DIODES ZXBM1021

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
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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
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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 0.1F
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.
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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
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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
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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 = 0.47F
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 =0.47F
ILCKCR = 5.5uA
400
ms
Output Off Time after lock is detected.
CLCK =0.47F
3
s
9. Measured when opposing Phase Output is Low
10. Measured when opposing Phase Output is High
ZXBM1021
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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 0.1F capacitor for a 25kHz input PWM frequency
applied to the PWMSPD input.
In PWM speed control mode, connect 0.1F 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
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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
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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.
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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
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CSPD Voltage vs Speed Control PWM Signal (PWMSPD) Duty Cycle
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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 0.1F 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.
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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 0.1F 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
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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
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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
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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
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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
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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
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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
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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
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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
( [email protected]/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
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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
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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
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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
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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).
Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes
without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the
application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or
trademark rights, nor the rights of others. Any Customer or user of this document or products described herein in such applications shall assume
all risks of such use and will agree to hold Diodes Incorporated and all the companies whose products are represented on Diodes Incorporated
website, harmless against all damages.
Diodes Incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthorized sales
channel.
Should Customers purchase or use Diodes Incorporated products for any unintended or unauthorized application, Customers shall indemnify and
hold Diodes Incorporated and its representatives harmless against all claims, damages, expenses, and attorney fees arising out of, directly or
indirectly, any claim of personal injury or death associated with such unintended or unauthorized application.
Products described herein may be covered by one or more United States, international or foreign patents pending. Product names and markings
noted herein may also be covered by one or more United States, international or foreign trademarks.
This document is written in English but may be translated into multiple languages for reference. Only the English version of this document is the
final and determinative format released by Diodes Incorporated.
LIFE SUPPORT
Diodes Incorporated products are specifically not authorized for use as critical components in life support devices or systems without the express
written approval of the Chief Executive Officer of Diodes Incorporated. As used herein:
A. Life support devices or systems are devices or systems which:
1. are intended to implant into the body, or
2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the
labeling can be reasonably expected to result in significant injury to the user.
B. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the
failure of the life support device or to affect its safety or effectiveness.
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
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