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How is the DC power regulated when charging the Lithium Ion Battery in an Iphone? I know the optimal voltage to charge the battery is 4.2v and most power supplies are rated 5V for both the wall chargers and the USB ports in computers. Is the voltage regulator in the lightning cable or is it part of the phones internal charging circuit?
[Re-Titled by Host]
iPhone 7 Plus, iOS 10.3.2
The charging is managed by a microcircuit in the phone - the Tristar(U2) IC.
The USB power spec, BTW, is 5 V +- 0.5 V, so essentially 4.5 to 5.5 volts. The phone requires a minimum of 0.5 amps to use external power, 1.0 amps to charge. Later models (7 and later) will charge faster if the USB power source can supply more than 1 amp, so using an iPad power adapter (2.2 amps) will reduce the charge time somewhat and will not hurt the phone.
I know that's more than you asked, but you might find it interesting.
The charging is managed by a microcircuit in the phone - the Tristar(U2) IC.
The USB power spec, BTW, is 5 V +- 0.5 V, so essentially 4.5 to 5.5 volts. The phone requires a minimum of 0.5 amps to use external power, 1.0 amps to charge. Later models (7 and later) will charge faster if the USB power source can supply more than 1 amp, so using an iPad power adapter (2.2 amps) will reduce the charge time somewhat and will not hurt the phone.
I know that's more than you asked, but you might find it interesting.
I appreciate the information. I am an EE and have made a few battery chargers with voltage regulators for charging NICAD batteries back when they were popular. The main reason I was curious where the regulator was that I have an IHOME external 2600maH (14.8WH) battery attatched via velcro to the bottom of the phone with a small USB-lightning cable attatched to it. It works well for long term video streaming and my battery health seems to be holding steady at 97%. I was only concerned that if should something should go wrong with the battery, but as long as there is a regulator inside the phone I feel a little better about this setup. Is there a regulator inside of the lightning connector too?
There is no regulator in the lightning connector, but there are 4 ICs in it that manage A/D-D/A conversion and that dynamically change the connections to the pins, allowing the plug to be inserted either side up. There's also a function that verifies that the cable is certified and safe to use with the phone.
The Tristar is used almost universally with Lithium chemistry batteries, in everything from the obvious phones and tablets to BT speakers and headsets. So look into it if you ever decide to charge Li batteries.
It's important to have "clean" power into the phone, as the Tristar is a rather delicate device. Using unregulated or pulsed power can damage the chip, a good reason to use only charging hardware that is certified as Made for iPhone. There's a cottage industry of 3rd party repairers who will replace the chip for people who have been careless with their sources of power.
Yes, I'm an EE also.
(OT... Larry, you're up today. Can you please assist me here: wifi disconnectivity)
I don't know how to reply. Thanks
Giulio
Done.
How is the DC power regulated when charging the Lithium Ion Battery in an Iphone?
