About MC33PT2000 not use self DC-DC boost voltage functionality

[Borden]

Dear NXP team:

       For the 3-cylinder injection, if the DC-DC Vboost voltage (65V) is generated using an external circuit instead of the built-in functionality of this chip, how should the registers and code be set?

[guoweisun · Accepted solution]

HI Borden

You can refer to below datasheet page38:

Application without boost voltage
For this purpose, it is possible to change the internal voltage divider ratio from 1/32 to 1/4 by setting the signal boost_mon_en high. To
detect undervoltage and use the signal uv_vboost to disable the pre-drivers, the uv_vboost bit needs to be set to “1” (refer to Table 162,
driver_status (1B2h)). The uv_vboost signal goes high as soon as the voltage at the VBOOST pin is below the threshold, if the VBOOST
UV monitor is enabled (Vboost_disable_en = 1).
The same digital filter used for the VBOOST voltage measurement is also used for the VBOOST UV monitoring mode. The DAC set point
value in this mode has to be chosen to fulfill two requirements:
• The pre-drivers must not be disabled at a battery voltage above 5.0 V
• The device internal charge pump only works properly down to a battery voltage of 4.7 V
The VBOOST UV threshold can be calculated using the following formula.
• VBOOST = (DAC_VALUE * 39.1 mV)

[Borden]

Thanks very much!!