ZXBM1021 SINGLE PHASE VARIABLE SPEED MOTOR CONTROL PRE-DRIVER Description Pin Assignments The ZXBM1021 is a high performance, low noise, single-phase, Direct Current Brushless (BLDC) motor pre-driver with variable PWM speed control and current control suitable for fan and blower (Top View) motors. For system flexibility the motor speed can be controlled by either an external PWM control signal or by a DC voltage signal from an external control voltage or from a Thermistor network. To prevent motor inrush current the device has a soft start feature. To help protect the motor coil, the ZXBM1021 provides rotor lock protection which shuts down the output drive if rotor lock is detected. The device automatically re-starts with soft-start when the rotor lock is removed. The ZXBM1021 monitors the motor current to provide a programmable over current limit. A Tachometer output is provided by the open collector output Frequency Generator (FG) pin which allows external interface to U-QFN4040-20 monitor motor rotation or speed. The FG output is the magnetic change frequency. The ZXBM1021 is available in space saving and low profile U-QFN4040-20 package. Features • Applications Operating voltage: 6.8V to 18V o Can be extended with external regulator • Personal, servers and mainframe computers cooling fans • Instrumentation and equipment cooling fans Home appliance fans and blowers • Speed control via external PWM, DC or Thermistor signals • • Low noise, high efficiency • Central heating blowers and extraction systems • Soft start • Industrial fans, blower and extractors • Integrated current control • Hand dryers • Reference voltage output • Hand-held power tools • Built-in Hall amplifier for direct connection of Hall element • Pumps • Rotor Lock Protection • Minimum speed setting • Frequency generator (FG) output • Thermally enhanced space saving low profile U-QFN4040-20 Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2) Halogen and Antimony Free. “Green” Device (Note 3) o Lock detection, output shutdown and automatic re-start package Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant. 2. See http://www.diodes.com for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green" and Lead-free. 3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and <1000ppm antimony compounds. ZXBM1021 Document number: DS Draft Rev. 1 1 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Typical Applications Circuit (Note 4) Notes: 4. FG pull-up resistor is not shown in the typical application circuit. Generally, the FG pull-up resistor is located at the system host end rather than the fan motor PCB. ZXBM1021 Document number: DS Draft Rev. 1 2 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Pin Descriptions Package types: QFN4040-20 Pin Number Pin Name 1 HBIAS Hall Bias Supply Voltage Output Pin. Output voltage is 1.75V typical to supply the external un-buffered (‘naked’) Hall element. A resistance can be added in series with Hall element if lower bias voltage is needed. 2 ThRef 5V Reference Voltage Output Pin. This voltage is used to supply the external networks. 3 PWMSPD 4 SPD DC Voltage Speed Control Input Pin. The control signal voltage should be between 3V for 0% (stop) to 1V for 100% (full speed) speed control. In DC voltage mode, connect a capacitor between SPD and ground. 5 CSPD Output Pin of the PWM Speed Control Input Signal Integrator. In PWM speed control mode, connect a 0.1F capacitor from CSPD pin to ground and connect CSPD pin to SPD pin. In DC voltage speed control mode, leave this pin unconnected. 6 SMIN Minimum Speed Setting Pin. Voltage between 3V to 1V on this pin sets the minimum speed the motor is run at between 0% to full speed. The lowest minimum speed achieved depends on the motor coil design. 7 CLCK Rotor Lock Detect, Auto Restart Timing and Soft-Start Timing Control Pin. Typically a 470nF capacitor is connected to this pin to set the soft-start (to full speed), lock detect and restart timings. 8 GND Supply Return Ground Pin 9 FG 10 SetTh Current Sense Threshold Setting Pin. Used to set the threshold voltage that represents the maximum current to be taken by the motor. The current sense voltage at Sense pin is compared to the SetTh voltage. 11 Sense Current Sense Pin. Input for the signal from a sense resistor in the ground return of the H-bridge circuit to represent the current taken by the motor. 12 SetThRef 13 Ph1Hi Phase 1 High-Side External Power Switch Drive Output Pin. This is a 50mA open-collector output. 14 Ph2Hi Phase 2 High-Side External Power Switch Drive Output Pin. This is a 50mA open-collector output. 15 Ph2Lo Phase-2 Low-Side External Power Switch Drive Output Pin. Darlington emitter follower output with active pull down to give source/sink current of 100mA/100mA. 16 Ph1Lo Phase-1 Low-Side External Power Switch Drive Output Pin. Darlington emitter follower output with active pull down to give source/sink current of 100mA/100mA. 17 V+OP Phase Low Output Supply Pin. Only the low side output drives for Ph1Lo and Ph2Lo are supplied by the V+OP pin. For external MOSFET power devices, a resistor from VCC pin to V+OP slows down the turn-on speed of the low-side MOSFET S and therefore helps prevent shoot-through during turn-on of low-side switches. For external Bipolar power devices, a resistor between the VCC pin and V+OP controls the current into the transistor base. 18 VCC Power Supply Pin 19 H+ Hall Device Positive Input Pin. When H+ is higher in relation to H-, Ph2 is active. 