IVC102: does it take long to stabilize after saturation?

Wataru,

You say that the voltage on the sensor is 430mV during exposure to ambient light. Is when disconnected from the IVC102?

Note that if you are connected as shown in figure 1, S1 should not be closed during the reset period. The control input to this switch should remain a logic high constantly. If you are not connected as shown in figure 1, please provide a diagram.

Regards, Bruce.

Hi Bruce,

Thank you for your response.

Yes, the 430mV is when the sensor is disconnected from the IVC102. It's really hard to measure the voltage with the sensor connected with the IVC102 as the sensor is installed really close to the integrator.

My configuration is pretty much the same as the one shown in the Figure 1 except only pin #3 and #4 are tied and connected to the cathode of the sensor and #5 and #6 are GND'ed as recommended in the datasheet. I originally had the S1 closed during the reset period, and changed it as you specified, keeping the S1 high and just controlling the S2, but it didn't help: it still takes long to stabilize after the ambient light exposure. To just give you an idea, the voltage difference over 10 seconds in the dark is about -10mV (yes, negative) and the signal looks really linear (straight). After the light exposure, it starts off in positive, takes 10 to 15 seconds to peak out and starts gradually reaching to the original state as attached (time in 100us, so 300,000 in the x-axis is 30 seconds).

The sensor MFR says that is shouldn't take this long and its recovery time is in 10's of microsecond.

I'd appreciate your support on this.

Regards,

Wataru

Wataru,

Hummmm? I cannot imagine this behavior coming from the IVC102 but I've learned to never say never. My suspicion, however, is with the sensor. I recommend some troubleshooting to isolate the culprit:

Disconnect the sensor. Try replicating the current produced by the sensor with a voltage source and high value resistor. For example, 10V through a 1M resistor provides a 10uA pulse to replicate the ambient light exposure. Apply this current while S2 is closed. Remove the current by breaking the 10M connection or removing the 10V. Then immediately open S2 to see if there is a recovery problem in the IVC102. The 1M resistor should be located very close to pin 2 to avoid noise pickup and stability problems.

Regards, Bruce. 

Bruce,

I haven't forgotten this, but haven't had chance to try what you suggested. I will get back to you once I try it out.

Thank you,

-Wataru

Hi All

I am trying to simulate the circuit in the IVC102 datasheet page 5 figure 1

Problem i get is it does not resett to zero, i have attached the pic bellow

im simulating voltage signals of 10ns and about 3V amplitude

Can i please be assisted concerning this

Kind Regards

Dear all

im just following up on this question, if any one can help me

Thanks in advance

Nico

Nico,

Your question is not related to the old thread that you have posted on. The support engineers for the IVC102 are not seeing that you added a new question to an old thread  so you are unlikely to get an answer.

I suggest that you post your question on a new thread. Attach your TINA file so that they can see the amplitude and timing of your circuit. Also, please explain why you have a voltage source applied as an input to the circuit. The IVC102 is intended to receive a current input signal.

Please be aware that I answered the previous questions on this thread when I was employed at TI. I am now retired and contribute on the forum only sporadically.

Hope this helps.

Regards, Bruce.

Thanks Bruce

Thanks i opened a new thread

Regards

Nico