L6228Q

Circuit description

Doc ID 14321 Rev 4

11/32

4

Circuit description

4.1

Power stages and charge pump

The L6228Q integrates two independent power MOS full bridges. Each power MOS has an

patterns are generated by the PWM Current Controller and the Phase Sequence Generator

(see below). Cross conduction protection is achieved using a dead time (t

value) between the switch off and switch on of two power MOSFETs in one leg of a bridge.

operates with a supply voltage in the range from 8 V to 52 V. It has to be noticed that the

12 V.

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

voltage above the power supply voltage. The bootstrapped supply voltage V

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

as shown in Figure 8. The oscillator output (VCP) is a square wave at 600 kHz (typical) with

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

in Table 6.

Figure 8.

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