20 H- Hall Device Negative Input Pin ZXBM1021 Document number: DS Draft Rev. 1 Description Speed Control PWM Signal Input Pin. PWM signal should be between 0% to 100% duty ratio. Frequency Generator Output to Provide a Tachometer Signal. This is a buffered output from the Hall amplifier. A variable voltage source used to set the voltage on the SetTh pin. 3 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Functional Block Diagram Notes: 5. The ZXBM1021 has an open-collector FG. Typically a pull-up resistor of 10kΩ is recommended from FG pin to the supply voltage. ZXBM1021 Document number: DS Draft Rev. 1 4 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Absolute Maximum Ratings (Note 6) @TA = +25°C, unless otherwise specified.) Symbol VCCMAX ICCMAX PDMAX TST TJ Characteristics Supply Voltage (Note 7) IC Input Current Power Dissipation Storage Temperature Range Maximum Junction Temperature ESD HBM Human Body Model (HBM) ESD Capability ESD MM Machine Model (MM) ESD Protection Notes: U-QFN4040-20 (See thermal de-rating curve on ‘Thermal Performance’ section) Values Unit -0.6 to 20 V 200 mA 820 mW o -55 to 150 150 C C 2 kV 300 V 6. Stresses greater than the 'Absolute Maximum Ratings' specified above may cause permanent damage to the device. These are stress ratings only; functional operation of the device at these or any other conditions exceeding those indicated in this specification is not implied. Device reliability may be affected by exposure to absolute maximum rating conditions for extended periods of time. 7. The absolute maximum VCC of 20V is a transient stress rating and is not meant as a functional operating condition. It is not recommended to operate the device at the absolute maximum rated conditions for any period of time. Recommended Operating Conditions Symbol Characteristic Conditions o Min Max o VCC Supply Voltage Operating, -40 C to 110 C 6.8 18.0 TA Operating Temperature Range Operating -40 110 Unit V o C Electrical Characteristics (@TA = +25°C, VDD = 12V, unless otherwise specified.) Symbol ICC Characteristics Supply Current Hall Connections VIN Hall Amplifier Input Voltage VCM Hall Amplifier Common Mode Voltage VHYS Hall Amplifier Input Hysteresis IBS Hall Amplifier Bias Current VHB Hall Bias Voltage IHB Hall Bias Output Current Capability Reference voltage Min Typ Max Unit No Load (Note 8) Conditions - 10 15 mA Diff peak to peak 40 0.5 IHB = 10mA o VThRef ThRef Reference Output Voltage IOThRef ThRef Output Current Capability PWM oscillator FPWM PWM Frequency DC Voltage Speed control VSPDL SPD Voltage Minimum VSPDH SPD Voltage Maximum SPD Pin Current at speed demand of 50% ISPD of the full speed and without minimum speed setting ISPD_SMIN2V LinSPD Notes: SPD Pin Current with minimum speed setting of 50% of the full speed SPD Pin voltage to output PWM linearity IOThRef = 10mA, +25 C o o IOThRef = 10mA, -40 C to +110 C 100% PWM drive 0% PWM drive VSPD = 2V SMIN = 0V VSPD = 3V Rspd =10k SMIN = 2V VSPD = 2V 1000 1.95 10 mV V mV nA V mA 5.15 5.25 10 V V mA VThRef 1.5 ±12 700 1.75 4.85 4.75 5 5 18 25 kHz 1 3 V V 0.5 2 100 µA µA 3 % 8. Measured with pins H+, H-, CLCK and CPWM and all other signal pins open circuit ZXBM1021 Document number: DS Draft Rev. 1 5 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Electrical Characteristics (Continued) (@TA = +25°C, VDD = 12V, unless otherwise specified.) Symbol Characteristics PWM Speed control VPWMSPDH PWMSPD High Level VPWMSPDL PWMSPD Low Level IPWMSPD PWMSPD High Level Input Current DPWMSPD PWM Speed Signal Duty Range Maximum Frequency of PWM Control FPWM_MAX Signal PWMSPD Pin PWM Duty Ratio to CSPD Output Voltage Linearity LinINT Conditions Min Typ Max Unit VCC 0.4 2 100 V V µA % 100 kHz 2 2.06 V -0.25 -0.5 µA 2 0.8 0 PWMSPD duty ratio 50%, PWM frequency FPWM = 25kHz 1.94 Minimum Speed Setting ISMIN SMIN Input Current VSMIN = 2V Soft-Start Time to Full Speed CLCK = 0.47F Soft start tss 3 s Lock Timing Lock Condition TLCKDET : TOFF ratio ILCKCL CLCK Charge Current – Soft Start (from lock) and in Lock Mode ILCKCR CLCK Charge Current – Run ILCKDL CLCK Discharge Current - Lock VCLCKTHH CLCK High Threshold Voltage VCLCKTHL CLCK Low Threshold Voltage Current Limit VSetThRef ISetThRef ISENSE ISetTh Output Drives VOH SetThRef Output Voltage 0.45 0.7 1.07 µA 3.25 5.5 9.0 µA 0.45 0.7 1.07 µA 5 0.6 Lock mode ISetThRef = 200uA ThRef0.17 SetThRef Output Current Sense Input Current SetTh Input Current Ph1Lo and Ph2Lo Output High Voltage VOLA Ph1Lo and Ph2Lo Output Low Voltage VOLB Ph1Lo and Ph2Lo Output Low Voltage IOH IOL 1:8 Lock mode, VCLCK = 2.5V Run mode Lock mode, VCLCK = 2.5V ThRef0.1V -20 -20 IOH = 100mA IOL =100mA (Note 9) IOH = 50uA (Note 10) Ph1Hi and Ph2Hi Output Low Voltage IOL Ph1Hi and Ph2Hi Output Sink Current Ph1Hi and Ph2Hi Off Output Leakage Current Commutation Delay IOFF tCD Output Flags IFGOL FG Low Level Output Current Capability VFGOL FG Low Level Output Voltage ThRef0.05 -200 -100 -100 VCC - 2.2 VCC - 1.7 IOH =50mA (Note 10) µA nA nA V 0.5 V 0.3 0.5 V 100 100 mA mA 0.5 V 50 mA ±100 nA 0.3 20 V 0.3 Ph1Lo and Ph2Lo Output Source Current Ph1Lo and Ph2Lo Output Sink Current VOLA V V 70 µs 10 0.4 IFGOL = 10mA mA V Lock conditions TLCKDET TOFF Notes: Lock Detect Time (time it waits for before next Hall signal before deciding to turn outputs off for fixed time) CLCK =0.47F ILCKCR = 5.5uA 400 ms Output Off Time after lock is detected. CLCK =0.47F 3 s 9. Measured when opposing Phase Output is Low 10. Measured when opposing Phase Output is High ZXBM1021 Document number: DS Draft Rev. 1 6 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Functional Descriptions H-Bias – Hall Bias Output This is a 1.75V nominal voltage source to bias a differential un-buffered Hall element sensor. If a Hall element requires a lower voltage than the H-Bias output, connect an appropriate value resistor between the H-Bias pin and the Hall element supply pin. H+ and H- – Hall Inputs The rotor position is detected by a Hall sensor, with the output applied to the H+ and H-pins. This sensor can be either a 4 pin 'naked' Hall device or of the 3 pin buffered switching type. For a 4 pin device the differential Hall output signal is connected to the H+ and H- pins. For a buffered Hall sensor the Hall device output is attached to the H+ pin, with a pull-up attached if needed, whilst the H- pin has an external potential divider attached to hold the pin at half VThRef. When H+ is high in relation to H-, Ph2 is the active drive. ThRef – Output Reference Voltage This is a 5V nominal reference output voltage. It is designed to 'source' current and therefore it will not 'sink' any current from a higher voltage. The total current drawn from the ThRef pin by any external circuitry, such as the minimum speed potential divider to SMIN pin, should not exceed 10mA. SPD –Speed control DC Voltage Input The voltage applied to the SPD pin provides control over the fan motor speed by varying the Pulse Width Modulated (PWM) drive ratio at the Ph1Lo and Ph2Lo outputs. The control signal takes the form of a variable DC voltage input of range 3V to 1V, representing 0% to 100% drive respectively. If variable speed control is not required this pin can be tied to an external potential divider to set a fixed speed or tied to ground to provide full speed i.e. 100% PWM drive. If required this pin can also be used as an enable pin. The application of a voltage >3.0V on this pin will force the PWM drive fully off, in effect disabling the drive, providing the minimum speed function is not active (see SMIN pin section below). To use a minimum speed setting or current control in DC voltage speed control mode, add a series resistor 10k or greater (R11 in typical application circuit for DC control in page 2) between speed control DC voltage input source and SPD pin. PWMSPD – Speed Control PWM Signal Input The duty ratio of the speed control PWM signal input to this pin controls the fan motor speed by varying the output drive PWM ratio at the Ph1Lo and Ph2Lo outputs. In the PWM speed control mode, the PWMSPD pin and the CSPD pin work together to the control the speed. The PWM signal input on the PWMSPD pin is integrated by the capacitor on the CSPD pin (See CSPD pin description). PWM control input signal to the PWMSPD pin needs to be a TTL logic levels. CSPD – PWM Speed Control Signal Integrator Output When PWM input signal is used to control the motor speed, PWM signal is integrated to DC voltage between 1V to 3V to for speed control. If PWMSPD pin input is TTL low, the output voltage on CSPD is 3V and if PWMSPD pin is TTL high, the CSPD pin output is at 1V. In order for the integrator function to be fulfilled an external capacitor is required. This would normally be a 0.1F capacitor for a 25kHz input PWM frequency applied to the PWMSPD input. In PWM speed control mode, connect 0.1F capacitor from CSPD pin to ground and connect CSPD pin to SPD pin. When in DC voltage speed control mode keep PWMSPD and CSPD pins unconnected. SMIN – Minimum Speed Setting A voltage can be set on this pin via a potential divider between the ThRef and GND pins. This voltage is monitored by the SPD pin to clamp the SPD control voltage so that it does not rise above SMIN voltage. As a higher voltage on the SPD pin represents a lower speed, the SMIN setting prevents the motor speed going lower than the minimum speed set by the SMIN pin. If this feature is not required the pin is left tied to ThRef so no minimum speed will be set. If the fan is being controlled from an external voltage source onto the SPD pin then either this feature should not be used or if the minimum speed setting is required then a 10k or greater resistor should be placed in series with the SPD pin. ZXBM1021 Document number: DS Draft Rev. 1 7 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Functional Descriptions (Continued) CLCK – Locked Rotor Timing Capacitor The CLCK pin will have a capacitor connected to ground. It is a multi-function pin providing timing for the lock detect, auto-restart and soft-start conditions. Different rates of charge and discharge of CLCK capacitor depending on the mode of operation (fan operation status) give the soft-start (TSS) to full speed, lock-detect time (TLCKDET) and lock time (TOFF) before next auto-start retry. When the motor is