LM34910C

SNVS517B – MAY 2007 – REVISED MARCH 2013

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PC BOARD LAYOUT

The LM34910C regulation, over-voltage, and current limit comparators are very fast, and respond to short

duration noise pulses. Layout considerations are therefore critical for optimum performance. The layout must be

as neat and compact as possible, and all of the components must be as close as possible to their associated

pins. The current loop formed by D1, L1, C2 and the SGND and ISEN pins should be as small as possible. The

ground connection from C2 to C1 should be as short and direct as possible.

If it is expected that the internal dissipation of the LM34910C will produce excessive junction temperatures during

normal operation, good use of the PC board’s ground plane can help considerably to dissipate heat. The

exposed pad on the bottom of the IC package can be soldered to a ground plane, and that plane should extend

out from beneath the IC, and be connected to ground plane on the board’s other side with several vias, to help

dissipate the heat. The exposed pad is internally connected to the IC substrate. Additionally the use of wide PC

board traces, where possible, can help conduct heat away from the IC. Judicious positioning of the PC board

within the end product, along with the use of any available air flow (forced or natural convection) can help reduce

the junction temperatures.

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