The CXB1549Q is a high-speed monolithic Laser Diode Driver/Current Switch with ECL/PECL input level. Open collector outputs are provided at the output pins (Q, QBX) and have the capacity of driving modulation current of 50mAp-p at a max. data rate of 1.25Gbps (Min.). Along with the modulation current generator there is the laser diode bias generator which has capacity of sourcing up to 60mA (Bias). The laser diode current can be controlled by either a voltage or current into the bias adjust pin (BiasAdj) and the bias set pin (SBias), depending on how these pins are configured. Control of the diode bias current is achieved through the APC (Automatic Power Control) circuitry. In order to avoid having a large current go through the laser diode, this IC also provides an Activity detector and Power on Reset functions for Laser Safety. The Activity detector circuit detects data edge transitions and if no data transition occur after a certain time period, then both the modulation and bias current are shutdown. The Power on Reset circuit holds the modulation and bias current off for a set period of time while the system power is applied. Additionally, this IC has an internal Duty Cycle correction circuit that can control the falling edge of the input pulse up to a maximum of 0.2ns (Min.).