LTC1069-7 查看數據表（PDF） - Linear Technology

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LTC1069-7

Linear Phase 8th Order Lowpass Filter

Linear Technology 

LTC1069-7

TYPICAL PERFORMANCE CHARACTERISTICS

Output Voltage Swing

vs Temperature

4.2

4.1

4.0

VS = ±5V

fCLK = 2.5MHz

fCUTOFF = 100kHz

– 4.5

RL = 10k

ISOURCE/ISINK = 1mA

– 4.6

– 4.7

–40 –20

0 20 40 60

TEMPERATURE (°C)

80 100

1069-7 G18

Supply Current

vs Supply Voltage

25 fCLK = 10Hz

20

25°C 85°C

15

– 40°C

10

5

0

01

2

3

4

5

6

SUPPLY VOLTAGE (±V)

1069-7 G19

Supply Current

vs Clock Frequency

22

21

20

19

VS = ±5V

18

17

16

15

14

13

12

11

VS = 5V

10

0.25 1.25 2.25 3.25 4.25 5.25

CLOCK FREQUENCY (MHz)

1069-7 G20

PIN FUNCTIONS

AGND (Pin 1): Analog Ground. The quality of the analog

signal ground can affect the filter performance. For either

single or dual supply operation, an analog ground plane

surrounding the package is recommended. The analog

ground plane should be connected to any digital ground

at a single point. For dual supply operation, Pin 1 should

be connected to the analog ground plane.

For single supply operation, Pin 1 should be bypassed

to the analog ground plane with a capacitor 0.47μF or

larger. An internal resistive divider biases Pin 1 to half the

total power supply. Pin 1 should be buffered if used to

bias other ICs. Figure 1 shows the connections for single

supply operation.

V+, V – (Pins 2, 7): Power Supplies. The V+ (Pin 2) and

V– (Pin 7) should be bypassed with a 0.1μF capacitor to

an adequate analog ground. The filter’s power supplies

should be isolated from other digital or high voltage analog

supplies. A low noise linear supply is recommended. Using

switching power supplies will lower the signal-to-noise

ratio of the filter. Unlike previous monolithic filters, the

power supplies can be applied in any order, that is, the

positive supply can be applied before the negative supply

and vice versa. Figure 2 shows the connections for dual

supply operation.

NC (Pins 3, 6): No Connection. Pins 3 and 6 are not

connected to any internal circuitry; they should be tied

to ground.

VIN (Pin 4): Filter Input. The filter input pin is internally

connected to the inverting inputs of two op amps through

a 36k resistor for each op amp. This parallel combination

creates an 18k input impedance.

ANALOG GROUND

PLANE

0.47μF

V+

0.1μF

VIN

1 AGND

VOUT 8 VOUT

2 V+

V– 7

3

LTC1069-7

NC

NC

6

4 VIN

CLK 5

STAR

SYSTEM

GROUND

DIGITAL

GROUND

PLANE

1k

CLOCK

SOURCE

1069-7 F01

Figure 1. Connections for Single Supply Operation

10697fa

6

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