running, the capacitor is discharged at every Hall signal change. CLCK pin provides the timing for the Locked Rotor monitor. In normal operation, and after the soft-start period, Lock Detect is enabled. If the Hall signal does not change (i.e. a rotor lock condition) within the Lock Detect time (TLCKDET), the outputs are disabled. In this condition the motor will not be driven for a set time TOFF. This TOFF time depends on the external CLCK capacitor value and its internal discharge current (ILCKDL). After the TOFF period device goes into a soft-start period (TSS) to re-start the motor. If the motor has not turned to generate a transition on the Hall inputs by the end of this period, motor re-enters motor lock TOFF period with outputs disabled. Once the fan is running normally at the end of a soft-start period, the motor is deemed as running and goes into lock-detection mode. The time periods of TSS, TLCKDET and TOFF are determined by the value of the external capacitor on the CLCK pin and the internal charge and discharge currents during these time periods. The currents during TSS, TLCKDET and TOFF are ILCKCL, ILCKCR and ILCKDL respectively. During soft-start mode, the SetThRef voltage is increased from 0 to Vref. A potential divider from SetThRef is used to generate SetTh voltage for current limit. As SetThRef ramps to nominal value, current limit set also ramps from 0 to nominal setting. This gradual release of current limit to full speed level provides the soft-start. FG – Frequency Generator (Tachometer) Output This is the Frequency Generator output and is a buffered signal from the Hall sensor. This is an open collector drive giving an active pull down with the high level being provided by an external pull up resistor. FG Timing Diagram ZXBM1021 Document number: DS Draft Rev. 1 8 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Functional Descriptions (Continued) Sense – Current Control Sense This pin is used by the current sensing circuit to monitor the current taken by the motor windings. The signal comes from a sense resistor in the low-side ground return of the external H-bridge driver. SetTh – Current Control Threshold Voltage This pin is used by the current sensing circuit as the reference voltage for the voltage on the sense pin to be compared against. If the voltage on the sense pin starts to exceed the voltage set on this pin the current control circuitry starts to back off the output drive PWM duty and thus reducing the current being supplied to the motor coil. SetThRef – SetTh and Start-up Reference This pin is derived from an internal start-up circuit and is used as the source voltage for the potential divider network attached to the SetTh pin. Under running conditions this voltage will be typically ThRef-0.1V. However, during start up the voltage ramps up from 0V to ThRef-0.1V at a rate determined by the capacitor on the CLCK pin giving a gradual release of current limit from 0 to nominal setting. ThRef-0.1V is equal to 4.9V typical. This low power pin is capable of supplying a maximum of 200µA. It should only be used to supply the potential divider network attached to the SetTh pin. Ph1Lo and Ph2Lo – Low-side external H-bridge Drive Output Ph1Lo and Ph2Lo outputs drive the low side of the external power device H-bridge that in turn drives the single phase winding. These outputs provide both the commutation and PWM waveforms. The outputs are active pull-up and active pull-down to help faster switching off when driving MOSFET devices with a high gate capacitance. When in the high state the outputs will provide up to 100mA of drive into the base or gates of external transistors as shown in the typical application circuit shown on the front page. When in the low state the active phase drive is again capable of sinking up to 100mA to aid turn off times during PWM operation. When the phase is inactive the output is held low by a 7.5k internal pull-down resistor. Ph1Hi and Ph2Hi – High-side External H-bridge Driver Ph1Hi and Ph2Hi are the high side outputs to the external H-bridge and are open collector outputs capable of sinking 50mA. This signal provides commutation only to the H-bridge. V+OP – Phase Outputs Supply Voltage This pin is the supply to the Phase outputs Ph1Lo and Ph2Lo only. This pin can be connected to VCC pin directly or through a resistor. For external Bipolar power devices the resistor on V+OP is used to control the current into the transistor base and its value is chosen accordingly. For external MOSFET power devices, the pin can be used to slow down the turn-on speed of the low-side MOSFETS. Slowing down the turn-on speed of low side switches helps to prevent parasitic turn-on of the high-side switches and thus helping to prevent shoot-through during turn-on of low-side switches. The gate resistor connected at Ph1Lo and Ph2Lo plus the resistor on V+OP controls the turn on speed of the MOSFET. The turn-off of speed of the MOSFETS is controlled by the gate resistor only. VCC – IC Supply voltage This provides the supply for the device's internal circuitry except Ph1Lo and Ph2Lo output stages, which are supplied from the V+OP pin. For 12V fans this can be supplied directly from the Fan Motor supply. For fans likely to run in excess of the 18V maximum