AN2816 datasheet(34/36 Pages) STMICROELECTRONICS

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PM6675S demonstration tests

AN2816

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10.11

Switching frequency

●

Switching frequency vs. input voltage

The constant on-time controller leads to a quasi-constant switching frequency, slightly

following the input voltage.

●

Switching frequency vs. output current

The switching frequency can decrease to very low values in pulse-skip mode but in non-

audible pulse-skip there is a lower limit (about 33 kHz). By increasing the load, however, the

switching frequency increases a bit, as a consequence of conduction and switching losses.

Figure 34.

Switching frequency vs. input voltage, VOUT = 1.5 V, IVOUT = 7 A, forced

PWM mode

Figure 35.

Switching frequency vs. output current, VOUT = 1.5 V, VIN = 12 V

AM01033v1

1.5 V switching frequency vs input voltage

250

300

350

400

450

500

550

600

Input voltage [V]

PWM @ 0 A

PWM @ 7 A

AM01034v1

Switching frequency vs load current

100

200

300

400

500

600

0.01

0.1

Output current [A]

Pulse SKIP

No aud. SKIP

PWM

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