STMicroelectronics LED815 Evaluation Boards EVALHVLED815W15 EVALHVLED815W15 Hoja De Datos
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EVALHVLED815W15
Device description
HVLED815PF
18/36
Doc ID 023409 Rev 4
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
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