AN8420FBP | DigiCamel IC Datasheet

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AN8420FBP (Under development) Spindle/Voice Coil Motor Drive IC @ Overview Wan mm The AN8&420FBP is an IC for the voice coil motor and Es the spindle motor drive of the hard disk drivesystem 7 EEEEEELERELER (HDD) . “SS io For the spindle motor drive, the acoustic noise level of | = 33 the spindle motor can be greatly improved by the sensor- a E43 ag The voice coil motor drive consists of the power amp. = ff, 5 circuits. Also, the AN8420FBP incorporates the auto- =| | =] retraction circuit which uses the B-EMF of the spindle SL EB. is optimum composition for HDD. = ™ $i] +£0.30

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i Features + Mt |: + Wide operating supply voltage range : The 5V and 12V III toa) sq 3 a systems supported 1492030 ‘yl q + Start circuit supported by the extemal clock input of spindle 1728000 3 * Spindle sensor-less function built-in 48-pim QEP Package (QFHOS4-P-1444) + Spindie snubber capacitor-less type supported + Small VCM cross-over distortion + Reduced voltage detection circuit built-in « Auto-retraction current adjustable by extemal resistor Panasonic 637

@ Block Diagram : $5344406566555454 ft TEL retouri (31) ' ro nearleliets Soo , ae | ier prs. we, | aL LT tl moe HT [Mle eat fo me] SR Lea O-@-@) ces 544 (=) eel oe ee

68 Panasonic

@ Absolute Maximum Ratings (Ta=25°C) Supply current ee ee Supply vokeage 2 ee v Spindle motor max. outpat current ee ee A Voice coil motor output voltage | Voww [Ot v Voice coil motor peak output current ee ee A Voice coil motor max. output current A Reason max. opt caren a SV VREF max. output current a a ee 7 Interface input volage v Ve © MON, Vessto MON iepatvolage | Va | 03 Vee¥03__—~+| Power disipaten a @ Recommended Operating Range (Ta=25C) ‘ Parameter Range Operating supply voltage | | Van 45V w SSV Operating supply voltage 2 | Vas 10.2V tw 13.8V @ Electrical Characteristics (Voc: =5V, Vor: 12V, Vs=12V, Ta=25+2U) Parameter |_Symbol_ | __Condition | min [typ [max T Unit Sleep Mode Tees supply current | hawt | Va=Veo“aev | — | — Tos] ma a Enable Mode swe f= fi [=] [= Va =0.8V inert ae Ves=0.8V oom ee el Vea™08V kere ae Panasonic 639

ll Electrical Characteristics (cont.) (Voci=5V, Voc2=12V, Vs=12V, Ta=25+2T) SP-D Block B-EMF Detection System ~ commewmewme Tet | [a ee Detection seastvity evel [ve | —*i| | | 2/ av B-EMF detection resistance | pom [oT to oof ko B-EMF detection R2 [ % | | 29] s8{ a7] xo BMF deccienviching toraboké lage (High) | Vaso [| | | | tes BEM denctonwichng tesbldwohage (Low) | Ve [| | | ST oo] _ Logic Block : U2, V2, W2 Terminal : an oe Lada [te | Either min [88 [10 | —2s | oa Lee ee el el or Go See boos ee — a sc ee Sink/source(delta current pt | atten tto —| 2 | — | 3s] nv Sink curent U2, V2,W2relativeeror | Mls | | 20] — | 201 wr Source cureat U2,V2,W2retiveenor | dio | sd 2.00] — | 20] pa EA Block Open loop gain | Aso [f=iKHz | ss] — | Input bias current pote 10 | 20 Tt Varn reference voltage |v [Ts Toast o27f iv Veer: oatpat impedance [Zam | w= tims | — | — wot

