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Appendix A - Signal Range Tables

The following tables cover most common situations with the LJTIA, but for other cases there is an online tool available at analog.com:

http://www.analog.com/en/design-center/advanced-selection-and-design-tools/interactive-design-tools/inamp.html?inamp=AD623%205V

“Differential Voltage” = Vin, “Common Mode Voltage” = Vcm, “Reference Voltage” = Voffset, “Gain” = Gain.  Our definitions of Vin, Vcm, and Voffset, can be found on the main page of the LJTIA datasheet.

The output amplifiers on the LJTIA have a range of about 0.01 volts to 4.5 volts (VS-0.5 actually).

The "Low" column on the left in the tables below is the minimum Vin.  Usually this is the Vin that results in the minimum Vout of 0.01 volts, but sometimes there are other limiting factors, so the "Low" column on the right shows the Vout corresponding to each Vin.

The "High 2.5V" and "High 4.5V" columns on the left are listing the upper limit of Vin that results in a Vout of 2.5 or 4.5 volts, although sometimes there other limiting factors and those Vout values cannot be achieved.  The columns on the right list the actual Vout that results from the Vin values on the left.

Example:  Assume Voffset of the LJTIA is set to 0.4V and gain of the LJTIA is set to x11.  Assume the Vin signals come from a bridge with 5 volt excitation, so Vcm is 2.5 volts.  The minimum Vin is about -0.035 volts and results in a Vout of about 0.01 volts.  A Vin of 0.191 volts results in a Vout of 2.5 volts.  The max Vin is 0.327 volts and results in a Vout of 4 volts, which is less than the Vout limit, thus the online calculator from Analog Devices told us there was some other limitation.

Table A1.1. Voffset = 0.4V

Vcm Vin (Differential) (Volts) Vout (Single Ended) (Volts)
Gain Low High 2.5 V High 4.5V Low High 2.5V High 4.5V
0V
1 -0.3 0.3 N/A 0.01 0.7 N/A
11 -0.0354 0.116 N/A 0.0106 1.58 N/A
51 -0.00764 0.0231 N/A 0.0104 1.58 N/A
201 -0.00194 0.00587 N/A 0.0101 1.58 N/A
1.25V
1 -0.39 2.1 3.68 0.01 2.5 4.08
11 -0.0354 0.191 0.334 0.0106 2.5 4.07
51 -0.00764 0.0412 0.0712 0.0104 2.5 4.08
201 -0.00194 0.0104 0.0183 0.0101 2.5 4.07
2.5V
1 -0.39 2.1 3.6 0.01 2.5 4
11 -0.0354 0.191 0.327 0.0106 2.5 4
51 -0.00764 0.0412 0.0803 0.0104 2.5 4.5
201 -0.00194 0.0104 0.0179 0.0101 2.5 4
Vin/2
1 -0.15 2.05 4.1 0.25 2.5 4.5
11 -0.0354 0.118 N/A 0.0106 1.7 N/A
51 -0.00764 0.024 N/A 0.0104 1.59 N/A
201 -0.00194 0.0059 N/A 0.0101 1.59 N/A

Table A1.2. Voffset = 1.25V

Vcm Vin (Differential) (Volts) Vout (Single Ended) (Volts)
Gain Low High 2.5 V High 4.5V Low High 2.5V High 4.5V
0V
1 -0.3 0.3 N/A 0.95 1.55 N/A
11 -0.107 0.107 N/A 0.073 2.43 N/A
51 -0.0231 0.0231 N/A 0.0719 2.43 N/A
201 -0.005879 0.00587 N/A 0.0701 2.43 N/A
1.25V
1 -1.24 1.25 3.25 0.01 2.5 4.5
11 -0.112 0.114 0.295 0.018 2.5 4.5
51 -0.0243 0.0245 0.0637 0.0107 2.5 4.5
201 -0.00616 0.00622 0.0162 0.0114 2.5 4.5
2.5V
1 -1.24 2.1 3.25 0.01 2.5 4.5
11 -0.112 0.191 0.295 0.018 2.5 4.5
51 -0.0243 0.0412 0.0637 0.0105 2.5 4.5
201 -0.00616 0.00622 0.0161 0.0114 2.5 4.5
Vin/2
1 -0.15 1.25 4.1 1.1 2.5 4.5
11 -0.0983 0.113 0.118 0.169 2.5 2.55
51 -0.0226 0.0236 N/A 0.0974 2.45 N/A
201 -0.00584 0.0059 N/A 0.0762 2.44 N/A

Click here to view the whole sheet as a webpage.