Controller

TPS51518

DL

14

VIN

MODE

GND

V5

15

VSNS

SLEW

20

2

6

VREF

UDG-11261

V1

1

GSNS

16

19

2.2 µF

#1

#2

#3

17

PwrPad

18

TRIP

VSNS

GSNS

0.1 µF

10 nF

3

4

5

V0

V3

V2

TPS51518

www.ti.com

SLUSAO8

– DECEMBER 2011

Thermal Shutdown

TPS51518 includes an internal temperature monitor. If the temperature exceeds the threshold value, 140

°C (typ),

is restarted with soft-start sequence when the device temperature is reduced by 10

°C (typ).

Layout Considerations

Certain issues must be considered before designing a layout using the TPS51518.

Figure 26. DC/DC Converter Ground System

•

side of the PCB (solder side). Other small signal components should be placed on another side (component

side). At least one inner plane should be inserted, connected to ground, in order to shield and isolate the

small signal traces from noisy power lines.

•

All sensitive analog traces and components such as VSNS, SLEW, MODE, V0, V1, V2, V3, VREF and TRIP

should be placed away from high-voltage switching nodes such as SW, DH, DL or BST to avoid coupling.

Use internal layer(s) as ground plane(s) and shield feedback trace from power traces and components.

•

The DC/DC converter has several high-current loops. The area of these loops should be minimized in order to

suppress generating switching noise.

high and low-side MOSFETs, and back to the capacitor(s) through ground. Connect the negative node of

#1 of Figure 26)

capacitor(s), and back to source of the low-side MOSFET through ground. Connect source of the low-side

Figure 26)

– Loop #3. The third important loop is of gate driving system for the low-side MOSFET. To turn on the

low-side MOSFET, high current flows from V5 capacitor through gate driver and the low-side MOSFET,

and back to negative node of the capacitor through ground. To turn off the low-side MOSFET, high current

Copyright

© 2011, Texas Instruments Incorporated

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Product Folder Link(s) :TPS51518