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@ Electrical Characteristics (cont.) (Voc: =5V, Voro= 12V, Vs=12V, Ta=25+2T) Parameter | Symbol [Condition min | typ | max | Unit Drive Output System i, louer= —0,1A cocnmannen ne | we [ee [=] ef] cremains ven [Rea || [| Coram Ytre)| sion | McetNevery | — | | =| . Tog —1A cena | von [RA mew [= | o@] |v Ouipot sation valuge (VarLower) | Van | lan=01A S| — | os — | Vv Ouiput saturation voluge (VearLower) | Van | lur=iA «dt | oas| — |v Toul oupetsauration votage | Vrouw | Vmu=VentVan | — | ass[ ial v Total ovipet saturation volinge 2 | Vrax_| Viou=Van¥Vun | — | tas 20| Vv Outpt leak carent [ke [Pci=ov S| | — | 10] ma Drive gain [|G [Romin os | 037] om | vv Current limiter voltage | Va [Ra=in | oa] 027 os iv pevnmanmetsne | w [tect | fae] fv Power-On Time Short Brake Block Saturation vokage (Veer Lower) | Vous [lor=100mA_—=—=S«d| | 005] as] Vv intertace Input Block CE Terminal rath oe ee el Input low voltage [ove [oof ~ T ~ Tv fits for Input high curene [we | Varaav «| is | =a om | xa [Motor Input low corer [ka | voraav «| 00-190] — | pA VCMENB, VCMCH, BRST, SELECT, PC Terminals Input high voltage ee ee es ee Taput low voltage a ee ee Input high cue a 8 ed Tepet on cocrat [uw [ww S| 2, — | 2] oa Intertace Output Block FG, POR, PWRGOOD Output high voltage [vw [u=-osma 30] 4az[ — Tv Ourput low volage | vo [is=-osma | — [oo] os] iv Monitor Block MON referee valloge a ‘Monitor Block : Vco-MON Threshold volage [Vows | ——~«bo as] igo] Hysteresis voltage | Pov [oT wo Ts Tv Monitor Block : Voce-MON Treaboldwoltage 2 re Hysteresis vohage 2 [veo | to so

@ Electrical Characteristics (cont.) (Vcci=5V, Voco=12V, Vs=12V, Ta=25+2T) Parameter [symbot_[ ___Condison | min] yp | max | Ua Monitor Block: Delay __ POR delay output time C=0.14F | 20[ — J] so] ms VecrMON=1.5V POR delay output current | tore | Voor =0.7V [wal = | ae! A Retraction Block Vocr-MON=1V Reference Voltage Block SVVazr reference voltage [Vow fo ee TST sav Via cut ipa i VCM Block Ven. Vaan Pos — ee Common-modeinput voltage range | Vso Jo | — | — | ~ | = Drive Output System . a Vvoucn=0.8V VA transmission gain 2 am2 | 3SToa 0275 | AV Nosigndimeauptvelage | Va | ————SS*dYS«S ws] Drive Output System Output saturation voltage (Waar Upper) [Vaan | lour=200mA | — [oas | — [Ov Output saturation voltage (Vsar Upper) | Vaare | lour=700ma_ | — || — |v Output saturation voltage (Vsqr Upper) | Vsars ee vom iv | — | os] — | v up swan valage Var Upped | Vans [lour=200mA =P | oa |v Oupat saratonvoage (Vans Upper) | Vous | bur=700na Si | os | — | ¥ el Output bias current Peo M@™ 6932652 001293b TT?

642 Panasonic

W@ Electrical Characteristics (cont.) (Voci=5V, Veco= 12V, Vs=12V, Ta=25+2T) Parameter |_symbot_ | Condition | min | typ | max | Unit OP1, OP2 Input bias current [tie PO 100 | Tt Tn Input offset voltage [Veo [oo =o — Tov Open loop gain [Gop [reiki Twos | — Gain band width | Bop | Gop=oup | to | 00 | — te OPT cuputiow voige [Van [toma | | | OP? output low voltage [Voge [touw=tma To Tos Tv Wi Electrical Characteristics (Design Reference Values) (Ta=25+2T) The following values are design reference values but not guaranteed ones. SPD Block EA Block ind wilt rue a Thermal Protection Circuit Themal potesionoperionempeatwe | Te [Sid SSC Cid SC Hysteresis temperature Pow ts VCM Block Tour=0.1Ams, Ri=1050 Ks for Output distortion ratio 1 Vvemen=2.0V, Rs=20 % £=500Hz Yogee B20” | os | ji i i vi =0.8V, Rs=20 % Output distortion ratio 2 f= 500H2 M@™ 6932452 0012937 9359 a Panasonic 643

