Specifications
EVALPFC-3kW-IPZ65R019C7
10
Application Note AN 2014-06
V1.1 January 2015
Figure 3: Frequency setting
The switching frequency can be changed by the changeable resistor R31. For easy adjustment please
consider to use the connection pins X8 to measure the value when the evaluation board is not connected to
mains.
4.3 Protection Features
4.3.1 Open loop protection (OLP)
The open loop protection is available for this IC to safe-guard the output. Whenever voltage at pin VSENSE
falls below 0.5V, or equivalently V
OUT
falls below 20% of its rated value, it indicates an open loop condition
(i.e. VSENSE pin not connected). In this case, most of the blocks within the IC will be shutdown. It is
implemented using a comparator with a threshold of 0.5V.
4.3.2 First over-voltage protection (OVP1)
Whenever V
OUT
exceeds the rated value by 8%, the first over-voltage protection OVP1 is active. This is
implemented by sensing the voltage at pin VSENSE with respect to a reference voltage of 2.7V. A VSENSE
voltage higher than 2.7V will immediately block the gate signal. After bulk voltage falls below the rated value,
gate drive resumes switching again.
4.3.3 Peak current limit
The IC provides a cycle by cycle peak current limitation (PCL). It is active when the voltage at pin ISENSE
reaches -0.2V. This voltage is amplified by a factor of -5 and connected to comparator with a reference
voltage of 1.0V. A deglitcher with 200ns after the comparator improves noise immunity to the activation of
this protection. In other words, the current sense resistor should be designed lower than -0.2V PCL for
normal operation.
Frequency vs Resistance
0
20
40
60
80
100
120
140
160
180
200
220
240
260
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250
Resistance/kohm
Frequency/kHz
19.2
232
43
100
20.2
221
49
90
21.2
210
55
80
23
200
62
70
25
191
74
60
26.2
169
86
50
29.5
150
106
40
31.5
140
141
30
34
130
211
20
36
120
249
17
40
110
278
15
Frequency
/kHz
Resistance
/kohm
Frequency
/kHz
Resistance
/kohm