How to switch sensor on/off

Development Boards Arduino
1

Hi,

I have a TMP006 temp. sensor which I would like to switch on and off.

therefore, I want to connect one output pin with V+ of the TMP006.

problem is, @ the output pin I only have ~1,8V, but the TMP006 needs ~3,6V. I thought I would just take a transistor and connect the base with the output pin, the collector/drain with the supply voltage of 3,3V … ?? would this work? which transistor would be suitable? or is there a better solution for this? it has to be guaranteed that the TMP006 can be switched off and on and current consumption isn’t that high…

thanks!!

2

What microcontroller are you trying to interface to the TMP006? The data lines of the TMP006 are designed for 3.3V I/O. If you want 1.8V I/O, you need the TMP006B.

A transistor would certainly work to switch the power supply voltage, but you would need a “high side switch”. See this tutorial, for example: http://jeelabs.org/2012/11/12/high-side-switching/

3

You could probably power the sensor with a GPIO pin. The power consumption seems low enough, but I guess that depends on the microcontroller used.

4

Looks like the non-B version only is guaranteed to a min voltage of +2.1v

You likely need a level translator on the i2c interface and if you want to switch it off, a simple high-side switch will work (it should be no more than one pnp transistor, and two resistors - the mcu pulls the line low to enable power, the mcu floats the line as an input to remove the power.

5

Example of level converter: https://www.sparkfun.com/products/12009

Example of high-side switch with pnp xstr: http://www.w9xt.com/page_microdesign_pt … ching.html

Note that the jeelabs.org example is good as well. But I doubt you need the complexity.

6

Hi, i’ve built the high side level switch from the 2nd posting and it seems to work quiet well - off: 0V on: almost 5V. But the problem is that the tmp006 still isnt working… I dont know if i dont get enough current or if its really a level shifting problem… Cause if i Connect the tmp006 directly with 5V everything is working fine…

7

You haven’t answered the question: what microcontroller are you using and how is it wired to the sensor?

8

^^ What he said. ^^

Also what address is the code using ?

9

logic level converter from sparkfun was the solution…!

10

Sparkfun TMP006 page tell us:

optimal operating voltage of 3.3V to 5V (tolerant up to 7V max)

So, why is it required to use a logic level converter??

Can you be more accurate, and describe from which level to which level you had to convert, and for which signal?

Thanks.

11

You have not read the initial post in this thread. He said he wanted to use a microprocessor pin working at 1.8 volt. The I2C pins on that microcontroller are probably also at that level. So the sensor would not be able to detect the pulses of SDA and SCL going high. Too far below voltage input high minimum. (Which in the datasheet on page 3 is 2.1 Volt)

But a 3 year old thread is unlikely to get attention of the threadstarter. He hasn’t been around since his last reply.

12

Oh, sorry, my mistake!