

7

6

+

5V

5

f

CLK

1062 TA07

Clock Tunable Notch Filter

For Simplicity Use R3 = R4 = R5 = 10k;

R5

= 1.234, =

R2

R1

V

IN

R2 R3

1

–5V

2

3

4

FB

AGND

V

DIVIDER
RATIO

LTC1062

–

B

C

OUT

OUT

V

OSC

f

CLK

f

NOTCH

8

7

6

+

5V

5

f

1062 TA08

CLK

79.3
1

R5R4

–

V

+

OUT

Frequency Response of the Bandpass Filter

–10

–20

–30

(dB)

–40

–50

–60

–70

–80

–90

20

10

0

0.5

1.5 2 2.5

1

VS = ±5V
R1

R2
R′1
R′2
VIN = 100mV

3 3.5 4 4.5

(kHz)

= 1

= 0.8

RMS

1062 TA09

Frequency Response of the Notch Filter

–10

0

10

20

30

(dB)

40

50

60

70

300 500 700 1100

100

(Hz)

900

1062 TA10

1062fd

9

LTC1062

TYPICAL APPLICATIO S

25.8k

V

IN

–5V

1µF

1

FB

2

AGND

LTC1062

3

–

V

4

DIVIDER
RATIO

10Hz, 10TH ORDER DC ACCURATE LOWPASS FILTER
60dB/OCTAVE ROLLOFF

0.5dB PASSBAND ERROR, 0dB DC GAIN
MAXIMUM ATTENUATION 110dB (f

U

B

C

OUT

OUT

OSC

Simple Cascading Technique

412k

0.1µF

8

7

6

+

V

5

–5V

100dB (f
95dB (f

CLK

1

2

3

4

CLK
CLK

FB

AGND

–

V

DIVIDER
RATIO

= 10kHz)
= 1kHz)

= 1MHz)

LTC1062

B

C

OUT

OUT

V

OSC

5V

3

8

7

6

+

5

0.1µF

1062 TA11

V

f

2

+

CLK

+

LTC1052

–

= 5V

= 1kHz

7

6

DC ACCURATE
OUTPUT

8

4

1

0.1µF

–5V

100Hz, 50Hz, 25Hz 5th Order DC Accurate LP Filter

25.8k

V

IN

(HIGH, GROUND, LOW)

CONTROL

0.1µF

1

FB

2

AGND

LTC1062

3

4

5V

100k

100k

–

V

DIVIDER
RATIO

100k

–5V 5V

0.1µF

1

13 5

2

1/2 CD4016

8

B

C

–5V

5V

100k

B

OUT

7

OUT

6

+

V

5

OSC

TO PIN 5 OF CD4016

BY CONNECTING PIN 4 OF THE LTC1062
HIGH/GROUND/LOW THE FILTER CUTOFF
FREQUENCY IS 100Hz/50Hz/25Hz

TO PIN 13 OF CD4016

OUT

10kHz
CLK IN

V

OUT

0.2µF

3

4

10

–5V

1062 TA12

1062fd

TYPICAL APPLICATIO S

7th Order 100Hz Lowpass Filter with Continuous Output Filtering, Output Buffering and Gain Adjustment

LTC1062

U

R3

2

–

C2

RMS

0.1µF

3

LTC1052

+

1

2.6k

V

IN

1µF

1

FB

2

AGND

3

–5V

V

4

5V

DIVIDER
RATIO

THE LTC1052 IS CONNECTED AS A 2ND ORDER SALLEN AND KEY LOWPASS FILTER WITH A CUTOFF
FREQUENCY EQUAL TO THE CUTOFF FREQUENCY OF THE LTC1062. THE ADDITIONAL FILTERING
ELIMINATES ANY 10kHz CLOCK FEEDTHROUGH PLUS DECREASES THE WIDEBAND NOISE OF THE FILTER

DC OUTPUT OFFSET (REFERRED TO A DC GAIN OF UNITY) = 5µV MAX
WIDEBAND NOISE (REFERRED TO A DC GAIN OF UNITY) = 60µV

OUTPUT FILTER COMPONENT VALUES

DC GAIN

R3

1

∞

10

3.57k

LTC1062

–

R4

0

32.4k

R1

B

OUT

OUT

C

OSC

R1

14.3k
46k

R2

C1

8

7

6

+

5V

V

5

10kHz
CLK IN

1062 TA13

R2

C1

53.6k
274k

0.1µF

0.01µF

C2

0.033µF

0.02µF

R4

5V

7

6

8

4

0.1µF

–5V

V

OUT

10µF

SOLID

TANTALUM

Single 5V Supply 5th Order LP Filter

R

V

IN

5V

25k

+

25k

FOR A 10Hz FILTER: R = 29.4k, C = 1µF, f

THE FILTER IS MAXIMALLY FLAT FOR

C C

1

FB

2

AGND

LTC1062

3

–

V

4

5V

DIVIDER
RATIO

12R

B

C

OUT

OUT

OSC

8

BUFFERED
OUTPUT

7

6

+

5V

V

5

CLK

2πRC

CLK

1

= 1kHz

f

C

=

1.84

DC ACCURATE
OUTPUT

1062 TA14

1062fd

11

LTC1062

TYPICAL APPLICATIO S

R

9.09k

V

IN

V

C
1µF

1

FB

2

AGND

LTC1062

3

–

–

V

4

DIVIDER
RATIO

U

A Lowpass Filter with a 60Hz Notch

R6

19.35k

B

C

OUT

OUT

OSC

R3

20k

R2

20k

8

7

6

+

V

+

V

5

CLK IN

2.84kHz

1

2πRC

f

CLK

=

100 • 1.62

R4

10k

–

A1

1/2 LT1013

+

R5

10k

C7

0.1µF

R7

20k

–

A2

1/2 LT1013

+

1062 TA15

V

OUT

Frequency Response of the Above Lowpass Filter

with the Notch f

–10

0

10

20

(Hz)