1 Pin Function Descriptions

Tate | Pinnane [Terminal tcipaon | Fancion T [PG [Power ground] round teal for power lek

2 Displays he “High” of PYRFGOOD opt ad FOR ua

4 Monitors the voltage whichis resistance-divided from the supply voltage of Von. 5 Outputs the reference voltage ofthe Vcci and Vecx power supply monitor circuit. 6 ‘Connects the SV system power supply with power supply input of control block. 7 Quiputs the reference voltage of speed control block. terminal reference voltage output is 1/2Vecr. 3 [S| Sigua ground Ground ein for signal lok 9 ut making the ped con

10 Taps the speed ono sigal

15 U2, V2 and W2 generate the slope wave for synthesizing the

terminal (2) trapezoidal wave.

16 U2, V2 and W2 generate the slope wave for synthesizing the

23 Terminal outputting the reference voltage of SV

23_[_W___| Wats ave ouput | Drives th W.phase of PD. 26 Monitors the voltage which is resistance-divided from the supply voltage of Voc. 2 Drives the V-phase of SPD. B Drives the U-Phae of SPD, =| PG [Powerground | Ground ein or power Dod 34 Detects the current flowing in the motor to limit the max. current. 35 Detects the current flowing in the motor to limit the max. current. 36 [VIN | Vpte EMF deson erin _| Revs he EMF input of Ure 37_[__VIN_[ V-phase B_EMF detection terminal _| Receives the B_EMF input of V-phase. 38 Receives the B_EMF input of W-phase. 2 [COM [Nena pun inptteminal | aps the nowrap volag of ine mo 40 ‘When Vec2 is sufficiently high voltage, the surplus voltage is applied terminal_ (SPD) to_Vce of the source side output transistor.

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@ Pin Function Descriptions (cont.) Tate | Pinmane | Teoma desripion | Fain 41 Power supply terminal to make up the reference voltage of SV Veer. 2 Inputs the reference volage.

3 Tp econo vohag

“ Desc th cure owing ti VOM, 45 Connected to the 12V sytem power supply throagh the power supply input of power block (VCM).

46 Wid teeminal Sor VCM

47~50| PG [Powerground __—_——_| Ground terminal for the power block ai Reraon oat

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53 Connects the current detection resistor between OUTI and RS. 54 Connects the load coil between QUT? and RS. 55 [RET [Rector noir otgeal_| Monts te eaon vote s1_| oR _[rosariyemronuimin? | apntneabe vege ny nese 58 Normal-phase input terminal for operational amp. 39 Reverse-phase input terminal for operational amp. 60 Ouipat terminal for operational amp. 61 Output terminal for operational amp. 62 | OP2IN | Operaionaanp 2revese-phseinutteminal_| Reverse-phase input terminal for operational amp. 63_| OP2IP __| Operaionalamp.lnomal-phae ipulernina | Normal-phase input terminal for operational amp. & Ground ein fo power bok @™ 6932852 0022939 701 ml Panasonic 645

1 Board for Evaluation (1)

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@ External Parts Pin No. Recommended value RI For LVD RI=12k0 R2 R2=68k0. R3 For speed control — RS For LVD R5=12kQ R6 R6=4.7k0 RT SPD common filter 3300 Rs = (0270) RO For power dissipation — (0330) R10 For stability RIO=510. RU RU=100 R2_| Sawmcemet SSC) RI3 VCM current sensing — (1.00) RI4 RIS For stability — = (220) R16 RIT = _(1200) a2sma R18 Protection resister 10kQ. RI9 cl For POR delay — __1pF) a 0048 fez) For speed control = ey cs Control amp phase compensation 0.22 uF ca ‘Trapezoidal waveform shaping — (0.022 yF) ca cof Fier 001 cio 008 uF ci SPD common filter 0.22 uF C12 C13 B_EMF filter — — (0.033 x) ci4 cis For stability 0.22 pF C16 cig ci9 For stability = (0.22nF) C20 C21 C22 Power supply by-passing = _ (0.001 F) ee MB 6932452 0012941 3bT ml ' Panasonic 647 Te

ll Board for Evaluation (2) [|< 4 ——O)2)-O-OOMOOOMOMOOOO® ete aA ee ! elf] DEP Se pe ale Fs ie eee Ts teal th ale Riga core | eel fs} -] RS IE ree ley Z oe d ES Vira fh Seer eeerees

