SNVSCI9A June 2024 – September 2024 LMR36503E-Q1
PRODUCTION DATA
Voltage at the EN pin controls the start-up or remote shutdown of the LMR36503E-Q1 family of devices. The part stays shut down as long as the EN pin voltage is less than VEN-WAKE = 0.4V. During the shutdown, the input current drawn by the device typically drops down to 0.5µA (VIN = 13.5V). With the voltage at the EN pin greater than the VEN-WAKE, the device enters the device standby mode, and the internal LDO powers up to generate VCC. As the EN voltage increases further, approaching VEN-VOUT, the device finally starts to switch, entering the start-up mode, with a soft start. During the device shutdown process, when the EN input voltage measures less than (VEN-VOUT – VEN-HYST), the regulator stops switching and re-enters the device standby mode. Any further decrease in the EN pin voltage, below VEN-WAKE, the device is then firmly shut down. The high-voltage compliant EN input pin can be connected directly to the VIN input pin if remote precision control is not needed. The EN input pin must not be allowed to float. The various EN threshold parameters and the values are listed in Electrical Characteristics. Figure 7-2 shows the precision enable behavior. Figure 7-3 shows a typical remote EN start-up waveform in an application. After EN goes high, after a delay of about 1ms, the output voltage begins to rise with a soft start and reaches close to the final value in about 2.67ms (tss). After a delay of about 2ms (tPGOOD_ACT), the PGOOD flag goes high. During start-up, the device is not allowed to enter FPWM mode until the soft-start time has elapsed. This time is measured from the rising edge of EN. Check Section 8.2.2.9.1 for component selection.