L6226Q_10 Datasheet, PDF (10/29 Pages) STMicroelectronics – DMOS dual full bridge driver

Circuit description
4
Circuit description
L6226Q
4.1
Power stages and charge pump
The L6226Q integrates two independent power MOS full bridges. Each power MOS has an
R_DS(on) = 0.73 Ω (typical value @ 25 °C), with intrinsic fast freewheeling diode. Cross
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.
Table 6.
C_BOOT
C_P
D1
D2
Charge pump external components values
Component
220 nF
10 nF
1N4148
1N4148
Value
Figure 5. Charge pump circuit
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Doc ID 14335 Rev 5