@ External Parts Pin No, Recommended value RI For LVD RI=12kQ R2 R2=68k2. R3 = RS For LVD RS=12kN R6 R6=4.7k0 R7 SPD common filter 3300 BE =~ ama) RS x0) RIO For stability RIO=S10 Ru RU=100 Ria = Gon) RB VCM current sensing — (19a) Rid RIS For stability — (2a) R16 CI For POR delay = Opry [Fier ow c Control amp phase compensation 0.22 uF [oy 6 Trapezoidal waveform shaping — — (0.022 F) fel 3 0088 C10 SPD common filter 0.22 nF cil C12 B_EMF filter — (0.033 .) = For stabili 0.22 uF GS for wr stability . ci6 Power supply by-passing 20.1 pF ci7 Cis c19 For stability — — (022yF) C20 M@ 6932852 0012943 132 Panasonic 649

I Sensor-less Drive Block Application 1. Drive Principle for sensor-less IC (AN8420) ‘The drive circuit of the sensor-less motor detects the B—EMF which is generated in the motor coil and operates the circuit by using it as the rotor position signal. ‘The AN8420 consists of the three-phase full-wave drive circuit. -AN8420SPD — | om | Torque control Spec tepatcnt — [-—~] vee [TT ‘External clock ob Sta ere iS B-EMF oie ; = Pan In order to start driving the sensor-less spindle motor for fixed commutation number, it excites the coil by force, timing with the internal OSC in the start circuit. This is called start mode. In the start mode, the excitation is started in the fixed sequence, independent on the position of stator and rotor magnets. It may move slightly to reverse direction in some position, however, it should follow the normal direction sequence in view of the circuit. In the start mode, electromotive force (B—EMF) is generated in the coil. The detection circuit detects this electromag- netic force (B— EMF) and the logical control receives input of that force to start the output circuit. This is called the detection mode. Adsorption of head on disk which requires large start torque of the motor can be reduced through harmonics excitation of the coil by the external clock. @@ £932852 0012944 075

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——— * Setting the commutation frequency in SPD start mode (1) QSC1 (Triangular wave oscillation terminal) ‘OSC! is an oscillation terminal which sets the commutation frequency at operation start. The commutation frequency at operation start is expressed by the following formula : fem = feel = & x~ Xe x Vip XlrXK where : femf : Commutation frequency C : Extemal capacitance foscl ‘ triangularwave oscillation ““"* Vre : Reference voltage inside IC (approx. 2.5V) Icy: Reference voltage inside IC (approx. 20 A) osc K__: Dispersion factor ce | Spulses { i High een “i oneness : Fo aS M@@ 6932852 0012945 94] 652

