22

LTC4244/LTC4244-1

42441f

PCB Layout Considerations

For proper operation of the LTC4244’s circuit breaker,

4-wire Kelvin sense connections between the sense resis-

layout should be balanced and symmetrical to minimize

wiring errors. In addition, the PCB layout for the sense

resistors and the power MOSFETs should include good

thermal management techniques for optimal device power

dissipation. A recommended PCB layout for the sense

resistor, the power MOSFET and the GATE drive compo-

nents around the LTC4244 is illustrated in Figure 15. In Hot

APPLICATIO S I FOR ATIO

Swap applications where load currents can be 10A, nar-

row PCB tracks exhibit more resistance than wider tracks

and operate at more elevated temperatures. Since the

sheet resistance of 1 ounce copper foil is approximately

0.45m

Ω/ , track resistance and voltage drops add up

quickly in high current applications. Thus, to keep PCB

track resistance, voltage drop and temperature to a mini-

mum, the suggested trace width in these applications for

1 ounce copper foil is 0.03” for each ampere of DC current.

In the majority of applications, it will be necessary to use

plated-through vias to make circuit connections from

component layers to power and ground layers internal to

LTC4244*

CURRENT FLOW

TO SOURCE

*ADDITIONAL DETAILS OMITTED FOR CLARITY

DRAWING IS NOT TO SCALE!

4244 F15

TRACK WIDTH W:

0.03" PER AMPERE

ON 1 OZ Cu FOIL

D

D

D

D

G

S

S

S

CURRENT FLOW

TO LOAD

CURRENT FLOW

TO LOAD

SENSE

RESISTOR

SO-8

VIA TO

GND PLANE

GND

GND

3.3V

3.3V

VIA/PATH

TO GND

GATE

R3

R5

C1

W

W

W

Figure 15. Recommended Layout for Power MOSFET, Sense Resistor and GATE Components for the 3.3V Rail