ZHCSCN3B June 2014 – March 2018 LM46000
PRODUCTION DATA.
The UVLO is adjusted using the external voltage divider network of RENT and RENB. RENT is connected between VIN and the EN pin of the LM46000 device. RENB is connected between the EN pin and the GND pin. The UVLO has two thresholds, one for power up when the input voltage is rising and one for power down or brownouts when the input voltage is falling. Equation 24 can be used to determine the rising VIN (UVLO) level:
The EN rising threshold for LM46000 is set to be 2.1 V. Choose the value of RENB to be 1 MΩ to minimize input current going into the converter. If the desired VIN (UVLO) level is at 5 V, then the value of RENT can be calculated using Equation 25:
Equation 25 yields a value of 1.37 MΩ. The resulting falling UVLO threshold can be calculated as follows: