FAN8420D3 FAIRCHILD | Alldatasheet
Document overview
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- PDF pages: 18
Technical content
Features
- 3-phase, full-wave, linear BLDC motor driver
- Power save at stop mode
- Built-in current limiter
- Built-in TSD (Thermal shutdown) circuit
- Built-in 3X and 1X hall FG output
- Built-in hall bias circuit
- Built-in rotational direction detector
- Built-in reverse rotation preventer
- Built-in short braker
- Corresponds to 3.3V DSP
Description
The FAN8420D3 is a monolithic IC, suitable for a 3-phase spindle motor driver of a CD-media system. 28-SSOPH-375 28-SSOPH-375SG2 Typical Applications
- Compact disk ROM (CD-ROM) spindle motor
- Compact disk RW (CD-RW) spindle motor
- Digital video disk ROM (DVD-ROM) spindle motor
- Digital video disk RAM (DVD-RAM) spindle motor
- Digital video disk Player (DVDP) spindle motor
- Other compact disk media spindle motor
- Other 3-phase BLDC motor
Ordering Information
Device Package Operating Temp. FAN8420D3 28-SSOPH-375SG2 −25°C ~ +75°C FAN8420D3TF 28-SSOPH-375SG2 −25°C ~ +75°C FAN8420D3 3-Phase BLDC Motor Driver
2 Rev. 1.0.1 Oct.. 2000. Pin Assignments Pin Definitions Pin Number Pin Name I/O Pin Function Description
1 NC - No connection
2 A3 O Output (A3)
3 NC - No connection
4 A2 O Output (A2)
5 NC - No connection
6 NC - No connection
7 A1 O Output (A1)
8 GND - Ground
9 H1+ I Hall signal (H1+)
10 H1 − I Hall signal (H1 −)
11 H2+ I Hall signal (H2+)
12 H2 − I Hall signal (H2 −)
13 H3+ I Hall signal (H3+)
14 H3 − I Hall signal (H3 −)
15 VH I Hall bias
16 NC - No connection
17 PC1 - Phase compensation capacitor
18 SB I Short brake
19 FG3X O FG waveform (3X)
20 DIR O Rotational direction output
21 ECR I Output current control reference
22 EC I Output current control voltage
1 2 3 4 5 6 7 8 9 10 11 12 13 14 1516171819202122232425262728 FAN8420D3 NC NC NC NC GND H1+ H1− H2+ H2− H3+ H3− CS1 VM NC VCC S/S EC FG1X ECR DIR FG3X SB PC1 NC VH FIN(GND) FIN(GND)
3Rev. 1.0.1 Oct. 2000. Pin Definitions (Continued) Internal Block Diagram Pin Number Pin Name I/O Pin Function Description
23 S/S I Power save (Start/Stop switch)
24 FG1X O FG waveform (1X)
25 VCC - Supply voltage (Signal)
26 NC - No connection
27 VM - Supply voltage (Motor)
28 CS1 - Output current detection
1 2 3 4 5 6 7 8 9 1 01 11 21 31 4 1516171819202122232425262728 FG1X Generator Start Stop Short Brake Reverse rotation Commutation Selector Detector Detection Upper Distributor Lower Distributor Hall amp TSD Hall Absolute Values Current sense Amp Output Current limit NC NC NC NC GND H1+ H1− H2+ H2− H3+ H3− VH NC SB PC1 FG3X DIR ECR EC S/S FG1X VCC NC VM CS1 Logic Generator FG3X GND GND
4 Rev. 1.0.1 Oct.. 2000. Equivalent Circuits Hall input Driver output Torque control input Hall bias input Start / Stop input Short brake input FG output Dir output 1kΩ 1kΩ50Ω 50Ω 4 7 50Ω 50Ω 100kΩ 40kΩ 30kΩ 50Ω 1kΩ 20kΩ 50Ω 10kΩ VCC 50Ω 30kΩ VCC 50Ω
5Rev. 1.0.1 Oct. 2000. Absolute Maximum Ratings (Ta = 25°°°°C) NOTE: 1. When mounted on a 76.2mm × 114mm × 1.57mm PCB (Phenolic resin material). 2. Power dissipation reduces 16.6mW/ °°°°C for using above Ta = 25°°°°C 3. Do not exceed P D and SOA (Safe operating area). Power Dissipation Curve Recommended Operating Conditions (Ta = 25°°°°C) Parameter Symbol Value Unit Maximum supply voltage (Signal) V CCmax 7V Maximum supply voltage (Motor) V Mmax 15 V Power dissipation P D 2.5note W Maximum output current I Omax 1.3 A Operating temperature range T OPR −25 ~ +75 °C Storage temperature range T STG −55 ~ +150 °C Parameter Symbol Min. Typ. Max. Unit Supply voltage V CC 4 . 555 . 5 V Motor supply voltage V M 3.0 12 14 V 3,000 2,000 1,000 0 25 50 75 100 125 150 175 Pd (mW) Ambient temperature, Ta [°C] SOA
