NCP1392 Datasheet, PDF (18/21 Pages) ON Semiconductor – High-Voltage Half-Bridge Driver with Inbuilt Oscillator

NCP1392B, NCP1392D
The dimming feature can be easily aid to the ballast
application by adding two bipolar transistors (Figure 14).
Transistor Q2 pullup BO input when dimming signal is high.
In the same time the Q1 discharges soft start capacitor via
diode D1. Ballast application is enabled (including
soft−start phase) when dimming signal becomes low again.
V_bulk
R_upper
D1
BO
R_lower
SW
I_hyste
R2
Rt
Voltage
R_fstart
R_t
Feedback
−
+
+
−
V_refEN
+
−
+
−
V_refBO
0.5ms
Filter
to AND gates
20ms
Filter
to AND gates
To PFC Delay
High Level for BOdisch time after V_CC ON
NCP1392
C_SS
R1
GND
Figure 37. Skip Mode Feature Implementation (Temperature Dependent, Cost Effective)
V_CC
R1
R6
Q1
R2
R3
Soft−Start After Skip (If Needed)
D1
V_bulk
R_upper
BO
R_lower
SW
I_hyste
C1
Q2
R5
Rt
Voltage
R_fstart
R_t
Feedback
−
+
+
−
V_refEN
+
−
+
−
V_refBO
0.5ms
Filter
20ms
Filter
to AND gates
to AND gates
To PFC Delay
High Level for BOdisch time after V_CC ON
NCP1392
C_SS
R4
GND
Figure 38. Skip Mode with Transistor Feature Implementation (Temperature Dependent, Cost Effective)
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