LM5122 misoperation of HO of pulses

Hi 

In diode emulation mode (MODE=GND), HO driver is enabled only when V(CSP-CSN) > about 7mV. 

In FPWM mode(MODE=VCC),  HO driver should be enabled at every cycles. If you do not see any HO-SW pulse in FPWM mode. Please check if V(BST-SW) is enough or not. 

Regards,

Hi. Excuse that I answered not immediately, it was occupied with other operation.

In the MODE=VCC mode such pattern, thus LO 1MHz, HO 200kHz frequencies turns out here. It in case of the switched-off transistors and absence of Vout. (I don't want to burn again)

To Vrezhima MODE=GND as anything HO (is more correct 1).
V (BST-SW) in norm.
V (CSP-CSN) I can't achieve stable tension...

Hi 

Looks like something is totally wrong.

What was your original switching frequency setting by RT pin? 200k Hz? 1MHz ? 

Can you post your schematic ? 

Regards,

Хорошо

Hi 

Please check whether VCC is current limited or not. Ivcc = 2 x Qg x 1M 

Please check MOSFET BVds rating. BVds should be higher than SW node spike. 

Also, please try around 500kHz switching first and then increase the switching frequency gradually.

Looks like you cannot have enough duty cycle range anyway since your off-time is too close to Forced LO off-time of LM5122.

Regards,