rating for the device this will be supplied from an external regulator such as a Zener diode or low drop out regulator. GND – Supply Return This is the device supply ground return pin and will generally be the most negative supply pin to the fan. ZXBM1021 Document number: DS Draft Rev. 1 9 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 5.50 100 5.40 90 5.30 80 5.20 70 PhLo Duty Cycle (%) ThRef (V) Typical Operating Characteristics 5.10 5.00 4.90 6V8 4.80 12V 4.70 18V 4.60 60 50 40 30 20 10 4.50 0 -50 -25 0 25 50 75 100 125 0 10 Ambient operating temperature T A (°C) 20 30 40 50 60 70 80 90 100 Speed control PWM signal (PWMSPD) duty cycle (%) PhLo Output Duty Cycle vs. Speed Control PWM Signal (PWMSPD) Duty Cycle ThRef vs Ambient Temperature 100 3.2 90 3.0 2.8 80 2.6 70 CSPD Voltage (V) Duty Cycle (%) 2.4 60 50 40 30 20 2.2 2.0 1.8 1.6 1.4 1.2 10 1.0 0 0.9 1.1 1.2 1.4 1.5 1.7 1.8 2.0 2.1 2.3 2.4 2.6 2.7 2.9 3.0 3.2 PhLo Output Duty Cycle vs Speed control DC Voltage (SPD) Document number: DS Draft Rev. 1 10 20 30 40 50 60 70 80 90 100 Speed control PWM signal (PWMSPD) Duty Cycle (%) Speed control DC voltage SPD (V) ZXBM1021 0 10 of 24 www.diodes.com CSPD Voltage vs Speed Control PWM Signal (PWMSPD) Duty Cycle June 2013 © Diodes Incorporated ZXBM1021 Application Note (continued) The ZXBM1021 is primarily controlled by a voltage on the SPD pin or a PWM signal on the PWMSPD pin. A voltage of 1V represents a 100% PWM at the Phase Outputs and in turn represents full speed. 3V on the SPD pin conversely represents 0% PWM. The motor can therefore be controlled simply by applying a control voltage onto the SPD pin with the minimal use of external components. This voltage control method easily lends itself to control by other signal types. For example if a thermistor is applied to the SPD pin a varying voltage can be generated at the SPD pin as the resistance of the thermistor varies with temperature. A common form of control of fans is by a PWM signal derived from a central processor or controller. This speed control PWM signal can be applied to PWMSPD pin. Motor speed is proportional to the duty ratio of the applied PWM speed control signal on PWMSPD pin. Voltage on the SMIN pin sets the minimum speed of the motor. If the speed demand by either DC signal on SPD pin or PWM signal on PWMSPD pin is lower than the minimum speed setting, motor will run at minimum speed. The design of a motor system will be set around the maximum speed, the minimum speed and the current of the motor. The design of the motor coil and the voltage on the output stage will set the maximum speed of the motor. The ZXBM1021 allows easy setting and control of the minimum speed and maximum motor current, as well as for controlling the speed. DC Speed Control The SPD pin will respond to an input DC voltage from 3V to 1V for 0% to 100% of the full speed. To allow internal minimum speed setting (SMIN) and current control (ILIM) circuits to adjust the SPD pin voltage, the speed control DC voltage signal should be driven in via a 10k series resistor. The series resistor allows the SPD pin to vary even when driven externally by a low impedance source. A 0.1F capacitor should be connected from the SPD pin to supply ground. 20 1 2 DC Speed Control (3V to 1V) R 10kΩ 3 4 5 C 0.1µF 19 18 17 16 HBIAS Ph1Lo ThRef Ph2Lo PWMSPD ZXBM1021 Ph1Hi SPD SetThRef CSPD Sense 6 7 8 9 15 14 13 12 11 10 When used in DC speed control mode, PWMSPD and CSPD pins should be left floating. ZXBM1021 Document number: DS Draft Rev. 1 11 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Application Note (Continued) This input also allows the fan to be driven by a thermistor, to allow the speed to be controlled according to temperature. An example circuit is shown below. o With the values shown, and a Beta value of 4000 for the NTC, the above circuit drives the ZXBM1021 with 3V (minimum speed) at 0 C, changing o to 1V (maximum speed) at 82 C, subject to tolerances. To minimize additional circuitry, the 5V ThRef output from the ZXBM1021 IC can supply the current required for the thermistor network circuit as long as the total current from ThRef does not exceed 10mA. PWM Speed Control An additional input allows for the use of PWM to control the fan speed. The ZXBM1021’s output speed is proportional to the duty cycle of the PWM input. 20 1 2 3 PWM Speed Control (TTL level, Duty ratio 0% to 100%) 4 5 C4 0.1µF 19 18 17 16 HBIAS Ph1Lo ThRef Ph2Lo PWMSPD ZXBM1021 Ph1Hi SPD SetThRef CSPD Sense 6 7 8 9 15 14 13 12 11 10 When using PWMSPD speed input, the SPD pin should be connected to CSPD with a 0.1F capacitor connected to ground. PWMSPD can be driven from a microcontroller with either 0-5V or 0-3.3V logic levels signal. The recommended frequency of the input PWM control signal is 25kHz. ZXBM1021 Document number: DS Draft Rev. 1 12 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Application Note (Continued) SMIN Minimum Speed Setting Minimum speed setting prevents the motor from running below a set speed regardless of whether the control applied is for a slower speed (either DC or PWM input). The minimum motor speed is chosen based on a speed below which the motor may or fail to start. The SMIN pin voltage sets a maximum voltage clamp for the SPD pin. For a DC voltage input into SPD pin, the voltage range 3V to 1V represents 0% to 100% of full speed. In order to set a minimum speed of 20%, SMIN should be set 20% into this range below 3V, i.e 2.6V 100% 90% 80% Motor speed (%) 70% 60% 50% 40% 30% SMIN = 2.6V 20% 10% SMIN = 3V 0% 3 2.8 2.6 2.4 2.2 2 1.8 1.6 1.4 1.2 1 DC speed control voltage at SPD pin (V) SPD and SMIN Voltages vs Motor Speed Minimum speed is set by the voltage on the SMIN pin, using a potential divider from the ThRef voltage output as shown below. 