In this tutorial, we are going to make a “Single Supply Laser Driver Amplifier Circuit”.
Laser diodes are common in most consumer electronics, LASER amplification by stimulated emission of Radiation and laser diodes are widely used in different domain applications, it gives focused light rays in the visible spectrum and laser diodes will perform well in regulated constant current. Depending on the application laser is chosen at different ranges of nm (nanometer) wavelengths and watts. As they are harmful and should have some sort of constant current circuit as basic protection.
For this we need a dedicated power source if we are using the battery-powered product then the laser diode easily drains out the battery charge and also laser diode requires a un fluctuate Constant Current supply. To solve these problems here, laser diode special driver circuits are used. They can work in two ways produce constant regulated voltage and produce constant current driven through the Laser Diode load. we designed a simple Single Supply Laser Driver Amplifier Circuit using IC LT1800.
The LT1800 is a low-power, high-speed rail-to-rail input and output operational amplifier with excellent DC performance. The LT1800 features reduced supply current, lower input offset voltage, lower input bias current, and higher DC gain than other devices with comparable bandwidth. LT1800 maintains its performance for supplies from 2.3V to 12.6V and is specified at 3V, 5V, and ±5V supplies. The inputs can be driven beyond the supplies without damage or phase reversal of the output.
Hardware Components
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | IC | LT1800 | 1 |
| 2. | Resistor | 1Ω,100KΩ,10KΩ,10Ω,330Ω | 1 |
| 3. | Potentiometer | 10KΩ | 1 |
| 4. | Transistor | FMMT619 | 1 |
| 5. | Diode | LM385BZ | 1 |
| 6. | Male Connector | – | 2 |
| 7. | Ceramic Capacitor | 39pF, 10µF | 1,1 |
| 8. | Connecting Wires | – | – |
| 9. | Power Supply | 5V | 1 |
LT1800 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of LT1800
Laser Driver Amplifier Circuit
Working Explanation
The LT1800 is available in the 8-pin SO package and can be used as a plug-in replacement for many op-amps to improve input/output range and performance.
This Circuit uses a 5V DC power supply, which can provide from any battery or single power supply source. Here the LT1800 maintains its performance for supply from 2.3V to 12.6V and is specified at 3V, 5V, and ±5V supplies.
LT1800’s Inverting input is connected to the Vout through C1 Capacitor and the Laser diode cathode through Resistor R5 as feedback. The non-inverting pin of the op-amp is connected to the variable Resistor RV1, this can be used to adjust the laser intensity.
Output laser diode connected with Vout pin through Q1 transistor FMMT619, this transistor Q1 uses as the current booster drives the current flow. To sense the current, this circuit uses voltage drop across a shunt resistor in series with the laser diode that is measured differentially. by using this Laser Diode Driver Circuit, we can apply constant current to the output laser diode.
Applications
We use this circuit where ever we need a laser diode for example.
- In DVD and CD players.
- Lasers have a high optical power level.
- Thus, doctors use them during medical operations.
- In the telecommunication and defense sectors.
- Due to their high intensity, drillers and miners use them for drilling.
- In high precision cutting instruments such as cutting metals Primary components in barcode readers.
