7

LTC1063

PI FU CTIO S

limited to a maximum value (Table 1), otherwise the filter’s

passband flatness will be affected. Refer to the Applica-

tions Information section for more details.

Output Pin (Pin 7, N Package)

Pin 7 is the filter output. This pin can typically source over

20mA and sink 2mA. Pin 7 should not drive long coax

cables, otherwise the filter’s total harmonic distortion will

degrade.

Clock Input Pin (Pin 5, N Package)

An external clock when applied to pin 5 tunes the filter

cutoff frequency. The clock-to-cutoff frequency ratio is

threshold levels are illustrated in Table 2. Square wave

clocks with duty cycles between 30% and 50% are strongly

recommended. Sinewave clocks are not recommended.

Clock Output Pin (Pin 4, N Package)

Any external clock applied to the clock input pin appears

at the clock output pin. The duty cycle of the clock output

equals the duty cycle of the external clock applied to the

clock input pin. The clock output pin swings to the power

supply rails. When the LTC1063 is used in a self-clocking

mode, the clock of the internal oscillator appears at the

clock output pin with a 30% duty cycle. The clock output

pin can be used to drive other LTC1063s or other ICs. The

drive is illustrated in Figure 3.

2.2k

–

–

3.4k

2.9k

–

5.5k

5k

2.7k

11k

11k

9.2k

24k

23k

21k

120k

120k

110k

Figure 1.

1063 F01

2

3

4

8

7

6

5

LTC1063

Table 2. Clock Pin Threshold Levels

POWER SUPPLY

1.5V

0.5V

3V

1V

4.5V

1.5V

4.8V

1.6V

4V

3V

9.6V

7.2V

12V

9V

Figure 2. Test Circuit for THD

CLOCK FREQUENCY (MHz)

1

200

180

160

140

120

100

80

60

40

20

0

310

1063 F03

24

5

6 78 9

Figure 3. Maximum Load Capacitance at the Clock Output Pin

50k

0.1

µF

1063 TC01

0.1

µF

CLOCK IN

–

+

LT1022

20pF

50k

8

7

6

5

1

2

3

4

LTC1063

TEST CIRCUIT