BL8080
Over Temperature Protection (OTP)
external transistor to enable the BL8080. The
hold-up capacitor
supplies VCC until the
BL8080 integrates a temperature detection circuit
that will shut down PWM output when the junction
auxiliary winding of transformer takes over. When
VCC drops below 4.5V, BL8080 stops work. This
UVLO hysterisis ensures that the hold-up
capacitor is adequate to supply VCC during
normal operation.
temperature exceeds 135℃.
s
When the
temperature drops down and the VCC voltage is
still over the UVLO voltage, the device resumes
operation.
Built-in Slope Compensation
Under Voltage Lockout (UVLO)
The voltage across the current sense resistor is
collected for current mode control and cycle by
cycle current limit. Built-in slope compensation
improves the stability and prevents sub-harmonic
oscillations when the device works in continue
conduction mode -especially when the duty cycle
exceeds 50%.
The turn-on and turn-off threshold voltage are
fixed internally at 8.8V and 4.5V, respectivelly.
Turn Off
Turn On
4.5
8.8
Supply Voltage(V)
VCC
Figure12. UVLO of BL8080
During start up, the hold-up capacitor should be
charged up to 8.8V by the start up resistor and
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