IN

30

/V

OUT

40

V

50

60

70

1

10 100 1k

fIN (Hz)

NOTCH

= f

CLK

/47.3

1062 TA16

12

1062fd

PACKAGE DESCRIPTIO

LTC1062

U

J8 Package

8-Lead CERDIP (Narrow .300 Inch, Hermetic)

(Reference LTC DWG # 05-08-1110)

CORNER LEADS OPTION

(4 PLCS)

.023 – .045

(0.584 – 1.143)

HALF LEAD

.045 – .068

(1.143 – 1.650)

FULL LEAD

OPTION

.300 BSC

(7.62 BSC)

.008 – .018

(0.203 – 0.457)

NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE
OR TIN PLATE LEADS

0° – 15°

OPTION

OBSOLETE PACKAGE

.005

(0.127)

MIN

.025

(0.635)

RAD TYP

.045 – .065

(1.143 – 1.651)

.014 – .026

(0.360 – 0.660)

.405

(10.287)

MAX

87

12

65

3

4

.220 – .310

(5.588 – 7.874)

.015 – .060

(0.381 – 1.524)

.100

(2.54)

BSC

.200

(5.080)

MAX

.125

3.175
MIN

J8 0801

1062fd

13

LTC1062

PACKAGE DESCRIPTIO

U

N8 Package

8-Lead PDIP (Narrow .300 Inch)

(Reference LTC DWG # 05-08-1510)

.255 ± .015*

(6.477 ± 0.381)

.400*

(10.160)

MAX

87 6

5

12

.300 – .325

(7.620 – 8.255)

.065

(1.651)

.008 – .015

(0.203 – 0.381)

+.035

.325

–.015
+0.889

8.255

()

–0.381

NOTE:

1. DIMENSIONS ARE

*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)

INCHES

MILLIMETERS

TYP

.045 – .065

(1.143 – 1.651)

.100

(2.54)

BSC

3

4

.130 ± .005

(3.302 ± 0.127)

.120

(3.048)

MIN

.018 ± .003

(0.457 ± 0.076)

.020

(0.508)

MIN

N8 1002

14

1062fd

PACKAGE DESCRIPTIO

.030 ±.005

TYP

N

U

SW Package

16-Lead Plastic Small Outline (Wide .300 Inch)

(Reference LTC DWG # 05-08-1620)

.050 BSC

.045 ±.005

16

N

.398 – .413

(10.109 – 10.490)

15 14

NOTE 4

13

LTC1062

12

10 9

11

.420
MIN

123 N/2

RECOMMENDED SOLDER PAD LAYOUT

.291 – .299

(7.391 – 7.595)

NOTE 4

.010 – .029

.005

(0.127)

RAD MIN

.009 – .013

(0.229 – 0.330)

NOTE:

1. DIMENSIONS IN

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)

(0.254 – 0.737)

NOTE 3

INCHES

(MILLIMETERS)

× 45°

.016 – .050

(0.406 – 1.270)

.325 ±.005

0° – 8° TYP

NOTE 3

.093 – .104

(2.362 – 2.642)

(1.270)

1

.050

BSC

.014 – .019

(0.356 – 0.482)

2345

TYP

6

.394 – .419

(10.007 – 10.643)

N/2

78

.037 – .045

(0.940 – 1.143)

.004 – .012

(0.102 – 0.305)

S16 (WIDE) 0502

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.

1062fd

15

LTC1062

U

TYPICAL APPLICATIO

A Low Frequency, 5Hz Filter Using Back-to-Back Solid Tantalum Capacitors

5.23k

V

IN

+

10µF

10µF

+

1

2

3

4

FB

AGND

V

DIVIDER
RATIO

LTC1062

–

B

C

OUT

OUT

OSC

+

V

V

OUT

8

BV

OUT

7

6

5V–5V

5

0.08µF

1062 TA17

RELATED PARTS

PART NUMBER DESCRIPTION COMMENTS

LTC1063 5th Order Butterworth Lowpass, DC Accurate Clock Tunable, No External Components

LTC1065 5th Order Bessel Lowpass, DC Accurate Clock Tunable, No External Components

LTC1066-1 8th Order Elliptic or Linear Phase, DC Accurate Clock Tunable, fc ≤ 120kHz

LTC1563-2/
LTC1563-3 Active RC, 4th Order Lowpass Very Low Noise, 256Hz ≤ fc ≤ 256kHz

LTC1564 10kHz to 150kHz Digitally Controlled Lowpass and PGA Continuous Time, Very High Dynamic Range, PGA Included

LTC1569-6 Linear Phase, DC Accurate, 10th Order No External Clock Required, fc ≤ 64kHz, S08

LTC1569-7 Linear Phase, DC Accurate, 10th Order No External Clock Required, fc ≤ 300kHz, S08

16

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

[phone] ● FAX: [phone]

●

www.linear.com

1062fd

LW/TP 1102 1K REV D • PRINTED IN USA

 LINEAR TE CHNO LOGY CORP O R ATIO N 1994