BD6590MUV
Technical Note
●Protection
・Over voltage protection
At such an error of output open as the output DC/DC and the LED is not connected to IC, the DC/DC will boost too much
and the VDET terminal exceed the absolute maximum ratings, and may destruct the IC. Therefore, when VDET becomes
sensing voltage or higher, the over voltage limit works, and turns off the output Tr, and the pressure up made stop.
At this moment, the IC changes from activation into non-activation, and the output voltage goes down slowly. And, when
the Feedback of LED1 isn’t returned, so that Vout will return normal voltage.
Vout
LED1 voltage
LED1 connection normal
LED2 connection
open
normal
LED1 FeedBack
return
off
return
PWMPOW, PWMDRV
Fig.6 VDET operating description
・External SBD open detect / Output short protection
In the case of external SBD is not connected to IC, or VOUT is shorted to GND, the coil or internal Tr may be destructed.
Therefore, at such an error as VDET becoming 0.05V or below, and turns off the output Tr, and prevents the coil and the IC
from being destructed. And the IC changes from activation into non-activation, and current does not flow to the coil (0mA).
・Thermal shut down
BD6590MUV has thermal shut down function.
The thermal shut down works at 175℃ or higher, and the IC changes from activation into non-activation.
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2011.07 - Rev.B
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