OFF-LINE START-UP AND BIAS SUPPLY GENERATION
The circuit in Figure 11 supplies VCC power to the
ML4821. Start-up current is delivered via R10. The IC
starts when VCC reaches 15.5V. After that time running
power is delivered through the tap on L1. The
configuration shown delivers a voltage proportional to the
PFC output bus voltage.
L1
NP NS
R10
39kΩ
2W
1µF
1µF
TO B+
TO IC
PIN 15
1000µF
NP ≈ VOUT
NS 14V
Figure 11. Bias and Start-up Circuit.
ML4821
Micro Linear
9