# External Mode error TI 28379D Buck Converter BOOSTXL

**URL:** https://forum.plexim.com/t/external-mode-error-ti-28379d-buck-converter-boostxl/2534
**Category:** TI C2000
**Tags:** external, buck-converter, f28379d, c2000
**Created:** [September 3, 2025, 12:15am UTC](https://forum.plexim.com/t/external-mode-error-ti-28379d-buck-converter-boostxl/2534 "2025-09-03T00:15:47Z")
**Posts on this page:** 1
**Showing post:** 2

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### Author: ![Munadir\_Ahmed](https://dub1.discourse-cdn.com/flex006/user_avatar/forum.plexim.com/munadir_ahmed/32/1540_2.png) [@Munadir\_Ahmed](https://forum.plexim.com/u/Munadir_Ahmed)
#### Post date: [September 3, 2025, 1:06pm UTC](https://forum.plexim.com/t/external-mode-error-ti-28379d-buck-converter-boostxl/2534/2 "2025-09-03T13:06:47Z")

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Hello, it appears that with external mode the processor (highest frequency ISR) is being pushed to the limit and you are running into task overrun issues. See [Higher PWM switching frequency in TI auto Code generation - #2 by Bryan\_Lieblick](https://forum.plexim.com/t/higher-pwm-switching-frequency-in-ti-auto-code-generation/2523/2) for a detail explanation

One thing you could try is to divide down the highest frequency task - this can be changed in the initialization parameter by adjusting the parameter “trigger\_divider”. For the 28379 it is set to 3. Try with the trigger divider set to 4.

This will change your control task execution rate from ~66.66kHz to 50kHz and with that reduction you might get the additional time needed to service the overhead added by the external mode.

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