UDG-09067

TPS51218

Thermal Pad

DRVL

4

5

VIN

1 mF

VFB

V5IN

6

V

OUT

2

TRIP

5

RF

0.1 mF

100 W

VTT_SENSE

VSS_SENSE

GND

TPS51218

SLUS935B

– MAY 2009 – REVISED FEBRUARY 2012

www.ti.com

from gate of the low-side MOSFET through the gate driver and GND pad of the device, and back to

source of the low-side MOSFET through ground. Connect negative node of V5IN capacitor, source of the

low-side MOSFET and GND pad of the device at ground as close as possible. (Refer to loop #3 of

Figure 19)

•

The trace

　from these resistors to the VFB pin should be short and thin. Place on the component side and

avoid via(s) between these resistors and the device.

•

Connect the overcurrent setting resistors from TRIP pin to ground and make the connections as close as

possible to the device. The trace from TRIP pin to resistor and from resistor to ground should avoid coupling

to a high-voltage switching node.

•

Connect the frequency setting resistor from RF pin to ground, or to the PGOOD pin, and make the

connections as close as possible to the device. The trace from the RF pin to the resistor and from the resistor

to ground should avoid coupling to a high-voltage switching node.

•

Connections from gate drivers to the respective gate of the high-side or the low-side MOSFET should be as

short as possible to reduce stray inductance. Use 0.65 mm (25 mils) or wider trace

　and via(s) of at least

0.5 mm (20 mils) diameter along this trace.

•

The PCB trace defined as switch node, which connects to source of high-side MOSFET, drain of low-side

MOSFET and high-voltage side of the inductor, should be as short and wide as possible.

LAYOUT CONSIDERATIONS TO REMOTE SENSING

Figure 20. Remote Sensing of Output Voltage Using the TPS51218

•

Make a Kelvin connection to the load device.

•

Run the feedback signals as a differential pair to the device. The distance of these parallel pair should be as

short as possible.

•

Run the lines in a quiet layer. Isolate them from noisy signals by a voltage or ground plane.

18

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