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bq24032A_USB Boot-up feature
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Q: bq24032A_USB Boot-up feature
I did some test with bq24032AEVM and I found that the USB boot-up didn't work like the datasheet said.
The current is limited to 100mA but I couldn't confirm the typical 150ms boot-up time.
I thought this feature is valid when the device is powering up with USB (PSEL=LOW) regardless to with or without AC and battery. Is there something I missed out??
Attached is a scope I got from the LAB, using EVM with Cout=450uF, PSEL=LOW, CE=High, ISET2=High, with no AC adapter and no battery.
CH2=V_usb, CH3=V_OUT, CH4=I_usb
As you can see, the current is limited to 100mA but there is no 150ms boot-up time, the start-up time depends only on the Output capacitor value and USB charge current.
A: Re: bq24032A_USB Boot-up feature
The boot feature is for the case when the processor is not powered and the CE pin is initially low, disabled, so the IC ignores the CE low for ~150ms and lets the OUT and BAT pin be powered. This time can be longer since the part will probably go into DPPM mode with the limited input current and the timer slowed.
Therefore to check this feature have CE tied low and insert the USB or AC, with PSEL low. I can verify this also, but am out of office until Tuesday.
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