CA3240EZ IC

Technical Specifications of CA3240EZ

Datasheet	CA3240EZ datasheet
Category	Integrated Circuits (ICs)
Family	Linear – Amplifiers – Instrumentation, OP Amps, Buffer Amps
Manufacturer	Intersil
Series	–
Packaging	Tube
Part Status	Active
Amplifier Type	General Purpose
Number of Circuits	2
Output Type	–
Slew Rate	9 V/μs
Gain Bandwidth Product	4.5MHz
-3db Bandwidth	–
Current – Input Bias	10pA
Voltage – Input Offset	5mV
Current – Supply	8mA
Current – Output / Channel	40mA
Voltage – Supply, Single/Dual (±)	4 V ~ 36 V, ±2 V ~ 18 V
Operating Temperature	-40°C ~ 85°C
Mounting Type	Through Hole
Package / Case	8-DIP (0.300″, 7.62mm)
Supplier Device Package	8-PDIP

CA3240EZ Introduction

The CA3240A and CA3240 are two operational amplifier integrated circuits that are better in many ways than their CA3140 counterparts. The chips have MOS and bipolar transistors on a single piece of silicon. MOSFET (PMOS) input transistors have a wide range of common-mode input voltage and high impedance. Bipolar output transistors, on the other hand, can send out a lot of current and have a wide range of output voltage. The CA3240A and CA3240 are easy to use because their packages are identical to the industry-standard 1458 operational amplifiers. In this article, we’ll talk about the CA3240A and CA3240 in detail, including their features, how they can be used, and what to think about when designing a circuit with them.

CA3240EZ Description

Dual versions of the well-liked CA3140 series integrated circuit operational amplifiers are the CA3240A and CA3240. They simply combine the advantages of MOS and bipolar transistors into a single monolithic device. High input impedance and a broad common-mode input voltage range are features of gate-protected MOSFET (PMOS) input transistors. The bipolar output transistors offer a large output current capacity and a wide output voltage swing. The 1458 operational amplifiers, the industry standard, are compatible with the CA3240A and CA3240 in similar packaging.

CA3240EZ Features

• CA3140 Dual Version.
• In-house Compensation.
• In the majority of applications, it replaces Industry Type 741 directly.
• Available Pb-Free (RoHS Compliant).

CA3240EZ Applications

• Automotive and portable instrumentation ground referenced single amplifiers.
• Amplifiers that sample and hold.
• Long-term timers and several vibrators (Micro seconds Minutes-Hours).
• Instruments for photocurrent.

Application Information

● Circuit Description

The schematic diagram of the CA3240 amplifier shows how one of its parts works. It has a differential amplifier stage with zener diodes (D3, D4, and D5) and PMOS transistors (Q9 and Q10) to protect against damage from a static discharge. Since Q2 and Q5 are wired together as a constant current source, they provide a constant current bias to the differential amplifier. This means that the common-mode rejection ratio will be high. An NPN current mirror connects the output of the differential amplifier to the base of the gain stage transistor Q13. This makes the change from single-ended to the differential that is needed.

The gain stage transistor Q13 is connected to an active load (Q3 and Q4) with a high impedance to get the highest possible open-loop gain. Through the emitter-follower output stage, the collector of Q13 is directly connected to the base of Q13. Two different circuits work together to pull down the output stage: the circuitry for the dynamic current-sink transistor Q16 and Q14 and Q15, which are connected to a constant current source. In Q16, the voltage between the output terminal and V+ affects the pulldown current, anywhere from 0 to 18 mA. In Q15, however, the pulldown current is always around 1 mA. The dynamic current sink works when the output terminal is about 15V less than V+. Then, both transistors Q21 and Q16 are turned on, which makes Q16 sink current from the output terminal to V-.

When the output is linear, this current always flows from either the load resistor or, if there isn’t one, the emitter of Q18. With a 2k load to ground, the goal of this dynamic sink is to get the output close to V- by 0.2V (VCE (sat)). When the load returns to V+, the 1mA of current from Q15 might not be enough to turn on the dynamic current sink (Q16). You can do this by putting a resistor (about 2k) between V- and the output.

● Output Circuit Considerations

This device doesn’t require the level-shifting circuitry typically required for the 741 series of op-amps. The output voltage can shift to the negative supply rail, letting it work directly with thyristors and power transistors.  In both cases, the amount of drive that can go to the device being driven is limited by a series resistor (RL). The transistors Q14 and Q15 coupled to a steady current are also present.

● Input Circuit Considerations

The typical VICR shows this device can take inputs as low as 0.5V below V-. To keep the input protection circuitry from getting damaged, you should use a series current-limiting resistor to keep the maximum input terminal current to less than 1 mA. Also, when the CA3240 is used as a unity-gain voltage follower, there should be some resistance between the inverting input and the output to limit the amount of current.

This resistance prevents extremely high input signal transients from directly driving the internal constant current source by forcing a signal through the input protection network, which could cause positive feedback through the output terminal. A resistor with 3.9k is enough. When the inputs are centered, and the device dissipates its normal amount of heat, the typical input current is 10pA. As the output sends more load current, the device dissipation increases. This will raise the chip’s temperature and cause the input current to go up.

It is well known that when large differences in input voltages are applied for long periods of time at high temperatures, MOSFET devices can show small changes in their properties, such as small changes in the input offset voltage. Both the voltage applied and the temperature increases the speed of these changes.

The process can be turned around, and offset voltage shifts with the opposite polarity do this. In most linear applications, where the difference in voltage is small and symmetrical, these small changes are about the same size as those in an operational amplifier with a bipolar transistor input stage.

Typical Applications

The CA3240E is used in an on/off touch switch to detect the presence of a tiny current flowing between two contact points on a touch plate made of a “grid” of PCB metallization. When the “on” plate is touched, electricity flows between the two parts of the grid. Because of this, the CA3240E’s terminal 7 output voltage will increase. The CA3059, both a latching circuit and a zero-crossing TRIAC driver, gets these positive transitions.

When Terminal 7 of the CA3240E gets a positive pulse, the CA3059 and its positive feedback circuitry (51k resistor and 36k/42k voltage divider) turn on the TRIAC and keep it on. When a positive pulse is sent to Terminal 1 (CA3240E), the TRIAC turns off and stays off, just like before. Remember that the power supply inside the CA3059 powers the CA3240E. The CA3240E is a good choice for this circuit because it can pick up the small currents caused by skin conduction and has a high enough impedance to stop electrical shocks.

Conclusion

In conclusion, the CA3240A and CA3240 dual operational amplifiers stand out from other models in the CA3140 series because they have both MOSFET and bipolar transistors on a single chip. This gives them many benefits, such as a high input impedance, a wide common-mode input voltage range, a high output current capability, and a wide output voltage swing.

Also, since they are directly compatible with the 1458 operational amplifiers, which are the industry standard, they are easy to add to existing circuits. With this detailed explanation of the CA3240A and CA3240, we hope to have helped readers learn more about these integrated circuits and how they can be used. Contact ICRFQ, a reliable electronic distributor in China, if you want to buy the CA3240EZ, a powerful dual-operational amplifier. Take advantage of this chance to improve your project and let ICRFQ help you succeed.

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