VIN

EN

MODE

BOOT

PG/SS

SW

L

GND

FB

EN

400 Q

TPS562211

Figure 7-2. Discharge VOUT through PG/SS Pin with TPS562211

7.3.6 Precise Enable and Adjusting Undervoltage Lockout

The EN pin provides electrical on and off control for the device. When the EN pin voltage exceeds the threshold

voltage, the device begins operation. If the EN pin voltage is pulled below the threshold voltage, the regulator

stops switching and enters the shutdown mode.

The EN pin has an internal pullup source current, which allows you to float the EN pin to enable the device. If an

application requires control of the EN pin, use external control logic interface to the EN the pin like the open-

drain or open-collector output logic.

The device implements internal undervoltage-lockout (UVLO) circuitry on the VIN pin. The device is disabled

when the VIN pin voltage falls below the internal VIN UVLO threshold. The internal VIN UVLO threshold has a

hysteresis of 400 mV.

If an application requires a higher UVLO threshold on the VIN pin, the EN pin can be configured as shown in

Figure 7-3. When using the external UVLO function, setting the hysteresis at a value greater than 400 mV is

recommended.

components are connected. The pullup current is also used to control the voltage hysteresis for the external

Equation 4 to calculate the values of R1 and R2 for a specified UVLO threshold. Once R1 and R2 have settled

down, the EN voltage can be calculated by Equation 5, which must be lower than 5.5 V with max VIN.

EN

Ip

Ih

R1

R2

VIN

Device

Figure 7-3. Adjustable VIN Undervoltage Lockout

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TPS562211

SLUSDX0 – SEPTEMBER 2020

Copyright © 2020 Texas Instruments Incorporated

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