L6229Q datasheet(11/28 Pages) STMICROELECTRONICS

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L6229Q

Circuit description

Doc ID 15209 Rev 3

11/28

Circuit description

5.1

Power stages and charge pump

The L6229Q integrates a three-phase bridge, which consists of 6 power MOSFETs

connected as shown on the block diagram (see Figure 1). each power MOS has an

RDS(ON) = 0.73 Ω (typical value @ 25 °C) with intrinsic fast freewheeling diode. Switching

patterns are generated by the PWM current controller and the hall effect sensor decoding

logic (see relative paragraph 3.3 and 3.5). Cross conduction protection is implemented by

using a dead time (tDT = 1 µs typical value) set by internal timing circuit between the turn off

and turn on of two power MOSFETs in one leg of a bridge.

Pins VSA and VSB must be connected together to the supply voltage (VS).

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 (VBOOT) is obtained

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

as shown in Figure 5. The oscillator output (pin VCP) is a square wave at 600 kHz (typically)

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

shown in Table 7.

Figure 5.

Charge pump circuit

Table 7.

Charge pump external component values

Component

Value

CBOOT

220 nF

10 nF

1N4148

CBOOT

VSA

VCP

VBOOT

VSB

D01IN1328

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