AN8267S Fan Motor Driver ■ Overview 12 6 11 7 10 8 9 (0.4) 5.5±0.3 7.6±0.3 ■ Application 2.05±0.2 13 5 0.9±0.25 14 4 0.1 0.2 +– 0.05 • (Operable at VCC=6V to 9.6V as well) 2-phase half-wave drive, built-in power transistor Built-in lock protective function and automatic reset function Built-in thermal protective circuit (operating temperature: 150˚C typ.) Built-in rotation display function 15 3 0.1±0.1 • • • 1.27 • Operating supply voltage range ; VCC=9.6 to 27.6V 16 2 0.9±0.25 (0.4) 0.4±0.25 ■ Features 1 10.09±0.3 Unit : mm The AN8267S is an IC to drive the brushless DC fan motors for internally cooling or blowing the air to the office automation equipments and measuring equipmennts. For drive of brush-less DC fan motor 1.16-pin PANAFLAT Plastic Package (SOP016-P-0300) ■ Block Diagram VS 14 IN (–) 1 IN (+) 16 TSD 5 Hall Bias C OUT1 OUT2 12 4 6 10 Lock Protect Automatic Reset – Hall Amp. + TSD VCC 11 VM 8 PGND CTRL Revolution Display 13 2 3 7 9 GND RD1 RD2 B1 B2 ■ Absolute Maximum Ratings (Ta=25˚C) Symbol Rating Supply voltage Parameter VCC 28.8 Supply current ICC 18 IO (peak) 1.5 A I2, I3 10 mA Output current (t=0.1s ) Circuit current (Inflow current) Unit V mA V2, V3, V6, V10 55 Power dissipation PD 735 Note 1) Operating ambient temperature Topr –30 to + 80 ˚C Storage temperature Tstg –55 to + 150 ˚C Circuit voltage (Applied voltage) V mW Note 1) When mounted to the glass epoxy PCB 50 × 50 × 0.8mm ■ Recommended Operating Range (Ta=25˚C) Parameter Symbol Range VCC 9.6V to 27.6V Operating supply voltage range ■ Electrical Characteristics (Ta=25˚C) Parameter Symbol Condition Supply current ICC Hall amp./Common mode input voltage VHI Input current IIH VCC=12V, VHI=2V Hall bias voltage VHB VCC=12V, IHB=–5mA Output saturation voltage VOsat VCC=12V, IO=0.5A Leak current IOleak VCC=12V, VO=55V min typ max VCC=12V, RL=OPEN 17 2 4 Unit mA VCC –2 V 50 µA 5 6 V 0.9 1.4 V 100 µA Bound protection Ct/Charging current Itc VCC=12V, V4=0V –12 –9.5 –7 µA Bound protection Ct/Charging current Itd VCC=12V, V4=4.3V 0.95 1.3 1.65 µA Threshold value voltage (1) VtH VCC=12V, Shut off 3.8 4.1 4.4 V Threshold value voltage (2) VtL VCC=12V, Recovered 0.6 0.95 1.3 V Rotation display/Output leak current IOL3 VCC=12V, VOL=55V 10 µA Output voltage VOL3 VCC=12V, IOL=5mA 0.4 V Rotation display/Output leak current IOL2 VCC=12V, VOL=55V 10 µA Output voltage VOL2 VCC=12V, IOL=5mA 0.4 V ■ Application Circuit VCC + C VCC VS 14 IN (–) 1 IN (+) 16 Hall Bias TSD 13 4 6 OUT1 10 Lock Protect Automatic Reset – Hall Amp. + TSD 5 GND 12 OUT2 11 VM CTRL Revolution Display 8 PGND 2 3 7 9 RD1 RD2 B1 B2 ■ Pins Descriptions Pin No. Symbol Pin No. Symbol 1 IN (–) Hall input (–) 9 B2 2 RD1 Rotation display 1 (pulse output) 10 OUT2 3 RD2 Rotation display 2 (H/L output) 11 VM Counter electromotive absorption 4 C Lock protection automatic reset 12 VCC Supply voltage pin 5 TSD Thermal shutdown 13 GND 6 OUT1 Motor coil output 1 14 VS 7 B1 Output base 1 15 NC P. GND Power ground 16 IN (+) 8 Pin name Pin name Output base 2 Motor coil output 2 Ground pin Hall bias Hall input (+) ■ Supplementary Explanation • Precautions for Using the AN8267S Observe the following in order to use the AN8267S safely and properly. Operating supply voltage range : 9.6V to 27.6V 1. Maximum applied voltage to the coil output Pins6 and 10 When driving the motor, the counter electromotive power of the coil is applied to the coil output Pins6 and 10 when the output transistor is turned off. (Refer to Fig.1) With the AN8267S, see to it that this counter electromotive power will be 55V or less at maximum. Hair-shaped Pulse of Counter Electromotive Power 1) When using the Zener diode Connect the Zener diode between the Pin11 of the AN8267S and the power line. The counter electromotive power which can be suppressed by the Zener diode is V CC –VD +VZ. Since VCCmax.=27.6V;VZmax.