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McShamrock
Joined: 29 Oct 2006
Posts: 39
Location: ITALY - Sardinia
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 24 Nov 2008 16:55 battery charger |
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Hi,
Simple question.
I am designing a battery charger circuit for a system whose power consumption is around 400mA peak and 300mA average.
The battery charger (for Li-Ion) is able to provide a current (during the constant current phase of charging procedure) which is 250mA.
To me it looks the battery charger is ok (let consider neglitable the time required for a possible battery to be charged) only if the system is switching on and the only load which is drawing current is the battery.
What is commonly done for a system which is aimed to be switch on during the charging phase of the battery: a or b (eventually c)?
a) battery charger which bears such a current amount able to power the system and simultaneously charge the battery (I guess the battery will have a short life in this case, as the current required by the system varies and then the charging procedure won't actually be at constant current)
b) separate the battery power chain from the system power chain during the charging procedure. In this way the current drawn by the battery will be provided by the charger output, whereas the current required by the system should be taken by the source which also feeds the battery charger. if this is the right way, any suggestion about possible implementation?
c) I do not know, please suggest
thank you,
nicola
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McShamrock
Joined: 29 Oct 2006
Posts: 39
Location: ITALY - Sardinia
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25 Nov 2008 15:55 Re: battery charger |
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noboby can help me?
thx,
N.
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KC_O_o
Joined: 01 Dec 2004
Posts: 15
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25 Nov 2008 18:39 Re: battery charger |
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Hi,
approach b is common.
Split the power supply into two rails: one to the system, another one just for charging.
In case, power supply is not available, battery act as backup.
Of course there will be protection diode to make sure current is not flow back from system to battery.
For longer battery life, you may also consider to stop charging when adaptor is on.
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McShamrock
Joined: 29 Oct 2006
Posts: 39
Location: ITALY - Sardinia
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26 Nov 2008 23:17 Re: battery charger |
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thank you for your support.
N.
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McShamrock
Joined: 29 Oct 2006
Posts: 39
Location: ITALY - Sardinia
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27 Nov 2008 15:27 Re: battery charger |
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Could someone suggest me a relevant application note or description document for a valid and commonly used implementation of circuit of which at point b?
Thank you.
N.
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