BQ51013B: Calculate the resistance value between OUT and RECT.

Laurence Seraye

Part Number: BQ51013B

Hi,

I work with the BQ51013B and I try to design it.
I saw in the datasheet (p.32) there an interface between RECT and OUT with capacitors that prevent mirror current. However, I saw on the design of eval kit, there is a resistor between OUT and RECT in more of this capacitor.

Do you know, How can I calculate it? And What is the utility of the resistor?

Hereto the Eval Kitbq51013b.pdf BQ51013BEVM.pdf and the datasheet of BQ51013B.

Best Regards

over 6 years ago

0 Bill Johns over 6 years ago

TI__Guru* 75906 points

Hello

The resistor between OUT and RECT, R1 and R17 on EVM. Is this the connection you have a question on?

Only R1 or 17 will be used, but not both at the same time. This is for FOD adjustment.

0 Laurence Seraye over 6 years ago in reply to Bill Johns

Prodigy 40 points

Hi,

Yes, I would like to know how to calculate R1, R17 and R15.
I would like also to understand the utility of those resistors.

Best Regards

0 Bill Johns over 6 years ago in reply to Laurence Seraye

TI__Guru* 75906 points

Hello

R1 and R17 are used for FOD calibration see below procedure.

R1 and R17 will adjusted the off set of received power curve, R-OS. This resistor was not required on the EVM and none was used. Typical only R17 is used.

While R2 will adjust the shape of received power curve as a function of output power, R-FOD.

Note that R4 and R2 together will set the charge current.

www.ti.com/lit/zip/sluc577

0 Laurence Seraye over 6 years ago in reply to Bill Johns

Prodigy 40 points

Hi Sir,

What about R15?

Best Regards

0 Bill Johns over 6 years ago in reply to Laurence Seraye

TI__Guru* 75906 points

Hello

R15 will limit current into D2 to desired level, determined by the users requirements.

Resistor R15 along with Zener diode D2 will provide power (logic high) to the EN1 and EN2 inputs. In many application EN1 and EN2 are not used and connected to ground or under the control of a mico controller that provides the logic high.

Current required by the EN1 and EN2 input is very low.

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BQ51013B: Calculate the resistance value between OUT and RECT.