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BQ51013B: Schematic review and part optimization

Johannes Hennrich
Prodigy 20 points
Part Number: BQ51013B
Other Parts Discussed in Thread: BQ25155, , BQ27220, BQ21061, BQ25125, BQ25190

We are planning the next revision of a product and want to add a few features to the power management and potentially simplify it or reduce the part count.

The current system has a LiPo battery and can be charged via a USB wall adapter. Battery charge current is 200 mA, system power consumption is 80–100 mA on average with short 500 mA bursts (radio TX) at 3.3 V.
Currently we use a BQ25155 PMIC and a TPSM828214 buck converter.
Of the BQ25155’s features we only use:

* Automatic PowerPath (LiPo / 5 V USB power)
* LiPo charger
* Reset controller (long button press = ship mode)

The other features of the BQ25155, like the integrated ADC and LDO, are not used.

 

ta1_power_schematic_1.pngThis works great so far. But for the next revision we want to add wireless charging and potentially a battery fuel gauge (likely BQ27220). We did some quick testing with the BQ51013B wireless receiver IC and got positive results with the following circuit:

ta2_power_schematic_1.png

We are looking for a small and cost-effective solution. All the mentioned BQ ICs are available as DSBGA, which is ideal for us.

Questions:

1. Is there anything I have missed in the design?
2. Since we do not use the ADC, we will use a BQ21061 instead of the BQ25155. Are they otherwise identical?
3. Can we optimize the design or reduce part count? E.g., use a PMIC with an integrated Qi receiver, buck converter or battery gauge? The BQ5105X contains a charger but lacks PowerPath and a reset controller. The BQ25125 is similar to the BQ25155 and has an integrated buck converter, but supports only 300 mA.
4. The TPSM828214 is a neat solution but expensive and harder to source. Can you recommend a standard buck converter (3.3 V, >500 mA transients, should work with low VIN for good battery utilization)?

 

Best regards,

Johannes Hennrich

  • 0
    TI__Guru** 106160 points

    Hello,

    We are on holiday and will respond next week, sorry for the delay.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    TI__Guru* 76936 points

    Hi Johannes

    I can assist with the wireless power part of the design.

    BQ51013B -- Above circuit looks good.  Output current needs to be set with ILIM and FOD resistor.  Also the C1 (Cs) and C2 (Cd) capacitor needs to be tuned with the coil.

    BQ51013B will support external power path circuit using AD and AD-EN circuit, see data sheet figure 9-11 page 37.

  • 0
    Prodigy 20 points

    Thank you for your replies. We had already tuned Cs/Cd and ILIM/FOD for different coils and charging currents and got the wireless power transfer working just fine. The values are left empty in the schematic because we have not settled for a specific coil. The whole circuit for the BQ51013b is very similar to the examples in the datasheet.

    But we are more interested in how the BQ51013b, the BQ25155 and the Buck Converter are working together, e.g. if there is additional power filtering required?

    Since posting the question I changed two things in the schematics:

    1. VINLS and LS_LDO are now both connected to GND instead of PMID. The datasheet is not very specific about this, but this seems more logical.

    2. Slightly increased some capacitor values.

  • 0 in reply to Johannes Hennrich
    TI__Mastermind 18695 points

    Hi,

    1. Shorting VINLS and LS_LDO to GND should be fine.

    2. Please refer to the table for recommended capacitance values

    Johannes Hennrich said:
    2. Since we do not use the ADC, we will use a BQ21061 instead of the BQ25155. Are they otherwise identical?

    That's right, ADC is the primary difference between the two.

    I believe the BQ25155 should work fine with the buck converter and the BQ51013b, though I'm not as familiar with the receiver myself.

    Johannes Hennrich said:
    Can we optimize the design or reduce part count? E.g., use a PMIC with an integrated Qi receiver, buck converter or battery gauge? The BQ5105X contains a charger but lacks PowerPath and a reset controller. The BQ25125 is similar to the BQ25155 and has an integrated buck converter, but supports only 300 mA.

    The BQ25190 might provide a bit more flexibility, but it does not integrate the Qi Rx or Gauge.

    Best Regards,

    Juan Ospina