SRP Hitachi Semiconductor, SRP Datasheet - Page 29

• Manufacturer Part Number: SRP
• Description: High Speed Current Mode PWM Control IC for Switching Power Supply
• Manufacturer: Hitachi Semiconductor

2. 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 R
Problem
Synchronized operation may not be possible if the amplitude of the external syncronous signal is too
large.
Reason
The R
Remedy (counter measure)
In this case, clamping is necessary using a diode with as small a V
barrier diode, as shown in figure 18.
T
/C
T
pin falls to a potential lower than the ground.
HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP
Input
V
18V
Time constant
IN
1 F
HA17384
C
Series
Figure 17 Sample Remedial Circuit
Figure 18 Sample Remedial Circuit
B
circuit
+
GND
HA17384
Series
Vref
V
R
51
IN
B
R
C
47
T
T
C
0.01 F
N
synchronous
T
/C
External
signal
Feedback
T
F
pin (pin 4).
value as possible, such as a schottky
Output
29