SNVSA46B June 2014 – January 2018 LM46001
Voltage on the ENABLE pin (VEN) controls the ON or OFF functionality of the LM46001. Applying a voltage less than 0.4 V to the ENABLE input shuts down the operation of the LM46001. In shutdown mode the quiescent current drops to typically 2.3 µA at VIN = 24 V.
The internal LDO output voltage VCC is turned on when VEN is higher than 1.2 V. The LM46001 switching action and output regulation are enabled when VEN is greater than 2.1 V (typical). The LM46001 supplies regulated output voltage when enabled and output current up to 1 A.
The ENABLE pin is an input and cannot be left open circuited. The simplest way to enable the operation of the LM46001 is to connect the ENABLE pin to the VIN pins directly. This allows self-start-up of the LM46001 when VIN is within the operation range.
Many applications benefit from the employment of an enable divider RENT and RENB in Figure 36 to establish a precision system UVLO level for the stage. System UVLO can be used for supplies operating from utility power as well as battery power. It can be used for sequencing, ensuring reliable operation, or supply protection, such as a battery discharge voltage level. An external logic signal can also be used to drive EN input for system sequencing and protection.