• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 63 subscribers
  • Views 425 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ76952: bq76952 reg1 and ddsg

markand
Prodigy 65 points
Part Number: BQ76952

Hello
I'm using the BQ76952 on the low side. I need to use ddsg and dchg for this configuration, but I think I need to set reg1 before these. Should reg0 (pre-regulator) be active when trying to activate REG1?
When I activate it, the resistor marked in the image gets very hot, instant high current is drawn through this line. Then bq76952 power on reset happens.

Could you please help to set reg1 to 3.3V and be able to use ddsg and dchg.

  • 0
    TI__Expert 4085 points

    Dear Markand,

    Yes, the preregulator needs to be active for REG1/2 to function properly. This is because REG1 and REG2 are powered from the preregulator which is held at roughly 5.5V. More information on this is covered in section 6.3.1 in the Technical Reference Manual.

    I have a few quick questions:

    1. When you say high current, how many amps are being drawn?

    2. Can you send a full pdf of your schematic?

    To enable reg1 to 3.3V, these steps must be done:

    1.  Set the bit at Settings:Configuration:REG0 Config[REG0_EN]

    2. Then set the bit at Settings:Configuration:REG12 Config[REG1_EN]

    3. To set to 3.3V, enter 0x6 as the value for this register Settings:Configuration:REG12 Config[REG1V_2:REG1V_0]

    To enable DCHG, do the following steps (nearly identical steps for DDSG):

    1. Set the bits at Settings:Configuration:DCHG Pin Config[1:0] to 0x2 to enable the DDSG function

    2. Set the bit at Settings:Configuration:DCHG Pin Config[5] high to use REG1 to power DCHG

    3. Set the bit at Settings:Configuration:DCHG Pin Config[7] low to have DCHG be active high

    Best,

    Asher Nederveld

  • 0 in reply to Asher Nederveld
    Prodigy 65 points

    Hello again
    I tried the values ​​you suggested. With the REG0_EN bit set, I saw a current of 65 mA. I saw the r26 resistor getting hot.
    I am sharing the schematic images so you can take a closer look.

    lowside_bq76952.pdf

  • 0 in reply to markand
    TI__Expert 4085 points

    Dear Markand,

    1. What sort of load in is on the REG1 pin?

    2.Is the 65mA current flowing from REG1 pin as well?

    3. What voltage are you seeing on the REG1 pin?

    65mA isn't an unheard of amount of current for the input pin to REGIN. Any current that the REG1 and REG2 pins pull will have to pass through the REGIN pin first. If REG1 is pulling 65mA, it isn't surprising that the r26 resistor is getting hot as its power dissipation would be roughly 1W given its resistance of 249 ohms. Generally, it is recommended to put multiple resistors in parallel and series to spread out power dissipation more.

    Best,

    Asher Nederveld