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| HA17384SPS Datasheet, PDF (27/29 Pages) Hitachi Semiconductor – High Speed Current Mode PWM Control IC for Switching Power Supply | |||
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HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP
Input
Time constant RB
circuit 51â¦
VIN
18V
VIN
CN
CB
1µF
+
HA17384
Series
GND
Output
Feedback
Figure 16 Sample Remedial Circuit
Externally Synchronized Operation
⢠Case
When, with a power supply using the HA17384S/H or HA17385H, externally synchronized operation is performed
by applying an external syncronous signal to the RT/CT pin (pin 4).
⢠Problem
Synchronized operation may not be possible if the amplitude of the external syncronous signal is too large.
⢠Reason
The RT/CT pin falls to a potential lower than the ground.
⢠Remedy (counter measure)
In this case, clamping is necessary using a diode with as small a VF value as possible, such as a schottky barrier
diode, as shown in figure 17.
Vref
HA17384
Series
RT
CT
47 0.01µF
External
synchronous
signal
Figure 17 Sample Remedial Circuit
Rev.3.00 Jun 15, 2005 page 27 of 28
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