NCL30083_15 Datasheet, PDF (30/35 Pages) ON Semiconductor – Dimmable Quasi-Resonant Primary Side Current-Mode Controller for LED Lighting with Thermal Fold-back

NCL30083
CS Pin Short Circuit Protection
Normally, if the CS pin or the sense resistor is shorted to
ground, the Driver will not be able to turn off, leading to
potential damage of the power supply. To avoid this, the
NCL30083 features a circuit to protect the power supply
against a short circuit of the CS pin. When the MOSFET is
on, if the CS voltage stays below V_CS(low) after the adaptive
blanking timer has elapsed, the controller shuts down and
will attempt to restart on the next V_CC hiccup.
V_VIN
CS
Adaptative
Blanking Time
Q_drv
V_CS(low)
S
Q
Q
CS_short
R
UVLO
BO_NOK
Figure 70. CS Pin Short Circuit Protection Schematic
Fault Management
OFF Mode
The circuit turns off whenever a major condition prevents
it from operating:
• Incorrect feeding of the circuit: “UVLO high”. The
UVLO signal becomes high when V_CC drops below
V_CC(off) and remains high until V_CC exceeds V_CC(on).
• OTP
• V_CC OVP
• OVP2 (additional OVP provided by SD pin)
• Output diode short circuit protection: “WOD_SCP
high”
• Output / Auxiliary winding Short circuit protection:
“Aux_SCP high”
• Die over temperature (TSD)
• Brown−Out: “BO_NOK” high
• Pin CS short circuited to GND: “CS_short high”
In this mode, the DRV pulses are stopped. The VCC
voltage decrease through the controller own consumption
(I_CC1).
For the output diode short circuit protection, the CS pin
short circuit protection, the output / aux. winding short
circuit protection and the OVP2, the controller waits 4
seconds (auto−recovery timer) and then initiates a startup
sequence (V_CC ≥ V_CC(on)) before re−starting switching.
Latch Mode
This mode is activated by the output diode short−circuit
protection (WOD_SCP), the OTP and the Aux−SCP in
version A only.
In this mode, the DRV pulses are stopped and the
controller is latched. There are hiccups on V_CC.
The circuit un−latches when V_CC < V_CC(reset).
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