bq24157 Rsns

Hirotsugu Kobayashi

Mastermind 9530 points

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I have two question about bq24157.

1. What is the maximum voltage of V(rsns)?

85mV is correct? If correct, is it including offset value?

2. How many ohms is the effective area of Rsns?

over 9 years ago

0 Hirotsugu Kobayashi over 9 years ago

Mastermind 9530 points

Please answer my question.

0 Jeff F over 9 years ago in reply to Hirotsugu Kobayashi

TI__Guru**** 165786 points

85mV is correct and includes offset.

I do not understand question 2.

0 Hirotsugu Kobayashi over 9 years ago in reply to Jeff F

Mastermind 9530 points

Thank you for your answer.
I understood the maximum value of Vrsns is 85mV included offset.

But table 9 is described below,
• Maximum charge current sense voltage offset is 37.4 mV (550 mA), default at 64.6 mV (950 mA) and the
maximum charge current option is 1.55 A (105.4 mV), if 55-mΩ sensing resistor is used.

105.4mV is over the rated Vrsns(85mV), is it correct?
Though safety limit register is possible to set over 85mV, but can't it be used?

0 Jeff F over 9 years ago in reply to Hirotsugu Kobayashi

TI__Guru**** 165786 points

Per Table 12 on d/s page 33, the maximum VI(REG) = 54.4mV + 27.2mV + 13.6mV +6.8mV + 37.4mV = 139.4mV. The maximum charge current rating for the IC is 1.55A so you will never reach 139.4mV. The example on page 33 is for ICHRG = 1.25A, which will only require 85mV when using a 68mohm resistor.

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bq24157 Rsns