NJM2352
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Ver.2003-07-18
■ PRINCIPLE OF OPERATION
The NJM2352 circuit block is shown on Fig. 1 and timing chart on Fig. 2. Function of COMP-2 is setting dead-time.
At point A is the square wave and at point B is the triangular wave. By putting two input signals (A, B) into COMP-2,
output (point C) voltage is held high level during rising period of triangular wave and the switching transistor is kept in the
off condition regardless the COMP-1 output level. So the maximum duty cycle of the NJM2352 is 50%.
The COMP-1 makes on-time of switching transistor longer when the output voltage is high and shorter when it is low.
Thus function of the COMP-1 is pulse wide modulation. When the AMP's output waveform is D, COMP-1 output is like E,
and NOR GATE output becomes high level only when both inputs, C, E, are low, and so the falling period of triangular
wave is the range of pulse width control.
D
E
B
A C
F
A
D
B
E
C
F
