TPS546B24A: VOUT SCALE LOOP IN TI FUSION

Hi Rajat,

Rajat Singh said:

Can you please VERIFY VOUT SCALE LOOP  value for below output voltage's?

1.2V - Vout Scale loop will be 0.5

1.5V  - Vout Scale loop will be 0.25

1.8V - Vout Scale loop will be 0.25

They are correct. For 1.2V, you can set VOSL to either 0.25 or 0.5, but if Vout adjustment needs to go above 1.5V, then VOSL should to be 0.25. 

Rajat Singh said:

Q2- What will be the VMAX and VMIN values for 1.2V output when vout scale loop will be 0.5

it will 0 to 1.4

or 

0.5 to 1.5V

You can set the VOUT_MAX and VOUT_MIN to either of those, it's up to you. This will ensure Vout doesn't go outside the range specified. The default value will depend on the value stored previously from the pin-detect value you had on your VSEL pin (refer to table 7-13), so you will need to change the value, write to hardware, and store it to NVM on your Fusion GUI. 

Thank you,
Tomoya

Hi Rajat,

Yes, you may be able to to regulate to 0.92V still with VOUT_SCALE_LOOP=0.25, but since we don't specify the accuracy of the error amplifier or reference below 0.25V, the tolerance on VOUT will be higher. Also, the tolerance on the OV and UV thresholds gets higher. Therefore, it is important to keep the reference voltage between 0.25V and 0.75V as specified in the EC table. 

Thank you,
Tomoya

Rajat Singh said:

Therefore, it is important to keep the reference voltage between 0.25V and 0.75V as specified in the EC table. 

Hi Tom,

I got it from excel calculator sheet.its clear that if we select VOUT SCALE LOOP =0.25 for 0.92 VREF is going below 0.25

thanks

Hi Rajat,

The reference voltage is calculated as VOUT x VOUT_SCALE_LOOP. So with VOUT=0.92V, you'd want to use the VOUT_SCALE_LOOP = 0.5, so that the internal reference voltage is 0.46V, which is well within the range. 

Thank you,
Tomoya

Hi Rajat,

Rajat Singh said:

1.8V and 3.3V comes under diffrent VOUT SCALE LOOP range so in that case i have to change vout scale loop every time when we switch voltage?

or is there any workaround for it?

There is no workaround for it. 

Thank you,
Tomoya

Rajat Singh 

It is possible to run the TPS546D24A with Vref programmed lower than 0.25V as long as they can tolerate the small increase in the tolerance of the output voltage as fixed offsets and drifts in the reference and error amplifier have a higher impact on output regulation accuracy under those condition.  The device itself does not prevent VOUT = 1.8V when VOUT_SCALE_LOOP is set to 0.125

So, if the customer wants to be able to adjust the output voltage dynamically between 1.8V and 3.3V without updating VOUT_SCALE_LOOP, or even without powering down the output voltage, they can do that with VOUT_SCALE_LOOP = 0.125.  The output regulation accuracy at 1.8V might not be within the normal +/- 1% accuracy expectation, but it should be close.

To configure the part as such you can pin-program the part for 3.34V output to get VOUT_COMMAND set to 3.34V, VOUT_SCALE_LOOP set for 0.125V, VOUT_MIN = 2.0V and VOUT_MAX = 6V.

Update VOUT_MIN to a value lower than 1.8V

Update VOUT_MAX to the maximum value you want the output to be programmed to, including Margining if you are using Margining for testing.

Update VOUT_COMMAND to the value you want VOUT to be set to, between VOUT_MIN and VOUT_MAX

Update PIN_DETECT_OVERRIDE so that the VOUT functions (VOUT_COMMAND, VOUT_MIN, VOUTMAX, and VOUT_SCALE_LOOP) are all based on NVM instead of Pin Detection.

Store those values to NVM.

If you are going to use the RESET_B function, make sure you execute a RESTORE_USER_ALL at this point to update the RESET voltage, since the RESET voltage is only updated on a power-on-reset or during a RESTORE.  It is not updated by a STORE function.