TPS60500, TPS60501

TPS60502, TPS60503

SLVS391B − OCTOBER 2001 − REVISED FEBRUARY 2002

11

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PRINCIPLES OF OPERATION

0.5x conversion mode

This conversion mode is internally selected if the input to output voltage ratio is greater than two (e.g. 3.6 V to

1.5 V conversion). In the 0.5x mode, the flying capacitors and the switches always work in parallel, which

reduces the resistance of the circuit compared to the other modes. In the first cycle, the flying capacitors are

charged in series with the output capacitors. In the second cycle, the flying capacitors are connected in parallel

with the output capacitor, which discharges the flying capacitors.

C1F

C2F

SW1

SW2

SW3

SW4

SW9

SW5

SW6

SW7

SW8

++

+

VIN

OUT

Co

SW1

SW2

SW3

SW4

SW9

SW5

SW6

SW7

SW8

++

+

VIN

OUT

Co

C1F

C2F

Phase 1: Charging of Flying Caps

Phase 2: Discharging of Flying Caps

Figure 24.

0.5x Conversion Mode

1/3x conversion mode

This mode was implemented to provide high efficiency even with an input to output voltage ratio greater than

three (e.g. 5 V to 1.5 V conversion). In the first cycle, the two flying capacitors are charged in series with the

output capacitor. In the next step, the flying capacitors which are charged to VIN/3, are connected in parallel

to the output capacitor.

SW1

SW2

SW3

SW4

SW9

SW5

SW6

SW7

SW8

++

+

VIN

OUT

Co

SW1

SW2

SW3

SW4

SW9

SW5

SW6

SW7

SW8

++

+

VIN

OUT

Co

C1F

C2F

C1F

C2F

Phase 1: Charging of Flying Caps

Phase 2: Discharging of Flying Caps

Figure 25.

1/3x Conversion Mode