Ordering number : EN6087B LB1975 Monolithic Digital IC For Fan Motor http://onsemi.com 3-phase Brushless Motor Driver Overview The LB1975 is a 3-phase brushless motor driver IC suited for use in direct PWM driving of DC fan motors for air conditioners, water heaters, and other similar equipment. Since a shunt regulator circuit is built in, single power supply operation sharing the same power supply for the motor is supported. Features • Withstand voltage 46V, output current 2.5A • Direct PWM drive output • 3 built-in output top-side diodes • Built-in current limiter • Built-in FG output circuit Specifications Absolute Maximum Ratings at Ta = 25°C Parameter Supply voltage Output current Symbol Conditions VCC max Ratings Unit 7 V VM max 46 V IO max 2.5 A 10 mA 3 W Maximum input current IREG max VREG pin Allowable power dissipation Pd max1 Independent IC Pd max2 With infinite hear sink 20 W Operating temperature Topr -20 to +100 °C Storage temperature Tstg -55 to +150 °C Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. Semiconductor Components Industries, LLC, 2013 May, 2013 D1708 MS / 21003AS (OT) / 52199RM (KI) No.6087-1/10 LB1975 Allowable Operating Ranges at Ta = 25°C Parameter Supply voltage range Symbol Conditions Ratings VCC Unit 4.5 to 6.7 VM 20 to 42 Input current range IREG FG pin applied voltage VFG FG pin output current IFG VREG pin 1 to 5 0 to VCC 0 to 10 V V mA V mA Electrical Characteristics at Ta = 25°C, VCC = 5V, VM = 30V Parameter Symbol Ratings Conditions min Supply current ICC typ 10 Unit max 14 18 mA Output Block Output saturation voltage Output leak current VOsat1(L) IO = 1.0A, VO(sink) 1.1 1.4 V VOsat1(H) IO = 1.0A, VO(source) 0.9 1.3 V VOsat1 IO = 1.0A, VO(sink) + VO(source) 2.0 2.6 V VOsat2(L) IO = 2.0A, VO(sink) 1.4 1.8 V VOsat2(H) IO = 2.0A, VO(source) 1.2 1.7 V VOsat2 IO = 2.0A, VO(sink) + VO(source) 2.6 3.4 V IOLeak(L) 100 IOLeak(H) Upper side diode forward voltage μA μA -100 VFH1 IO = 1.0A 1.2 1.6 V VFH2 IO = 2.0A 2.1 2.6 V Hall Amplifier Input bias current IHB -4 μA -1 Common-mode input voltage range VICM 1.5 Hall input sensitivity VHIN 60 VCC-1.5 V Hysteresis width ΔVIN(HA) 23 32 39 mV Input voltage (low to high) VSLH 6 16 25 mV Input voltage (high to low) VSHL -25 -16 -6 mV 0.5 V mVp-p FG Pin (speed pulse output) Output low-level voltage VFGL IFG = 5mA Pull-up resistor value RFG 7.5 10 12.5 kΩ VRF 0.45 0.50 0.55 V 150 180 °C 40 °C Current Limiter Limiter Thermal Shutdown Thermal shutdown operating TSD Design target Value (junction temperature) ΔTSD Design target Value (junction temperature) temperature Hysteresis width Low-Voltage Protection Operating voltage VLVSD Non-operating voltage VLVSD(OFF) Hysteresis width ΔVLVSD 3.5 3.8 4.1 V 4.3 4.5 V 0.4 0.5 0.6 V 2.95 3.10 3.25 V PWM Oscillator Output high-level voltage VOH(OSC) Output low-level voltage VOL(OSC) 1.38 1.45 1.59 V Amplitude VOSC 1.50 1.65 1.71 Vp-p Oscillator frequency fOSC 19.6 23.0 27.6 kHz -110 -94 -83 μA 1.6 2.1 2.6 kΩ 6.6 7.0 7.2 V Charge current ICHG Discharge resistance RDCHG C = 2200pF VREG Pin Pin voltage VREG IREG = 1.5mA Continued on next page. No.6087-2/10 LB1975 Continued from preceding page. Parameter Symbol Ratings Conditions min typ Unit max VCTL Pin Input voltage Input bias current VCTL1 Output duty 0% 1.1 1.4 1.7 V VCTL2 Output duty 100% 3.2 3.5 3.8 V IB1(CTL) VCTL = 0V -82 IB2(CTL) VCTL = 5V μA 92 μA 2.46 V VCTL Amplifier Reference voltage VCREF Output voltage 2.23 2.35 VCOUT1 VCTL = 0V 3.90 4.20 4.40 V VCOUT2 VCTL = 5V 0.60 0.80 1.10 V Start/Stop Pin High-level input voltage range VIH(S/S) VCC-1.5 VCC V Low-level input