20 1 2 R9 12kΩ 3 4 5 R10 13kΩ 19 16 Ph1Lo ThRef Ph2Lo PWMSPD ZXBM1021 Ph1Hi SPD SetThRef CSPD Sense The SMIN voltage is given by SMIN =ThRef Document number: DS Draft Rev. 1 17 HBIAS 6 ZXBM1021 18 7 8 9 15 14 13 12 11 10 R10 R9+R10 13 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Application Note (Continued) ThRef is capable of driving 10mA, but it is not necessary to draw much current for SMIN. Set R10+R9 in the range 5kΩ-50kΩ (1mA - 100µA). ThRef may also be used to drive a thermistor circuit, so care must be taken to keep the total current drawn from ThRef to the correct level. Example: Required SMIN of 20% = 2.6V SMIN =ThRef 2.6V = 5V R10 R9+R10 R10 R9+R10 Solve for R9 R9 = 2.4 R10 2.6 Choose R10 = 13k and solve for R9 which gives R9 = 12k. The current in R10+R9 string = 5/25000 = 200µA If SMIN is not required, the SMIN pin should be pulled up externally to ThRef by 1kΩ Motor Current Limit The motor current limit on ZXBM1021 compares the voltage on the Sense pin against the threshold voltage on the SetTh pin. The current limit is triggered when the voltage at the Sense pin exceeds the threshold at SetTh. The device lowers the output PWM drive duty ratio if the voltage on the Sense pin rises above the threshold voltage on the SetTh pin. The threshold value at SetTh pin is set using R7 and R8 between SetThRef, SetTh and GND. The Sense voltage is generated by the motor current flowing through the sense resistor. It is recommended to use 100mΩ for the sense resistor on the Sense pin, and vary the current limit by changing R7 and R8. Ph2Hi V+OP VCC Ph2Lo PWMSPD ZXBM1021 Ph1Hi SPD SetThRef CSPD Sense SMIN 5 ThRef 6 7 8 15 Motor coil 14 13 12 11 SetTh 4 16 FG 3 17 Ph1Lo GND 2 18 HBIAS CLCK 1 19 H+ H- 20 R7 10 9 Rsense R8 The current limit, ILIM, is given by ILIM SetThRef R7 RSENSE R8 R8 Note that SetThRef has a maximum output current of 200µA, therefore R7+R8 must be larger than 25kΩ. ZXBM1021 Document number: DS Draft Rev. 1 14 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Application Note (Continued) Example: Required ILIM = 2A ILIM SetThRef R7 R8 RSENSE R8 where SetThRef = (ThRef -0.1V) = 4.9V typical 2A Solve for R7 R7 = R8 R7 R8 0.1Ω 4.9V 4.9 R8 0.2 Choose R8 = 2k and solve for R7 which gives R7 = 47k. The current in R7+R8 string = 4.9/49000 = 100µA which is within maximum output current capability of the SetThRef pin. It is important that the current limit be set above the intended average current of the motor. In practice, due to the variable nature of the motor current through a commutation cycle, it is usually necessary for the current limit to be set higher than the peak current drawn at the beginning of each commutation cycle. The top trace shows the motor coil current, while the lower trace shows the Sense pin voltage. As the current flow direction in the motor coil changes at each commutation cycle, the motor current in the top trace is shown as positive and negative current. The current flowing in the Rsense is always in the same direction and therefore the sense pin reads the magnitude of the motor coil current. Current limiting may prevent the motor from reaching full speed, despite the average current being significantly lower than the current limit. The system will limit the tail-end current according to the current limit set. Current limit setting can also be used to remove the tail-end current. Example of using current limit to reduce tail-end current at full speed is shown in fibelow Current limit set much higher than the peak tail-end current (Peak tail-end current = 180mA typ, Current limit set at 0.485mA ) ZXBM1021 Document number: DS Draft Rev. 1 15 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Application Note (Continued) Current limit set lower than the peak tail-end current (Tail-end current = 145mA typ, Current limit set at 0.166mA) CLCK Value The value of CLCK affects three important timings for the ZXBM1021: Soft Start, Lock Detect and Off-time. Soft Start When the system is initially powered on, it will go through the soft-start period, during which the motor is gradually ramped to full speed. The soft start operation relies on the current control feature being implemented and generally the current limit is set slightly above the normal running current. In the soft start process, at power-on the voltage at CLCK will rapidly increase to the low threshold, VCLCKTHL (0.6V). Then, CLCK will be charged from 0.6V up to the high threshold, VCLCKTHH (5V) at a constant current, ILCKCL, which is typically 0.7µA. The the time taken to charge the capacitor form VCLCKTHL to VCLCKTHH level depends on the value of CLCK capacitor. The soft-start time tss is given by: tSS CLCK VCLCKTHH VCLCKTHL ILCKCL Since VCLCKTHH, VCLCKTHL