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Operational Amplifiers / Comparators

FAQ

What types of products are available?

Please refer to the top of the Op-amp/Comparator page. We offer a broad lineup of products in multiple package types optimized for a wide range of applications, including high voltage resistance models and easy-to-use CMOS units featuring low voltage operation.

Meaning of electrical characteristic of Op-amp/Comparator

For terms that are typically used to indicate the electrical characteristics of op amps and comparators,
please refer to the 'Op Amp/Comparator Tutorial.' (PDF:539KB).
The table of contents is listed below.



Table of Contents: Op-Amp / Comparator Tutorial
     
1. What is Op-Amp / Comparator?
  1. 1 Model of amplifier (Vomtage amplifier) and Op-Amp
  1. 2 What is Op-Amp / Comparator?
  1. 3 Op-Amp and Comparator circuit construction
     
2. Absolute power supply voltage
  2. 1 Rated power supply voltage
  2. 2 Rated differential input voltage
  2. 3 Rated common mode input voltage
  2. 4 Maximum power dissipation and storage temperature range
  2. 5 Electrostatic discharge tolerance
     
3. Electrical characteristic of op-amp and comparator
  3. 1 Circuit current / quiescent current Icc / Iq and power consumption
  3. 2 Input offset voltage Vio
  3. 3 Input bias current / input offset current Ib / Iio
  3. 4 Common mode input voltage range Vicm / CMR
  3. 5 Maximum output voltage (output voltage range) Vom / Voh, Vol
  3. 6 Common Mode Rejection Ratio (CMRR)
  3. 7 Power Supply Rejection Ratio (PSRR)
  3. 8 Large signal voltage gain (Large amplitude voltage gain, open loop voltage gain) Av
  3. 9 Slew Rate (SR)
  3. 10 Response time tre / tpHL / tpLH
  3. 11 Open loop voltage gain frequency characteristics and unity gain frequency / gain bandwidth product
  3. 12 Model of negative feedback system and oscillation condition
  3. 13 Total Harmonic Distortion plus Noise (THD + N)
  3. 14 Equivalent input noise source

What is the difference between single and dual supply op-amps?

Single supply op-amps feature ground sense functionality, enabling support for ground level input. Dual supply op-amps, however, although compatible with single supply operation, will not function correctly with ground level input.

What is the difference between CMOS and bipolar op-amps?

CMOS op-amps, due to their construction, feature exceedingly small input bias current (on the order of pA/fA) and low power consumption, making them ideal for low voltage logic IC peripheral circuitry and sensor applications requiring low input bias current. Additional characteristics include input/output full swing operation with a dynamic range between ground level and the supply voltage.
Bipolar op-amps feature high voltage resistance and broad operating voltage range, making them compatible with a wide variety of applications. In addition, the element matching precision is generally superior to CMOS op-amps, resulting in a smaller input offset voltage. However, the input bias current (based on the transistor Base current) will increase. Bipolar op-amps also display better element noise characteristics then their CMOS counterparts.

Dual supply op-amp operating voltage range

The operating voltage range of dual supply op-amps listed in the specifications must be extrapolated. The BA4558RF, for example, lists an operating voltage range of ±4V to ±15V, meaning VCC/VEE = +4V/-4V to +15V/-15V, signifying a VCC-VEE voltage difference of 8-30V (during single power supply operation).

What is the processing method of unused circuits?

The method is contained in the usage precautions.
In the case of op-amps, a negative feedback circuit (i.e. voltage follower) is formed and the input/output voltage setting method for determining the DC operating point within the common mode input voltage and output voltage ranges follows the usual method. For comparators, in order to ensure that the output terminal is open and the output voltage is fixed to either High or Low the voltage difference between the inverting and non-inverting terminals must be allowed. If it is difficult to provide a potential difference between the input terminals both terminals should be connected and the potential set to a value within the common mode input voltage range.

Input/output full swing and output full swing op-amps

Input/output full swing op-amps allow both the input and output voltages to vary between ground level and the power supply voltage. Examples of this type are the BU7261SG, BU7241SG, BU7262SF, and BU7242SF CMOS op-amps. Output full swing op-amps enable only the output voltage to be set between ground and the supply voltage. ROHM offers a full lineup of output full swing (low saturation) op-amps, including the BA2115F and BA4510F.

What's the difference between BA2904 and BA10358?

The BA2904F features largely the same electrical characteristics as the BA10358F, but with improved ESD resistance and a wider operating temperature range. A maximum operating temperature of 125ºC is possible due to optimization of processes and circuitry. This makes the BA2904F ideal for ideal not only for high reliability applications, but for conventional sets currently using the BA10358F as well. System quality is improved and pin compatibility eliminates the need for troublesome substrate modification.

BA10393 input voltage range

The BA10393F features an input voltage range between 0V and VCC-1.5V (single supply operation), and can operate if a voltage within this range is applied to either the inverting or non-inverting input terminal, even if the voltage of the other terminal exceeds the recommended range (the output will switch from High to Low or Low to High based on the input voltage difference). However, in this case the response characteristics of the particular application must be verified. Similar products are the BA10339, BA2903, and BA2901.

BA10358 output voltage range

The BA10358F features an output voltage range between 0V and Vcc-1.5V (at Ta=25ºC, RL=2kΩ).
Low and High levels correspond to 0V and Vcc-1.5V, respectively, meaning if the Low level is greater than 0V High will exceed Vcc-1.5V. There are times when a maximum limit for the Low voltage level is required. In this case the recommended value is 250mV. If the output sync current in the BA10358F is less than 10uA a voltage close to the Ground level will be output. However, if the sync current exceeds 10uA the Low level output will not be close to Ground due to the large output current required for PNP transistor operation.

Op Amps
(Operational Amplifiers) /
Comparators

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