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TPS65132: Output Current Limits and I2C

Part Number: TPS65132
Other Parts Discussed in Thread: TLV9102, TPS61391,

Hello there,

I have a few questions regarding the TPS65132 - I have described my goals and questions follow.

Aim: To generate (i) dual rail voltage supply of +/-5V for two summing op-amps TLV9102 and, (ii) supply an input of +5V to a boost converter (TPS61391) that will generate upto +75V with a negative charge pump to -75V (with a load current of 2mA).

Questions:

  1. What is the pre-programmed output current of the positive terminal? Is it always 200mA (as mentioned in the LDO section of the datasheet?)
  2. The pre-programmed output current of the negative terminal of the TPS65132 is 40mA and of the TPS65132S is 80mA, is this correct? And these can be programmed to be higher (80mA, 150mA appropriately)?
  3. What is the output voltage level of the REG pin on the TPS65132? What is the output current capability of that pin? Why is there a separate pin?
    1. Should I use the REG pin as the input to the boost converter (as per the specs given in the aim), or the VPOS?
  4. Is there a way to hardwire +/-5V with maximum output currents on both VPOS and VNEG, and avoid using the I2C?
  5. Can I drive ENN and ENP together from the same GPIO pin of the SoC? Are there any current requirements?

I would also like to send my schematic for review, so please share a contact or email address if available. Thank you.

Ashwati

  • Hello,

    Thank you for your post. I have few other support tasks ahead of this one but should be able to review and and provide feedback by Thursday, 3/4. Thank you for your patience.

    Kind Regards,

    Liaqat

  • Hello,

    Below are the answers to your questions in order.

    A1.   Always 200mA or more from OUTP rail.

    A2.  There is no TPS65132 part number and there has to some suffix after that will determine what the pre-programmed level of the current from negative rail is. For TPS65132S, the pre-programmed current level is 80mA. All devices in the TPS65132 category can be programmed to 40mA or 80mA and TPS65132S can source up to 150mA when SYNC input signal is at logic high.

    A3.   There is no fixed output voltage level on the REG pin. This is the output of the boost converter and its voltage level will to what is needed to maintain adequate headroom to provide programmed voltages on OUTP/OUTN rails. There is no current specification for REG output voltage as it is not intended to be connected to a external load directly. I recommend to use VPOS output rail for connecting any external load.

    A4.  The only devices in this family of devices that have the +/-5.0V as the default output voltage are the A0, B0 and L0 versions of the device but they all have negative rail current programmed at 40mA. To program them to 80mA will require writing registers via I2C interface.

    A5. Yes, you should be able to drive ENP/ENN from the same GPIO of the SOC. These are typical 200k ohm pull down resistors on these pins in the device so overall load on the SOC output driver will be typical 100k ohm.

    Kind Regards,

    Liaqat

  • Hello Liaqat,

    Thank you for the very clear responses. I will update my schematic accordingly. I have a few follow up questions:

    6. What should I do with the REG pin if I am not connecting it to anything?

    7. From the ECAD file I obtained from the website (for Eagle), it seems to be only for the A0, do you happen to have access to the TPS65132S version?

    8. May I send my schematic for review? Let me know if there is a list/email address.

    Thanks!

    Ashwati