Introduction of laser drive circuit

about TOF The most common and simplest laser drive circuit for laser ranging is the resonance type 、 Capacitor discharge driver , The circuit is shown in the figure below ,MOS tube Q1 Through distributed inductance L1 And laser tubes DL Discharge in a resonant manner （C1）. To solve the problem of inductance （L1） And the fast current rise time required for the realization , C1 Charged to a higher voltage （ Usually 25 V to 150 V), Required withstand voltage 、 It has very short conduction time at peak current , And the conduction time is 1 Within nanoseconds or less . At present, the conduction speed is only GaN It can be done .

The working process is as follows ： When Q1 When it's turned off ,Vin adopt Rin to C1 Charge ,Rin The size of the determines the charging speed , The amount of electricity on the capacitor when it is finally fully charged Q=C1*Vin, Then when Q1 When it opened C1 Start discharging , Electric quantity from Q=I*Ton discharge , Discharge current I= (Vin-Vdlf-VD) / Rds, So there is Q=C1*Vin=[(Vin-Vdlf-VD) / Rds]*Ton, According to this relation, we can know the capacitance C1 and Vin The choice of .

Capacitor discharge type has another circuit structure , As shown in the figure below ：

The structure of the two circuits is different , The first is one diode less than the second , The first kind of laser driving pulse width is completely determined by the driving pulse width ,