Other Parts Discussed in Thread: LM5156EVM-BST
Tool/software:
Hello team,
If EN and SYNC are used(UVLO is not used), how to connect both EN signal and SYNC signal with this one pin?
Is an additional FET required?
Best Regards,
Austin
This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
Tool/software:
Hello team,
If EN and SYNC are used(UVLO is not used), how to connect both EN signal and SYNC signal with this one pin?
Is an additional FET required?
Best Regards,
Austin
Hi Austin,
Thanks for reaching out.
SYNC and shutdown can be implemented like it is done in LM5156EVM-BST:
For enable, you can connect UVLO pin to a MCU or another enable circuit with a resistor.
Best regards
Moritz
Hi Moriz,
Thanks for reply.
According to datasheet, 1.5us logic high is required for device EN. If the customer uses the circuit like figure 9-16, external sync frequency cannot be greater than 333kHz. Is this correct?
The customer will not use UVLO.
Also, the customer wants to control device on/off by MCU and sync clock by external
If my understanding is correct, can you check below schematic will be okay?
Best Regards,
Austin
Hi Austin,
Yes, this schematic should work.
I would recommend to add a resistor (~1k) at the output of the MCU.
Best regards
Moritz
Hi Moritz,
Thanks for reply.
Can you confirm the external frequency range?
In the datasheet, "the device is enabled if fSYNC stays in high logic state for longer than 1.5 µs", which means f_sync is limited at 333kHz(1/ (1.5us *2)) or does it mean it stays ENABLE state until disable condition (LOW ~ 35us)?
Best Regards,
Austin
Hi Austin,
or does it mean it stays ENABLE state until disable condition (LOW ~ 35us)?
Yes, this is what it means.
So you can also apply higher switching frequencies than 333kHz.
Best regards
Moritz
Hi Moritz,
Thanks for quick reply.
If the fixed clock frequency(500kHz) is applied with figure 9-16 case, it seems device cannot be enabled.
How about this case?
Best Regards,
Austin
Hi Austin,
first there has to be a high-signal for at least 1.5us, then the clock signal can be applied.
Best regards
Moritz