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Can I change BQ24008PWP with BQ24002PWP?

turgut

Nov 8, 2022
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Hello,
I have a question.
Im using BQ24002PWP Charger IC you can see in the schematic which I add. But I want to change IC with BQ24008PWP Charger IC because of TMR_EN feature.(to out of order the timers.)
BQ24002PWP use 2 individual LED.
BQ24008PWP use 1 bi color LED.
In datasheet write "The output stage is totem pole for the bq24001 and bq24003 and open-drain for the bq24002."
and "The output stage is totem pole for the bq24007 and bq24008."
I dont know what the mean is totem pole. I looked a little but didnt understand too much.
So the question is can I change BQ24002PWP with BQ24008PWP without changing my circuit? If I can, can you describe or draw it how?

Schematic;

BQ24002_BQ24008_Schematic_for_TI.png


Also what i want with more visual;

BQ24002_BQ24008_Schematic_for_TI1.png
 

Harald Kapp

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Nov 17, 2011
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"totem-pole" means you have two output transistors: One is responsible for driving high-level, the other is responsible for driving low-level (Wikipedia).
"open-drain" (or open-collector fpr bipolar technology) means there is only one driving transistor, usually the one responsible for low-leveloutput. An external driving source is required to generate a high-level when the low-level driver is off. Typically a resistor is used.
When you replace a totem-pole output by a open-drain output, you need to provide that external high-level source and it must be able to supply the required current.

As to whether you can repalce one chip by the other, I'm sorry but I don'r have the tie to study the datasheets and compare them for you.
 

turgut

Nov 8, 2022
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Well actually I compared them already. But the real question is Stat2 pin which write Status display output 2 (for bq24008 only) in datasheet. Also writes in datasheet for bq24008 for single bicolor led. This led couldnt be I think because in schematic's of bq24008 Stat2 as N/C.
I connected bq24008 it charges well the battery there is not a problem about it. But Stat2 pin gives same results as 4.9V in 2 different conditions. (Condition 1 - Battery connected, Condition 2 - Battery Not Connected) I tried with different bq24008 IC if IC has fault but values were same.
Also I checked if Stat2 works with pwm but wasnt. So im exploring but i need different views.
 

Harald Kapp

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because in schematic's of bq24008 Stat2 as N/C.
Not in the datasheet. There it is stated:
page 6: STAT2 Status display output 2 (for bq24008 only)
Only the BQ24007 has T´STAT2 = N/C.
But Stat2 pin gives same results as 4.9V in 2 different conditions.
Acc. to the datasheet page 17, the conditions are as follows:
1672327761813.png

To use a bicolor LED, use this schematic (from your original post)
1672328040428.png

D1 is the red LED, D2 is the green LEd of the single bicolor LED (alternativelya you can use 2 separate LEDs as shown in the schematic, but then you will not have the yellow effect for FAULT.
 

turgut

Nov 8, 2022
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I already using 2 serarate LEDs. The problem is Stat2 led should go OFF when battery didnt connected or charged battery as %100. And just battery charging Stat2 would go ON. But Stat2 LED is only turned ON.
Is power led working as well. Yes.
Is bq24008 charging as well. Yes, but i need charging status led's working. I ordered bi color LED to try everything but i know it will not work.
Thank you from now. And happy new year.
 
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