LS7290

LS7290 STEPPER MOTOR CONTROLLER FEATURES: July 2011 Controls Bipolar and Unipolar motors Cost-effective replacement for L297 Full, ½ step mode selected with mode input Direction control Reset input Step control input Enable input PWM chopper circuit for current control Two peak-current comparators with external reference input Step control frequency and duty cycle controlled by an external frequency source or by an internal crystal controlled oscillator (typically 8 MHz) All inputs and outputs TTL/CMOS compatible (TTL for 5V operation) 3V to 5.5V Operation (VDD – VSS) LS7290 (DIP), LS7290-S (SOIC), LS7290-TS (TSSOP) – See Figure 1. PIN ASSIGNMENT TOP VIEW DESCRIPTION: The LS7290 generates Phase Drive outputs a nd PWM output s for controlling twophase Bipolar Motors or four-phase Un ipolar Motors, respectively. The LS7290 contains a mod e controlled loo k-up table for generating the motor duty cycle drive sequences. There are four outputs which are used to drive two H-Bridges for the two motor windings in the Bipolar motor or the fo ur driver transistors for the t wo ce ntertapped windings in the Unipolar motor (Refe r t o Table 2). The LS7290 can st ep a motor in full steps and half steps. The refresh rate is set using an internal oscillato r controlled by a crystal or by use of an external input clock. Typical refresh rate is equal to 31.25kHz with the clock frequency set at 8MHz. Peak-current feedback control using pulse-width modulation is used...