They combine the advantages of MOS and bipolar transistors on the same monolithic chip. The bipolar output transistors allow a wide output voltage swing and provide a high output current capability. The CAA and CA are compatible with the industry standard operational amplifiers in similar packages. Dual Version of CA?
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They combine the advantages of MOS and bipolar transistors on the same monolithic chip. The bipolar output transistors allow a wide output voltage swing and provide a high output current capability. The CAA and CA are compatible with the industry standard operational amplifiers in similar packages.
They are not intended for use in Reflow solder processing applications. Dual Version of CA? Internally Compensated? Sample and Hold Amplifiers? Photocurrent Instrumentation? Intrusion Alarm System? Active Filters? Function Generators? Instrumentation Amplifiers? Copyright Intersil Americas Inc. All Rights Reserved All other trademarks mentioned are the property of their respective owners.
This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. NOTES: 1. Short circuit may be applied to ground or to either supply. V 2 FN R10 Q19 1K Q4 R11 20? Q11 R3 ? Q12 R4 ? R5 ? All resistance values are in ohms.
It consists of a differential amplifier stage using PMOS transistors Q9 and Q10 with gate-to-source protection against static discharge damage provided by zener diodes D3, D4, and D5.
Constant current bias is applied to the differential amplifier from transistors Q2 and Q5 connected as a constant current source.
This assures a high common-mode rejection ratio. The output of the differential amplifier is coupled to the base of gain stage transistor Q13 by means of an NPN current mirror that supplies the required differential-to-single-ended conversion. The gain stage transistor Q13 has a high impedance active load Q3 and Q4 to provide maximum open-loop gain.
The collector of Q13 directly drives the base of the compound emitter-follower output stage. Pulldown for the output stage is provided by two independent circuits: 1 constant-currentconnected transistors Q14 and Q15 and 2 dynamic currentsink transistor Q16 and its associated circuitry.
When this condition exists, transistors Q21 and Q16 are turned on causing Q16 to sink current from the output terminal to V-. This current always flows when the output is in the linear region, either from the load resistor or from the emitter of Q18 if no load resistor is present.
The purpose of this dynamic sink is to permit the output to go within 0. This may be accomplished by placing a resistor Approx. Output Circuit Considerations Figure 23 shows output current-sinking capabilities of the CA at various supply voltages. Output voltage swing to the negative supply rail permits this device to operate both power transistors and thyristors directly without the need for level-shifting circuitry usually associated with the series of operational amplifiers.
Figure 3 shows some typical configurations. Note that a series resistor, RL, is used in both cases to limit the drive available to the driven device. Moreover, it is recommended that a series diode and shunt diode be used at the thyristor input to prevent large negative transient surges that can appear at the gate of thyristors, from damaging the integrated circuit.
However, a series currentlimiting resistor is recommended to limit the maximum input terminal current to less than 1mA to prevent damage to the input protection circuitry. Moreover, some current-limiting resistance should be provided between the inverting input and the output when the CA is used as a unity-gain voltage follower. This resistance prevents the possibility of extremely large inputsignal transients from forcing a signal through the inputprotection network and directly driving the internal constantcurrent source which could result in positive feedback via the output terminal.
The typical input current is on the order of 10pA when the inputs are centered at nominal device dissipation. As the output supplies load current, device dissipation will increase, raising the chip temperature and resulting in increased input current. Figure 4 shows typical input-terminal current versus ambient temperature for the CA Both applied voltage and temperature accelerate these changes.
The process is reversible and offset voltage shifts of the opposite polarity reverse the offset. In typical linear applications, where the differential voltage is small and symmetrical, these incremental changes are of about the same magnitude as those encountered in an operational amplifier employing a bipolar transistor input stage. The advantage of using the CAE in this circuit is that it can sense the small currents associated with skin conduction while allowing sufficiently high circuit impedance to provide protection against electrical shock.
This circuit operates on the principle that most liquids contain enough ions in solution to sustain a small amount of current flow between two electrodes submersed in the liquid. The current, induced by an 0. The changes in voltage for both the upper and lower level sensors are processed by the CA to activate an LED whenever the liquid level is above the upper sensor or below the lower sensor. The CAE is ideal for this application because its input common-mode voltage range includes ground, allowing the supply to adjust from 20mV to 25V without requiring a negative supply voltage.
Also, the ground reference capability of the CAE allows it to sense the voltage across the 1? The CA transistor array functions as a reference for both constantvoltage and constant-current limiting. The 2N power Darlington is used as the pass element and may be required to dissipate as much as 40W. Figure 8 shows the transient response of the supply during a mA to 1A load transition.
Precision Differential Amplifier Figure 9 shows the CAE in the classical precision differential amplifier circuit. The CAE is ideally suited for biomedical applications because of its extremely high input impedance. To insure patient safety, an extremely high electrode series resistance is required to limit any current that might result in patient discomfort in the event of a fault condition.
In this case, 10M? A without affecting the performance of the circuit. Figure 10 shows a typical electrocardiogram waveform obtained with this circuit. F 6 ? The voltages from the CAE outputs are subtracted in the second stage CA so that only the difference is amplified. In this manner, the circuit can be used over a wide range of ambient light conditions without circuit component adjustment. Also, when used with a light source, the circuit will not be sensitive to changes in light level as the source ages.
Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable.
However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.
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