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FAN8420D3
3-Phase BLDC Motor Driver
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-375SG2 28-SSOPH-375
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. -25C ~ +75C -25C ~ +75C FAN8420D3 28-SSOPH-375SG2
FAN8420D3TF 28-SSOPH-375SG2
Rev. 1.0.1 Oct. 2000.
(c)2000 Fairchild Semiconductor International
FAN8420D3
Pin Assignments
FG1X
FG3X
VCC
ECR
CS1
VM
NC
EC
NC 16 13 H3+
28
27
26
25
24
23
22
21
20
19
18
17
15
FAN8420D3
1 NC
2 A3
3 NC
4 A2
5 NC
6 NC
7 A1 FIN(GND)
8 GND
9 H1+
10 H1-
11 H2+
12 H2-
14 H3-
Pin Definitions
Pin Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Pin Name NC A3 NC A2 NC NC A1 GND H1+ H1- H2+ H2- H3+ H3- VH NC PC1 SB FG3X DIR ECR EC I/O O O O I I I I I I I I O O I I No connection Output (A3) No connection Output (A2) No connection No connection Output (A1) Ground Hall signal (H1+) Hall signal (H1-) Hall signal (H2+) Hall signal (H2-) Hall signal (H3+) Hall signal (H3-) Hall bias No connection Phase compensation capacitor Short brake FG waveform (3X) Rotational direction output Output current control reference Output current control voltage Pin Function Description
2
Rev. 1.0.1 Oct.. 2000.
VH
SB
FIN(GND)
PC1
S/S
DIR
FAN8420D3
Pin Definitions (Continued)
Pin Number 23 24 25 26 27 28 Pin Name S/S FG1X VCC NC VM CS1 I/O I O FG waveform (1X) Supply voltage (Signal) No connection Supply voltage (Motor) Output current detection Pin Function Description Power save (Start/Stop switch)
Internal Block Diagram
FG1X VCC ECR CS1 PC1 DIR S/S VM NC NC EC VH 15 14 H3- Hall TSD Upper Distributor Detection Detector Hall amp 12 H2- 13 H3+ SB 18 GND FG3X 19
28
27
26
25
24 FG1X Generator
23
22 - +
21
20
17
16
Start Stop
Reverse rotation
Current sense Amp
Output Current limit
1 NC
2 A3
3 NC
4 A2
5 NC
6 NC
7 A1 GND
Lower Distributor
8 GND
9 H1+
Commutation Selector
Logic
Absolute Values
FG3X Generator 10 H1-
Rev. 1.0.1 Oct. 2000.
H2+
Short Brake 11
3
FAN8420D3
Equivalent Circuits
Hall input Driver output
27 9 50 11 13 1k 1k 50 12 14 10
28
2
4
7
Torque control input
Hall bias input
50 21 50 22 - 100k
+
15
Start / Stop input
Short brake input
50 23
40k 18 30k
50
1k
20k
FG output
VCC VCC
Dir output
10k 50 19 24
30k 50 20
4
Rev. 1.0.1 Oct.. 2000.
FAN8420D3
Absolute Maximum Ratings (Ta = 25C)
Parameter Maximum supply voltage (Signal) Maximum supply voltage (Motor) Power dissipation Maximum output current Operating temperature range Storage temperature range Symbol VCCmax VMmax PD IOmax TOPR TSTG Value 7 15 2.5note 1.3 -25 ~ +75 -55 ~ +150 Unit V V W A C C
NOTE: 1. When mounted on a 76.2mm x 114mm x 1.57mm PCB (Phenolic resin material). 2. Power dissipation reduces 16.6mW/C for using above Ta = 25C 3. Do not exceed PD and SOA (Safe operating area).
Power Dissipation Curve
Pd (mW) 3,000 2,000 SOA 1,000 0
0
25
50
75
100
125
150
175
Ambient temperature, Ta [C]
Recommended Operating Conditions (Ta = 25C)
Parameter Supply voltage Motor supply voltage Symbol VCC VM Min. 4.5 3.0 Typ. 5 12 Max. 5.5 14 Unit V V
Rev. 1.0.1 Oct. 2000.
