BOOSTXL-TPS650861: I2C communication issue

Hi Jainendra,

With the default TPS650861 settings, all rails except VTTLDO are enabled by the CTL1 pin (unless they are force disabled). Pulling CTL1 high should allow BUCK4 to enable and output the correct voltage. Have you flipped the CTL1 switch to the OFF position? (The CTLx signals for the BOOSTXL device are pulled high when the switches are flipped to the OFF position). 

There is also a way to force BUCK4 to turn on using I2C. You can use the I2C_RAIL_EN register (R = 0xA0) to turn on BUCK4 regardless of any CTLx input signal. Check to see if you get the correct output after forcing BUCK4 to turn on.

Regards,

James

Hi Jainendra,

Take a look at our OTP Generator if you would like to set up custom programming settings for the TPS650861. With this document, you can choose the settings you want for each rail and create your own sequencing (the "Overview" tab will even show you the binary value needed for specific output voltage values).

On the "Script Generator" tab, you can see a list of the required register values that match your settings. You can write these values into your registers in order to implement your custom program.

For more information on each section of the OTP Generator, check out the TPS65086100 Non-Volatile Memory Programming Guide. This guide will go through and describe each section of the OTP Generator and how to use it. I highly recommend this document since it will explain each part of of the TPS650861 programming process.

Section 4.5 in the programming guide explains how to use the raw commands from the script generator without access to IPG-UI (this helps since you are using a different system to communicate with the PMIC).

BUCK4 and SW2 are not turning on from CTL1 or from register changes because, by default, they are force disabled. Below is a picture from the OTP Generator that shows the TPS650861 default settings before programming. As long as "Force disable by default?" is set to "Yes" for all rails, they will not turn on. The only way to turn on a rail that is force disabled is to manually change its disable bit from 0 -> 1 through I2C, and then enable it with the I2C_RAIL_ENx registers.

Regards,

James

Hi Jainendra,

Information on all the relevant registers can be found in the TPS650861 datasheet.

Section 5.11 shows all the 0x5E address registers with their names and purpose. Starting in Section 5.11.2 you can find more detailed descriptions of each bit field and the different options available to you.

Section 5.12 shows all the 0x38 address registers with their names and purpose. Section 5.12.2 is the beginning of the details on the bit fields for these registers.

Section 5.4 has two tables that show the bit values that control the BUCK outputs. The two tables are separated by step size setting (10mV vs 25mV). This step size setting is handled in the 0x38 addressed registers.

Section 5.5.2 also has two tables that describe the bit values needed for setting LDO output voltages.

SWB1 and SWB2 can also be enabled manually using the I2C_RAIL_EN register (0xA1).

Regards,

James

Hi Jainendra,

The SWVTT_DIS register (R = 0x9F) can be set to a value of 0xF0 to ensure that the load switches and the VTT LDO are not disabled. 

NOTE: You will need to make sure that the load switches are set for the correct PGOOD threshold or you will trigger a power fault and the PMIC will reset. If you want your load switches to indicate power good at 3.3V you will need to access the 0x38 addressed registers and do the following:

• Set register 0x1A to a value of 0x63
• Set register 0x23 to a value of 0xE3
• Set register 0x26 to a value of 0xE3

Once this is done you can enable the load switches using the I2C_RAIL_ENx registers and you should not trigger a power fault.

Even if you are programming the PMIC using a custom set-up, I would recommend downloading the IPG-UI software so that you can look at the register map for the TPS650861 device. The register map has descriptions of each register and bit field. Some of the descriptions will tell you what conditions need to be met for the settings to work. This is what the software shows under the SWA1 enable bit field:

If you decide to install IPG-UI you will need to run this additional installation program to add the TPS650861 device file to you device library. This file will allow you to look at the register map.

Regards,

James

Hi Jainendra,

When you program the TPS650861 by burning the OTP, all the registers are burned with their current values. It is not possible to burn only 1 register at a time. The device has two OTP memory banks which allows for two different OTP configurations but after you burn the second bank you have no other spaces for alternate settings.

This is different than simply writing to a register. Any of the programmable registers can be written as many times as you want, but they can only be burned into OTP memory twice. You cannot burn only one register. The programming must be done for all registers at once.

Regards,

James