NCP1060_16 Datasheet, PDF (22/31 Pages) ON Semiconductor – High-Voltage Switcher for Low Power Offline SMPS

NCP1060, NCP1063
350
NCP1060
300
NCP1063
250
200
150
100
50
0
40
50
60
70
80
90
100
110
I_COMP [mA]
Figure 39. Ipk set−point is frozen at lower power demand (I_LMOP ≥ 285 mA)
Feedback and Skip
Figure 40 depicts the relationship between COMP pin
voltage and current. The COMP pin operates linearly as the
absolute value of COMP current (I_COMP) is above 40 mA. In
this linear operating range, the dynamic resistance is
17.7 kW typically (R_COMP(up)) and the effective pull up
voltage is 2.7 V typically (V_COMP(REF)). When I_COMP is
decreases, the COMP voltage will increase to 3.2 V.
3.5
3
2.5
2
1.5
1
0.5
0
-180 -160 -140 -120 -100 -80 -60 -40 -20 0
I_COMP [μA]
Figure 40. COMP Pin Voltage vs. Current
Figure 41 depicts the skip mode block diagram. When the
COMP current information reaches I_COMPskip, the internal
clock setting the flip−flop is blanked and the internal
consumption of the controller is decreased. The hysteresis of
internal skip comparator is minimized to lower the ripple of
the auxiliary voltage for V_CC pin and V_OUT of power supply
during skip mode. It easies the design of V_CC over load
range.
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