voltage range VIL(S/S) 0 1.5 V Input open voltage VIO(S/S) VCC-0.5 VCC V Hysteresis width ΔVIN(S/S) High-level input current IIH(S/S) V(S/S) = VCC Low-level input current IIL(S/S) V(S/S) = 0V 0.35 0.50 0.65 V -10 0 +10 μA -280 -210 μA Forward/Reverse Pin High-level input voltage range VIH(F/R) VCC-1.5 VCC Low-level input voltage range VIL(F/R) 0 1.5 V V Input open voltage VIO(F/R) VCC-0.5 VCC V Hysteresis width ΔVIN(F/R) High-level input current IIH(F/R) V(F/R) = VCC Low-level input current IIL(F/R) V(F/R) = 0V 0.35 0.50 0.65 V -10 0 +10 μA -280 -210 μA Package Dimensions unit : mm (typ) 3147C Pd max -- Ta 15 12.7 11.2 R1.7 0.4 8.4 28 1 14 20.0 4.0 4.0 26.75 (1.81) 1.78 0.6 Allowable power dissipation, Pd max -- W 24 With infinite heat sink 20 16 12 8 4 3 Independent IC 0 -20 0 20 40 60 80 100 120 Ambient temperature, Ta -- °C 1.0 SANYO : DIP28H(500mil) No.6087-3/10 LB1975 Pin Assignment VCOUT VCTL OSC 28 27 26 (NC) VCREF IN1− 25 24 23 IN1+ 22 IN2− IN2+ 21 20 IN3− IN3+ FG1 19 18 17 10 11 12 FG2 GND1 16 15 LB1975 1 2 VCC VREG 3 5 S/S F/R 5 6 7 8 9 (NC) OUT1 OUT2 OUT3 (NC) (NC) GND3 GND2 13 14 RF VM Top view Truth Table Input IN1 1 H 2 H 3 H 4 L 5 L 6 L IN2 L L H H H L Forward/reverse control IN3 F/R Source → Sink L OUT2 → OUT1 H OUT1 → OUT2 H L L L H H F/R L OUT3 → OUT1 H OUT1 → OUT3 L OUT3 → OUT2 H OUT2 → OUT3 L OUT1 → OUT2 H OUT2 → OUT1 L OUT1 → OUT3 H OUT3 → OUT1 L OUT2 → OUT3 H OUT3 → OUT2 FG output FG1 FG2 L L L H L L H H H L H H FG output 0V to 1.5V VCC − 1.5V to VCC 100 FG1 FG2 Duty -- VCTL characteristics 80 Duty -- % Forward rotation Low Reverse rotation High Output 60 40 20 0 VCTL1 Control voltage, VCTL -- V VCTL2 No.6087-4/10 LB1975 Block Diagram and Peripheral Circuit VREG VCC VCC S/S F/R FG1 FG2 Reg LVDS TSD VM Hys.Amp H VM IN1 OUT1 H H OUT2 Logic IN2 OUT3 IN3 RF 31kΩ VCTL 40kΩ Current Limiter VCTL Amp PWM OSC VCTL 0.5V 2.35V VCREF VCOUT OSC GND1 GND2 GND3 Pin Functions Pin No. 1 Pin name VCC Pin voltage 4.5V to 6.7V Function Equivalent circuit Power supply for blocks other than the output block. 2 VREG 0.0V to 7.3V Shunt regulator output pin (7V). 3 S/S 0.0V to VCC Start/stop control pin. 2 VCC Low: start High or Open: stop 20kΩ Typical threshold voltage for VCC = 5V: approx. 2.8V (low to high) 3.8kΩ 3 approx. 2.3V (high to low) Continued on next page. No.6087-5/10 LB1975 Continued from preceding page. Pin No. 4 Pin name F/R Pin voltage 0.0V to VCC Function Equivalent circuit Forward/reverse pin. VCC Low: forward High or Open: reverse 20kΩ Typical threshold voltage for 3.8kΩ VCC = 5V: approx. 2.8V (low to high) 4 approx. 2.3V (high to low) 6 OUT1 Output pin 1. 7 OUT2 Output pin 2. 8 OUT3 Output pin 3. 13 RF 0.0V to VCC VCC 14 Output current detect pin. 6 7 8 Connect resistor Rf between this pin and ground. Output current is limited to value set with VRF/Rf. (Current limiter operation) 200Ω 0.5V 13 14 VM Output block power supply. 11 GND3 Output block ground. 15 GND1 Ground for blocks other than the output 12 GND2 block. 17 FG1 0.0V to VCC Speed pulse output pin 1 with built-in pull-up VCC resistor. 10kΩ 16 17 16 FG2 0.0V to VCC Speed pulse output pin 2 with built-in pull-up resistor. 22 23 20 21 IN1+ IN1IN2+ IN2- 19 IN3+ IN3- 26 OSC 18 1.5V to VCC − 1.5V Hall input pin. IN+ > IN- : High input VCC IN+ < IN- : Low input 18 20 22 1.0V to VCC This pin sets the PWM oscillation frequency. 300Ω 300Ω 19 21 23 VCC Connect a capacitor between this pin and ground. 