_—$. «Filter for B—EMF detection and noise rejection (2) UIN, VIN and WIN (U-, V- and W-phase B—EMF detection terminals) + In order to reject the noise such as of electromotive force which is generated from the motor, the capacitor for filter is connected. ‘* When the constant of the capacitor for filter is set too large, the optimum energization timing during the rated rotation of spindle motor is missed, and the consumption current during the rated rotation of spindle motor is increased. Therefore, the constant should be set, taking into consideration the relationship with the spindle motor. The phase deviation from the optimum energization timing during the rated rotation due to improperly set CR time constant, 4 can be given in the following simple calculation : NXP PSCARX GOT *360 (DEC) N : Rated rotation number (rpm) P : Motor pole number CC : Time constant of B—EMF detection filter R ; Time constant of B—EMF detection filter (built in IC) * Automatic switching of B—EMF detection resistor with speed increased Fig. 1 shows the B~EMF detection block. ‘The B—EMF detection terminal of U-, V- and W-phase is connected with the drive output terminal of U-, V- and W-phase through the resistor (R1=20k, typ.) As shown in Fig.l, the resistor (R2=8kO, typ.) is connected with R1 in parallel by the trapezoidal wave maximum output. Fig.2 illustrates the automatic switching by the MON1 of B—EMF detection. ‘When the speed of spindle motor is increased, the MONI, the maximum output of trapezoidal wave of U2, V2 and W2. is de- creased, corresponding to the rotation number of spindle motor. The auto-switching function for B~EMF detection resistance is provided in order not to increase the consumption current dur- ing the rated rotation when the time constant of the B—EMF detection filter should be set large because of desired spindle motor start. When the speed of spindle motor is increased, the voltage of MONI, the maximum value of trapezoidal wave is decreased. Then, when the maximum value of trapezoidal wave reaches 0.9 V, the resistor which is connected between the B—EMF detec- tion terminal of U-, V- and W-phase and the drive output terminal of U-, V- and W-phase, is switched to the value : R= RUR2=20k0/BkA Sapprox. 5.7k. s When the B—EMF detection resistor switching function by the MONI, the maximum value of trapezoidal wave is not used, JMO the MON] terminal should be connected to the GND or MON terminal. The COMMON filter should be used when the voltage applied to the COM terminal exceeds the input voltage range. Me 6932852 0022947 685 a Panasonic 653

B—EMF Detection Block Diagram [ae | | UN MminG <7 C) connow o C) iwosy i —) i Energization phase switching logic slope production i lI v2 Ramo Fig.1 @® = £932452 0012948 714

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+ Auto-switching by MON1 of B—EMF detection Fig.2 illustrates the motor rotation number N and FG proportional to the motor rotation number when the speed of spindle motor is increased ; the voltage waveform of MONI, the trapezoidal wave maximum value ; and switching of resistance R built-in the IC of B—EMF detection filter. Image illustration of motor rotation number N and FG FG, N (802) 1200¢pM frre i | | When 8-pole Hl 1 motor is used C1 Hl i (3082). 450qpM fen : : i MONI i Image illustration of the voltage! | i ‘waveform of trapezoidal wave i : maximum value, MONI i : Approx. 24V [css ' i : H | Approx. 1.5V threshold level | i | When capacitor of U2, V2 0 1 i T R i i Switching of the resistor built-in i i IC of B—EMF detection filter i i R1520kQ. i RUR2*5.7K 0 T Fig.2 a So6932852 00120949 650 655

(3) Trapezoidal wave shaping terminal (Capacitor of U2, V2 and W2) Its set constant is related with the number of poles of three-phase motor, as shown in the following : Ex) When the motor with 8 poles is used 2 CC: Capacitance value of capacitor of U2, V2 and W2 Q=cv=it V : DC voltage (200 to 400mV) i ¢ Constant current (10 2A) t 1 FG (three-phase pole) cycle X 1/6 FG frequency under 3600 rpm of three-phase 8-pole motor > = 3600rpm_ ,, B-pole FO= “Gosec <2 =240Hz a T= re 54.1 7sec t= ZX T695 psec Q=it=10 pA X 695 psec6.95 X 10-* (q) Setting V=316mV (DC=200mV to 400mV) , — it _ 695x10~ C= = Bieta 70-022 uF ‘Therefore, when it is used under the rated rotation number of 3600rpm jn case of three-phase 8 poles motor, the capacitance value of capacitor of U2, V2 and W2 is 0.22 F. When a motor with 4, 6 or 12 poles is used, follow the above example to review the constant. (4) Drive Amp. The AN8420FBP is an IC of current drive type. The motor drive current I, is determined by the voltage of OUT terminal, as shown in Fig.3. vS=Ves See Vref our Fig.3 Drive Characteristics @™§ 6932852 0012950 372 ——

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\\Cs for Motor AN8420FBP Is forMotor AN 20F BP (7) Servo circuit The following shows an example of the servo circuit using the PWM input > (Ex.1) (In case of speed control for IN1H with DC voltage) C)} O VREF | 4 1/2Vecl <— en. a oo O Pw input (Ex. 2) (Incase of variable servo system gain) vee C) O < O ICs for <q IMotor Fig.4 2852 02953 209 MM 657

