TPS63805 datasheet(13/42 Pages) TI

13 / 42 page

VEAmp

IPEAK

TON

TOFF

IIND

Figure 9-7. Peak-Current Boost Operation

9.4.1.3 Buck-Boost Operation

When VI is close to VO, the TPS63805, TPS63806, and TPS63807 operate in buck-boost mode where all

switches are active and the device repeats 3-cycles:

• TON: Boost-charge phase where boost low-side and buck high-side are closed and the inductor current is built

• TOFF: Buck discharge phase where boost high-side and buck low-side are closed and the inductor is

discharged

• TCOM: VI connected to VO where all high-side switches are closed and the input is connected to the output

VEAmp

IPEAK

TON

TOFF

IIND

TCOM

Figure 9-8. Peak-Current Buck-Boost Operation

9.4.1.4 Buck Operation

When VI is greater than VO (and the voltages are not close enough to trigger buck-boost operation), the

TPS63805, TPS63806, and TPS63807 operate in buck mode where the buck high-side and low-side switches

are active. The boost high-side switch is always turned on and the boost low-side switch is always turned off.

This lets the TPS63805, TPS63806, and TPS63807 operate as a classical buck converter.

VEAmp

IPEAK

TON

TOFF

IIND

Figure 9-9. Peak-Current Buck Operation

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TPS63805, TPS63806, TPS63807

SLVSDS9E – JULY 2018 – REVISED AUGUST 2021

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TPS63805 Datasheet(PDF) 13 Page - Texas Instruments