5
FAN8420D3
Electrical Characteristics
(Unless otherwise specified, Ta=25C, VCC=5V, VM=12V) Parameter Quiescent circuit current 1 Quiescent circuit current 2 START / STOP On voltage range Off voltage range HALL BIAS Hall bias voltage HALL AMP Hall bias current Common-mode input range Minimum input level H1 hysteresis level TORQUE CONTROL Ecr Input voltage range Ec Input voltage range Offset voltage (-) Offset voltage (+) Ec Input current Ecr Input current Input / output gain FG FG output voltage (H) FG output voltage (L) Duty (reference value) OUTPUT BLOCK Saturation voltage (upper TR) Saturation voltage (lower TR) Torque limit current DIRECTION DETECTOR Dir output voltage (H) Dir output voltage (L) SHORT BRAKE On voltage range Off voltage range VSBon VSBoff 2.5 0 VCC 1.0 V V VDIRh VDIRl Ifg=-10A Ifg=10A 4.5 4.7 0.5 V V VOH VOL ITL IO=-300mA IO=300mA RCS=0.5 560 0.9 0.4 700 1.4 0.7 840 V V mA VFGh VFGl Ifg=-10A Ifg=10A 4.5 4.9 50 0.5 V V % ECR EC ECoff- ECoff+ ECin ECRin GEC EC=1.9V EC=1.9V EC=1.9V ECR=1.9V EC=1.9V, RCS=0.5 0.2 0.2 -80 20 -5 -5 0.56 - - -50 50 -0.5 -0.5 0.71 3.3 3.3 -20 80 - - 0.84 V V mV mV A A A/V IHA VHAR VINH VHYS 1.0 60 5 0.5 20 2 4.0 40 A V mVpp mVpp VHB IHB=20mA 0.4 1.0 1.8 V VSSon VSSoff Output driver on Output driver off 2.5 0.0 VCC 1.0 V V Symbol ICC1 ICC2 Conditions At stop mode At start mode Min. Typ. 5 Max. 0.2 10 Unit mA mA
6
Rev. 1.0.1 Oct.. 2000.
FAN8420D3
Electrical Characteristics (Continued)
1. Calculation Of Gain & Torque Limit Current
VM IO VM
Current / Voltage Convertor - Vin EC ECR + - Gm Absolute Values + + + + Vmax - VM R1 -
- VS Output RS Current sense + CS1 (Pin 28)
Negative Feedback loop U V W IO
Driver
Power Transistors
Commutation Distributor H1 H2
H3
Max. output current limiting
0.355 is GM times R1 and is a fixed value within IC.
0.355 Gain = -------------- [ A V ] RS
Vmax (see above block diagram) is set at 350mV.
350 [ mV ] Vmax Itl = --------------- = ----------------------RS RS
Rev. 1.0.1 Oct. 2000.
7
FAN8420D3
Application Information
1. Torque Control & Output Current Control
VM + VM VCS - Current Sense AMP - TSD EC Gain Controller RCS
Torque AMP ECR + - + ECR-EC
IO Driver M
* By amplifying the voltage difference between EC and Ecr from servo IC, the torque sense amp produces the input (VAMP) for the current sense amp. * The output current (IO) 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, EC 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.
Current [mA] 700 500 EcoffEcoff+ Reverse Forward ECR > Ec ECR < Ec Rotation Forward rotation Stop after detecting reverse rotation
6 -50mV 0
0.71[A/V] 50mV ECR -EC
The input range of ECR and EC is 0.2 V ~ 3.3 V ( RNF = 0.5[] )
8
Rev. 1.0.1 Oct.. 2000.
FAN8420D3
2. Short Brake
MOTOR VCC OFF
ON OFF
18
2 1k ON 20k 4 7
Pin # 18 High Low
Short brake On Off
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
MOTOR VCC OFF
23 Start Stop
2 40k OFF 30k 4 7
Pin # 23 High Low
Start/Stop Operate Stop
When power save function is active, all power TRs turn off.
Rev. 1.0.1 Oct. 2000.
9
FAN8420D3
4. Tsd (Thermal Shutdown)
Gain Controller BIAS Q2
When the chip temperature rises above 175C, the Q2 turns on and the output driver shuts down. When the chip temperature falls off to about 150C, then the Q2 turns off and the driver operates normally. TSD has the temperature hysteresis of about 25C.