+ VCM operation description (8) Relationship among Ven. (control voltage), Vrer2 (reference voltage) and output voltage The following shows the relationship among Ver, ‘Vrer2 and output voltage Ves! : Ven (i) When VCMCH=High, C) asl = Ven. ~ Vesr2 > Veer as ver= Tae O On++ VCMCH — Vesl a= et OC [o> OO Fig.5 (9) Image illustration of the input and output DC characteristics Fig.6 is the input and output characteristic chart, under the following condition ; Voc=12V, Rs=20, VCM (RL) =150 em=0.5 (A/V). The current flowing in the VCM when re | Vor. —Vaer | =1.25V : IL625mA bv 1 225 33__De (v) ‘Vu terminals should be used when large load of power 10 i \\oure | i ¢ dissipation is applied to the package. i i | Refer to Fig.7. 3 i i | Fig.6 @™ 6932452 0012952 145 mo Panasonic 658 ee

Diagram of monitor block, retraction block, and the AN8420VCM_ oO RI RL = i oy = ven C}-fo> m3 — | = Tt — 7 O i 7 ; I vo uvw “ne i i Low:retracto off RET bi Motor O O ror ewRo00 Fig.7 W™ 69324852 0012953 061 659

Voltage monitor and retraction furiction (10) Voltage monitor By the voltage monitor function, Vocl and Vcc? can be monitored. ‘The monitor function for Vecl which is built in the IC is related to the DELAY, PWRGOOD, POR and RETRACT functions. The following shows the threshold level set by Vc} monitor : (Vecl | LH) Vipv=4.40 (V) (typ) (Vocl 7 HL) Vipv=4.25 (V) (typ) ‘The monitor function for Voc2 whicit is set with extemal resistance is related to PWRGOOD, POR and RETRACT functions. The following calculation gives the threshold level set by Voc2 monitor : Voea= ER? Vos (Vox? ! LH) Veo2= BAER (Vous —VHysteresis width) (Voc? : H+L) ‘Vusons=1.2V (typ) VHysteresis width=47.5mV (typ) Veet R Vec?—MON RI ze Fig8 The following shows the image illustration of DELAY, PWRGOOD and POR by the voltage of Vecl and Vec2. (Ex. 1) Voc? RL Vurono one —— aE (Vasons — Vier itn) Voecl { i p= i V:1.2V (typ) ' DELAY “yi Gan om) i PWRGOOD | \\ Fig. @@! 6932652 0032954 T16 660 a

(Ex. 2) 14R2 Veco ee tone RI+R2 Yao of Veet Day + / LV (V:1.2V (typ) f : a. i (Can (typ) i i Fig.10 WM 6932852 0032955 154 me Panasonic 661

+ Retraction function ‘The AN8420FBP has the forced retraction function at power-on and the retraction function at power-off. The retraction function at power-on uses the power supply of VCC2 and the back electromotive force of spindle motor. When “High” signal is applied to the forced retraction terminal, CRET, the retraction circuit starts operation. On the other hand, when “Low” signal is applied to it, the retraction circuit does not start operation. The retraction function at power-off uses the back electromotive force of the motor. In addition, the retraction current flows from the RETOUTI terminal to the RETOUT2 terminal. (Ex. 1) Image illustration of the terminal voltage at retraction Voo2 enn RUR2 (VMONS— Vivi win) Voel | i i 1 Approx. 3V ‘OFF i RETRACT ON i Uncertain Fig.11 — Ss 6932852 002295b 890 662 ee

(Ex. 2) Vec2 wenn Risk? (Vator — Vices with) Vee! a Se OFF | RETRACT ON | Uncertain Fig.12 (Ex. 3) Voc2 RI+R2 Ve? ; i IMotor Vee i ; ag ope reas OFF j OFF Fig.13 h So6932852 00120957 727? 663

Product Information

AN8420FBP specifications and overview.

Summary

Spindle/Voice Coil Motor Drive IC

Description

Spindle/Voice Coil Motor Drive IC

Source title AN8420FBP Datasheet(PDF) - Panasonic Semiconductor

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