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bq27200 21V PGM: thin trace allowed?

Anonymous
Anonymous
Other Parts Discussed in Thread: BQ27200

Hi,

I would like to ask a question with bq27200.

For [pin 10, PGM] which would get connected to 21V programming voltage, is there any requirement on trace width?

From the bq27200 EVM sluu210 layout, we see that the trace connecting [pin 10, PGM] has almost equal length t the pin lead, which from datasheet drawing we know is approximately 0.28mm = 0.28×(1000/25.4) = 11.02 mil.

In addition, in page 3 ELECTRICAL CHARACTERISTICS of the datasheet, the programming current is shown to 15mA. This is certain within the current carrying ability of all practically possible trace widths. For example, assuming the trace is on the surface layer (top or bottom) and a thickness of 0.5oz/ft2 copper, temperature rise 10°C, only a width of 0.12mil would be sufficient to carry the current.

However, since the voltage is high, there are perhaps other considerations other than current carrying ability alone. For example, in table 6-1 of IPC 2221 Generic Standard on Printed Board Design, trace spacing have different minimum value under different voltage ratings, of which [0, 15]V and [16, 30]V are two distinct classes, and the 21V PGM voltage belongs to the 2nd class which is different from all other parts.

My routing is dense so that there is not too much extra space for this [pin 10, PGM] connecting trace. I would like to confirm if a 4mil wide, 0.5oz/ft2 trace would be enough for it?

 

Zheng