Rohm BM2P0161-EVK-003, Руководство пользователя

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© 2018 ROHM Co., Ltd.
No. 60UG092E Rev.001
JULY.2018
User’s Guide
BM2P0161-EVK-003
1-2
．
Selecting operation mode
Flyback converter of fixed frequency PWM switching send power from primary side to secondary side using
Transformer. Transformer operation mode are blow three modes.
CCM
（
Continuous Current Mode
）
Primary MOSFET turn ON before secondary coil discharge complete.
BCM
（
Boundary Current Mode
）
Primary MOSFET turn ON timing is just secondary coil discharge. Mode
name from looks like bounding ball, secondary current wave form touch to GND at the same time primary coil
current grow-up from GND.
DCM
（
Dis-continuous Current Mode
）
Primary MOSFET turn ON timing has some interval after secondary coil
discharge. Coil current is dis-continue.
BM2P0161 can be operate CCM, BCM and DCM.
This reference board transformer design target is BCM point at input DC260V (185V) and LOAD 12V/2A.
Figure 11. Switching waveform (MOSFET Vds,Ids)
Figure 12. Operation mode – Input Voltage and Peak current (MOSFET Drain, Diode)
BCM BCM BCM BCM
DCM
DCM DCM
DCM
Operating wave form of MOSFET
Drain voltage and current.
Primary
MOSFET Drain
Peak Current
Input
Voltage
CCM DCM
BCM
Point
Vds
Ids
Vds
Ids
Vds
Ids
Secondary
Diode
Peak Current
Input
Voltage
CCM DCM
BCM
Point