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I2C switch/multiplex

Started by Mikko OH2HVJ December 27, 2016
I've got a task of cramming in a GPS receiver with I2C interface to an
existing small board. The receiver is rather power hungry (50uA) even in sleep
mode compared to the target of 3uA at 2.8V.

I was planning on isolating the GPS receiver from the system with a
P-fet in the power line and analog dual switch on the I2C lines. These
being controlled PCA9570 or similar I2C GPIO extender.

All these should be crammed to 10x15mm PCB space with low cost.

Any other ideas or recommendations for the components ?

--
mikko
On Tue, 27 Dec 2016 15:37:18 +0200, Mikko OH2HVJ
<mikko.syrjalahti@nospam.fi> wrote:

>I've got a task of cramming in a GPS receiver with I2C interface to an >existing small board. The receiver is rather power hungry (50uA) even in sleep >mode compared to the target of 3uA at 2.8V. > >I was planning on isolating the GPS receiver from the system with a >P-fet in the power line and analog dual switch on the I2C lines. These >being controlled PCA9570 or similar I2C GPIO extender. > >All these should be crammed to 10x15mm PCB space with low cost. > >Any other ideas or recommendations for the components ?
Maybe take a look at TI's TS3USB series of low-resistance switches. -- John Larkin Highland Technology, Inc jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On Tuesday, December 27, 2016 at 8:35:19 AM UTC-5, Mikko OH2HVJ wrote:
> I've got a task of cramming in a GPS receiver with I2C interface to an > existing small board. The receiver is rather power hungry (50uA) even in sleep > mode compared to the target of 3uA at 2.8V. > > I was planning on isolating the GPS receiver from the system with a > P-fet in the power line and analog dual switch on the I2C lines. These > being controlled PCA9570 or similar I2C GPIO extender. > > All these should be crammed to 10x15mm PCB space with low cost. > > Any other ideas or recommendations for the components ? > > -- > mikko
You might consider using an i2c switch/multiplexer, e.g. the TCA9453a, a 14-pin TSSOP. That operates from i2c commands, which might save you the PIO expander. You could use it as a disconnect / bus isolator; you don't have to use both output ports. I'm using one in a current design. TI has a good selection page: http://www.ti.com/product/TCA9543A/compare# Cheers, James Arthur Cheers, James Arthur