ZHCSHO5C December 2017 – March 2023 LMZM23601
PRODUCTION DATA
When the input voltage level decreases and approaches the output voltage level, the buck regulator reaches its maximum duty cycle or minimum off-time requirement for each switching cycle. At this point the output is no longer regulated and follows the input voltage minus the voltage drops from VIN to VOUT.
To maximize the input voltage range for which the output is still regulated, the LMZM23601 features frequency foldback at low input voltage. This operation extends the switching period and, for a given fixed minimum off-time, it prolongs the maximum duty cycle of the regulator. As a result, the output voltage can still be well regulated even as the input voltage level is very close to the output voltage. This feature can be useful for battery applications (maximizing the useful battery range) or in applications where large input voltage variations can be expected.