Forums

I2C pullup voltage

Started by Micron Engineering August 10, 2004
LPC2xxx i/o are +5V tolerant; I have to interface an existing I2C +5V
bus system with an LPC2xxx baseed board. Voltage on the bus is +5V, is
it possible to connect pullup resistors on LPC2xxx directly to +5V?
Thanks,
Massimo Manca, Micron Engineering



An Engineer's Guide to the LPC2100 Series

I've not verified it with the LPCxxx datasheet but Philips devices do it so
in general. You can directly pullup to +5V because on the i2c pins there
isn't a normal protection diode. Philips use there a combination of zener
diodes to protect against static discharge.
Have a look to the datasheet under Maxium Ratings and seek for the two i2c
pins maximum voltage.
This works even in times if the i2c bus is active and your LPCxxx is without
power!

- Henry

-----Ursprgliche Nachricht-----
Von: Micron Engineering <>
An: <>
Datum: Dienstag, 10. August 2004 10:35
Betreff: [lpc2000] I2C pullup voltage >LPC2xxx i/o are +5V tolerant; I have to interface an existing I2C +5V
>bus system with an LPC2xxx baseed board. Voltage on the bus is +5V, is
>it possible to connect pullup resistors on LPC2xxx directly to +5V?
>Thanks,
>Massimo Manca, Micron Engineering >Yahoo! Groups Links