# switched capacitor converter with continuous conversion ratio resonant switched capacitor converter

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Switched Capacitor Converter with

continuous conversion ratio

Mert Turhan

20.06.2017

DC/DC converter topologies 1

► Capacitive Converter ► Inductive Converter ► Linear Regulator

Advantages of Switched Capacitor Converter (SCC)

• No magnetic elements − No inductive switching losses − Can be fabricated as IC

• High power density

2

0

20

40

60

80

100

120

140

160

Energy Density (µJ/mm2)

Energy density of an inductor and a capacitor

Inductor (10µH Coilcraft SMT)

Capacitor (1µF T-Y Ceramic)

149

~1

Integration 3

► Inductive ► Capacitive

Source: V. Wai Shan Ng ,'Switched Capacitor DC-DC Converter: Superior where the Buck Converter has Dominated', PhD Berkely

DC-DC step-down inductor based with the inductor marked. Vin=5V-23V, Vout=1V-17V and Iout=3A

DC-DC step-down switched-capacitor converter (SCC) Vin=7.5V-13V, Vout=1V and Iout=1A

Why not SCC?

• Output voltage regulation is tied to efficiency

• Not suited for high current/power

• Lots of switches and gate driver

• Voltage balancing for many caps

• Current stress

4

Voltage Conversion for Dickson Converter 5

3:1 Dickson Converter First phase, odd switches are open

Second phase, even switches are open

Step-up Switched Capacitor Converter 6

Resonant Switched Capacitor Converter

• Even the efficiency increases, the output voltage is discrete and is tied to the load

7

60

65

70

75

80

85

90

95

100

0,3 0,8 1,3 1,8

Ef fi

ci en

cy (

% )

Output Current (A)

Conventional SCC without Lr

r=20mΩ r=50mΩ

Resonant SCC with Lr r=20mΩ

r=50mΩ

1,5

1,7

1,9

2,1

2,3

2,5

0,3 0,8 1,3 1,8 O

u tp

u t

V o

lt ag

e (V

) Output Current (A)

Conventional SCC without Lr

r=20mΩ r=50mΩ

Resonant SCC with Lr r=20mΩ

r=50mΩ

SCC with Continuous Conversion Ratio

8

Derivation of SCC with Continuous Conversion Ratio 9

The step-up SCC 10

• To connect the capacitor cells in order to increase the conversion ratio

Step-up SCC with 2 SCs 11

Conversion Ratio versus duty cycle (δ)

Operation of the step-up SCC

12

Efficiency

Parameters

C1, C3 0.1µF

C2, C4 10µF

L 2.2µH

fsw 215kHz

Vin 20-40V

Pout 100W

13

Loss distribution of the converter

14

Size comparision

• Four Level Boost Converter (FLBC) Balancing circuit was not taken into account

15

• SCQRC

%12 less

Conclusions

• Capacitors may be used in order to minimize the size of the inductor

• There is no unbalancing problem at charge pump topoplogy

• Capacitor cells may be used to increase conversion ratio without extra loss

16

Switched Capacitor Converter with

continuous conversion ratio

Mert Turhan m.turhan@tue.nl

20.06.2017

18

Source: Asmarashid Bin Ponniran, Koji Orikawa, and Junichi Itoh,

Minimum Flying Capacitor for N-Level Capacitor

DC/DC Boost Converter