BQ500414Q Datasheet, PDF (25/34 Pages) Texas Instruments – Qi Compliant Wireless Power Transmitter Manager

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Layout Example (continued)
bq500414Q
SLUSBE4B – JANUARY 2014 – REVISED JUNE 2014
Continuous GND
Figure 16. Continuous GND Layout
Proper current sensing layout technique is very important, as it directly affects the FOD and PMOD performance.
When sampling the very low voltages generated across a current sense resistor, be sure to use the so called,
"Four-wire" or "Kelvin-connection" technique. This is important to avoid introducing false voltage drops from
adjacent pads and copper power routes. It is common power supply layout technique.
In the below screen shot of a Texas Instruments PCB layout, the current sense resistor is R64. Notice the R18
and R15 sensing resisters are connected to the pads of R64 so there is no measurement error introduced by
copper conduction losses or copper resistance temperature dependency.
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