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Regulators and Battery charger

Shafeeq Muhammed
Expert 1200 points
Other Parts Discussed in Thread: TPS62821, TPS62827, TPS61089, TPS61022

Hi,

For our new design, we have to use 12 V power supply and 3.7V battery as power input. 

Battery operation is only for 30 minutes if power fails.

My maximum current requirement is 50 Watts.

My requirements are below.

1A max at 12V rai

5A max at 5V rail.

3.5A max at 3.3V rail.

200 mA max at 1.5V rail.

I need to use a single cell Li-Ion battery charger also in my circuit.

Can you suggest a possible power tree with available regulators and battery charger from TI.

Note: My battery cut-off voltage is 3V.

And all above mentioned voltage should be available if main power (12V) fails (at battery operated time).

Best Regards,

Shafeeq

  • 0
    Expert 1200 points
    No sequencing is required
  • 0 in reply to Shafeeq Muhammed
    TI__Genius 14876 points

    Hi Muhammed,

    To make this backup circuitry you would need to use two extra diodes so the 3.7V battery could take over and power your circuit while the main power supply is down.

    I recommend the TPS62821 for the 1.5V rail at 200 mA max.
    And the TPS62827 for the 3.3V rail at 3.5A max.
    These two parts have high efficiency and low operating quiescent current.

    I redirected your question to another TI expert for the other power rails, so you can have the best fit for your application.
    Thank you very much reaching to us.

    Best Regards,
    Dorian

  • 0 in reply to Dorian Brillet de Cande
    Expert 1200 points

    Hi Dorian,
    As the input is 12 and the battery is single cell Li-Ion, If the main power is ON, input will be constant 12 V and when the power fails, the input will be from battery which will vary from 3V to 4.2V. So the total input range will be 3V to 12V. This input voltage I have to convert to my required range (12V, 5V, 3.3V and 1.5V). So to convert it to 12V, 5V and 3.3V, I have to use buck-boost or SEPIC for each voltage( I can't use one buck-boost or SEPIC to convert the input voltage to one voltage and from there generating other voltage, because the current rating required for that buck-boost or SEPIC will be very high,and for that current rating no SEPIC or buck-boost are not available), It will make my design more complex. So we are planning to work with the attached power tree.
    Is there any better option that we can follow.
    Please suggest.
    Regards,
    Shafeeq

  • 0 in reply to Shafeeq Muhammed
    TI__Mastermind 46905 points
    Hi Shafeeq,
    i would suggest using the 3V~4.5v rail to power the 12V output boost, to reduce the output current requirement of the 5V output boost.
    then I suggest TPS61022 for the 5V boost and TPS61089 for the 12V boost.

    the charger IC is critical in the power tree. I assign to the thread to other TI expert supporting charger IC.
  • 0 in reply to Jasper Li
    Expert 1200 points
    Hi Jasper,
    Thanks for your suggestion. When I try to do the design with WEBENCH for the suggested parts, With TPS61022 (Vin=3V to 4.5V) I can get 5V/4A. for my 5V requirement it is enough. With TPS61089 (Vin=3V to 4.5V), I can get 12/1.5A. How do you suggest for 3.3V regulator. With the suggested regulator I will not be able to convert 3.3V from 5V and 12V (because current capability is less).
    Please suggest for 3.3V regulator also?
    Thanks & Regards,
    Shafeeq
  • 0 in reply to Shafeeq Muhammed
    TI__Mastermind 46905 points
    Hi Shafeeq,
    TPS62827 is suggested from 5V to 3.3V 3.5A. i'm not sure why did you "current capability is less".
  • 0 in reply to Jasper Li
    Expert 1200 points
    Hi Jasper,
    You have suggested TPS61022 to generate 5V from 3V-4.5V rail. When I run the design with webench, with input 3V to4.5V and output 5, I will be able to get maximum of 4A. I have a requirement of 4A on 5V rail. Then how can I use one more buck regulator on that 5V rail? If I have to generate 3.3V from the 5V rail, then 5V regulator should be capable to provide at-least 6.5A (considering 90% efficiency for TPS62827. 4A for 5V peripherals and 2.5A for 3.3V regulator) .
    Thanks & Regards,
    Shafeeq
  • 0 in reply to Shafeeq Muhammed
    TI__Mastermind 21590 points

    Hello Shafeeq,

    What is your required charge current for the battery charger?