PM6686 datasheet(28/50 Pages) STMICROELECTRONICS

部品番号	PM6686

部品情報	Constant ON-time control

PDF	50 Pages

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メーカー	STMICROELECTRONICS [STMicroelectronics]

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28 / 50 page

Device description

PM6686

28/50

Doc ID 15281 Rev 4

8.1.3

PWM

PWM implements the continuous current mode (CCM). During TON, the high-side MOSFET

is turned on and the inductor current starts increasing. When the Ton is elapsed the high-

side MOSFET is turned off and after a dead time during which neither MOSFET conducts,

the low-side MOSFET turns on. The inductor current decreases until these three conditions

are verified:

●

Output voltage reaches the regulation voltage

●

Inductor current is below the current limit

●

TOFFMIN is elapsed

When these conditions are satisfied a new TON starts.

PWM operation mode has a quasi-constant switching frequency, avoiding any audible noise

issue and the continuous current mode assures better load transitions despite of a lower

efficiency at light loads.

Figure 47.

Inductor current and output voltage in PWM mode

Ton

Toff

Inductor

current

Output

voltage

Vreg

PM6686 データシート(PDF) 28 Page - STMicroelectronics