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TPS562201: Protection against reverse polarity for TPS562201

Mario Carvalho
Prodigy 130 points
Part Number: TPS562201

Hi! We are using TPS562201 in our product to generate +5V from a Lead-acid battery source (14.4V or less). While testing, I have discovered that, according to Maximum Absolute Ratings, any reversal in polarity is really destructive - immediately - no second chance - component blows away. But we need to take MAXIMUM advantage from this battery life in the 12V range (pre-Buck converter stage),  so we need to have as minimal added voltage drop in the circuit as possible. I thought about using 2A 350mV Schottky Diodes as a protection, but their reverse current can rise up to 3mA on 15V range. Do you think this is enough protection or this level of reverse current (don´t have an idea how much voltage would this generate on Vin) can be also destructive so there is no suitable protection for this component? Thanks in advance.

  • 0
    TI__Mastermind 33765 points
    Hi

    Below are some suggestions for your reference:
    1. if the output and load ground has no return path to VBAT ground, then you can use N-FET on input GND path as reverse protection, 50 mohm RDS(on) will not drop 0.1V at 2A input current
    2. if above condition is not OK, then use P-FET on VBAT path with little higher cost.
    3. if you don't want to use MOSFET, then use Schottky blocking diode on VBAT path, also parallel a small Schottky diode(IF 200mA) between TPS562201 Vin and GND pin as leakage current path.
  • 0 in reply to Andy Chen
    Prodigy 130 points

    Hi Andy,

    I think the third one will be a winner - this little Schottky with kathode on Vin and anode on GND will make the difference, it sinks any leakage current from the main Schottky, clever solution! Although MOSFET solution would be also OK for me.

    Thank you very much for your help! I am pretty new at these Buck converters (I'm from the linear regulator age) so I did not have to worry about reverse polarity in the past (those 78xx guys have reverse polarity protection, at the cost of huge size and inefficiency).