ZHCSNC7 December 2021 LM25148
PRODUCTION DATA
The EN pin can be connected to a voltage as high as 42 V. The LM25148 has a precision enable. When the EN voltage is greater than 1 V, controller switching is enabled. If the EN pin is pulled below 0.5 V, the LM25148 is in shutdown with an IQ of 2.3 μA (typical) current consumption from VIN. When the enable voltage is between 0.5 V and 1 V, the LM25148 is in standby mode with the VCC regulator active but the controller is not switching. In standby mode, the non-switching input quiescent current is 124-μA typical. The LM25148 is enabled with a voltage greater than 1.0 V. However, many applications benefit from using a resistor divider RUV1 and RUV2, as shown in Figure 8-1, to establish a precision UVLO level. TI does not recommend leaving the EN pin floating.
When using precision enable and a VCCX supply, place a series diode with the cathode connected to the LM25148 VCCX pin.
Use Equation 1 and Equation 2 to calculate the UVLO resistors given the required input turn-on and turn-off voltages.