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2022-09-23 11:28:12
ZXBM1004 Variable Speed Single Phase Brushless DC Motor Controller
illustrate
ZXBM1004 is a single-phase DC brushless motor pre-driver with PWM function suitable for variable speed control of fan and blower motors. The controller is used for fan or blower speed by external PWM signal, thermistor or DC voltage.
Features compatible with external PWM speed control
Compliant thermistor control Minimum speed setting Low noise auto restart Built-in Hall amplifier Speed pulse (FG) and locked rotor (RD) output up to 18V input voltage (60V with external regulator)
Qsop16 package related application instructions:
AN41 - Thermistor Control
AN42 - External PWM Control
AN43 - Connection with Motor Winding Applications Mainframes and PCs Fans and Blowers Instrumentation Fans Central Heating Blowers Automotive Climate Control
block diagram
in function description
H+-Hall Input H--Hall Input The rotor position is detected by the Hall sensor, and the output is applied to the H+ and H- pins. The sensor can be a 4-pin "bare" Hall device or a 3-pin buffered switch type. For 4-pin devices, the differential Hall output signals are connected to the H+ and H- pins. For buffered Hall sensors, the Hall device output is connected to the H+ pin and a pull-up if needed, while the H- pin has an external voltage divider connection that keeps the pin at half VCC. When h+ is relative to
H-, ph2 is the active drive.
THREF - Network Reference This is a nominal 3V reference voltage. It's designed to "source" so it doesn't "sink" any current from higher voltages.
The total current drawn from the minimum speed potential divider leads to pin SMIN and any voltage setting network should not exceed 1Ma at maximum temperature.
The voltage applied to the SPD pin by the speed control input controls the fan motor speed by varying the pulse width modulation (PWM) drive ratio at the PH1LO and PH2LO outputs. Control signals take the form of voltage inputs in the range of 3V to 1V, representing 0% to 100% drive, respectively.
If variable speed control is not required, this pin can be used with an external potentiometer divider to set a fixed speed, or connected to ground to provide full speed, ie 100% PWM drive.
This pin can also be used as an enable pin if desired. Applying a voltage greater than 3.0V will force a complete shutdown of the PWM driver, effectively disabling the driver.
SS ETS Min Speed Min The voltage can be set on this pin by a voltage divider between THREF and GND. This voltage is monitored by the SPD pin so that it cannot go higher than this pin. Since a higher voltage on the SPD pin indicates a lower RPM, the lower RPM range of the fan is limited. If this feature is not required, the pin is tied to THREF, so no minimum speed will be set.
If the fan is controlled on the SPD pin by an external voltage source, this function should not be used, or if required, a resistor greater than 1K should be placed in series with the SPD pin.
CS ETS PWM Frequency PWM This pin has an external capacitor to set the PWM frequency of the phase drive output. A typical 24kHz PWM frequency is available with a capacitor value of 0.1nF.
c-Locked Rotor Timing Capacitor LCK Company If the fan stops spinning for any reason, i.e. a blocked fan blade or a stuck bearing, the unit will go into a locked rotor condition. In this case, after a predetermined time (tlock), the rd pin will go high and the phase output will be disabled. After a further delay (TOFF), the controller will re-enable the phase drive for a defined period of time (ton) in an attempt to restart the fan. This (TOFF) and (TON) cycle will repeat indefinitely or until the fan is restarted.
Ground This is the device power ground return pin, usually the most negative power supply pin for the fan.
rd - Stalled Rotor Error Output This pin is the locked rotor output mentioned in the C LCK Timing section above. High when the rotor is stopped and low when it is running.
This is an open collector driver that provides a high active pull-down through an external pull-up resistor.
fg - frequency generator (speed) output This is the frequency generator output, which is the buffered signal of the hall sensor.
This is an open collector driver that provides a high active pull-down through an external pull-up resistor.
PH1LO and PH2LO - Low-Side External H-Bridge Drivers This pair of outputs drives the low-voltage side of an external high-power h-bridge device, which in turn drives the single-phase windings. These outputs provide commutation and pwm waveforms. The outputs are Darlington emitter follower with active pulldown to help turn off faster using bipolar devices. When in the high state, the output will drive up to 80mA to the base or gate of an external transistor, as shown in the following typical application circuit.
When in the low state, the active phase drive is able to sink to 16ma at low drive to help turn off time during pwm operation. When the phase is inactive, the internal pull-down resistor keeps the output low.
PH1HI and PH2HI - High Side External H-Bridge Drivers These are the high-side outputs of the external H-bridge and are open collector outputs capable of sinking 100mA. This signal only provides commutation to the H-bridge.
V+OP- Phase output power supply voltage This pin is the power supply for the phase output and will be connected differently depending on the external transistor type.
For bipolar devices, this pin will be connected to the VCC pin through a resistor. The resistor is used to control the current into the base of the transistor, so its value is chosen accordingly.
For mosfet devices, the pins will be connected directly to the vcc pins.
V-Applied Voltage Cocos This is the supply voltage for the internal circuits of the device. For 5V to 12V fans can be powered directly from the fan motor. For devices where the fan may run over the 18V maximum rating, this will be provided from an external voltage regulator such as a Zener diode.
application information
The ZXBM1004 is mainly controlled by the voltage on the SPD pin. A voltage of 1V represents 100% pulse width modulation at the phase output, which in turn represents full speed. 3V on the SPD pin in turn represents 0% PWM. Therefore, the motor can be controlled by simply applying a control voltage to the SPD pin with minimal external components.
This voltage control method is easily controlled by other signal types. For example, if a thermistor is applied to the SPD pin, as the resistance of the thermistor changes with temperature, a changing voltage will be produced on the SPD pin.
A common form of fan control is a pwm signal generated by a central processing unit or controller. This signal can be converted into a voltage and adjusted as needed to compensate for motor non-linearity, including minimum speed characteristics.
See application notes an41, an42 and an43 for full application details and further examples of how to control the zxbm1004.
Typical circuit of thermistor controlling speed
Typical circuit for 48V input and external PWM control