14
Digital Interface Specifications
The interface provides the following connections:
o
RS-232 interface
o
Interlock input
o
Enable input
o
Trigger input
The RS-232 interface gives access to all internal settings and registers. It uses a
communication speed of 115200 baud with 8 data bits, 1 stop bit and even parity. In order to
test the interface connection, the
PING
or
init
command may be used, depending on which
protocol should be used. It does not change any settings of the driver.
The interlock input signal controls the internal power conditioner as well as the pulse
output stage. It must be enabled before the enable signal. Otherwise, the driver enters an
error condition and will not produce any output current. If the interlock drops during
normal operation, the power conditioner as well as the current output is disabled and the
capacitor bank is discharged. The enable signal must be disabled before the interlock can
be re-enabled.
The storage discharge slowly. Be careful when powering off the driver as they
may still hold a high voltage. Touching them might result to an electrical shock.
The enable input controls the current regulator and the internal trigger generator. When it
is enabled, the driver will generate output pulses according to the configured settings.
The trigger input is used in the external trigger mode. When configured, it will control
the output current generation.
The trigger output signal provides a signal with the same pulse width and repetition rate
as the current output.
Power Supply
To obtain a good pulsing performance with the driver, it requires an appropriate power supply
unit (PSU). The PSU has to supply not only the power that is delivered to the laser diode but
also the power to compensate for the losses in the driver itself. The device is equipped with a
buck-boost DC-DC converter which allows it to generate a capacitor voltage that is higher
than the input voltage.