0
\$\begingroup\$

I bought a NEO-6 u-blox 6 GPS Module (datasheet, pages 9 and 14), which has a standard serial connection. I have a USB to serial converter, which is 5v logic. This board says it can be supplied 3v-5v, and I have seen people say that it is 3.3v logic, but these people always say to power the board from 3.3v. My question is: If I power the module with 5v, will the logic become 5v tolerant?

\$\endgroup\$
3
  • 2
    \$\begingroup\$ Please fix your question and link to the datasheet and not to an eBay page that has no data. Read the data sheet and update your question if there's something you need help with. Give references to the page numbers, etc. in your question and not in the comments. \$\endgroup\$
    – Transistor
    Mar 14, 2016 at 20:27
  • 1
    \$\begingroup\$ This should be answered in the datasheet, without which we can't answer either. \$\endgroup\$ Mar 14, 2016 at 20:29
  • \$\begingroup\$ I've added the datasheet, I'll add page numbers when I find the pages. \$\endgroup\$ Mar 14, 2016 at 20:30

3 Answers 3

2
\$\begingroup\$

With no datasheet, it's difficult to say. Generally speaking, V In High max will be VCC + 0.6 maximum. And V Out High will be at least VCC * 0.7 to max VCC. This is true 90% of the time.

But you never know of the IC has multiple internal voltage levels. Some ICS may have 5V VCC, which it regulates internally to 3.3 and 1.8, and logic will be tied to the 3.3v.

And that module has a sot-23-5 IC, which may be a voltage regulator. So while the module is 5V in, the actual IC runs on 3.3v.

So datasheet is important here.

Update: The IC's data sheet confirms what I said above. Max 3.6V VCC for that specific GPS IC. The 5 pin sot-23-5 is likely the mic5218-3.3 3.3V low dropout linear regulator. No 5V tolerance at all on the data pins.

\$\endgroup\$
1
  • \$\begingroup\$ Datasheet, datasheet, datasheet. I completely forget to look at those some times, the datasheet even says the board is not 5v tolerant. Thanks for the quick answer! \$\endgroup\$ Mar 14, 2016 at 20:33
1
\$\begingroup\$

That depends on the circuit. If it is a 3V chip with a 3V low-drop regulator it will never really run on the 5V you supply. If it is a 3-5V chip it will in general adjust its logic levels.

For your case, the datasheet of the GPS module (http://www.kayraelektronik.com/download/gps-moduller/NEO/NEO-6_DataSheet_(GPS.G6-HW-09005).pdf) states that the module itself is 3.6V maximum, so I suspect that the PCb contains a voltage regulator.

The electrical specs doe not state that the pins are 5V tolerant.

\$\endgroup\$
2
  • \$\begingroup\$ I can still power the module with 5v, right? \$\endgroup\$ Mar 15, 2016 at 0:15
  • \$\begingroup\$ If the documentation of your PCB says so. Thie datasheet is of the GPS module itself, so that is no use to figure this out. \$\endgroup\$ Mar 15, 2016 at 6:28
1
\$\begingroup\$

A schematic for a similar (the same?) board is at this website (posted by G4ZFQ, who cited K9IVB as the source of the schematic). It shows that the I/O pins are directly connected from the GPS module to the board's I/O pins. The module's datasheet states that that the I/O terminal's maximum voltage is 3.6 V, so it would not be 5 V tolerant.

The board does contain a 3.3V regulator that is used to convert the input power supply voltage (3-5V) to 3.3V, but the GPS module itself never gets 5V.

\$\endgroup\$

Not the answer you're looking for? Browse other questions tagged or ask your own question.