UC1823A, UC2823A, UC2823B,

UC3823A, UC3823B, UC1825A,

UC2825A, UC2825B, UC3825A, UC3825B

SLUS334E − AUGUST 1995 − REVISED SEPTEMBER 2010

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6

APPLICATION INFORMATION

The oscillator of the UC3823A, UC3823B, UC3825A, and UC3825B is a saw tooth. The rising edge is governed by a current

the outputs. Selection of RT should be done first, based on desired maximum duty cycle. CT can then be chosen based

3V

(10 mA)

1.6

UDG−95102

Figure 1. Oscillator

10 M

1 M

100 k

10 k

1 k

10 k

100 k

Figure 2

OSCILLATOR FREQUENCY

vs

TIMING RESISTANCE

Figure 3

1 k

10 k

70

75

80

85

90

95

100

100 k

MAXIMUM DUTY CYCLE

vs

TIMING RESISTANCE

(1)