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Pulse Width Modulation (PWM) Circuit
Figure 2-19 shows the internal circuit of the TL4941C.
The output control (pin 13) is fixed at "L", and the IC's internal push-pull circuit is therefore never used.
The wired OR of the EA 1 and EA2 outputs is input to the negative terminal of the PWM, a sawtooth
waveform from the oscillator is input to the positive terminal, and the PWM modulated waveform is
output as shown in Fig. 2-20.
Output Control
.--------------------{13)--......-----,
GND
RT
CT
Dead Time
Control
Non Inv.
Input
Inv.
Input
Non Inv.
Input
Inv.
Input
Feedback
Reference
Regulator
Low Voltage
J------...,
Stop
OSC
Dead Time
COMPARATOR
PWM COMPARATOR
Always -L-
Figure 2-19. IC 494 Internal Circuit
2-21
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