LTC1069-7

6

10697fa

TYPICAL PERFORMANCE CHARACTERISTICS

Output Voltage Swing

vs Temperature

Supply Current

vs Supply Voltage

Supply Current

vs Clock Frequency

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.

TEMPERATURE (°C)

–40

–4.7

–4.5

4.2

0

40

60

1069-7 G18

–4.6

4.1

4.0

–20

20

80

100

VS = ±5V

fCLK = 2.5MHz

fCUTOFF = 100kHz

RL = 10k

ISOURCE/ISINK = 1mA

SUPPLY VOLTAGE (±V)

0

12

1069-7 G19

36

25

20

15

10

5

0

45

85°C

–40°C

25°C

fCLK = 10Hz

CLOCK FREQUENCY (MHz)

0.25

1.25

2.25

3.25

4.25

5.25

1069-7 G20

22

21

20

19

18

17

16

15

14

13

12

11

10

VS = ±5V

VS = 5V

1069-7 F01

1k

V+

LTC1069-7

CLOCK

SOURCE

0.47μF

0.1μF

ANALOG GROUND

PLANE

8

7

6

5

1

2

3

4

STAR

SYSTEM

GROUND

DIGITAL

GROUND

PLANE

AGND

V+

NC

VIN

VOUT

V–

NC

CLK

VOUT

VIN

Figure 1. Connections for Single Supply Operation