6 Rev. 1.0.1 Oct.. 2000.
Electrical Characteristics
(Unless otherwise specified, Ta=25°C, VCC=5V , VM=12V) Parameter Symbol Conditions Min. Typ. Max. Unit Quiescent circuit current 1 I CC1 At stop mode - - 0.2 mA Quiescent circuit current 2 I CC2 At start mode - 5 10 mA START / STOP On voltage range V SSon Output driver on 2.5 - V CC V Off voltage range V SSoff Output driver off 0.0 - 1.0 V HALL BIAS Hall bias voltage V HB IHB=20mA 0.4 1.0 1.8 V HALL AMP Hall bias current I HA -- 0 . 5 2 µA Common-mode input range V HAR - 1.0 - 4.0 V Minimum input level V INH -6 0 - - m V p p H1 hysteresis level V HYS - 5 20 40 mVpp TORQUE CONTROL Ecr Input voltage range E CR -0 . 2 − 3.3 V Ec Input voltage range E C -0 . 2 − 3.3 V Offset voltage (−)E Coff− EC=1.9V −80 −50 −20 mV Offset voltage (+) E Coff+ EC= 1 . 9 V 2 05 08 0 m V Ec Input current E Cin EC=1.9V -5 -0.5 −µ A Ecr Input current E CRin ECR=1.9V -5 -0.5 −µ A FG FG output voltage (H) V FGh Ifg=-10µA4 . 5 4 . 9 - V FG output voltage (L) V FGl Ifg=10µA- - 0 . 5 V Duty (reference value) - - 50 - % OUTPUT BLOCK Saturation voltage (upper TR) V OH IO=−300mA - 0.9 1.4 V Saturation voltage (lower TR) V OL IO=300mA - 0.4 0.7 V Torque limit current I TL RCS=0.5Ω 560 700 840 mA DIRECTION DETECTOR Dir output voltage (H) V DIRh Ifg=-10µA4 . 5 4 . 7 - V Dir output voltage (L) V DIRl Ifg=10µA- - 0 . 5 V SHORT BRAKE On voltage range V SBon -2 . 5 - V CC V Off voltage range V SBoff -0 - 1 . 0 V
7Rev. 1.0.1 Oct. 2000. Electrical Characteristics (Continued) 1. Calculation Of Gain & Torque Limit Current 0.355 is GM times R1 and is a fixed value within IC. Vmax (see above block diagram) is set at 350mV . EC ECR Gm Absolute Values Current / Voltage Convertor R1Vin Driver VM Vmax Max. output current limiting VM VM Negative Feedback loop IO RS VS CS1 (Pin 28) Output Current sense Power Transistors Commutation Distributor U V W H1 H2 H3 IO Gain 0.355 RS Itl Vmax RS RS
8 Rev. 1.0.1 Oct.. 2000.
Application Information
- Torque Control & Output Current Control
- By amplifying the voltage difference between E C and Ecr from servo IC, the torque sense amp produces the input (VAMP) for the current sense amp.
- The output current (I O) is converted into the voltage (VCS) through the sense resistor (RCS) and compared with the VAMP. By the negative feedback loop, the sensed output voltage, VCS is equal to the input VAMP. Therefore, the output current (IO) is linearly controlled by the input VAMP.
- As a result, the signals, E C and ECR can control the velocity of the Motor by controlling the output current (IO) of the driver.
- The range of the torque voltage is as shown below. Torque AMP EC ECR VM ECR-EC Current Sense AMP TSD Gain Controller Driver M RCSVCS IO VM Forward Ecoff+Ecoff- Reverse Current [mA]
0 ECR -EC
ECR > Ec Forward rotation ECR < Ec Stop after detecting re- verse rotation The input range of ECR and EC is 0.2 V ~ 3.3 V ( RNF = 0.5[Ω ] ) 500 700 50mV-50mV 0.71[A/V]
9Rev. 1.0.1 Oct. 2000. 2. Short Brake When the pick-up mechanism moves from the inner to the outer spindle of the CD, the brake function of the reverse voltage is commonly employed to decrease the rotating velocity of the spindle Motor. However, if the spindle motor rotates rapidly, the brake function of the reverse voltage may produce more heat at the Drive IC. To remove this shortcoming and to enhance the braking efficiency, the short brake function is added to FAN8420D3. When the short brake function is active, all upper power TRs turn off and all lower power TRs turn on, and the motor slows down. But FG and DIR functions continue to operate normally. 3. Power Save When power save function is active, all power TRs turn off. Pin # 18 Short brake High On Low Off Pin # 23 Start/Stop High Operate Low Stop VCC ON OFF 20kΩ 1kΩ MOTOR OFF ON Start Stop VCC 30kΩ 40kΩ MOTOR OFF OFF
10 Rev. 1.0.1 Oct.. 2000. 4. Tsd (Thermal Shutdown) When the chip temperature rises above 175°C, the Q2 turns on and the output driver shuts down. When the chip temperature falls off to about 150°C, then the Q2 turns off and the driver operates normally. TSD has the temperature hysteresis of about 25°C. 5. Rotational Direction Detection
- The forward and the reverse rotations of the CD are detected by the D-F/F and the truth table is shown in the above.
