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MAX1555 equivalent (LiPo battery charger and power source)
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PICdude
Mon, 20 Sep 10 22:32:35 +0000
As implied, I'm looking for a MAX1555 replacement -- to charge a LiPo
battery while in-circuit (powering the target app). The substitutes
I've found so far are not clear on whether they can only be used as a
standalone charger or whether they can also power the target circuit
at the same time.

I need this for a single 3.7V LiPo cell and target current consumption
will be ~100mA (150mA conservative max).

FWIW, the MAX1555 is not easily available (surprise, surprise), and
I'm building a quick app for a friend, so I need a substitute. Anyone
have a preferred chip for this?

Thanks,
-Neil.



6 replies folowing
Brent Brown
Mon, 20 Sep 10 22:52:49 +0000
On 20 Sep 2010 at 15:32, PICdude wrote:

> As implied, I'm looking for a MAX1555 replacement -- to charge a LiPo
> battery while in-circuit (powering the target app). The substitutes
> I've found so far are not clear on whether they can only be used as a
> standalone charger or whether they can also power the target circuit
> at the same time.
>
> I need this for a single 3.7V LiPo cell and target current consumption
> will be ~100mA (150mA conservative max).
>
> FWIW, the MAX1555 is not easily available (surprise, surprise), and
> I'm building a quick app for a friend, so I need a substitute. Anyone
> have a preferred chip for this?
>
> Thanks,
> -Neil.


I've just been looking at the Linear Technologies range of charger IC's. They have
"PowerPath" feature which I think appllies to what you're doing - charging battery
and supplying load at the same time.

Brent Brown, Electronic Design Solutions
16 English Street, St Andrews,
Hamilton 3200, New Zealand
Ph: +64 7 849 0069
Fax: +64 7 849 0071
Cell: +64 27 433 4069
eMail: brent.brown@clear.net.nz


dicsEE
Mon, 20 Sep 10 23:06:43 +0000
 
PICdude
Mon, 20 Sep 10 23:06:43 +0000
I looked at some of those (LTC4099 IIRC), and was dismayed with the
20-pin package and significant number of external components (relative
to the MAX1555). I'm currently looking at the MCP73812 as it comes in
a very nice small SOT23-5 package, though I'm currently changing the
circuit a bit so the power to the circuit can be switched off when
charging.



Quoting Brent Brown :

> I've just been looking at the Linear Technologies range of charger
> IC's. They have
> "PowerPath" feature which I think appllies to what you're doing -
> charging battery
> and supplying load at the same time.




Mon, 20 Sep 10 23:19:26 +0000
Hi Neil,

Except you need double-input as the MAX1555, I would go with MCP73811. Take
a look on datasheet for more info, it works fine up to 450mA charge load,
and feeds both circuit and battery.

Regards

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of
PICdude
Sent: Tuesday, September 21, 2010 12:33 AM
To: piclist@mit.edu
Subject: [EE] MAX1555 equivalent? (LiPo battery charger and power source)

As implied, I'm looking for a MAX1555 replacement -- to charge a LiPo
battery while in-circuit (powering the target app). The substitutes I've
found so far are not clear on whether they can only be used as a standalone
charger or whether they can also power the target circuit at the same time.

I need this for a single 3.7V LiPo cell and target current consumption will
be ~100mA (150mA conservative max).

FWIW, the MAX1555 is not easily available (surprise, surprise), and I'm
building a quick app for a friend, so I need a substitute. Anyone have a
preferred chip for this?

Thanks,
-Neil.


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PICdude
Tue, 21 Sep 10 00:21:24 +0000
Excellent. I'm looking at the MCP73812, because it seems to have
adjustable charge current rather than just 2 levels (at least that's
what it seems at first pass). Have you actually used this? And do
you know if it can power the target circuit from the charger? This
application will have a single-cell 3.7V 500mah LiPo battery and will
be charged by USB.

Thanks,
-Neil.



Quoting arocholl@gmail.com:

> Hi Neil,
>
> Except you need double-input as the MAX1555, I would go with MCP73811. Take
> a look on datasheet for more info, it works fine up to 450mA charge load,
> and feeds both circuit and battery.
>
> Regards



Ariel Rocholl
Tue, 21 Sep 10 09:02:19 +0000
Yes, I've used MCP73811 (not 73812) in a few (low quantity) projects with
success. I've used them in circuits asking for up to 150mA while charging a
1000mAh lipo.

It works really nice and that include testing done to revive deep descharged
battery.

Regards
Ariel Rocholl

2010/9/21 PICdude

> Excellent. I'm looking at the MCP73812, because it seems to have
> adjustable charge current rather than just 2 levels (at least that's
> what it seems at first pass). Have you actually used this? And do
> you know if it can power the target circuit from the charger? This
> application will have a single-cell 3.7V 500mah LiPo battery and will
> be charged by USB.
>
> Thanks,
> -Neil.
>
>
>
> Quoting arocholl@gmail.com:
>
> > Hi Neil,
> >
> > Except you need double-input as the MAX1555, I would go with MCP73811.
> Take
> > a look on datasheet for more info, it works fine up to 450mA charge load,
> > and feeds both circuit and battery.
> >
> > Regards
>
>

PICdude
Wed, 22 Sep 10 12:55:14 +0000
Awesome, thanks. I'm being cautious about this because I've seen the
youtube videos of LiPo explosions.



Quoting Ariel Rocholl :

> Yes, I've used MCP73811 (not 73812) in a few (low quantity) projects with
> success. I've used them in circuits asking for up to 150mA while charging a
> 1000mAh lipo.
>
> It works really nice and that include testing done to revive deep descharged
> battery.
>
> Regards
> Ariel Rocholl
>