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Chapter 17 Gate Drive Unit (GDUV4)
MC9S12ZVM Family Reference Manual Rev. 1.3
Freescale Semiconductor
650
NOTE
Optional RC filter to VBS pin should be used to avoid overshoot above
maximum voltage on VBS pin. The RC filter needs to be carefully designed
in order not to influence the charging time of the bootstrap capacitor C
BS
.
17.4.4
Charge Pump
The GDU module integrates the necessary hardware to build a charge pump with external components.The
charge pump is used to maintain the high-side driver gate source voltage V
GS
when PWM is running at
100% duty cycle. The external components needed are capacitors and diodes. . The supply voltage of the
charge pump driver on pin CP is V
VLS.
The output voltage on pin CP typically switches between 0 and
11V. The charge pump clock frequency depends on the setting of GCPCD bits.