LTC1562CN#PBF Datasheet LTC1562CG#PBF, LTC1562IG#PBF, LTC1562AIG#PBF | P13-P15

13

LTC1562

1562fa

TYPICAL APPLICATIONS

U

(Basic)

Quad 3rd Order Butterworth Lowpass Filter, Gain = –1

Quad 3rd Order

Butterworth f

–3dB

f

–3dB

f

–3dB

f

–3dB

f

–3dB

f

–3dB

f

–3dB

Lowpass Filters 20kHz 40kHz 60kHz 80kHz 100kHz 120kHz 140kHz

C

IN

220pF 1000pF 1000pF 1000pF 1000pF 1000pF 1000pF

R

INA

44.2k 4.32k 3.16k 2.43k 1.96k 1.87k 1.69k

R

INB

205k 57.6k 24.3k 13.0k 8.06k 5.11k 3.4k

R

Q

249k 61.9k 27.4k 15.4k 10.0k 6.98k 5.11k

R2 249k 61.9k 27.4k 15.4k 10.0k 6.98k 5.11k

All four sections have identical R

INA

, R

INB

and C

IN

values. All resistor values are ±1%

FREQUENCY (Hz)

10k

GAIN (dB)

10

0

–10

–20

–30

–40

–50

–60

100k 1M

1562 TA05b

f

–3dB

= 100kHz

1

2

3

5

6

8

9

10

20

19

18

16

15

13

12

11

INV B

V1 B

V2 B

V

+

SHDN

V2 A

V1 A

INV A

INV C

V1 C

V2 C

V

–

AGND

V2 D

V1 D

INV D

LTC1562

R

IN1B

R

IN1A

R

IN3A

V

IN1

V

IN3

C

IN1

V

IN2

1562 TA05a

V

OUT2

V

OUT3

V

OUT4

V

OUT1

R

IN3B

–5V

5V

R

Q1

R21

R23

0.1µF

R

Q3

R24

R

Q4

R

Q2

R22

C

IN2

C

IN3

R

IN2B

R

IN2A

V

IN4

C

IN4

R

IN4B

R

IN4A

SCHEMATIC INCLUDES PIN NUMBERS FOR 20-PIN PACKAGE.

PINS 4, 7, 14, 17 (NOT SHOWN) ALSO CONNECT TO V

–

Amplitude Response

14

LTC1562

1562fa

TYPICAL APPLICATIONS

U

(Basic)

1

2

3

5

6

8

9

10

20

19

18

16

15

13

12

11

INV B

V1 B

V2 B

V

+

SHDN

V2 A

V1 A

INV A

INV C

V1 C

V2 C

V

–

AGND

V2 D

V1 D

INV D

LTC1562

R

IN2

R

IN4

R

IN1

V

IN2

V

IN1

SCHEMATIC INCLUDES PIN NUMBERS FOR 20-PIN PACKAGE.

PINS 4, 7, 14, 17 (NOT SHOWN) ALSO CONNECT TO V

–

V

OUT1

1562 TA03a

V

OUT2

R

IN3

–5V

5V

R

Q1

R21

R23

0.1µF

R

Q3

R24

R

Q4

R

Q2

R22

Dual 4th Order Lowpass Filters Amplitude Response

FREQUENCY (Hz)

10k

GAIN (dB)

10

0

–10

–20

–30

–40

–50

–60

–70

–80

100k 1M

1562 TA03b

BUTTERWORTH

f

–3dB

= 100kHz

10kR21, R23, R

IN1

, R

IN3

=

Quick Design Formulas for Some Popular Response Types:

2

100kHz

ƒ

C

Butterworth

(Maximally Flat Passband)

for f

C

10kHz to 140kHz

14.24k

2

100kHz

ƒ

C

Chebyshev

(Equiripple Passband)

for f

C

20kHz to 120kHz

3.951k

2

100kHz

ƒ

C

Bessel

(Good Transient Response)

for f

C

10kHz to 70kHz

5.412kR

Q1

, R

Q3

=

100kHz

ƒ

C

7.26k

100kHz

ƒ

C

5.066k

100kHz

ƒ

C

10kR22, R24, R

IN2

, R

IN4

=

2

100kHz

ƒ

C

7.097k

2

100kHz

ƒ

C

4.966k

2

100kHz

ƒ

C

13.07kR

Q2

, R

Q4

=

Notes: f

C

is the cutoff frequency: For Butterworth and Bessel, response is 3dB down at f

C

. For Chebyshev filters with

±0.1dB passband ripple up to 0.95 f

C

, use LTC1562 “A” grade.

Example: Butterworth response, f

C

= 50kHz. from the formulas above, R21 = R23 = R

IN1

= R

IN3

= 10k(100kHz/50kHz)

2

= 40k. R

Q1

= R

Q3

= 5.412k(100kHz/50kHz) = 10.82k. R22 = R24 = R

IN2

= R

IN4

= 10k(100kHz/50kHz)

2

= 40k.

