The PBL 3775/1 is a switch-mode (chopper), constant-current driver IC with two channels, one for each winding of a two-phase stepper motor. The circuit is similar to Ericssons PBL 3773/1. While several of Ericssons dual stepper motor drivers are optimized for micro-stepping applications, PBL 3775/1 is equipped with a disable input to simplify half-stepping operation. The PBL 3775/1 contains a clock oscillator, which is common for both driver channels, a set of comparators and flip-flops implementing the switching control, and two output H-bridges, including recirculation diodes. Voltage supply requirements are + 5 V for logic and + 10 to + 45 V for the motor. The close match between the two driver channels guarantees consistent output current ratios and motor positioning accuracy.