Positive buck-boost recommend

Hi Zehui

Do you want to configure BUCK device to be a positive buck-boost converter  Or do you want to select a buck-boost device? 

Thank you

Hi Gui,

I searched here https://www.ti.com/power-management/non-isolated-dc-dc-switching-regulators/buck-boost-inverting/overview.html for buck-boost device. Few devices suit for my application with high price, while the solution in the application note has a better cost. In fact, I don't have a preference for these two solution. I care for the performance and cost, mostly. I might be ill-considered as I'm not familiar with this buck-boost application. I’d really appreciate it if you could point out the pros and cons.

Hi Zehui

I will hand over this to the buck-boost team for now, and you can share your application needs for them to help select the proper device.

Thank you

Hi Zehui,

Thanks for reaching out, may I know what is the application and the Buck-Boost device used for?

We have released the four-integrated buck-boost converter TPS552892 which can suit operation condition. You can find more details from the product page. https://www.ti.com/product/TPS552892-Q1

Let me know if you have any more questions.

BRs,

Bryce

Hi Bryce,

Thanks for help.

I need to power a off-board device for 12V/500mA. A good solution is generating it from battery voltage. So the operating condition is :

Vin = 9 ~ 16 Vout = 12V Iout = 500mA

TPS552892 seems suitable for operation but the cost is much higher than the LMR14050 in the application note. I don't know if there is any disadvantage of LMR14050 solution. It will be kind of you if you could compare these and point out the pros and cons.

Hi Zehui,

The price on ti.com is highly decided by the volume you will use. You can ask TI fae and sales for price support. If you don't know who to contact with, please add my friend so I can tell you.

We have also introduced this device to Hirain Tianjin team, and they are evaluating it at HUD projects.

Regarding to the app note usage, you will need external two MOSFETs, two rectifying diodes and one TVS diode, the solution cost is higher compared with single TPS552892. And it could only work in DCM mode and the voltage ripple could be large, the EMI is worse.

TPS552892 is much easier to design, layout and debug. It also has many features which benefits your system design, like FPWM mode, dithering function, power good indication, cable drop compensation, output current limit. FPWM can achieve low ripple and fixed switching frequency which helps EMI test. And dithering function can help you pass EMI test easily.

Let me know if you have any more questions.

BRs,

Bryce

Hi Bryce,

Thanks.

We don't need large current so the external MOSFETs and diodes won't cost much. I'll check the realistic price with my FAE anyway. And it is shown that buck-boost can work in CCM and DCM mode. 

Hi Zehui,

Yes, the circuit in app note could only work in DCM in light load which cause large voltage ripple and bad EMI in automotive applications. So I see many automotive customers choose FPWM mode.

You can also mention TPS552872 which is the lower current version, I think it's enough for your application.

BRs,

Bryce

Hi Bryce,

I searched TPS552872 and couldn't find any information.