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LTC1569-6

Linear Phase, DC Accurate,

Low Power, 10th Order Lowpass Filter

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One External R Sets Cutoff Frequency

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Root Raised Cosine Response

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3mA Supply Current with a Single 3V Supply

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Up to 64kHz Cutoff on a Single 3V Supply

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10th Order, Linear Phase Filter in an SO-8

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DC Accurate, VOS(MAX) = 5mV

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Low Power Modes

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Differential or Single-Ended Inputs

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80dB CMRR (DC)

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82dB Signal-to-Noise Ratio, VS = 5V

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Operates from 3V to

±5V Supplies

The LTC

®1569-6 is a 10th order lowpass filter featuring

linear phase and a root raised cosine amplitude response.

The high selectivity of the LTC1569-6 combined with its

linear phase in the passband makes it suitable for filtering

both in data communications and data acquisition sys-

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Data Communication Filters for 3V Operation

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Linear Phase and Phase Matched Filters for I/Q

Signal Processing

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Pin Programmable Cutoff Frequency Lowpass Filters

tems.

Furthermore, its root raised cosine response offers

the optimum pulse shaping for PAM data communica-

tions. The filter attenuation is 50dB at 1.5 • fCUTOFF, 60dB

at 2 • fCUTOFF, and in excess of 80dB at 6 • fCUTOFF. DC-

accuracy-sensitive applications benefit from the 5mV

maximum DC offset.

The LTC1569-6 sampled data filter does not require an

external clock yet its cutoff frequency can be set with a

single external resistor with a typical accuracy of 3.5% or

better. The external resistor programs an internal oscilla-

tor whose frequency is divided by either 1, 4 or 16 prior to

being applied to the filter network. Pin 5 determines the

divider setting. Thus, up to three cutoff frequencies can be

obtained for each external resistor value. Using various

resistor values and divider settings, the cutoff frequency

can be programmed over a range of six octaves. Alterna-

tively, the cutoff frequency can be set with an external

clock and the clock-to-cutoff frequency ratio is 64:1. The

ratio of the internal sampling rate to the filter cutoff

frequency is 128:1.

The LTC1569-6 is fully tested for a cutoff frequency of

64kHz with a single 3V supply.

The LTC1569-6 features power saving modes and it is

available in an SO-8 surface mount package.

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

FREQUENCY (kHz)

1

0

–20

–40

–60

–80

–100

10

100

1000

1569-6 TA01a

18

27

36

45

1

µF

3V

1/4

1/16

1/1

3V

REXT = 10k

100pF

1

µF

2k

3.48k

3V

LTC1569-6

EASY TO SET fCUTOFF:

fCUTOFF =

64kHz (10k/REXT)

1, 4 OR 16

1569-6 TA01

IN+

IN–

GND

V–

OUT

VIN

VOUT

V+

RX

DIV/CLK

Frequency Response, fCUTOFF = 64kHz/16kHz/4kHz

Single 3V Supply, 64kHz/16kHz/4kHz Lowpass Filter

APPLICATIO S

FEATURES

TYPICAL APPLICATIO

DESCRIPTIO