I was reading Analog Devices MAX4238ASA+ datasheet, but I didn't find the output current to know which ADC I can put after it.
What is the maximum current in normal use?
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2 Answers
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The output is characterized in terms of load resistance. See the section "Output Voltage Swing" in the "Electrical Characteristics" table. As long as the load represented by your ADC is greater than 1 kΩ (or 10 kΩ), it will be able to drive the specified output range.
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\$\begingroup\$ If i well understand that depend of the ADC, what is the name of this specifie in a ADC datasheet. For exemple the ADS1115 ti.com/lit/ds/symlink/… \$\endgroup\$– DamanZ4Commented Mar 20 at 7:23
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\$\begingroup\$ What is it that you are designing, and why are you having so much trouble reading data sheets? For the ADS1115, it's the very first thing under "Electrical Characteristics": "Common-mode input impedance" and "Differential input impedance". \$\endgroup\$ Commented Mar 20 at 11:23
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\$\begingroup\$ I was looking for "resistance" but yeah impedance is better. M ohm seems to be good \$\endgroup\$– DamanZ4Commented Mar 20 at 11:55
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The output is current limited so the usual max current rating is not available.
Two graphs from page five (shown below) indicate how close to the rails that can be achieved based on output current. This information is sufficient to justify a particular load. If approaching the rails to within 150mV, then the maximum output current is 10mA.
There is also a line on the front page that guarantees rail to rail operation for load resistance greater than 1kΩ.
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\$\begingroup\$ How can i limit this voltage to 150mV ? \$\endgroup\$– DamanZ4Commented Mar 20 at 7:24
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\$\begingroup\$ The voltage in the figures is the saturation voltage of the op-amp output transistors. More output current increases the saturation voltage, as the charts show. So keeping the current low will limit the saturation voltage to small values. \$\endgroup\$ Commented Mar 20 at 11:16