Forced Quasi Resonant ZVS flyback controller
Functional Description
VVCC(t)
Initial startup and normal operation
VVCCon = 20.5 V
VCC brown-in window
VVCCSS
VVCCBI = 9.1 V
VVCCoffOP = 7.2 V
VCC self supply takes over
t
t
VHV(t)
VVACpeak
ca. 1.2ms internal boot sequence
VAC brown-in condition fulfilled
IVCC(t)
Start of GD0 switching
IVCCop
IVCCop1 = 7.5 mA
IVCCUVOFF = 30 µA
t
TYPICAL STARTUP SEQUENCE
Figure 4
Typical startup sequence
4.1.2
Brown-in monitoring
Once the IC is activated, brown-in monitoring is enabled for input brown-in protection (see Chapter 4.3.4) by measuring
the current at HV pin through the internal shunt resistor RM (see Chapter 4.2.2). If the input brown-in is not detected before
VCC falls below VVCCBI, the startup cell measurement unit remains enabled until VCC falls down to VVCCoff
.
Data Sheet
8
Revision 2.0
2020-08-20