2V 94μA 200Ω 26 2.1kΩ Continued on next page. No.6087-6/10 LB1975 Continued from preceding page. Pin No. 27 Pin name VCTL Pin voltage 0.0V to 6.7V Function Equivalent circuit Output duty cycle control pin. 31kΩ • VCTL ≤ VCTL1 VCC Duty cycle 0% • VCTL1 < VCTL < VCTL2 Duty cycle is controlled by VCTL • VCTL ≥ VCTL2 Duty cycle 100% 40kΩ 2.35V 24 VCREF 0.0V to VCC − 2.0V VCTL amplifier internal reference voltage pin (2.35V). 27 VCC 100μA 200Ω 24 23.5kΩ 28 VCOUT 0.7V to VCC − 0.7V VCTL amplifier output pin. 28 31kΩ VCC 200Ω No.6087-7/10 LB1975 IC Description 1. Direct PWM Drive The LB1975 employs the direct PWM drive principle. Motor rotation speed is controlled by varying the output duty cycle according to an analog voltage input (VCTL). This eliminates the need to alter the motor power supply voltage. Compared to previous ICs using the PAM principle (such as the LB1690), this allows simplification of the power supply circuitry. The VCTL input can be directly supplied by a microcontroller, motor speed can, therefore, be controlled directly from the microcontroller. For PWM, the source-side output transistors are switched on and off so that the ON duty tracks the VCTL input. The output duty cycle can be controlled over the range of 0% to 100% by the VCTL input. 2. PWM Frequency The PWM oscillator frequency fPWM [Hz] is set by the capacitance C [pF] connected between the OSC pin and GND. The following equation applies: fPWM ≈ 1 / (1.97 × C) × 108 Because output transistor on/off switching is subject to a delay, setting the PWM frequency to a very high value will cause the delay to become noticeable. The PWM frequency therefore should normally be kept below 40kHz (typ.), which is achieved with a capacitance C of 1300pF or higher. For reference, the source-side output transistor switching delay time is about 2μs for ON and about 4μs for OFF. 3. Output Diodes Because the PWM switching operation is carried out by the source-side output transistors, Schottky barrier diodes must be connected between the OUT pins and GND (OUT1 to OUT3). Use diodes with an average forward current rating in the range of 1.0 to 2.0A, in accordance with the motor type and current limiting requirements. If no Schottky barrier diodes are connected externally, or if Schottky barrier diodes with high forward voltage (VF) are used, the internal parasitic diode between OUT and GND becomes active. When this happens, the output logic circuit may malfunction, resulting in feed-through current in the output which can destroy the output transistors. To prevent this possibility, Schottky barrier diodes must be used and dimensioned properly. The larger the VF of the externally connected Schottky barrier diodes, or the hotter the IC is, the more likely are the parasitic diodes between OUT and GND to become active and the more likely is malfunction to occur. The VF of the Schottky barrier diodes must be determined so that output malfunction does not occur also when the IC becomes hot. If malfunction occurs, choose a Schottky barrier diode with lower VF. 4. Protection circuits 4-1. Low voltage protection circuit When the VCC voltage falls below a stipulated level (VLVSD), the low voltage protection circuit cuts off the source-side output transistors to prevent VCC related malfunction. 4-2. Thermal shutdown circuit (overheat protection circuit) When the junction temperature rises above a stipulated value (TSD), the thermal shutdown circuit cuts off the sourceside output transistors to prevent IC damage due to overheating. Design the application heat characteristics so that the protection circuit will not be triggered under normal circumstances. 