5. Rotational Direction Detection
VCC
H2+ H2-
+ -
DIR 20 D Q
Rotation Forward Reverse
20
DIR Low High
CK H3+ H3- + - D-F/F
* 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 H1H2H3 with a 120C phase difference.
H1
H2
H3
(a) Reverse rotation
On the other hand, if the spindle rotates in forward rotation, the phase relationship is H3H2H1 as shown in fig.(b)
10
Rev. 1.0.1 Oct.. 2000.
FAN8420D3
H1
H2
H3
(b) Forward rotation Therefore, the output of the rotational direction detector is low, when the spindle rotates forward, and high in the reverse rotation.
6. Reverse Rotation Prevention
EC ECR
+ -
Current Sense Amp
H2+ H2-
+ - A D CK D-F/F Q
Low Active
H3+ H3-
+ -
Gain Controller
Driver
M
* 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. Reverse rotation preventer ECECR Brake and stop
Rotation Forward Reverse
H2 H L
H3 HL HL
D-F/F(Q) H L
Rev. 1.0.1 Oct. 2000.
11
FAN8420D3
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
7. Fg Out
H1- H1+ 24 FG1X H2- H2+ 19 FG3X
H3- H3+
8. Hall Sensor Connection
VCC VCC
HALL 1 HALL 1 HALL 2 HALL 3
HALL 2
HALL 3
15 VH
15 VH
12
Rev. 1.0.1 Oct.. 2000.
FAN8420D3
9. Connect A By-pass Capacitor, 0.1f Between The Supply Voltage Source
Vcc
25 0.1F
(1) the heat radiation fin is connected to the internal gnd of the package. connect that fin to the external gnd.
Rev. 1.0.1 Oct. 2000.
13
FAN8420D3
10. Input-output Timing Chart
H1 +
H2 +
H3 +
A1 output current (H1 -)+(H2 +)
A1 output voltage
A2 output current (H2 -)+(H3 +)
A2 output voltage
A3 output current (H3 -)+(H1 +)
A3 output voltage
14
Rev. 1.0.1 Oct.. 2000.
FAN8420D3
Test Circuits
10A 20mA
14 5V 12V VR1 IM3 A IM2 A 10A 15 VM7 V RCS 0.5 VM6 VR2 VR3
V VM5
13
V VM3
VR5 10A 15
IM1 A
IM2 A VM6 V VM4 0.1F
28 CS1
27 VM
26 NC
25 VCC
24 FG1X
23 SS
22 EC
21 ECR
20 DIR
19 FG3X
18 SB
17 PC1
16 NC
15 VH
FAN8420D3
NC 1 A3 2 NC 3 A2 4 NC 5 NC 6 A1 7 GND 8 H1+ 9 IM4 SW1 VM8 V c b a c b SW2 a V c b SW3 a V A VR8 VR9 A H1- 10 IM5 A H2+ 11 IM6 A H2- 12 IM7 A H3+ 13 IM8 A H3- 14 IM9
VR10 VR11 VR12 VR13
RL=5
RL=5
RL=5
SW13 a b
V
VM1
V VM2
12V 300mA 300mA
Rev. 1.0.1 Oct. 2000.
15
FAN8420D3
Typical Application Circuits
0.5 1 NC CS1 28 27 26 VM (12V)
2 3 4 5 6 7
A3 NC
VM NC
A2 NC NC
VCC FG1X SS
25 VCC (5V) 24 ST 23 SP 22 1.675V
A1
EC
FAN8420D3
8 9 HALL 1 10 H1- FG3X 19 GND ECR 21
H1+
DIR
20
Servo Signal
11 HALL 2 12 13 HALL 3 14
H2+ H2-
SB PC1
18 R2 17 16 0.1F
H3+ H3-
NC VH
15 R1
16
Rev. 1.0.1 Oct.. 2000.
FAN8420D3
Rev. 1.0.1 Oct. 2000.
17
FAN8420D3
DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. LIFE SUPPORT POLICY FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR INTERNATIONAL. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user.
www.fairchildsemi.com 12/1/00 0.0m 001 Stock#DSxxxxxxxx 2000 Fairchild Semiconductor International
2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.

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