4.5-V to 14.5-V Input, 6-A Synchronous Buck, Integrated Power Solution TPS84620 FEATURES DESCRIPTION

TPS84620

SLVSA43D – OCTOBER 2010 – REVISED OCT 2012 www.ti.com

Sequencing (SS/TR)

Many of the common power supply sequencing methods can be implemented using the SS/TR, INH and

PWRGD pins. The sequential method is illustrated in

Figure 37

using two TPS84620 devices. The PWRGD pin of the first device is coupled to the INH pin of the second device which enables the second power supply once the primary supply reaches regulation.

Figure 38

shows sequential turn-on waveforms of two TPS84620 devices.

TPS84620

INH/UVLO

PWRGD

SS/TR

TPS84620

INH/UVLO

PWRGD

SS/TR

UDG-10106

Figure 37. Sequencing Schematic Figure 38. Sequencing Waveforms

Simultaneous power supply sequencing can be implemented by connecting the resistor network of R1 and R2 shown in

Figure 39

to the output of the power supply that needs to be tracked or to another voltage reference source.

Figure 40

shows simultaneous turn-on waveforms of two TPS84620 devices. Use

Equation 2

and

Equation 3

to calculate the values of R1 and R2.

R1

=

(

V

OUT2

´

12.6

)

0.8

(2)

R2

=

0.8

´

R1

(

V

OUT2

-

0.8

)

(3)

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Copyright © 2010–2012, Texas Instruments Incorporated

TPS84620

SLVSA43D – OCTOBER 2010 – REVISED OCT 2012 www.ti.com

TPS84620

VOUT

INH/UVLO

STSEL SS/TR

V

OUT1

TPS84620

VOUT

INH/UVLO

V

OUT2

R1

STSEL SS/TR

R2

UDG-10107

Figure 39. Simultaneous Tracking Schematic Figure 40. Simultaneous Tracking Waveforms

Copyright © 2010–2012, Texas Instruments Incorporated

Product Folder Links: TPS84620

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