Sharp 2Y0A02 Sensor Current Spikes

The IR Range sensor works as advertised in my digital circuits. It does however produce a lot of noise. There are 1 KHZ spikes all over the power lines, making it tough to use a sensitive microphone.

Some testing, using a 1.1 ohm resistor, revealed that the sensor draws 200 ma current spikes that are 120 usec wide, with a 1 KHZ frequency. These spikes have a rise/fall time of about 1 usec. The recommended 10 UF capacitor does not help.

The only solution i found was to add a battery/regulator specifically for this device.

Has anyone had a similar experience?



The noise you describe is typical of this device. It emits a very bright IR pulse every millisecond, drawing a large burst of current in the process. However, I am surprised that adding a decoupling capacitor does not have an affect on the behavior. In what way does the problem continue to manifest itself once you’ve added the capacitor? Can you describe how (and where) you are connecting the capacitor? Have you tried a larger cap?

- Ben

Hi Ben,

I added a variety of capacitors, up to 250UF, 0.33uf ceramic, and a tantalum 3.3uf – all together at the very end of the 10" cable.

Every Voltage point, including the 7.2V input to the project shows spikes – not as fast, but about 50 - 100 mv. The output of an electret mike, and of an opamp that amplifies another electret have about 500 mv of spikes.

I assume that the problem is mine and I’ll try to solve it. Can you give me a typical setup that you use with values and type for the capacitors you use?



Just to be clear, when you say you put the capacitor at the end of the 10" cable, do you mean that you are connecting it across power and ground (observing proper polarization) right next to the sensor? What is your power supply? Also, I don’t understand the comment about the spikes being “not as fast”. Are you saying that the noise you see is not at the same 1 kHz frequency as the the sensor’s IR bursts, or are you just trying to say that the duration of each spike is longer?

I haven’t used these sensors in systems that have been so sensitive to noise, so I haven’t had to worry about adding external capacitors (my approach has been to average sensor readings to effectively apply a software low-pass filter to the sensor output). In more typical robotics applications, problems mainly seem to arise when people are using many of these sensors simultaneously or aren’t averaging the outputs, and from what I’ve heard, adding the 10 uF capacitors recommended by the datasheet near each sensor usually improves performance in such cases.

- Ben

Hi Ben,

By ‘not as fast’ I mean that the rise/fall times are longer. I put the capacitors at the end of the cable, not next to the sensor, which leaves the inductance of the cable to deal with. I use a properly bypassed 7805 regulating from a 7.2V battery, or ac adapter.

It would be better if Sharp added the proper high frequency capacitors to the sensor itself.

I used this sensor in several projects, and it works ok, but as I just learned it may not be a good neighbor to sensitive analog circuits like electret mic circuits.

This was not meant to be a complaint, I just thought that it’s an item of interest.