FS26 Configuration Without Boost

[michael86]

Hello, The datasheet and application notes for the FS26 discuss using the boost in front end and back end mode.

1. There is an OTP setting VBST_CFG_OTP with option to set to front-end or back-end. What should this setting be set to for no boost?

2. We have part number FS2613 AMDA3AD. The datasheet says VBST_CFG_OTP is set to front-end. Does this mean if we remove the boost circuitry it will not work?

3. If VBST_CFG_OTP is set to front-end, can we set VBSTDIS to 1 to disable the boost and not have the boost circuitry?

4. Is there other OTP or MCU configuration that needs to be done when not using the boost converter?

[jbirchy · Accepted solution]

From NXP Apps:

1. There is an OTP setting VBST_CFG_OTP with option to set to front-end or back-end. What should this setting be set to for no boost?

WS: This should be configured as back-end mode.

1. We have part number FS2613 AMDA3AD. The datasheet says VBST_CFG_OTP is set to front-end. Does this mean if we remove the boost circuitry it will not work?

WS: Customer will anyway not be able to start up the device (see datasheet p.23, the state machine when VBST_CFG_OTP = 0). Do you know why did they choose this OTP if they don’t want to use the Boost controller ?

1. If VBST_CFG_OTP is set to front-end, can we set VBSTDIS to 1 to disable the boost and not have the boost circuitry?

WS: In order to do so, they would need to start up the device, have the RSTB released to allow the MCU to write in M_REG_CTRL2 register.

Unfortunately, as I explained in the previous bullet, the device will be stuck with no possibility to reach this point.

1. Is there other OTP or MCU configuration that needs to be done when not using the boost converter?

WS: When the boost is not used, the OTP configuration needed is only to set VBST_CFG_OTP = 1 and VSUP_UVTH_OTP = 1. Of course, the unused pins must be handled as described in the datasheet p. 13, but the MCU has no action to take.

[diazmarin09]

Hello Michael,

I hope everything is great with you.

Do you mean that, you do not want to use the BOOST regulator in your design? If that is the case, you may follow the recommendation below:

Connection if not used: open when BOOST is used in back-end.

Please make sure VBST_CFG_OTP = 1 (back-end mode).

I hope this information helps.

Regards,

David

[michael86]

Hi David!

Correct - I do not want to use the BOOST regulator. 

Currently we have several samples of the FS26 that have OTP configuration factory set VBST_CFG_OTP = 0.

Is there any way we can use these samples without the boost? 

[diazmarin09]

Hello Michael,

Do you mean that your devices are already programmed?

Regards,

David