MPXV5004GC6 responsivity and filter

[masahirokiniwa]

I have two questions MPXV5004GC6's characteristics and function.

1. MPXV5004GC6 responsivity

   I need fast response to change of pressure.

   When the pressure change from 0kPa to 100Pa, 300Pa, 500Pa or 1kPa, can it change the output level faster than 10ms?

   Could you tell me its response speed at each pattern (0 to 100Pa, 0 to 300Pa, 0 to 500Pa, 0 to 1kPa)?

   I will use it for 0 to 3kPa range. If you have better device, please tell it.

2. MPXV5004GC6's filter

   It suggest to use external low pass filter by AN1646.

   However I couldn't find about internal filter on its datasheet.

   Does it have internal low-pass filter?

[reyes · Accepted solution]

Hi,

[A1] Responsivity:

About your question regarding the response time of the MPXV5004GC6 pressure sensors, unfortunately we do not have specific data, tests or documentation on the frequency response of our pressure sensors.

As you certainly know the MPXV4005GC6 is an integrated pressure sensor containing the transducer, temperature compensation and calibration circuitry along with amplifier on chip to increase the output signal. It is a linear system with no internal sampling.

The Response Time is defined as the minimum time that the device needs for the output to go from 10% to 90% of its final value when a pressure is applied and is typically 1ms.

So, in some way the sampling rate for read this unit is 1kHz.

The response rising time is 1.0 mS, the falling-time depends on the capacitance value of your decoupling circuitry, if we assume the capacitance is zero, then ~1mS would also be expected for the falling time, if the pressure is fluctuating faster than this, the output may not be able to track the signal. So, if the Freescale Pressure Sensors have a response time of 1mS, then, if you take samples faster than that, you would also read noise and non-stable states of the sensor.

We're sorry we do not have the data you're looking for I hope you will find this information useful.

[A2] Filter:

MPXV5004GC6 does not have an internal filter, we recommend to use +5.0V to power supply this device and use one 1.0uF plus one 0.01uF decoupling capacitors placed close to Vs pin of the pressure sensor to make the Power Supply Decoupling, and a 470pF capacitor close to the Vout pin as an output filter capacitor (check figure 4 of the datasheet), and just in case that additional filtering is needed, then you can refer to the recommended filters on the application note AN1646, but if you are using the pressure sensor in a non-noisy environment you should not need more than the supply decoupling and output filtering.

AN1646: http://cache.freescale.com/files/sensors/doc/app_note/AN1646.pdf 

Have a great day,
Jose

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