ML4812

5

FUNCTIONAL DESCRIPTION

OSCILLATOR

voltage reaches the upper threshold, the comparator

changes state and the capacitor discharges to the lower

threshold through Q1. While the capacitor is discharging,

Q2 provides a high pulse.

The Oscillator period can be described by the following

relationship:

Figure 2. Oscillator Timing Resistance vs. Frequency

Figure 1. Oscillator Block Diagram

Figure 3. Output Saturation Voltage vs. Output Current

10

SYNC

9

RT

16

CT

EXTERNAL

CLOCK

+

-

5.6V

ISET

8.4mA

CT

RT

ISET

CSYNC

RSYNC

CLOCK

tD

RAMP VALLEY

RAMP PEAK

V(CT)

10

OSCILLATOR FREQUENCY (kHz)

10

100

1000

8

5

3

2

1

10nF

20nF

5nF

2nF

1nF

85%

80%

70%

90%

15

14

13

3

2

1

0

OUTPUT CURRENT (mA)

0

200

400

800

600

VCC

VCC = 15V

80µs PULSED LOAD

120Hz RATE

GND

SOURCE SATURATION

LOAD TO GROUND

SINK SATURATION

LOAD TO VCC

TT

T

OSC

RAMP

DEADTIME

=+

where:

V

V

D

OUT

IN

ON

=

-

1

and:

T

CV

mA I

DEADTIME

T

RAMP VALLEY TO PEAK

SET

=

´

-

84

.