ZHCSFE3B March 2016 – November 2017 LM5161
PRODUCTION DATA.
The LM5161 contains a dual level undervoltage lockout (EN/UVLO) circuit. When the EN/UVLO pin voltage is below 0.35 V (typical), the regulator is in a low current shutdown mode. When the EN/UVLO pin voltage is greater than 0.35 V (typical) but less than 1.24 V (typical), the regulator is in standby mode. In standby mode, the VCC bias regulator is active but converter switching remains disabled. When the voltage at the VCC pin exceeds the VCC rising threshold VCC(UV) = 3.98 V (typ) and the EN/UVLO pin voltage is greater than 1.24 V, normal switching operation begins. An external resistor voltage divider from VIN to GND can be used to set the minimum operating voltage of the regulator.
EN/UVLO hysteresis is accomplished with an internal 20-μA (typical) current source (IUVLO(HYS)) that is switched on or off into the impedance of the EN/UVLO pin resistor divider. When the EN/UVLO threshold is exceeded, the current source is activated to effectively raise the voltage at the EN/UVLO pin. The hysteresis is equal to the value of this current times the upper resistance of the resistor divider, (RUV2) (See Functional Block Diagram.)