TPS5102

DUAL, HIGH-EFFICIENCY CONTROLLER FOR NOTEBOOK PC POWER

SLVS239 - SEPTEMBER 1999

21

POST OFFICE BOX 655303

APPLICATION INFORMATION

synchronization (continued)

Ct

Rt

TPS5102

An external resistor is added into the circuit, but Rt is still removed. Ct is kept to be a part of RC circuit generating

triangle waveform for the controller. Assuming the peak value of the square is known, the resistor and the

capacitor can be adjusted to achieve the correct peak-to-peak value and the offset value.

layout guidelines

Good power supply results will only occur when care is given to proper design and layout. Layout will affect noise

pickup and generation and can cause a good design to perform with less than expected results. With a range

of currents from milliamps to tens or even hundreds of amps, good power supply layout is much more difficult

than most general PCB designs. The general design should proceed from the switching node to the output,

then back to the driver section and, finally, parallel the low-level components. Below are several specific points

to consider

before the layout of a TPS5102 design begins.

to Vref5, Vref, INV, LH, and COMP.

plane close to the source of the low-side FET.

reduce stray inductance. This becomes more critical if external gate resistors are not being used.

be as short and as wide as possible.

LL) should be placed close to the TPS5102.

capacitors should be placed in parallel with the bulk capacitors and connected close to the drain of the

high-side FET and to the source of the low-side FET.

and LL should be routed very close to each other to minimize differential-mode noise coupling to these

traces.