PM6686 datasheet(44/50 Pages) STMICROELECTRONICS

44 / 50 page

Diode selection

PM6686

44/50

Doc ID 15281 Rev 4

Typical components values are: C1 = 1 µF and C2 = 1 µF.

11.3.3

VREF2 and VREF3 capacitors

A 10 nF to 100 nF ceramic capacitor on VREF2 pin must be added to ensure noise

rejection. If VREF3 voltage is not used the pin can be left floating, otherwise a 10 nF to 100

nF bypass ceramic capacitor should be mounted.

11.3.4

LDO output capacitors

Bypass the output of the linear regulator with 4,7 µF ceramic capacitor closer to the LDO

pin. In most applicative conditions the ceramic output capacitor can be enough to ensure

stability.

11.3.5

Bootstrap circuit

The external bootstrap circuit is represented in the next figure:

Figure 57.

Bootstrap circuit

The bootstrap circuit capacitor value CBOOT must provide the total gate charge to the high-

side MOSFET during turn on phase. A typical value is 100 nF.

A resistor RBOOT on the BOOT pin could be added in order to reduce noise when the

phase node rises up, working like a gate resistor for the turn on phase of the high-side

MOSFET. A typical value is RBOOT = 1 Ω.

RBOOT

PHASE

CBOOT

RBOOT

PM6686 Datasheet(PDF) 44 Page - STMicroelectronics