MCP73834 and leds

[Marco Trapanese]

Hi,

MCP73834, here the ds:

http://ww1.microchip.com/downloads/en/DeviceDoc/22005b.pdf

page 17, table 5-1.
Standard hook-up. 10k on therm pin to gnd.

When I power the IC without inserting a battery both leds turn on (=
system test mode). The ds says:

"The system test mode is entered by driving the THERM
input greater than (VDD-100 mV) with no battery
connected to the output."

There is no battery connected, indeed, but the THERM input is
pulled-down with the 10k resistor. So how could the 73834 enter is such
a state?

Marco

 

[Marco Trapanese]

Il 06/04/2013 19:42, Jim Thompson ha scritto:

Looks like one of those occasions I always hated at Motorola... data
sheet written by someone other than the chip designer.

What VDD ??

5V

Marco

 

[Marco Trapanese]

Il 06/04/2013 21:51, Jim Thompson ha scritto:

Looks like that's what it is supposed to do. See...

http://www.analog-innovations.com/SED/Marco_Trapanese_MCP73834_Question.pdf

Thank you very much!
What's the bottom line, then?
I mean, the LTVT signal will be always high, no matter the presence of
the battery.
I'm afraid about the charging: no problem (I guess) if it enters the
system test mode without the bat, but I'd like it will charge it...

Marco

 

[Marco Trapanese]

Il 07/04/2013 18:24, Jim Thompson ha scritto:

I haven't worked my way thru the whole data sheet, so I don't know. I
did a LiIon charger chip a gezillion years ago, and there was some
very precise voltage measurements that controlled charging (and
discharge limits in my case).

With poorly written data sheets you're stuck with experimentation and
prayer >:-}

It seems it works... in the afternoon I charged a Li-Ion battery at very
low current (about 250 mA). After few hours the end-of-charge led lit
up, eventually.

Marco