iC-NZ QFN28

Description

Three-channel laser diode pulse regulator iC-NZ enables the continuous wave operation of laser diodes and spike-free switching with defined current pulses in a frequency range of up to 155 MHz. The three channels can be accumulatively pulsed via inputs LENL, LENM and LENH. The peak optical power of the laser diodes is regulated separately for high, middle and low levels and adjusted using the three external resistors RMH, RMM and RML. The iC is activated via pin EN which triggers a self-test of the device. The system is enabled if no errors are detected. Any errors are signaled at pin NERR. The (average) current monitor can be set using external resistor RSI. Over-current is signalled at NERR, causing the iC to be shut down. To ensure that the selected laser class is maintained a second monitor input SMD (safety monitor diode) is needed. This optional photo diode monitors the laser power. Exceeding the monitor window, set-up by RSMD, triggers a permanent reset. This is reported at output NERR and can be deleted when the system is restarted at EN. For high pulse frequencies the device can be switched into controlled burst mode at input REGEN. A previously settled operating point is maintained throughout the burst phase. When the iC is switched on all safety-relevant signals per tinent to the current monitor, SMD and control unit are checked. These units are in turn monitored for the following: overcurrent, shor t circuits, open pins and whether the laser is switched off in terms of output power. With the exception of the latter these checks are carried out intermittently during operation. So that the device is single-failure-proof various safety check routines are also implemented. To this end a second SMD (safety monitor diode) monitoring the laser power is required. The laser power must stay within a defined range during operation (thus maintaining the laser class). If this range is left, the system is shut down and an error message is generated.

Features