NJM3777 DUAL STEPPER MOTOR DRIVER n GENERAL DESCRIPTION n PACKAGE OUTLINE The NJM3777 is a switch-mode (chopper), constant-current driver with two channels: one for each winding of a two-phase stepper motor. The NJM3777 is equipped with a Disable input to simplify half-stepping operation. The NJM3777 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 NJM3777E3(SOP24) diodes. Voltage supply requirements are + 5 V for logic and + 10 to + 45 V for the motor. Maximum output current is 900mA per channel. n FEATURES Dual chopper driver 900 mA continuous output current per channel Digital filter on chip eliminates external filtering components Package SOP24 JEDEC 300 mil (batwing) n BLOCK DIAGRAM Phase Dis V C E 1 1 R1 1 1 NJM3777 V V CC CC R Q + S M A1 Logic M B1 V MM1 + V MM2 M B2 Logic M A2 RC S Q + R Dis E Phase V C GND 2 2 R2 2 2 Figure 1. Block diagramNJM3777 n PIN CONFIGURATION NC 1 24 NC MB MB 2 23 2 1 E E 3 22 2 1 21 4 MA MA 1 2 20 VMM 5 VMM 1 2 NJM GND 6 19 GND 3777E3 GND 7 18 GND 17 VR 8 VR 2 1 C2 16 9 C 1 10 15 Phase Phase 2 1 11 14 Dis Dis 2 1 RC 12 13 V cc Figure 2. Pin configuration n PIN DESCRIPTION SOP Symbol Description 1 NC Not connected 2M Motor output B, channel 1. Motor current flows from M to M when Phase is HIGH. B1 A1 B1 1 3E Common emitter, channel 1. This pin connects to a sensing resistor R to ground. 1 S 4M Motor output A, channel 1. Motor current flows from M to M when Phase is HIGH. A1 A1 B1 1 5V Motor supply voltage, channel 1, +10 to +40 V. V and V should be connected together. MM1 MM1 MM2 6, 7, GND Ground and negative supply. Note: these pins are used thermally for heat-sinking. 18, 19 Make sure that all ground pins are soldered onto a suitably large copper ground plane for efficient heat - sinking. 8V Reference voltage, channel 1. Controls the comparator threshold voltage and hence the output current. R1 9C Comparator input channel 1. This input senses the instantaneous voltage across the sensing resistor, 1 filtered by the internal digital filter or an optional external RC network. 10 Phase Controls the direction of motor current at outputs M and M . Motor current flows from M to M when 1 A1 B1 A1 B1 Phase is HIGH. 1 11 Dis Disable input for channel 1. When HIGH, all four output transistors are turned off, which results in a 1 rapidly decreasing output current to zero. 12 RC Clock oscillator RC pin. Connect a 12 kohm resistor to V and a 4 700 pF capacitor to ground to obtain CC the nominal switching frequency of 23.0 kHz and a digital filter blanking time of 1.0 m s. 13 V Logic voltage supply, nominally +5 V. CC 14 Dis Disable input for channel 2. When HIGH, all four output transistors are turned off, which results in a 2 rapidly decreasing output current to zero. 15 Phase Controls the direction of motor current at outputs M and M . Motor current flows from M to M when 2 A2 B2 A2 B2 Phase is HIGH. 2 16 C Comparator input channel 2. This input senses the instantaneous voltage across the sensing resistor, 2 filtered by the internal digital filter or an optional external RC network. 17 V Reference voltage, channel 2. Controls the comparator threshold voltage and hence the output current. R2 20 V Motor supply voltage, channel 2, +10 to +40 V. V and V should be connected together. MM2 MM1 MM2 21 M Motor output A, channel 2. Motor current flows from M to M when Phase is HIGH. A2 A2 B2 2 22 E Common emitter, channel 2. This pin connects to a sensing resistor R to ground. 2 S 23 M Motor output B, channel 2. Motor current flows from M to M when Phase is HIGH. B2 A2 B2 2 24 NC Not connected