The EN pin provides precision ON and OFF control for the TPSM265R1. Once the EN pin voltage exceeds the threshold voltage, the device starts operation. The simplest way to enable the TPSM265R1 is to connect EN directly to VIN. This allows the TPSM265R1 to start up when VIN is within its valid operating range. An external logic signal can also be used to drive the EN input to toggle the output on and off and for system sequencing or protection.

The TPSM265R1 implements internal undervoltage lockout (UVLO) circuitry on the VIN pin. The device is disabled when the VIN pin voltage is below the internal VIN UVLO threshold. The internal VIN UVLO rising threshold is 2.95 V (max) with a typical hysteresis of 300 mV.

If an application requires a higher UVLO threshold, the EN input supports adjustable UVLO by connecting a resistor divider from VIN to the EN pin. The EN pin connects to an internal comparator referenced to a 1.212-V bandgap voltage with 68-mV hysteresis. However, applications requiring specific power-up and power-down requirements can program the hysteresis voltage independently using the HYS pin. Figure 7-2 shows the resistor divider connection to establish a precision UVLO level with fixed internal hysteresis. Figure 7-3 shows the resistor divider connection used to set the precision UVLO level as well as the adjustable hysteresis.

Figure 7-2 Programmable V_IN UVLO with Fixed Hysteresis

Figure 7-3 Programmable V_IN UVLO with Adjustable Hysteresis

Use Equation 2 and Equation 3 to calculate the input UVLO voltages turnon and turnoff voltages, respectively.

Equation 2.

Equation 3.

There is also a low I_Q shutdown mode when EN is pulled below 0.6 V (typ). If EN is below this shutdown threshold, the internal LDO regulator powers off, shutting down the bias currents of the TPSM265R1. The TPSM265R1 operates in standby mode when the EN voltage is between the shutdown and precision enable thresholds.