UCC21521: Isolated voltage for "functional isolation" between CHA and CHB

Hi, Eason,

Please review this video. If you have any remaining questions, please let us know.

https://training.ti.com/ti-precision-labs-isolation-what-are-creepage-and-clearance

Best regards,

Don

Hi Eason,

We don't have any comparison like that where we know how much board space is saved between having 2 single channels vs 1 dual channel driver as far as I know. However the dual channel gate driver has additional features for ease of use which could be complicated to implement with using 2 single channel drivers like deadtime control. Deadtime control is our drivers way of preventing both outputs from turning on which could cause shoot-through in a half bridge circuit. The dual channel drivers output can also run off a single supply to power one channel and a bootstrap to power the other, saving you the cost of using 2 isolated supplies. Another advantage of the dual channel driver is a more compact pcb with less IC's, combining the low side driver and high side in one package saves you the space that 2 single channel drivers take up. However there are some situations where you may prefer 2 single channel drivers to a dual channel driver, if the creepage distance between the two channels isn't enough distance or if your layout forces you to use 2 gate drivers in different areas of the board to operate the half-bridge. 

This device can work under 1500V DC, in this situation, is this distance enough? Well there are additional factors that come into play here, the 1500V spec refers to the max voltage between the two channels internally. Generally we see the DC bus voltage on these drivers between 600-1200V because outside of the driver there are environmental factors that have large impact on this ch-ch voltage limit. There are various standards that publish these limits that take into account environmental factors and one of them is IEC60664-1. I'll email you a link to it. 

Regards,

Krystian