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Singh.Harjit
Visitor II
April 18, 2021
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VL53L1CX (DocID031281 Rev 3) question about IOVDD & 2V8 mode XSHUT - needs pull up resistor or can it be direct connected to AVDD?

  • April 18, 2021
  • 2 replies
  • 1130 views

Question #1:

In my system, I have 3.3V available, so I was planning to use that for AVDDVCSEL & AVDD since it is within the range but the I2C interface will run at 1.8V.

The 1.8V seems fine from a Vih/Vil point of view.

My concern is around IOVDD and 2V8 mode. Given the above situation, I cannot tell if I need to use USE_I2C_2V8k or not.

In DocID031281 Rev 3, Section 5.2, Table 14 on page 23, it talks about IOVDD - but this isn't a pin. Digging further:

Note 4 says:

The default driver mode is 1V8.

2V8 mode is programmable using device settings loaded by the driver. For more details please refer to the VL53L1X API user manual (UM2356)

UM2356 says:

2.5.9 VDDIO configuration

As described in the datasheet, the user can select two modes for a VDDIO value of 1V8 or 2V8 modes.

The selection of the mode is made directly in the code though a compilation key called USE_I2C_2V8k.

If this compilation key is defined, the system will go into 2V8 mode, otherwise, it will be kept in the default 1V8 mode.

Question #2:

dOES XSHUT - needs Apull up resistor or can it be direct connected to AVDD?

    This topic has been closed for replies.
    Best answer by John E KVAM

    You can indeed connect XShut to AVDD. But then you lose the ability to reboot it if you need to.

    VDDIO does come in two flavors. And there is a #define in the code to tell the sensor if you are using  USE_I2C_2V8.

    This flag causes an additional write to the sensor.

    Clearly the sensor has to work to be able accept this command. And it does. Setting the 2V8 flag just adds a bit of margin.

    But if you are sure you will never want to reboot the sensor - or have multiple sensors, you can hook the XShut to AVDD.

    • john

    2 replies

    S
    Singh.HarjitAuthor
    Visitor II
    April 23, 2021

    @John E KVAM​ - please help. I need this to send the board out.

    J
    John E KVAMAnswer
    ST Employee
    April 23, 2021

    You can indeed connect XShut to AVDD. But then you lose the ability to reboot it if you need to.

    VDDIO does come in two flavors. And there is a #define in the code to tell the sensor if you are using  USE_I2C_2V8.

    This flag causes an additional write to the sensor.

    Clearly the sensor has to work to be able accept this command. And it does. Setting the 2V8 flag just adds a bit of margin.

    But if you are sure you will never want to reboot the sensor - or have multiple sensors, you can hook the XShut to AVDD.

    • john

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