and ILCKCL are fixed, this becomes simply: tSS CLCK 6.29 6.29 10 10 For the default value of CLCK, 0.47µF, soft-start time is: tSS 0.47 10 0.47 6.29 2.96s This is the 3s stated in the datasheet electrical parameter section. Lock Detect When the motor is running, the hall sensor will follow the rotor magnetic flux density to detect the commutation point. Should the rotor lock, the signal from the hall sensor will cease. The value of CLCK defines the lock detect time period before the ZXBM1021 shuts down the outputs in order to prevent damage to the coil. The ZXBM1021 internal system returns CLCK voltage to the low threshold, VCLCKTHL (0.6V), each time the hall sensor provides a commutation signal. CLCK then charges at the run current, ILCKCR, which is typically 5.5µA. If the voltage on CLCK reaches the high threshold, VCLCKTHH (5V), before the hall sensor provides the next commutation signal then the system will shut down by entering the lock condition. tLCKDET CLCK VCLCKTHH VCLCKTHL ILCKCR The thresholds voltage and charge current are fixed, therefore the time depends only on the value of CLCK: tLCKDET CLCK 0.8 10 For the default value of CLCK, 0.47µF, tLCKDET is as follows: tLCKDET 0.47 10 0.8 10 0.47 0.8 0.376s This should not interfere with normal operation of a fan as the time period for lock detection is many times longer than the expected time for one revolution. As the hall sensor will detect 4 transitions in a single revolution, 0.376s between transitions would equate to a rotational speed of 40rpm. For use in systems where extremely low rotation speeds are required, the lock detect time can be increased by making the CLCK capacitor value larger. ZXBM1021 Document number: DS Draft Rev. 1 16 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Application Note (Continued) Off time If the above lock detection causes a device shutdown, CLCK is used again to provide the time period, tOFF. This is the time for which the device will remain shut down after rotor lock is detected. The output shutdown period, tOFF, depends CLCK being discharged from the high threshold to the low threshold at the discharge current ILCKDL, typically 0.7µA. tOFF CLCK VCLCKTHH VCLCKTHL ILCKDL As above, the threshold voltages and discharge current are fixed, therefore the time depends only on the value of CLCK: tOFF CLCK 6.29 10 6.29 10 10 For the default value of CLCK, 0.47µF, tOFF is as follows: tOFF 0.47 0.47 6.29 2.96s A note on probing CLCK Due to the very small charge and discharge currents involved with CLCK, putting an oscilloscope probe onto that node can have a significant impact on the charge time. The above graph shows simulation for the impact on soft-start tSS. A typical 10X voltage probe will have 10MΩ resistance, which is enough to increase soft-start time from 3 seconds to over 5 seconds. Probing this point can be useful in understanding the operation of the system but it is important to be aware of the impact that the scope probe will have on the operation of the circuit. ZXBM1021 Document number: DS Draft Rev. 1 17 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Application Note (Continued) Output device driving In order to drive the output stage efficiently, it is important to minimise shoot-through currents. The ZXBM1021 has a built-in delay (commutation dead-time) to allow time for re-circulating currents to be absorbed however parasitic shoot-through can still occur. This is when the rapid switchon of the low-side MOSFET causes a low-going pulse through the high-side MOSFET to the gate, causing it to switch on momentarily. Slowing the switch-on of the low-side MOSFET can eliminate this effect. D2 System supply (12V) D1 20 19 R12 18 17 16 R1 1 2 3 4 5 HBIAS Ph1Lo ThRef Ph2Lo PWMSPD ZXBM1021 Ph1Hi SPD SetThRef CSPD Sense 6 7 R4 R3 R6 R5 Optional, system dependent 8 9 Motor coil R2 15 14 13 12 11 10 Rsense The resistors R1 to R6 and R12 in the diagram allow for control of switch-on and switch-off times for the top and bottom MOSFETs separately. High-side MOSFETs switching speed: R3 and R5 control the discharge of the gates of the high-side P-channel MOSFETSs, limiting the switch-on speed. R4 and R6 control the charging of the gates of the P-channel MOSFETs, limiting the switch-off speed. Low-side MOSFETs switching speed: R1 and R2 are series gate resistors for the N-channel FETs, affecting both switch-on and switch-off times. R12 is the series resistor for the V+OP pin of the ZXBM1021. This resistor is effectively in series with R1 or R2 when that low-side N-channel device is switched on, limiting the switch-on time. R12 allows to vary the switch-on time relative to the switch-off time to prevent parasitic shoot-through at turn-on. When using bipolar output devices the resistors serve similar functions in limiting the base currents of the transistors. ZXBM1021 Document number: DS Draft Rev. 1 18 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Application Note (Continued) External Drive Transistors Diodes offers a range of devices that are ideally suited to interface between the ZXBM1021 pre-driver and the motor. The following tables show a selection of products. For more comprehensive listings or the latest information please refer to the Diodes website: www.diodes.com