R

Q2

= R

Q4

= 13.07k(100kHz/50kHz) = 26.14k. Use nearest 1% values.

100kHz

ƒ

C

17.53k

100kHz

ƒ

C

3.679k

100kHz

ƒ

C

1562 TA03 TABLE

15

LTC1562

1562fa

TYPICAL APPLICATIONS

U

(Basic)

8th Order Lowpass Filters Amplitude Response

R21 = R

IN1

= 10k

Quick Design Formulas for Some Popular Response Types:

2

100kHz

ƒ

C

Butterworth

(Maximally Flat Passband)

for f

C

10kHz to 140kHz

R21 = 7.51k , R

IN1

= 2.2R21*

, R

IN4

=

2

100kHz

ƒ

C

Chebyshev

(Equiripple Passband)

for f

C

20kHz to 120kHz

Bessel

(Good Transient Response)

for f

C

10kHz to 70kHz

R

Q1

= 6.01k

100kHz

ƒ

C

R

Q1

= 119.3k

100kHz

ƒ

C

100kHz

ƒ

C

+ 560kHz

100kHz

ƒ

C

+ 530kHz

R24*

2.2

100kHz

ƒ

C

+ 2440kHz

R22 = R

IN2

= 10k

2

100kHz

ƒ

C

R22 = R

IN2

= 14.99k

2

100kHz

ƒ

C

R

Q2

= 9k

Notes: f

C

is the cutoff frequency: For Butterworth and Bessel, response is 3dB down at f

C

. For Chebyshev filters with

±0.1dB passband ripple up to 0.95 f

C

, use LTC1562 “A” grade. *The resistor values marked with an asterisk (*) in the

Chebyshev formulas (R21 and R24) should be rounded to the nearest standard finite-tolerance value

before

computing

the values dependent on them (R

IN1

and R

IN4

respectively).

Example: Chebyshev response, f

C

= 100kHz. The formulas above give R21 = 7.51k, nearest standard 1% value 7.50k.

Using this 1% value gives R

IN1

= 16.5k, already a standard 1% value. R

Q1

= 18.075k, nearest 1% value 18.2k.

R22 = R

IN2

= 14.99k, nearest 1% value 15k. R

Q2

= 11.02k, nearest 1% value 11k. R23 = R

IN3

= 7.15k, already a

standard 1% value. R

Q3

= 18.75k, nearest 1% value 18.7k. R24 = 26.7k, already a standard 1% value. This gives

R

IN4

= 12.14k, nearest 1% value 12.1k. R

Q4

= 8.75k, nearest 1% value 8.66k.

100kHz

ƒ

C

R

Q2

= 279.9k

100kHz

ƒ

C

R23 = R

IN3

= 10k

2

100kHz

ƒ

C

R23 = R

IN3

= 7.15k

2

100kHz

ƒ

C

R

Q3

= 5.1k

100kHz

ƒ

C

R

Q3

= 118.1k

100kHz

ƒ

C

R24 = R

IN4

= 10k

2

100kHz

ƒ

C

R24 = 26.7k

2

100kHz

ƒ

C

R

Q4

= 25.63k

100kHz

ƒ

C

R21 = R

IN1

= 2.61k

2

100kHz

ƒ

C

R

Q1

= 3.63k

100kHz

ƒ

C

R22 = R

IN2

= 2.07k

2

100kHz

ƒ

C

R

Q2

= 5.58k

100kHz

ƒ

C

R23 = R

IN3

= 2.96k

2

100kHz

ƒ

C

R

Q3

= 3.05k

100kHz

ƒ

C

R24 = R

IN4

= 3.14k

2

100kHz

ƒ

C

R

Q4

= 2.84k

100kHz

ƒ

C

R

Q4

= 8.75k

100kHz

ƒ

C

1562 TA04 TABLE

1

2

3

5

6

8

9

10

20

19

18

16

15

13

12

11

INV B

V1 B

V2 B

V

+

SHDN

V2 A

V1 A

INV A

INV C

V1 C

V2 C

V

–

AGND

V2 D

V1 D

INV D

LTC1562

R

IN2

R

IN4

R

IN1

V

IN

V

OUT

1562 TA04a

R

IN3

–5V

5V

R

Q1

R21

R23

0.1µF

R

Q3

R24

R

Q4

R

Q2

R22

SCHEMATIC INCLUDES PIN NUMBERS FOR 20-PIN PACKAGE.

PINS 4, 7, 14, 17 (NOT SHOWN) ALSO CONNECT TO V

–

FREQUENCY (Hz)

GAIN (dB)

10

0

–10

–20

–30

–40

–50

–60

–70

–80

–90

10k 100k 500k

1562 TA04b

CHEBYSHEV

f

C

= 100kHz

LTC1562CN#PBF

LTC1562CN#PBF

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