4-3. Current limiter The current limiter cuts off the source-side output transistors when the output current reaches a preset value (limiter value). This interrupts the source current and thereby limits the output current peak value. By connecting the resistance Rf between the RF pin and ground, the output current can be detected as a voltage. When the RF pin voltage reaches 0.5V (typ.), the current limiter is activated. It performs on/off control of the source-side output transistors, thereby limiting the output current to the value determined by 0.5/Rf. 5. Hall Input Circuit The Hall input circuit is a differential amplifier with a hysteresis of 32mV (typ.). The operation DC level must be within the common-mode input voltage range (1.5V to VCC − 1.5V). To prevent noise and other adverse influences, the input level should be at least 3 times the hysteresis (120 to 16mVp-p). If noise at the Hall input is a problem, a noise-canceling capacitor (about 0.01μF) should be connected across the Hall input IN+ and IN− pins. 6. FG Output Circuit The Hall input signal at IN1, IN2, and IN3 is combined and subject to waveform shaping before being output. The signal at FG1 has the same frequency as the FG1 Hall input, and the signal at FG2 has a frequency that is three times higher. No.6087-8/10 LB1975 7. Start/Stop Control Circuit The start/stop control circuit turns the source-side output transistors OFF (motor stop) when a High signal is input at the S/S pin or when the pin is Open. When a Low signal is input at the S/S pin, the source-side output transistors are turned ON, and the normal operation state is established (motor start). 8. Forward/Reverse Switching The LB1975 is designed under the assumption that forward/reverse switching is not carried out while the motor is running. If switching is carried out while the motor is running, reverse torque braking occurs, leading to a high current flow. If the current limiter is triggered, the source-side output transistors are switched off, and the sink-side output transistors go into the short brake condition. However, because the current limiter of this IC cannot control the current flowing in the sink-side output transistors, these may be destroyed by the short brake current. Therefore F/R switching while the motor is running is permissible only if the output current (IO) is limited to a maximum of 2.5A using the motor coil resistance or other suitable means. F/R switching should be carried out only while a High signal is input to the S/S pin or the pin is Open (stop condition), or while the VCTL pin conforms to the following condition: VCTL≤ VCTL1 (duty cycle 0%). In any other condition, F/R switching will result in feed-through current. The F/R pin should therefore be fixed to Low (forward) or High or Open (reverse) during use. 9. VCC, VM Power Supplies When the power supply voltage (VCC, VM) rises very quickly when a power is first applied, a feed-through current may occur at the output. If the current remains below about 0.2A to 0.3A, it does not pose a problem, but such a possibility should still be prevented by slowing down the voltage rise at power-on. Especially if the F/R pin is set to High or Open (reverse), a quick rise in VCC is likely to cause feed-through current. This should be prevented by ensuring that ΔVCC / Δt = 0.2V/µs or less. Feed-through current can also be prevented by first switching on VCC and then VM during power-on. The sequence at power-down should be as follows. Provide a stop input to the S/S pin or a duty ratio 0% input to the VCTL pin. When the motor has come to a full stop, switch off VM and then VCC. If power is switched off while the motor is still rotating or a current is flowing