Test Procedure for the STK681-310GEVB Evaluation Board Evaluation Board Setup [Supply Voltage] Vcc1 (10 to 42V): Power Supply for DC motor Vcc2 (5V) : Power Supply for internal logic IC [Operation Guide] 1. Motor Connection: Connect the motor to OUT1 and OUT2. 2. Initial Condition Setting: Set to signal condition IN1=H, IN2=H, and INH=L. 3. Power Supply: At first, supply DC voltage to Vcc2(5.0V). Next, supply DC voltage to Vcc1. 4. Set to Forward or Reverse signal condition with INH=Low. Turn “High” INH signal. Output current flows between OUT1 and OUT2. 5. Motor Operation [Setting the current limit using the Vref pin] Without external resistance R3, output current is limited to Iomax. You can limit to below Iomax by installing R3. As for Iomax of STK681-310, 0.42V is generated with 5V, internal resistance 82k (R1) and 7.5k (R2), then Iomax=4.2A is designed by comparing with internal current sensing resistor Rs. In case of without external resistance R3 Iomax=(Vcc2×R2/(R1+R2))÷Rs R1 STK681-300 82kΩ STK681-310 82kΩ STK681-320 82kΩ R2 5.1kΩ 7.5kΩ 5.1kΩ Rs 0.1Ω 0.1Ω 0.056Ω Including external resistance R3 Io= ((Vcc2×(R2×R3)/(R2+R3))/(R1+(R2×R3)/(R2+R3)))÷Rs If you mount external resistor R3=7.5k, for instance, you can limit to 2.1A, which is half of Iomax (4.2A) of STK681-310. 12/30/2013 1 www.onsemi.com Allowable power dissipation, PdPK - W Allowable power dissipation (Reference value) Allowable power dissipation, PdPK (no heat sink) - Ambient temperature, Ta 3.5 3 2.5 2 1.5 °C 1 0.5 0 0 20 40 60 80 100 120 Ambient temperature, Ta - Waveform example STK681-310(Current limit 4.2A setting) IN1 and IN2; 5V/div, Output current; 2A/div IN1 IN2 OUT1 Output current Positive direction is source current. Peak 6A FORWARD 12/30/2013 BRAKING 2 www.onsemi.com STK681-310(Current limit 2A setting) IN1 5V/div, OUT1 20V/div, Output current; 2A/div IN1 OUT1 OUT1 Output current Positive direction is source current. Current limit active. Output is chopped. FORWARD Current control is slow decay. STK681-300, 310 and 320 control Bipolar Transistor or MOSFET at High side by constant-current PWM control system. Current control enters Slow decay mode. STK681-300, 310 12/30/2013 STK681-320 3 www.onsemi.com STK681-310(Current limit 4.2A setting) IN1 and IN2; 5V/div, Output current; 2A/div IN1 IN2 OUT1 Output current Positive direction is source current. FORWARD 12/30/2013 BRAKING 4 www.onsemi.com