MOSFETs Part Number BVDSS (V) ID (A) RDS(on) @ VGS = 10V (4.5V for 20V parts) (Ω) N P N P N P N P N P N P N P 20 -20 20 -20 30 -30 40 -40 40 -40 60 -60 60 -60 7.4 -5.9 4.5 -3.2 7.1 -7.4 7.5 -7.3 7.2 -5.2 4.7 -3.9 5.1 -4.8 0.020 0.033 0.035 0.074 0.028 0.025 0.025 0.025 0.028 0.050 0.055 0.085 0.045 0.055 Type BVDSS (V) ID (A) RDS(on) @ VGS = 10V (Ω) Package 100 7.7 0.085 TO252-3L Type Package Power switch: N-channel MOSFETs DMC2020USD DMC2038LVT DMC3028LSD DMC4040SSD DMC4028SSD ZXMC4559DN8 ZXMC6A09DN8 Part Number SO8 TSOT26 SO8 SO8 SO8 SO8 SO8 Power switch: N-channel MOSFETs ZXMN10A09K N ZXMN10A25K N 100 4.0 0.125 SOT223 ZXMN10A11G N 100 2.4 0.35 SOT223 ZXMN10A08DN8 2xN 100 2.1 0.25 SO8 ZXMN10B08E6 N 100 1.9 0.230 SOT23-6 ZXMN10A07Z N 100 1.4 0.7 SOT89 ZXMN6A09K N 60 11.2 0.04 TO252-3L ZXMN6A25K N 60 10.7 0.05 TO252-3L DMN6068LK3 N 60 8.5 0.068 TO252-3L ZXMN6A09G N 60 7.5 0.04 SOT223 ZXMN6A25G N 60 6.7 0.05 SOT223 ZXMN7A11K N 60 6.1 0.120 TO252-3L ZXMN6A09DN8 2xN 60 5.6 0.04 SO8 DMN6068SE N 60 5.6 0.068 SOT223 ZXMN6A08G N 60 5.3 0.08 SOT223 ZXMN6A25DN8 2xN 60 4.7 0.055 SO8 ZXMN6A11Z N 60 3.6 0.120 SOT89 ZXMN6A07Z N 60 2.2 0.250 SOT89 ZXMN6A07F N 60 1.4 0.250 SOT23 ZXBM1021 Document number: DS Draft Rev. 1 19 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Application Note (Continued) Part Number Type BVDSS (V) ID (A) RDS(on) @ VGS = 10V (Ω) Package -100 -5.9 0.150 TO252 Power switch: P-channel MOSFETS ZXMP10A18K P ZXMP10A18G P -100 -3.7 0.150 SOT223 ZXMP10A17E6 P -100 -1.6 0.350 SOT26 ZXPM6A17DN8 2xP -60 -3.2 0.125 SO8 ZXMP6A18K P -60 -10.4 0.055 TO252 DMP4025LSD 2xP -40 -7.6 0.025 SO8 DMP4015SPS P -40 -13 0.011 POWERDI5060-8 ZXMP4A16G P -40 -6.4 0.060 SOT223 DMP3008SFG P -30 -11.7 0.017 POWERDI3333-8 Part Number Type VCEO (V) IC (A) VCE(sat) @IC/IB ( mV@A/mA ) Package BJTs Power switch: NPN BJT FZT855 NPN 150 4 65 @ 0.5/50 SOT223 FMMT624 NPN 125 1 150 @ 0.5/50 SOT23 ZX5T853G NPN 100 6 125 @ 2/100 SOT223 ZXTN19100CZ NPN 100 5.25 65 @ 1/100 SOT89 ZXTN25100BFH NPN 100 3 135 @ 0.5/10 SOT23 ZXTN25100DFH NPN 100 2.5 170 @ 0.5/10 SOT23 FCX493 NPN 100 1 300 @ 0.5/50 SOT89 FCX1053A NPN 75 3 200 @ 1/10 SOT89 ZXTN19060CG NPN 60 7 155 @ 1/10 SOT223 ZX5T851G NPN 60 6 135 @ 2/50 SOT223 DXT2010P5 NPN 60 5 70 @ 1/10 PowerDI5 FCX493A NPN 60 1 500 @ 1/50 SOT89 FCX619 NPN 50 3 260 @ 2/50 SOT89 FMMT619 NPN 50 2 220 @ 2/50 SOT23 FCX619 NPN 50 3 260 @ 2/50 SOT89 Drive buffer and level shift FMMT493 NPN 100 1 300 @ 0.5/50 SOT89 FMMT493A NPN 60 1 250 @ 0.5/50 SOT23 ZXTN2038F NPN 60 1 250 @ 0.5/50 SOT23 DSS41604 NPN 60 1 140 @ 0.5/50 SOT563 ZXBM1021 Document number: DS Draft Rev. 1 20 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Thermal Performance (1) Package type: QFN4040-20 0.9 0.8 Maximum Power (W) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 Rthja = 45°C/W 0.0 ‐50 ‐25 0 25 50 75 100 125 150 o Ambient Operating Temperature ( C) U‐QFN4040‐20 Derating Curve Notes: 11. The power dissipation de-rating curve for ZXBM1021 in U-QFN4040-20 package is based on 2”x2” FR4 substrate, 2oz copper, 1.6mm thick PCB with minimum recommended pad layout on the top layer with thermal vias to all copper bottom layer and the ‘junction to ambient’ thermal resistance (Rthja) of 45°C/W. ZXBM1021 Document number: DS Draft Rev. 1 21 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Ordering Information Part Number Package Code Packaging ZXBM1021JB20TC JB20 U-QFN4040-20 Quantity 13” Tape and Reel Part Number Suffix 3000/Tape & Reel TC Marking Information (1) Package type: U-QFN4040-20 ZXBM1021 Document number: DS Draft Rev. 1 Part Number Package Identification Code ZXBM1021JB20TC QFN4040-20 ZXBM 1021 22 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 Package Outline Dimensions (All dimensions in mm.) Please see AP02002 at http://www.diodes.com/datasheets/ap02002.pdf for latest version. (1) Package type: U-QFN4040-20 A1 A3 A Seating Plane D (Pin #1 ID) e E2 E D2 L U-QFN4040-20 Dim Min Max Typ A 0.55 0.65 0.60 A1 0 0.05 0.02 A3 0.15 b 0.20 0.30 0.25 D 3.95 4.05 4.00 D2 2.40 2.60 2.50 E 3.95 4.05 4.00 E2 2.40 2.60 2.50 e 0.50 BSC L 0.35 0.45 0.40 Z 0.875 All Dimensions in mm b Z (8x) Suggested Pad Layout Please see AP02001 at http://www.diodes.com/datasheets/ap02001.pdf for the latest version. (1) Package Type: U-QFN4040-20 X3 Dimensions X1(10x) C X X1 X2 X3 Y Y1 Y2 Y3 Y1(10x) Y2 Y3 X2 Value (in mm) 0.500 0.350 0.600 2.500 4.300 0.600 0.350 2.500 4.300 Y(10x) 1 X(10x) ZXBM1021 Document number: DS Draft Rev. 1 C 23 of 24 www.diodes.com June 2013 © Diodes Incorporated ZXBM1021 IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). 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Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support devices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of Diodes Incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related information or support that may be provided by Diodes Incorporated. Further, Customers must fully indemnify Diodes Incorporated and its representatives against any damages arising out of the use of Diodes Incorporated products in such safety-critical, life support devices or systems. Copyright © 2013, Diodes Incorporated www.diodes.com ZXBM1021 Document number: DS Draft Rev. 1 24 of 24 www.diodes.com June 2013 © Diodes Incorporated