NJM3773 DUAL STEPPER MOTOR DRIVER n GENERAL DESCRIPTION n PACKAGE OUTLINE The NJM3773 is a switch-mode (chopper), constant-current driver with two channels: one for each winding of a two-phase stepper motor. The NJM3773 is also equipped with a Disable input to simplify half-stepping operation. The circuit is well suited for microstepping applications together with an external micro controller. The current control inputs are low current, high impedance inputs, which allows the use of unbuffered NJM3773E3 NJM3773D2 DAC or external high resistive resistor divider network. The NJM3773 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 NJM3773FM2 are +5 V for logic and +10 to +45 V for the motor. Maximum output current is 750mA per channel. n FEATURES Dual chopper driver 750 mA continuous output current per channel High impedance current control inputs Digital filter on chip eliminates external filtering components Packages DIP22 / PLCC28 / SOP24 JEDEC 300mil (Batwing) n BLOCK DIAGRAM Phase Dis V C E 1 1 1 R1 1 NJM3773 V V CC CC Q R + S M A1 Logic M B1 V MM1 + V MM2 M B2 Logic M A2 RC S Q + R Phase Dis V C GND E 2 2 2 2 R2 Figure 1. Block diagramNJM3773 n PIN CONFIGURATIONS M 1 22 M B1 B2 NC 1 NC 24 E E 2 21 1 2 MB MB 2 23 2 1 M M 3 20 A1 A2 E E 3 22 2 1 M 5 25 Phase A2 2 4 21 MA V V MA 4 19 1 2 MM1 MM2 E 6 24 Dis 2 2 20 VMM 5 VMM 1 2 NJM GND 5 18 GND M 7 23 V B2 CC GND 6 GND 19 3773E3 NJM M 8 22 GND 6 17 GND B1 RC GND 7 18 GND NJM3773FM2 3773D2 GND 9 21 Dis 17 1 VR 8 VR 1 2 V 7 16 V R1 R2 E 10 20 Phase C2 1 9 16 1 C 1 C 8 15 C M 11 19 C 10 15 A1 Phase Phase 1 2 1 1 2 Dis 11 14 Dis 1 2 Phase 9 14 Phase 1 2 RC 12 13 V cc Dis Dis 10 13 1 2 RC 11 12 V CC Figure 2. Pin configurations n PIN DESCRIPTION SOP DIP PLCC Symbol Description 21 8M Motor output B, channel 1. Motor current flows from M to M when Phase is HIGH. B1 A1 B1 1 32 10 E Common emitter, channel 1. This pin connects to a sensing resistor R to ground. 1 S 43 11 M Motor output A, channel 1. Motor current flows from M to M when Phase is HIGH. A1 A1 B1 1 54 12 V Motor supply voltage, channel 1, +10 to +40 V. V and V should be connected together. MM1 MM1 MM2 6,7 5, 6, 1-3, 9, GND Ground and negative supply. Note: these pins are used thermally for heat-sinking. 18,19 17, 18 13-17, Make sure that all ground pins are soldered onto a suitably large copper ground plane 28 for efficient heat sinking. 87 18 V Reference voltage, channel 1. Controls the comparator threshold voltage and hence the R1 output current. 98 19 C Comparator input channel 1. This input senses the instantaneous voltage across the 1 sensing resistor, filtered by the internal digital filter or an optional external RC network. 10 9 20 Phase Controls the direction of motor current at outputs M and M . Motor current flows from M 1 A1 B1 A1 to M when Phase is HIGH. B1 1 11 10 21 Dis Disable input for channel 1. When HIGH, all four output transistors are turned off, which 1 results in a rapidly decreasing output current to zero. 12 11 22 RC Clock oscillator RC pin. Connect a 12 kohm resistor to V and a 4 700 pF capacitor to ground CC to obtain the nominal switching frequency of 23.0 kHz and a digital filter blanking time of 1.0m s. 13 12 23 V Logic supply voltage, nominally +5 V. CC 14 13 24 Dis Disable input for channel 2. When HIGH, all four output transistors are turned off, which 2 results in a rapidly decreasing output current to zero. 15 14 25 Phase Controls the direction of motor current at outputs M and M . Motor current flows from M 2 A2 B2 A2 to M when Phase is HIGH. B2 2 16 15 26 C Comparator input channel 2. This input senses the instantaneous voltage across the 2 sensing resistor, filtered by the internal digital filter or an optional external RC network. 17 16 27 V Reference voltage, channel 2. Controls the comparator threshold voltage and hence the R2 output current. 20 19 4 V Motor supply voltage, channel 2, +10 to +40 V.V and V should be connected together. MM2 MM1 MM2 21 20 5 M Motor output A, channel 2. Motor current flows from M to M when Phase is HIGH. A2 A2 B2 2 22 21 6 E Common emitter, channel 2. This pin connects to a sensing resistor R to ground. 2 S 23 22 7 M Motor output B, channel 2. Motor current flows from M to M when Phase is HIGH. B2 A2 B2 2 V 12 4 V MM1 MM2 GND 13 3 GND GND 14 2 GND GND 15 1 GND GND 16 28 GND GND 17 27 V R2 V 18 C R1 26 2