PC/CP300 Electronics Laboratory II

Operational Amplifiers Prelab Requirements

Resources

• Understanding and Interpreting Standard-Logic Data Sheets
  [ S. M. Nolan and J. M. Soltero, Texas Instruments, May 2003]
  
  
• LM741: data sheet from local server
• LM324: data sheet from local server
• TL074: data sheet from local server; from Texas Instruments
• TLC2254: data sheet from local server; from Texas Instruments
• TLC2264: data sheet from local server; from Texas Instruments
• TLE2074: data sheet from local server, from Texas Instruments

Note that all of the above data sheets refer to a family of chips.  For example, the first data sheet for the LM741, contains data for the LM741A, LM741, and LM741C.  When answering the following questions, I am only interested in the data for the chip specifically named in the above list, i.e. the LM741.

1. Operational amplifier data sheets, like most data sheets contains a general description of the device, a pin diagram, a maximum ratings list, and a list of input/output characteristics. Op-amp data sheets also contain an internal circuit diagram which is beyond the scope of this course. The best data sheets also contain sample op-amp circuits which can be very useful.
   • What is the difference between the maximum ratings list and the operational ratings list? 
   • For the LM741 what is the operational ratings list called in the data sheet?
2. For an operational amplifier, the key items in the maximum ratings list are:
   • supply voltage - maximum voltage that can be used to power the op-amp
   • maximum power dissipation - maximum power the op-amp can dissipate
   • differential input voltage - maximum voltage that can be applied across the V+ and V- inputs
   • input voltage - maximum voltage that can be applied between an input and ground
   • operating temperature range - temperature range for operation within the manufacturer's specifications
   • output short circuit duration - amount of time that the op-amp output can be short circuited to ground or to a supply voltage before destroying the chip; use of terms which imply "infinity" means the op-amp has an internal circuit to turn off the op-amp output and protect the internal circuitry.
   The key terms in the electrical characteristics list are:
   • input offset voltage - voltage that must be applied to one input for the output voltage to be zero
   • input resistance - resistance of either input when the other input is grounded
   • output resistance - resistance of the op-amp's output
   • output short-circuit current - maximum output current that the op-amp can deliver to a load
   • supply current - current that the op-amp will draw from the power supply
   • large signal voltage gain - minimum open-loop gain

   Compare the input characteristics of the LM741, LM324, and TLC2254 operational amplifiers on the basis of:

   • supply voltage (maximum)
   • differential input voltage (maximum)
   • input voltage (maximum)
   • input voltage (operational - may be given as a typical voltage range or as a function of the supply voltage)
   • input resistance (operational)
   • range of output voltages in terms of the supply voltages
   • open-loop gain (minimum)
   • output short-circuit current
3. Explain the difference between the differential input voltage maximum and the input voltage maximum.  Using an example may help.
   
   
4. Operational amplifiers can be compared on the basis of configuration (single, dual ,quad), power (low, high), noise (low), offset (low), voltage (high), and speed (high). Compare all of the six operational amplifiers listed above on the basis of key functional differences, i.e. why would I want to use one over another.