NCP100 Ver la hoja de datos (PDF) - ON Semiconductor
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NCP100 Datasheet PDF : 12 Pages
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NCP100
The circuit performs the same as the one in Figure 21 with
the exception of the effects of Rcomp. As IK increases, the
voltage across Rcomp also increases by:
Vcomp + IKA Rcomp
Vcomp effectively adjusts the NCP100 programmed VKA
voltage slightly down since the R1/R2 voltage divider will
try to hold the point it is connected to at the programmed
voltage. The regulator VKA will now be lowered by the
value of the Vcomp. This effect can compensate for the
NCP100’s intrinsic positive impedance versus cathode
current (IK) to allow for 0 W or even a negative dynamic
impedance.
Figure 23 shows this phenomenon for a program voltage
of 1.0 V. The NCP100 intrinsic positive dynamic impedance
response is the Rcomp = 0 W curve. A 0 W dynamic
impedance regulator response is realized with Rcomp =
0.15 W. Negative dynamic impedance responses are
achieved with Rcomp u 0.15 W.
Figure 24 shows the characteristic at a programmed VKA
of 6.0 V. The 0 W dynamic impedance value corresponds to
Rcomp = 2.9 W.
Figure 25 shows the dynamic impedance versus cathode
compensation resistance for programmed voltages of 1.0 V,
3.3 V and 6.0 V. It can be seen that any value up to the
positive intrinsic dynamic impedance of the NCP100 can be
realized. The other limit is that with a high enough negative
dynamic impedance, the NCP100 V may drop below the
minimum operating VKA voltage of 0.9 V, which can result
in unpredictable performance.
20
Rcomp= 3.1 W
= 1.5 W
= 0.15 W
15
=0W
Rcomp |ZKA|
10
(W)
0
(W)
0.2
0.15 0
1.5 −1.4
5.0 3.1 −1.6
IK = 0.1 mA to 20 mA
TA = 25° C
Figure 22
0
0.94 0.95 0.96 0.97 0.98 0.99 1.00 1.01
VKA, CATHODE VOLTAGE (V)
Figure 23. Cathode Current vs. Cathode Voltage for
Programmed VKA = 1.0 V
20
= 2.9 W
= 4.4 W
= 1.5 W
15
=0W
10
Rcomp= 5.8 W
5.0 IK = 0.1 to 20 mA
TA = 25° C
Figure 22
0
5.94 5.96 5.98
6.00
Rcomp
W
0
1.5
2.9
4.4
5.8
|ZKA|
W
2.9
1.4
0
−1.6
−2.9
6.02 6.04 6.06
VKA, CATHODE VOLTAGE (V)
Figure 24. Cathode Current vs. Cathode Voltage for
Programmed VKA = 6.0 V
3.0
IK = 1.0 mA to 20 mA
2.0
f ≤1.0 kHz
= 6.0 V
Figure 22
1.0
TA = 25° C
0
= 3.3 V
−1.0
−2.0
VKA= 1.0 V
−3.0
0
1.0
2.0
3.0
4.0
5.0
Rcomp, CATHODE COMPENSATION RESISTANCE (W)
Figure 25. Dynamic Impedance vs. Cathode
Compensation Resistance
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