NCP1729_16 Datasheet, PDF (10/23 Pages) ON Semiconductor – Switched Capacitor Voltage Inverter

NCP1729
V_in
+
1
OSC
2
3
6
5
+
4
−V_out
+
+
+
+
+
Capacitors = 3.3 mF
Figure 24. Negative Output Voltage Tripler
A single device can be used to construct a negative voltage tripler. The output voltage is approximately equal to −3.0 V_in
minus the forward voltage drop of each external diode. The performance characteristics for the above converter are shown
below. Note that curves A and C show the circuit performance with economical 1N4148 diodes, while curves B and D are with
lower loss MBRA120E Schottky diodes.
0
−2.0
A
−4.0
B
C
−6.0
−8.0
−10.0
D
−12.0
−14.0
T_A = 25°C
−16.0
0
10
20
30
40
50
I_out, OUTPUT CURRENT
Figure 25. Tripler Load Regulation, Output
Voltage vs. Output Current
Curve
A
B
C
D
V_in (V)
3.0
3.0
5.0
5.0
All Diodes
1N4148
R_out (W)
247
MBRA120E
228
1N4148
198
MBRA120E
188
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