in the motor coil (including motor restraint or inertia rotation), a counter electromotive current or kickback current may flow on the VM side, depending on the motor type and power-off procedure. If this current cannot be absorbed by the VM power supply or a capacitor, VM voltage may rise and exceed the absolute maximum VM rating for the IC. Ensure that this does not happen through proper design of the VM power supply or through use of a capacitor. Because the LB1975 incorporates a shunt regulator, it can be used on a single power supply. In this case, supply VCC (6.3V typ.) to the VREG pin via an external NPN transistor and resistor. When not using the regulator, leave the VREG pin open. 10. Power Supply Stabilizing Capacitors If the VCC line fluctuates drastically, the low-voltage protection circuit may be activated by mistake, or other malfunctions may occur. The VCC line must therefore be stabilized by connecting a capacitor of at least several μF between VCC and GND. Because a large switching current flows in the VM line, wiring inductance and other factors can lead to VM voltage fluctuations. As the GND line also fluctuates, the VM line must be stabilized by connecting a capacitor of at least several µF between VM and GND, to prevent exceeding VM max or other problems. Especially when long wiring runs (VM, VCC, GND) are used, sufficient capacitance should be provided to ensure power supply stability. 11. VCREF Pin, VCOUT Pin These pins are always used in the Open condition. If chattering occurs in the PWM switching output, connect a capacitor (about 0.1μF) between VCREF and ground or between VCOUT and GND. 12. IC Heat Dissipation Fins A heat sink may be mounted to the heat dissipation fins of this IC, but it may not be connected to GND. The sink should be electrically open. No.6087-9/10 LB1975 13. Sample calculation for internal power dissipation (approximate) The calculation assumes the following parameters: VCC = 5V VM = 30V Source-side output transistor ON duty cycle 80% (PWM control) Output current IO = 1A (RF pin average current) (1) ICC power dissipation P1 P1 = VCC × ICC = 5V × 14mA = 0.07W (2) Output drive current power dissipation P2 P2 = VM × 11mA = 30V × 11mA = 0.33W (3) Source-side output transistor power dissipation P3 P3 = VO(source) × IO × Duty(on) = 0.9V × 1A × 0.8 = 0.72W (4) Sink-side output transistor power dissipation P4 P4 = VO(sink) × IO = 1.1V × 1A = 1.10W (5) Total internal power dissipation P P = P1 + P2 + P3 + P4 = 2.22W 14. IC temperature Rise Measurement Because the chip temperature of the IC cannot be measured directly, measurement according to one of the following procedures should always be carried out. 14-1. Thermocouple measurement A thermocouple element is mounted to the IC heat dissipation fin. This measurement method is easy to implement, but it will be subject to measurement errors if the temperature is not stable. 14-2. Measurement using internal diode characteristics of IC This is the recommended measurement method. It makes use of the parasitic diode incorporated in the IC between FG1 and GND. Set FG1 to High and measure the voltage VF of the parasitic diode to calculate the temperature. (Our company data: for IF = −1mA, VF temperature characteristics are about −2mV/°C) 15. NC Pins Because NC pins are electrically open, they may be used for wiring purpose etc. ON Semiconductor and the ON logo are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of SCILLC’s product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent-Marking.pdf. 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