26. April 2019 at 17:39

The 12 bit digital data APC – – D 0: Power supply monitor circuit 16, FIG. According to the present invention, there is provided a solution to the problems of the prior art relating to automatic power control and protection of a laser diode. This crowbars the laser. The output may be pulsed by applying a TTL square signal to enable pin. There is no disclosure in this patent of protecting the laser diode from over or under temperature conditions, among other problems. The output current is set by applying an analog signal to the current set pin on the control connector.

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Analog signal THR – – DAC 20, which is the output of the transimpedance amp 7, is input to summing amp 5, which drives voltage controlled current source 4, which sinks current from the laser diode 1.

Accordingly preventing this is of great importance. This application is a continuation-in-part of the latter U.

Once triggered, they depend on the current -limiting circuitry of the power supply or, if that fails, the blowing of the line fuse or tripping the circuit breaker. Other key protection features include a user adjustable driver current limit, over-current protection, overt-temperature protection and protection against reverse current transients.

Experimentation to ensure that the time delay for the thyristor to trigger is not too long against removing the Oaser.

The purpose of the protection circuit, according to the present invention, is to provide a means to protect the laser diode 1 from over laser beam power conditions, over and under temperature conditions, and transient voltage or current spikes on power up and power down conditions. Manufacturer’s set their own lowest direct pricing. One failure mode is for many analogue regulated supplies is that the series pass transistor can fail with a short circuit appearing between the collector and emitter.

A runaway condition occurs when there is a rise in temperature of integrally crowbaf laser diode 1 and integral photodiode 2. They are also used in medical equipment and laser measurement equipment such as spectrometers, lidar and range finders.

Practical Electronics/Crowbar circuit

If this happens the full unregulated voltage can appear at the output, and this would place an intolerably high voltage on the whole system causing many ICs and other components to fail. Gate 48 is driven high by signal.

The enable pin can also be used in the quasi-CW mode. Active crowbars are commonly used to protect the frequency converter in the rotor circuit of doubly fed generators against high voltage and current transients caused by the voltage dips in the power network.

LDY High Power Diode Laser Drivers | Lumina Power

In other languages Add links. It is necessary to chose a Zener diode with the right voltage. Following is a more detailed description of the automatic power control APC and laser protection circuit of the present invention: The output may be pulsed crowwbar applying a TTL square signal to enable pin. As will be described later, the threshold level is not the same as that defined by laser diode manufacturers, but is a level at which the laser power output functional dependence upon laser current is linear.

Even 10 volts would be sufficient to destroy many chips used today, particularly the more expensive and diodf ones. The power supply monitor 16 monitors the power supply voltage. The linear region is known as the lasing region and the non-linear lower level region is known as the light emitting or spontaneous emission region. Either of these signals 90,91 can apply the crowbar switch 14 to the laser diode 1 to prevent thermal damage. On power down, diode 36 becomes reversed biased, isolating the crowbar node 43 from VBB as it drops to 0 volts, and connecting it to capacitor This invention relates in general to laser diodes and, more particularly, to an automatic power control circuit with means of protecting the laser diode from over power, over or under temperature, and transient voltage or current spikes on power up and power down conditions.

SCR Thyristor Crowbar | Overvoltage Protection Circuit | Electronics Notes

LIN – – SEL 17 high, the threshold clock 70 is enabled to oscillate, until the laser diode 1 at threshold condition is reached and signal. Views Read Edit View history. Integral to the laser diode 1 is a photodiode 2, which monitors light output from the back facet of the laser diode 1. A power hold circuit 35, used to hold power to the crowbar switch 14 on power down, consists of diode 36, resistor 37, diode 38, resistor 39, capacitor 40, resistor 41 and diode Counter 72 can be, for example, a 12 bit counter including cascaded 4 bit counters 73, 74 and The small resistor, often around ohms from the gate of the thyristor or SCR to ground is required so that the Zener can supply a reasonable current when it turns on.

The laser output power is monitored by back facet photodiode 2 which monitors the power on the back facet of the laser diode 1.

The minimum pulse duration microseconds. In a diide description of the preferred embodiments of the invention presented below, reference is made to the accompanying drawings in which like numerals refer to like elements.

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