PBL3771/1

• Dual chopper driver in a single package.
• 650 mA output current per channel.
• Close matching between channels for high microstepping accuracy.
• Selectable slow/fast current decay for improved high-speed microstepping.
• Improved low-level linearity.
• Specially matched to Dual DAC PBM 3960.
• Selection of packages, 22-pin "batwing" DIP, 24 pin "batwing" SOIC or 28-lead PLCC with lead-frame for heat-sinking through PC board copper.

The PBL 3771/1 is a switch-mode, constant-current driver IC (chopper) with two channels, one for each winding of a two-phase stepper motor. The circuit is especially developed for use in microstepping applications ofPBL3771/1 in conjunction with the matching dual DAC (Digital-to-Analog Converter) PBM 3960. A complete driver system of PBL3771/1 consists of these two ICs, a few passive components and a microprocessor for generation of the proper control and data codes required for microstepping.

The PBL 3771/1 contains a clock oscillator, which is common for both driver channels; a set of comparators and flip-flops implementing the switching control; and two H-bridges with internal recirculation diodes. Voltage supply requirements are +5 V for logic and +10 to +45 V for the motor. Maximum output current is 650 mA per channel.

A special logic function of PBL3771/1 is used to select slow or fast current decay in the output stage for improved high-speed microstepping.

The close match of PBL3771/1 between the two driver channels guarantees consistent output current ratios and motor positioning accuracy.