Circuit description

L6227Q

10/27

4

Circuit description

4.1

Power stages and charge pump

The L6227Q integrates two independent power MOS Full Bridges. Each power MOS has an

conduction protection is achieved using a dead time (td = 1

µs typical) between the switch

off and switch on of two power MOS in one leg of a bridge.

Using N-channel power MOS for the upper transistors in the bridge requires a gate drive

voltage above the power supply voltage. The bootstrapped (VBOOT) supply is obtained

through an internal oscillator and few external components to realize a charge pump circuit

as shown in

Figure 5. The oscillator output (VCP) is a square wave at 600 kHz (typical) with

10 V amplitude. Recommended values/part numbers for the charge pump circuit are shown

in

Table 6.

Figure 5.

Charge pump circuit

Table 6.

Charge pump external components values

Component

Value

220 nF

10 nF

D1

1N4148

D2

1N4148

D2

D1

VCP

VBOOT

D01IN1328