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MAX213 driver side not working

Matthew Slivkoff
Prodigy 50 points
Other Parts Discussed in Thread: MAX213, MAX202

I have implemented a MAX213 transceiver with 0.1uF caps (25V rated) on a prototype board.

I'm powering the device with 5V DC regulated and EN and (Not) SHDN lines are high (5V+).

The device is working to convert input RS232 levels to TTL levels on all 4 channels. (ie RIN's to ROUT's)

However it cannot convert the input TTLS (DIN's) on pins 7,6,20 and 21 to receive any outputs.

I've tried replacing the caps. I was wondering if anyone had any clues about what could be wrong. Is the device cooked?

Cheers

Matt

  • 0
    Guru 22270 points

    Hello Mathew,

    Make sure that the SHDN pin is tied to the +5.  If it is left unconnected, it will float to the low side.

    Thanks,

    ~~Mark as VERIFIED if this answers your question

  • 0
    Prodigy 50 points

    I've swapped the chip over with a new one from the same batch. Markings are 94AD8SK G4, MAX213I

    I'm getting a slighlty ripply 5V on the V+ pin and 0V on the V- pin. The data sheet would indicate i should be looking for +/- 10 on these respective pins.

    I have reversed the (not) SHDN pin logic and tested that too...

  • 0 in reply to Matthew Slivkoff
    Guru 22270 points

    Double and triple check the polarity of the caps in your connection.  One of them could be hooked up in reverse.  Usually for me, two new separate chips with the same problem indicates I have made the same mistake twice.

  • 0 in reply to Greenja
    Prodigy 50 points

    Thanks for the ideas.

    It certainly seems like the device is in shutdown, however all 4 receivers were working (not just 4 and 5).

    I'm using non-polar ceramic 0806 caps, 25V rated. I've successfully used the same caps with other RS232 transceivers (ie max202's) in other projects.

    I wonder if for some reason the 213 needs polar caps? I couldn't find that in my December 2005 version of the datasheet.

  • 0 in reply to Matthew Slivkoff
    Guru 22270 points

    The data sheet says that non-polarized ceramics are acceptable.  I made the suggestion of polarity based on a common mistake I usually encounter.  The only other thing I can suggest is to check the ground connections to the caps.

  • 0 in reply to Matthew Slivkoff
    TI__Guru**** 165316 points

    Matthew,

    Non polarized capacitors are fine. Check the connections carefully.
    V+ and V- should be almost +/-10V
    C1+ should toggle between VCC and V+ levels
    C1- should toggle between GND and VCC levels
    C2+ should toggle between GND and V+ levels
    C2- should toggle between V- and GND levels

  • 0 in reply to Ron Michallick
    Prodigy 50 points

    Thanks Ron, i've replaced the chip again, along with all capacitors and have quadruple-checked all connections and the circuit layout.

    I get:

    C1+ Rippling between +4.8 and +5 (Vcc)

    C1- toggle between GND and Vcc

    C2+ toggle between GND and Vcc

    C2- GND (with high frequency noise)

    I'm going to look for alternatives. Thanks for everyone's help.