out

ref

R2

V

V

1

R3

é

ù

=

´

+

ê

ú

ë

û

(

)

ENfalling

STOP

ENfalling

p

h

R4 V

R5

V

V

R4 I

I

´

=

-

+

+

ENfalling

START

STOP

ENri sin g

ENfalling

p

h

ENri sin g

V

V

V

V

R4

V

I

1

I

V

æ

ö

-

ç

÷

ç

÷

è

ø

=

æ

ö

-

+

ç

÷

ç

÷

è

ø

EN

Ip

Ih

R4

R5

VIN

Device

10

TPS54302

SLVSDG6A – MAY 2016 – REVISED MAY 2016

www.ti.com

Product Folder Links: TPS54302

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Copyright © 2016, Texas Instruments Incorporated

Feature Description (continued)

Figure 13. Adjustable VIN Undervoltage Lockout

(1)

Where:

(2)

7.3.6 Safe Startup into Pre-Biased Outputs

The device has been designed to prevent the low-side MOSFET from discharging a pre-biased output. During

monotonic pre-biased startup, both high-side and low-side MOSFETs are not allowed to be turned on until the

internal soft-start voltage is higher than FB pin voltage.

7.3.7 Voltage Reference

The voltage reference system produces a precise ±2.5% voltage-reference over temperature by scaling the

output of a temperature stable bandgap circuit. The typical voltage reference is designed at 0.596 V.

7.3.8 Adjusting Output Voltage

The output voltage is set with a resistor divider from the output node to the FB pin. It is recommended to use

divider resistors with 1% tolerance or better. Start with 100 k

Ω for the upper resistor divider, use Equation 3 to

calculate the output voltage. To improve efficiency at light loads consider using larger value resistors. If the

values are too high the regulator is more susceptible to noise and voltage errors from the FB input current are

noticeable.

(3)

7.3.9 Internal Soft-Start

The TPS54302 device uses the internal soft-start function. The internal soft start time is set to 5 ms typically.