STMicroelectronics EVALHVLED815W10 and EVALHVLED815W15 Evaluation Board for the Offline LED Driver with Primary-Sensing and High Power Fact EVALHVLED815W10 Hoja De Datos
Los códigos de productos
EVALHVLED815W10
DocID023409 Rev 5
17/34
HVLED815PF
Device description
34
Figure 13. Timing diagram: normal power-up and power-down sequences
4.4
Secondary side demagnetization detection and triggering
block
block
The demagnetization detection (DMG) and triggering blocks switch on the Power MOSFET
if a negative-going edge falling below 50 mV is applied to the DMG pin. To do so, the
triggering block must be previously armed by a positive-going edge exceeding 100 mV.
if a negative-going edge falling below 50 mV is applied to the DMG pin. To do so, the
triggering block must be previously armed by a positive-going edge exceeding 100 mV.
This feature is used to detect transformer demagnetization for QR operation, where the
signal for the DMG input is obtained from the transformer's auxiliary winding used also to
supply the IC.
signal for the DMG input is obtained from the transformer's auxiliary winding used also to
supply the IC.
Figure 14. DMG block, triggering block
The triggering block is blanked after MOSFET's turn-off to prevent any negative-going edge
that follows leakage inductance demagnetization from triggering the DMG circuit
that follows leakage inductance demagnetization from triggering the DMG circuit
AM13563v1
VCC
DRAIN
Vcc
ON
Vcc
restart
t
t
VIN
V
Start
5.5 mA
t
t
Power-on
Power-off
Normal operation
CV mode
CC mode
Normal operation
I
CHARGE
AM13564v1
DMG
60mV
110mV
BLANKING
TIME
TURN-ON
LOGIC
STARTER
S
R
Q
LEB
+
-
Rf b
Aux
Rdmg
DMG
CLAMP
To Driv er
From CC/CV Block
From OCP