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LB1695M データシート(PDF) 5 Page - Sanyo Semicon Device |
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LB1695M データシート(HTML) 5 Page - Sanyo Semicon Device |
5 / 7 page LB1695M Functional Description 1. Hall input circuit The Hall input circuit is a differential amplifier with a hysteresis of 30 mV (typical). The operating DC level must fall within the common-mode input voltage range (1.5 V to VCC - 1.8 V). We recommend providing inputs with a swing of at least three times the hysteresis, i.e. 120 to 160 mV p-p, to prevent noise from interfering with circuit operation. Insert capacitors in the Hall amplifier IN+ and IN– inputs if capacity is found to be problematic during noise evaluation. 2. Protection circuits • Low voltage protection circuit If the VCC voltage falls below a stipulated level (VLVSD), the sink side output transistor is turned off. This circuit prevents incorrect operation at low VCC voltages. • Thermal protection circuit If the junction temperature exceeds a stipulated temperature (TSD), the sink side output transistor is turned off. This circuit protects the IC from thermal damage. Applications must be designed so that this circuit only operates in abnormal conditions. 3. FG output circuit This circuit outputs signals that are synthesized from the IN1, IN2, and IN3 Hall amplifier input signals and to which wave shaping has been applied. FG1 has the same frequency as the Hall inputs, and FG2 has a frequency three times that of the Hall inputs. 4. Forward/reverse control circuit This IC is designed assuming that applications will not perform motor forward/reverse (F/R) control operations while the motor is turning. Through currents will flow in the output if the motor direction is switched while the motor is turning and ASO will become a problem. We recommend performing F/R control operations with the VM power supply in the off state, i.e. when the motor is stopped. 5. VCC and VM power supplies If the power supply slew rate at power on is excessive, through currents will flow in the output and ASO will become a problem. The power supply slew rates must not exceed ∆V CC/∆t = 0.04 V/µs and ∆VM/∆t = 0.16 V/µs. Also, at power on it is desirable to bring up the VCC voltage first, and then bring up the VM voltage. At power off, it is desirable to bring down VM first, and then bring down VCC only after the motor has stopped. If VCC is turned off after VM but while the motor is still turning due to inertia, the VM voltage may rise beyond the voltage handling capacity of the IC. 6. Power supply stabilization capacitors If large fluctuation occur in the VCC line, the low-voltage protection circuit may operate incorrectly. Capacitors (with values of a few µF) must be inserted in the VCC line (between VCC and ground) to stabilize the power supply. Since large switching current flow in the VM line, fluctuations in the IC VM voltage may occur due to inductances in the wiring pattern. Capacitors must be inserted in the VM line (between VM and ground) so that incorrect operation and voltages in excess of the IC voltage handling capacity do not occur. In particular, if the application wiring lines (VM, VCC, and ground) are long, capacitors adequate to stabilize the power supply lines must be used. 7. Current limiter circuit When the output current reaches the current set as the output current (the limit value), the current limiter circuit turns off the sink side output transistor to limit the output current to the limit value. The RF pin is used to detect the output current. In particular, the output current is detected as a voltage using the Rf resistor, which is inserted between the RF pin and ground. The current limiter operates when the Rf pin reaches 0.5 V (typical) and thus the output current is limited to a value of 0.5/Rf. • Output off time After the current limiter circuit operates and limits the current by turning off the sink side output transistor, it provides a fixed off period (referred to as the output off time), after which it turns the transistor back on. As opposed to current limiter techniques that operated the output in an unsaturated state, the use of an output switching system of this type for the current limiter has the advantage that ASO during current limiter operation is less likely to be a problem. The output off time is determined by the charging time of the capacitor connected to the C pin. When the current limiter operates, the circuit starts to charge the C pin capacitor, and the output off time is the time required to charge the capacitor to a voltage of 2 V (typical). When the capacitor voltage reaches 2 V, the sink side output is turned on again. The capacitor charge current is a fixed current determined by the resistor R connected to the R pin. The C charge No. 5802-5/7 LB1695M |
同様の部品番号 - LB1695M |
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同様の説明 - LB1695M |
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