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GDU Charge Pump "CP Pin" Can Not Output The Correct Wave(Frequence and Duty) I Want

Question asked by chding ding on Sep 27, 2018
Latest reply on Oct 3, 2018 by chding ding

GDU init as follwing:

         

void initGDU(void)
{

GDUE_GCPE = 1; // charge pump

GDUE_GCSE0 = 1; // enable Current Sense Amplifier 0

GDUF = 0xff; // Flag Register - clear all error flags

GDUBCL = 0x0F; // Set coil current limit to maximum 750mA

GDUCLK1_GBOCD = 0b10001; // Set boost frequency ~ 0.52MHz

GDUCLK1_GBODC = 0b11; // Set duty cycle to 75%

GDUE_GBOE = 1; // Enable boost


GDUCLK2_GCPCD = 2; // Fbus / 32

GDUCTR = 0x93;//0x13; // blanking time

GDUDSLVL = 0x77; // desat. level

GDUE_GFDE = 1; // enable FET pre-driver

GDUDSE = 0x77; // Clear Desaturation Error Flags
}

 

 

   The Schematic like this,

I use Oscilloscope test CP pins, the output single like this

 

 

I set Frequence  = 0.52MHz,  but output Frequence is 0.39MHz,   the duty i set is 75%, but the output is 50%.

 

so i want to know how to correct it.

 

Thank you Very much. 

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