LTC1569-6_1 View Datasheet(PDF) - Linear Technology

Part Name

Description

MFG CO.

LTC1569-6_1

Linear Phase, DC Accurate, Low Power, 10th Order Lowpass Filter

Linear Technology 

LTC1569-6

PIN FUNCTIONS

RX (Pin 6): Connecting an external resistor between the RX

pin and V + (Pin 7) enables the internal oscillator. The value

of the resistor determines the frequency of oscillation. The

maximum recommended resistor value is 40k and the

minimum is 3.8k. The internal oscillator is disabled by

shorting the RX pin to V – (Pin 4). (Please refer to the

Applications Information section.)

OUT (Pin 8): Filter Output. This pin can drive 10kΩ and/or

40pF loads. For larger capacitive loads, an external 100Ω

series resistor is recommended. The output pin can ex-

ceed the power supply voltages by up to ±2V without

latchup.

BLOCK DIAGRA

IN+ 1

IN– 2

GND 3

V– 4

10TH ORDER

LINEAR PHASE

FILTER NETWORK

POWER

CONTROL

DIVIDER/

BUFFER

8 OUT

7 V+

6 RX

REXT

5 DIV/CLK

PRECISION

OSCILLATOR

1569-6 BD

APPLICATIONS INFORMATION

Self-Clocking Operation

The LTC1569-6 features a unique internal oscillator which

sets the filter cutoff frequency using a single external

resistor. The design is optimized for VS = 3V, fCUTOFF =

64kHz, where the filter cutoff frequency error is typically

<1% when a 0.1% external 10k resistor is used. With

different resistor values and internal divider settings, the

cutoff frequency can be accurately varied from 1kHz to

64kHz. As shown in Figure 1, the divider is controlled by

the DIV/CLK (Pin 5). Table 1 summarizes the cutoff

frequency vs external resistor values for the divide-by-1

mode.

1 IN+

OUT 8

2 IN–

V+ 7

LTC1569-6

REXT

3 GND

RX 6

DIVIDE-BY-16

V+

4 V– DIV/CLK 5

DIVIDE-BY-4

fCUTOFF = 64kHz (10k/REXT)

1, 4 OR 16

100pF

V–

DIVIDE-BY-1

Figure 1

1569-6 F01

5

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