= 55V– 27.6V + 0.7V=28.1V Therefore, if you keep VZ at 28V or less, the counter electromotive power will not exceed 55V. 2) When using the capacitor Connect the capacitor between the base and collector of the coil output transistor as shown in Fig.3. Counterflow Preventive Diode Motor Generated Voltage 14 Hall Element 16 55Vmax. 13 Output Transistor OFF ON 14 Hall Element 12 11 Zener Diode 6 1 AN8267S 16 13 4 Fig.2 8 11 6 AN8267S 7 9 10 4 8 OFF Fig.1 Coil Output Waveform (Suppressing the Counter Electromotive Power) To suppress the counter electromotive power by the moter coil to 55V at maximum, do as follows. Counterflow Preventive Diode 12 1 10 Dull a rise Fig.3 A capacitor value is as follows. C : 1,000pF to 10,000pF C : 1000pF—10000pF This capacitor can dull a rise of the counter electromotive power of the coil output. Select the capacitor so that maximum voltage of the counter electromotive power Vmax. will not exceed 55V. ■ Supplementary Explanation (Cont.) 2. Occurrence of radio noises When driving the motor with the AN8267S, radio noises (noises which come out of the radio when the motor is driven near it) may occur. The radio noises are more likely to occur as the counter electromotive power of the coil output pin rises more steeply. So, they can be eliminated by attaching the external part mentioned in 1-2) above. When the lock protective function is being activated, coil current supply/stop intervals are about 1 : 7 in terms of time ratio. Assuming the external capacitor of the Pin4 to be of 1µF, the supply/stop time ratio is about 0.3sec. : 2sec. Lock Protective Function ON/OFF Time Calculation Expression Reference Voltage 1 (V1) Reference Voltage 2 (V2) toff Steep Rise ton Gentle Rise Fig.6 Fig.4 3. AN8267S lock protection When the motor fan is locked, the AN8267S has a function to protect the motor and IC. (lock protection operational principle) If the motor fan is locked, a sine wave signal is not input from the Hall element any more and the potential of the Pin4 external capacitor increases. (Fig.5a) During this period, the IC is still supplying the coil current to rotate the motor fan. Then, if the voltage at the Pin4 reaches the reference voltage 1 set inside the IC, the electric charge in the external capacitor of the Pin4 is discharged constantly, thus reducing the voltage at the Pin4. (Fig.5b) The IC stops supplying the coil current when this constant current discharge starts. If the voltage at the Pin4 reaches the reference voltage 2, the IC starts charging a constant current to the external capacitor of the Pin4 and supplies the coil current again, thus repeating the above-mentioned operation. Assuming the charging current to be Ich and the discharging current to be IDC ; At charge time ; ∫ I ch dt = I chC· ton 1 C V1 –V2 = (V1–V2) ·C I ch ∴t on= At discharge time 1 C V1–V2 = ∫I DC dt = I ch · toff C (V1–V2) ·C IDC ∴t off= Each value (typ.) of the AN8267S is ; V1=4V Ich=9.5µA V2=0.95V IDC=1.3µA When C=1µF ; ton=0.32s C : External capacitor's capacity toff=2.35s Reference Voltage 1 Reference Voltage 2 a b Fig.5 The external capacitor of the Pin4 is always kept in the discharge state by a signal from the Hall element at the time of stationary rotation. 4. Rotation output Pins2 and3 The Pins2 and 3 are of open collector output. The Pin2 is a pulse output pin synchronized with a signal from the Hall element. Therefore, the Pin2 is switched over depending on the polarities of the Hall input Pins1 and 16. 1 16 2 L H H H L L Polarities of Pins2, 1, and 16 ■ Supplementary Explanation (Cont.) The Pin3 is switched over in synchronization with coil current supply/stop. 1. Coil current ON : L 2. Coil current OFF : H 6. Hall input Pins1 and 16 Input a sine wave signal from the Hall element to the Pins1 and 16. The input DC voltage of those pins should be 2Vmin. or more. It is recommended to connect the Hall element and DC bias resistor between the Pins1 and GND. The Hall element sine wave signal Vi to be input to the Pins1 and 16 should be ; 15mVp–p< = Vi < = 400mVp–p The maximum applied voltage for both Pins2 and 3 is 55V. 5. TSD (Thermal Shut Down)Pin5 The AN8267S incorporates the overheat protective circuit. If the chip temperature of the IC reaches 150˚C (typ.), the coil current stops. Since the Pin5 is a TSD circuit operation checking pin, leave it “open” when the motor is driving normally. 14 1 Hall Element AN8267S 16 R : DC Bias Resistor Fig.7 7. Precautions for wiring When mounting the AN8267S onto the PCB, pay attention to the following points as to its wiring. Counterflow Preventive Diode Coil Power Supply IC Power Supply 14 Separate 12 11 6 1 Hall Element 10 AN8267S 16 13 4 8 GND PGND Separate Fig.8 • power line The power pin of the AN8267S is the Pin12. Separate it from the power line to the moter coil. Wiring to the motor coil should be made as thick and short as possible. • GND line The AN8267S has two GND Pins (8 and 13). Since the Pin8 serves as the GND pin for the coil output power transistor, separate from GND of the Pin13 as much as possible. Wiring to the Pin8 should be also as thick and short as possible.