5

LTC1069-6

Output Voltage Swing

vs Temperature

AMBIENT TEMPERATURE (

°C)

– 40

–20

0

20406080

0

20

40

60

80

4.5

2.5

4.0

2.0

1069-6 G13

Supply Current vs Supply Voltage

TOTAL SUPPLY VOLTAGE (V)

0

0

2

5

4

8

10

1069-6 G12

1

4

3

26

12

14

16

85

°C

–40

°C

25

°C

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 single supply operation, Pin 1 should be

bypassed to the analog ground plane with a 0.47

µFcapaci-

tor or larger. An internal resistive divider biases Pin 1 to

0.4366 times the total power supply of the device (Figure

1). That is, with a single 5V supply, the potential at Pin 1

is 2.183V

±1%. As the LTC1069-6 is optimized for single

supply operation, the internal biasing of Pin 1 allows

optimum output swing. The AGND pin should be buffered

if used to bias other ICs. Figure 2 shows the connections

for single supply operation.

Figure 1. Internal Biasing of the Analog Ground (Pin 1)

NC

1

2

3

4

8

7

6

5

NC

CLK

LTC1069-6

1069-6 F01

AGND

11.325k 8.775k

µF

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. Switching power supplies will lower the

signal-to-noise ratio of the filter. Unlike previous mono-

lithic 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 3 shows the con-

nection for dual supply operation.

AGND

NC

1

2

3

4

8

7

6

5

1k

NC

CLK

LTC1069-6

ANALOG GROUND PLANE

DIGITAL

GROUND

PLANE

0.47

µF

0.1

µF

1069-6 F02

CLOCK

SOURCE

STAR

SYSTEM

GROUND

Figure 2. Connections for Single Supply Operation