Tip / Sign in to post questions, reply, level up, and achieve exciting badges. Know more

cross mob

TLD5190: Changing from buck-boost mode to buck or boost, hysteresis?

TLD5190: Changing from buck-boost mode to buck or boost, hysteresis?

IFX_Publisher2
Community Manager
Community Manager
Community Manager
1000 replies posted First like given 750 replies posted

The TLD5190 uses one inductor and 4 external MOSFETs. This topology is able to operate in boost, buck-boost and buck mode. https://www.infineon.com/export/sites/default/en/about-infineon/company/contacts/support/images/TLD5... image1.
The regulation mode at startup is in buck mode. The device automatically performs the mode change by measuring the DC-DC duty cycles of the low-side gate drivers LSGD1 and LSGD2.  https://www.infineon.com/export/sites/default/en/about-infineon/company/contacts/support/images/TLD5....
Mode change duty cycle thresholds and hysteresis are approximately constant in frequency. Typical duty cycle threshold conditions at switching frequency of 300kHz are:
1. For increasing duty cycles (increasing output voltage):
-Buck to buck-boost = condition is buck duty cycle  = 100% - 13% (LSGD1) = 87% 
2. For decreasing duty cycles (decreasing output voltage):
-Boost to buck-boost = condition is boost duty cycle = 11% (monitor LSGD2)
-Buck-boost to buck = condition is buck duty cycle = 100% - 29% (LSGD1) = 71% 
The hysteresis is approximately 16%.
The https://www.infineon.com/export/sites/default/en/about-infineon/company/contacts/support/images/TLD5... diagram, extracted from the datasheet, shows how buck and boost duty cycles enter in regulation.
For more information please see the datasheet on the https://www.infineon.com/cms/en/product/power/lighting-ics/litix-automotive-led-driver-ic/litix-powe... of TLD5190.

0 Likes
90 Views