TPS62933O datasheet(17/47 Pages) TI

17 / 47 page

be configured as shown in Figure 8-4. When using the external UVLO function, setting the hysteresis at a value

greater than 500 mV is recommended.

The EN pin has a small pullup current, Ip, which sets the default state of the EN pin to enable when no external

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

UVLO function when the EN pin voltage crosses the enable threshold. Use Equation 3 and Equation 4 to

calculate the values of R1 and R2 for a specified UVLO threshold. Once R1, R2 are settled down, the VEN can

be calculated by Equation 5, which must be lower than 5.5 V with max VIN.

VIN

Device

Figure 8-4. Adjustable VIN Undervoltage Lockout

(3)

EN_FALL

STOP

EN_FALL

(4)

V +R

R +R

(5)

where

• Ip = 0.7 µA

• Ih = 1.4 µA

• VEN_FALL = 1.17 V

• VEN_RISE = 1.21 V

• VSTART = input voltage enabling the device

• VSTOP = input voltage disabling the device

8.3.7 External Soft Start and Pre-Biased Soft Start

The SS pin is used to minimize inrush current when driving capacitative load. The TPS62933 device uses

the lower voltage of the internal voltage reference, VREF, or the SS pin voltage as the reference voltage and

regulates the output accordingly. A capacitor on the SS pin to ground implements a soft-start time. The device

has an internal pullup current source that charges the external soft-start capacitor. Use Equation 6 to calculate

the soft time (tSS, 0% to 100%) and soft-start capacitor (CSS).

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TPS62933

SLUSEA4A – JUNE 2021 – REVISED DECEMBER 2021

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TPS62933O Datasheet(PDF) 17 Page - Texas Instruments