BQ25710: To use BQ25710 As Back-up Power Path using stack SuperCaps

Lakshminarayana

Part Number: BQ25710
Other Parts Discussed in Thread: BQ24780S, LM5155-Q1, LM5155, LM5122

Hi,

I have few question on BQ25710.

I have an application where I/P is 24V and Load requires V in the range 22-24V.

I want to implement Back-up Power path using SuperCaps(series) when in power outage(Source is disconnected) at the source to give output Voltage in the range of 22-24V.

* If I use 2.7V Supercaps (series of 4 to make 10.8V).This IC can boost the 10.8V to make 24/22V right? OR Do I have to use series SuperCaps stacks up-to 22/24V?

* If I have to implement Back-up Power path using this charger IC how do I do that? OR are there any charger with Back-up Power Patch controller?

Thanks.

over 6 years ago

0 Joel Hernandez II over 6 years ago

TI__Mastermind 25800 points

Hey Lakshminarayana,

We tested a conceptual two-chip solution utilizing the BQ24780S multi-cell charge controller and an external boost converter to implement an application such as the one you are developing. Please see the block diagram below. Here, the system is powered directly by the input source as long as it is present. For this concept, a 2S supercapacitor implemention was used, but it can be extended to the voltage range you are looking for. When the input is removed, it triggers the charger's internal comparator to enable the external boost converter to drive the system load using the supercapacitor input.

Regards,

Joel H

0 Lakshminarayana over 6 years ago in reply to Joel Hernandez II

Genius 3790 points

Thanks for your reply.

Capacitor Voltage is boosted(24V) when in supply is removed right?

As I can see Boost Back-up LM5155-Q1 is capable of providing max. the current of 2A. Are there any Boost Back-up with higher current ratings?

Any Design guidelines for integrating ChargerIC with Switch Boost Regulator.

0 Lakshminarayana over 6 years ago in reply to Lakshminarayana

Genius 3790 points

Any feedback on this?

0 Joel Hernandez II over 6 years ago in reply to Lakshminarayana

TI__Mastermind 25800 points

Hey Lakshminarayana,

There are more boost controllers available here: http://www.ti.com/power-management/non-isolated-dc-dc-switching-regulators/step-up-boost/boost-controllers-external-switch/products.html. As long as the controller has an Enable pin, it should work for this design. The limitation is typically the soft-start time in order to regulate fast enough to support the system load.

The LM5155 controller is an asynchronous controller, meaning the current limit will be dictated by the power loss through the diode.

For more information about the Boost Controllers, you can post another thread requesting recommendations.

As a first pass, you can look at the LM5122 which is a synchronous boost controller, so your power limits will be based on the frequency and the size of the external MOSFETs.

Regards,

Joel H

Power management

Power management forum

BQ25710: To use BQ25710 As Back-up Power Path using stack SuperCaps