Overview
The L6221AS, produced by STMicroelectronics, is a monolithic quad Darlington switch designed for high current, high voltage switching applications. This component is particularly suited for driving inductive loads such as solenoids, relays, and DC motors. The L6221AS features four non-inverting inputs, each controlled by a logic input and a common enable input, making it compatible with TTL logic circuits. The device includes integral fast recirculation diodes, which are essential for managing the back-EMF generated by inductive loads.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Output Voltage | 50 | V |
| Output Current (Continuous) | 1.8 | A |
| Output Current (Peak, Repetitive, 10% Duty Cycle) | 2.5 | A |
| Output Current (Peak, Non-Repetitive, t = 10 μs) | 3.2 | A |
| Logic Supply Voltage | 4.5 - 5.5 | V |
| Operating Temperature Range (Junction) | -40 to +150 | °C |
| Storage Temperature Range | -55 to +150 | °C |
| Collector Emitter Saturation Voltage (VCE(sat)) | 1.0 - 1.6 | V |
| Turn-on Delay Time | 2 | μs |
| Turn-off Delay Time | 5 | μs |
Key Features
- Four non-inverting inputs with a common enable input
- Output voltage up to 50 V and output current up to 1.8 A
- Very low saturation voltage
- TTL-compatible inputs for direct connection to logic circuits
- Integral fast recirculation diodes for inductive load management
- Ability to parallel any number of inputs and outputs of the same device
Applications
The L6221AS is designed for high current, high voltage switching applications, particularly in driving inductive loads such as:
- Solenoids
- Relays
- DC motors
- Other high-current, high-voltage switching applications
It is also suitable for use in applications requiring fast switching times and low saturation voltages.
Q & A
- What is the maximum output voltage of the L6221AS?
The maximum output voltage of the L6221AS is 50 V.
- What is the maximum continuous output current of the L6221AS?
The maximum continuous output current of the L6221AS is 1.8 A.
- What is the logic supply voltage range for the L6221AS?
The logic supply voltage range for the L6221AS is 4.5 to 5.5 V.
- Is the L6221AS compatible with TTL logic circuits?
- What type of diodes are integrated into the L6221AS?
The L6221AS includes integral fast recirculation diodes.
- Can the inputs and outputs of the L6221AS be paralleled?
- What is the operating temperature range for the L6221AS?
The operating temperature range for the L6221AS is -40 to +150°C (junction temperature).
- How should the collectors be placed when driving inductive loads?
The collectors should be placed close together to avoid different current partitioning at turn-off.
- What is the purpose of the Zener diode in series with the integral free-wheeling diodes?
The Zener diode increases the voltage across which energy stored in the load is discharged, speeding the current decay.
- How can the thermal resistance of the L6221AS be reduced?
The thermal resistance can be reduced by soldering the GND pins to a suitable copper area of the printed circuit board or to an external heat sink.