- The rotational direction of the CD can be explained by the output waveforms of the Hall sensors. The three outputs of Hall sensors be H1, H2 and H3 respectively. When the spindle rotates in reverse direction, the Hall sensor output waveforms are shown in Fig.(a). The phases order are in H1→ H2→ H3 with a 120°C phase difference. On the other hand, if the spindle rotates in forward rotation, the phase relationship is H3→ H2→ H1 as shown in fig.(b) Gain Controller BIAS VCC DIR D-F/F D Q CK H2+ H3+ H3− H2− Rotation DIR Forward Low Reverse High (a) Reverse rotation
11Rev. 1.0.1 Oct. 2000. Therefore, the output of the rotational direction detector is low, when the spindle rotates forward, and high in the reverse rota- tion. 6. Reverse Rotation Prevention
- When the output of the OR Gate, A is LOW, it steers all the output current of the current sense Amp to the Gain Controller zero. The output current of the Driver becomes zero and the motor stops.
- As in the state of the forward rotation, the D-F/F output, Q is HIGH and the motor rotates normally. At this state, if the control input is changed such that EC>ECR, then the motor rotates slowly by the reverse commutation in the Driver. When the motor rotates in reverse direction, the D-F/F output becomes Low and the OR Gate output, becomes LOW. This prevents the motor from rotating in reverse direction. The operation principle is shown in the table and the flow chart. Rotation H2 H3 D-F/F(Q) Reverse rotation preventer E C<ECR EC>ECR Forward H H →→→→ LH F o r w a r d - Reverse L H →→→→ L L - Brake and stop (b) Forward rotation Current Sense Amp Gain Controller DriverD-F/F M D Q CK H3+ H3− H2+ H2− EC ECR A Low Active
12 Rev. 1.0.1 Oct.. 2000. 7. Fg Out 8. Hall Sensor Connection Forward rotation at EC < ECR Rotating speed is decreased due to reverse torque at EC >ECR. (Motor still rotates forward) At the moment that the motor rotates in reverse, the reverse rotation preventer makes the output power transistor open. Rotating reverse at short time due to motor inertia Stop within 1/6 turn reverse rotating H1− H1+ H2− H2+ H3− H3+ FG1X FG3X VCC HALL 1 HALL 2 HALL 3 15 VH VCC HALL 1 HALL 2 HALL 3 15 VH
13Rev. 1.0.1 Oct. 2000. 9. Connect A By-pass Capacitor, 0.1µµµµf Between The Supply Voltage Source (1) the heat radiation fin is connected to the internal gnd of the package. connect that fin to the external gnd. 25Vcc 0.1µF
14 Rev. 1.0.1 Oct.. 2000. 10. Input-output Timing Chart H1 + H2 + H3 + A1 output current (H1 −)+(H2 +) A3 output current (H3 −)+(H1 +) A3 output voltage A2 output voltage A2 output current (H2 −)+(H3 +) A1 output voltage
15Rev. 1.0.1 Oct. 2000. Test Circuits 123456 78 9 1 0 1 1 1 2 1 3 1 4 1516171819202122232425262728 FAN8420D3 V V VVV A A A A A A A A A A V V 12V IM3 VM7 RCS 0.5Ω IM2 VR1 10µA VM6 VR2 IM1 VR3 IM2 VR5 0.1µF VM4 10µA
14 VM5
13 VM3
a b c SW2 a b c SW1 a b cVM8 VR8 RL=5ΩRL=5ΩRL=5Ω SW13 a b VM1 12V 300mA VM2 300mA V 10µA VM6 NC A3 NC A2 NC NC A1 GND H1+ H1 − H2+ H2 − H3+ H3 − VHNCPC1SBFG3XDIRECRECSSFG1XVCC NCVMCS1 V
16 Rev. 1.0.1 Oct.. 2000. Typical Application Circuits HALL 1 HALL 3 Servo Signal ST HALL 2 1.675V SP VCC (5V) VM (12V) FAN8420D3 0.5Ω 0.1µF NC NC NC NC GND H1+ H1− H2+ H2− H3+ H3− CS1 VM NC VCC FG1X SS EC ECR DIR FG3X SB PC1 NC VH
17Rev. 1.0.1 Oct. 2000.
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