Datasheet

L6229Q Circuit description
Doc ID 15209 Rev 3 11/28
5 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
R
DS(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 (t
DT
= 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 VS
A
and VS
B
must be connected together to the supply voltage (V
S
).
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 (V
BOOT
) 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 Tab l e 7 .
Figure 5. Charge pump circuit
Table 7. Charge pump external component values
Component Value
C
BOOT
220 nF
C
P
10 nF
D1 1N4148
D2 1N4148
D2
C
BOOT
D1
C
P
V
S
VS
A
VCP VBOOT VS
B
D01IN132
8