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. According to a feature of the present invention, a laser diode automatic power control circuit includes means for protecting the laser diode from over power conditions, over and under temperature conditions and transient voltage or current spikes on power up and down conditions. It should be about 1V higher than the nominal supply voltage. Price and Delivery Quote. A clamp prevents the voltage from exceeding a preset level.

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This will then provide a short circuit to ground, thereby protecting laserr circuitry that is being supplied form any damage and also blowing the fuse that will then remove the voltage from the series regulator. On power up, capacitor 40 is charged through current path resistor 39, diode 38 and diode Thus the generator can ride through the fault and quickly continue the operation even during the voltage dip.

Patents disclose various laser diode control techniques which do not sufficiently solve the diove of automatic power control and protection of a laser diode: The minimum pulse duration microseconds.

This crowbars the laser. The SF6 series drivers provide protection features which are simple to set-up and more than adequate to protect your LD. Views Read Edit View history.

SCR Thyristor Crowbar | Overvoltage Protection Circuit | Electronics Notes

Analog signal LIN – – DAC 21, which is the output of the transimpedance amp 11, is input to summing amp 5, which drives voltage controlled current source 4, which sinks current from the laser diode 1.

Operation of the circuit begins by autothresholding, which is a means to automatically bring the laser power to a threshold level. We make it simple to buy from top Global suppliers. This allows capacitor 40 to be fully charged. Functionally, this feedback loop stabilizes the laser diode against variations in laser slope efficiency change in output optical power per unit current changeand laser threshold current current at which the laser becomes single mode.


SCR Thyristor Crowbar: overvoltage protection circuit

Other signals which, when asserted lowcause the laser current to be shunted by the crowbar FET 34 are: The laser at threshold detector 10 monitors the laser power, and when a preset laser threshold power is reached causes the digital signal. The laser imaging apparatus of the present invention includes a laser diode for producing a laser light output, an electrical power supply for supplying electrical power to said laser diode, a shunt circuit for shunting power around said dide diode, a laser power monitor for monitoring the laser light output of said lasrr diode, a thermal monitor for monitoring the temperature of said laser diode, a power supply monitor for monitoring the voltage power supply driving said laser diode and control means for controlling said shunt means to shunt power around said laser diode in response to one or more of the following signals: A power-on doide circuit asserts the digital signal.

This is especially useful in a device using TTL components as these are very sensitive to overvoltage. The Zener diode voltage is chosen to be slightly above that of the output rail.

Practical Electronics/Crowbar circuit

It operates by putting a short circuit or low resistance path across the voltage output V oquite like were one to drop a crowbar across the output terminals of the power supply. Many bench top power supplies have a crowbar circuit to protect the connected equipment. These high power drivers offer a highly reliable crowbar clamp to short the current and disable power to your laser diode. A crowbar circuit is distinct from a clamp in pulling, once triggered, the voltage below the trigger level, usually close to ground.


Laser Diode Driver, OEM Small Form Factor Industrial Driver

In other projects Wikimedia Commons. Supplier Directory For everything from distribution to test equipment, components and more, our directory covers it. If the power supply is to be used with radio transmitters, the filtering on the input to the gate may need to be a little more sophisticated, otherwise RF from the transmitter may get onto the gate and cause false triggering. Undervoltage sensing circuits 59 and 60 respectively sense whether VDD voltage is over a predetermined value.

This page was last edited on 26 Decemberat When the overpower condition occurs, the digital signal.

It is necessary to chose a Zener diode with the right xrowbar. I for the following discussion of protection of laser diode 1. Analogue power supply failure modes 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 power hold circuit 35, used to dikde power to the crowbar switch 14 on power down, consists of diode diiode, resistor 37, diode 38, resistor 39, capacitor 40, resistor 41 and diode The circuit must have a fuse or circuit-breaker, as without it the power supply or the crowbar circuit will be damaged.

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.

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