Voltage Levels AT86RF212

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Remo Roy Kavanal
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Posted by Remo Roy Kavanal: Wed. Sep 30, 2015 - 01:22 PM
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Hi,

I have observed that the input and output logic levels(voltage levels)are same for the transceiver AT86RF212. Usually the input low-high range is less than the output low-high range. Is there a mistake in the datasheet? 

AT86RF212 has a direct interface with AT1281V in Atmel's schematics but when I checked the logic levels, they do not match as AT1281V's V0H IS 2.3V and AT86RF212's VIH is 2.6V if we take Vcc as 3V. Please someone help me with these issues as I have an ongoing project with AT86RF212B and AT1281V.

Thank You 

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Wireless, General Wireless Discussions
Last Edited: Fri. Oct 16, 2015 - 12:22 AM
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alexru
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Posted by alexru: Thu. Oct 1, 2015 - 05:42 PM
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Those are absolute limits. In reality all outputs will be equal to Vcc, especially if they are driving low load (a digital input).

 

 

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Last Edited: Thu. Oct 1, 2015 - 05:43 PM
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ka7ehk
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Posted by ka7ehk: Thu. Oct 1, 2015 - 05:54 PM
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There are TWO sets of input voltage specs.

 

One is the absolute maximum which you will find in a small table at the very start of the Electrical Characteristics section. You exceed these voltages at your peril. Exceeding them is likely to damage the chip.

 

The second  is typically found in a table often named "Common DC Characteristics". It lists "Input High Voltage" and "Input Low Voltage". These are the high and low threshold voltages. You need to exceed the Input High Voltage for the pin to guarantee that the pin recognize a logic high level, and you need to exceed the Input Low Voltage (in the downward direction) to guarantee that the pin recognizes a logic low voltage. Note, that the input MAY recognize logic high at a lower voltage than this, and MAY recognize logic low at a higher voltage than this. Those numbers simply tell you what the manufacturer is willing to guarantee over the full range of supply voltage and temperature.

 

Output levels, on the other hand, are typically specified with some load (which the spec sheet should tell you about). Operated into a CMOS logic input, the output voltages are VERY close to Vcc and ground.

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

Last Edited: Thu. Oct 1, 2015 - 05:57 PM
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