ICL7621 CMOS Operational Amplifier

Overview

The ICL7621 is part of the ICL761X/762X/764X series of monolithic CMOS operational amplifiers. These devices are designed to deliver high-performance operation at low supply voltages while offering selectable quiescent currents. The ICL7621 is particularly well-suited for applications requiring ultra-low input current and minimal power consumption. Its CMOS architecture ensures high input impedance and low input bias currents, making it an excellent choice for precision analog circuits.

The ICL7621 is available in dual configurations, providing designers with flexibility in circuit design. It serves as a low-power replacement for many standard op-amps, offering improved performance in portable and battery-operated applications.

Features

• Wide Operating Voltage Range: ±1V to ±8V, enabling use in both low-voltage and standard voltage applications.
• High Input Impedance: 10¹²Ω, minimizing loading effects on signal sources.
• Ultra-Low Input Current: 1pA (typical), significantly lower than BIFET operational amplifiers.
• Rail-to-Rail Output Swing: Output voltage swings close to both supply rails (V+ and V-).
• Flexible Configuration: Available in dual configurations (ICL7621) with single (ICL7611) and quad (ICL7641) options in the series.
• Low Power Consumption: Selectable quiescent currents allow optimization for power-sensitive applications.
• CMOS Technology: Provides excellent noise performance and high input impedance.

Applications

The ICL7621 is ideal for a wide range of applications where low power consumption, high input impedance, and precision performance are required. Key application areas include:

• Portable Instruments: Battery-powered devices benefit from the low power consumption and wide operating voltage range.
• Telephone Headsets: High input impedance and low noise make it suitable for audio signal conditioning.
• Hearing Aid/Microphone Amplifiers: The ultra-low input current and low power operation are critical for these sensitive applications.
• Meter Amplifiers: Precision measurement circuits leverage the high input impedance and low offset characteristics.
• Medical Instruments: Reliable performance in low-power, high-precision medical devices.
• High Impedance Buffers: Ideal for interfacing with sensors and other high-impedance sources.

Electrical Characteristics

The following table summarizes the key electrical specifications of the ICL7621 under typical operating conditions (unless otherwise noted):

Absolute Maximum Ratings

• Supply Voltage (V+ to V-): ±8V
• Input Voltage Range: (V-) - 0.3V to (V+) + 0.3V
• Operating Temperature Range: -55°C to +125°C
• Storage Temperature Range: -65°C to +150°C

DC Characteristics

• Input Offset Voltage: 5mV (max)
• Input Bias Current: 1pA (typ)
• Input Offset Current: 1pA (typ)
• Common Mode Rejection Ratio (CMRR): 70dB (min)
• Supply Voltage Rejection Ratio (SVRR): 70dB (min)
• Large Signal Voltage Gain: 50V/mV (min) at ±5V supply

AC Characteristics

• Gain Bandwidth Product: 0.5MHz (typ)
• Slew Rate: 0.5V/µs (typ)
• Input Noise Voltage: 30µV_p-p (0.1Hz to 10Hz)

Package Information

The ICL7621 is available in multiple package options to suit various assembly and thermal requirements. The following packages are commonly available:

• 8-Pin PDIP (Plastic Dual In-Line Package): Industry-standard through-hole package for easy prototyping and testing.
• 8-Pin SOIC (Small Outline Integrated Circuit): Surface-mount package for space-constrained applications.

Package Dimensions

• PDIP: 9.81mm x 6.35mm body, 2.54mm pin spacing.
• SOIC: 4.90mm x 3.90mm body, 1.27mm pin spacing.

Thermal Characteristics

• Junction-to-Ambient Thermal Resistance (θ_JA): 100°C/W (PDIP), 160°C/W (SOIC).
• Maximum Junction Temperature (T_J): 150°C.

Conclusion

The ICL7621 CMOS operational amplifier offers a unique combination of ultra-low input current, high input impedance, and low power consumption, making it an excellent choice for precision analog applications. Its wide operating voltage range and flexible packaging options provide designers with versatile solutions for portable, medical, and high-impedance signal conditioning circuits. With performance characteristics that surpass many traditional op-amps, the ICL7621 is a reliable component for demanding low-power applications.