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? e93x03-te sony reserves the right to change products and specifications without prior notice. this information does not convey any license by any implication or otherwise under any patents or other right. application circuits shown, if any, are typical examples illustrating the operation of the devices. sony cannot assume responsibility for any problems arising out of the use of these circuits. description the CXA1940N is a read/write amplifier for the thin film head of hard disk drives and designed to handle up to 4-channel heads. features operate on single +5v power supply. low power consumption. read : 95mw write (i w =20ma) : 130mw+i w 5 power save : 5.5mw write current can be varied through an external resistor. built-in stabilizing circuit provides stable current during voltage and temperature drift. drives up to 4 heads. designed for two-terminal thin-film or mig heads. built-in power save function. read amplifier emitter follower output featuring 290 times gain (typ.). built-in write unsafe detection circuit. built-in supply voltage monitor circuit prohibits incorrect write during power on or abnormal voltage. built-in ic protection circuit for short of head and gnd. differential input capacitance for read : 14pf (typ.). write data input minimum pulse width : 10ns read data output become high impedance in write mode to improve read data offset when switching from write to read mode. unselected head dc voltage is gnd potential. self switching damping resistance (rd=310 ) 4ch. read/write amplifier for thin film head of hard disk drive 20 pin ssop (plastic) CXA1940N block diagram and pin configuration driver amp driver driver driver mode control head select power on/off detector write unsafe detector t-ff v cc hs1 hs0 rdx rdy ps r/w nc h3x h2y h2x h1y h1x h0y h0x gnd ic protector h3y wc wdi wus write current source amp amp amp amp 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 20 19
? CXA1940N structure bipolar silicon monolithic ic function read, write and write unsafe detection for hdd, power supply on/off detection. absolute maximum rating (ta=25?) supply voltage v cc 7v write current i w 25 mao-p operating temperature topr ?0 to +75 ? storage temperature tstg ?5 to +150 ? allowable power dissipation p d 375 mw recommended operating conditions supply voltage v cc 5v?0 % write current i w 5 to 20 mao-p
? CXA1940N no. symbol equivalent circuit description 1 gnd 2 h0x 3 h0y 4 h1x 5 h1y 6 h2x 7 h2y 8 h3x 9 h3y 10 nc 11 wus 12 wdi 13 v cc 14 hs1 15 hs0 19 r/w 20 ps head. 4 channels provided. write unsafe detection output. open collector output. when it is off in write mode, it means an error is detected. write data input. at ?igh? ? ?ow? input is triggered. 5v power supply head select signal input. selects one of 4 heads according to table 2. read/write signal input. at ?igh? read, at ?ow? write. power save signal input. at ?igh? power save. v cc gnd 2k 2k 2 3 4 5 6 7 8 9 v cc gnd 11 v cc gnd 2.1v 1.4v 12 v cc gnd 2.1v 14 15 20 19 pin description
? CXA1940N 16 rdx 17 rdy 18 wc read amplifier output. a setting resistor for the write current value is connected between this pin and gnd. no. symbol equivalent circuit description v cc gnd 16 17 gnd 1.25v v cc 18
? CXA1940N sym- sw conditions bol no. item measurement conditions min. typ. max. unit 1-1 1-2 1-3 2-1 2-2 2-3 2-4 3-1 3-2 4 5 6 7 8 current consump- tion for read current consump- tion for write current consump- tion for power save digital input ?ow input voltage digital input ?igh input voltage digital input ?ow input current digital input ?igh input current write unsafe output saturation voltage write unsafe output leak current supply power on/off detector threshold voltage write current setting range write current tolerance read amplifier differential voltage gain frequency band width (?db) i r i w i p v il v ih i i l i ih v wus i wus v th i w ? iw a v bw test point : i 4 test point : i 4 test point : i 4 digital input : pins 12, 14, 15, 19, 20 ?igh?applied voltage : 5v ?ow?applied voltage : 0v test point : i 3 , i 5 , i 6, i 7 , i 8 output current : 1ma test point : v 1 test point : i 2 when v cc is lowered from 5v in write mode and i w does not flow anymore, v cc voltage is set to v thoff . when v cc is raised from 3v and i w starts to flow, v cc voltage is set to v thon . input voltage sg1 : 1mvp-p, 300khz load resistance (rdx, rdy) : 1k test point : v4 [vp-p] frequency at which a v lowers by 3db av= v4 sg1 12 19 26 ma 17 26 35 +i w +i w +i w 0.6 1.1 1.5 ma 0.8 v 2.0 v ?0 ? 70 ? 0.5 v 20 ? 3.6 3.9 4.3 v 520 -8 8 % 245 290 335 v/v 30 mhz ma ba aaa baa aa ba ba aaa baa aa aa ba aaa baa aa bb aa aaa aaa aa aa aa aaa bab ba bb ba aab caa aa aa ba aae caa aa aa ba aaa baa aa aa ba aaa baa aa aa ba aaa baa aa aa ba aac baa ab ba ba aac baa ab ba 1 2 3 4 5 6 7 8 9 101112 electrical characteristics (unless otherwise specified, v cc =5v, ta=25?, write current i w =20ma) mao-p
? CXA1940N head impedance : 0 , when the read amplifier output voltage is amplified 100 times and voltage passed though a lpf (low pass filter of cutoff frequency 15mhz) is v n [vrms], test point : v 5 in-phase input voltage sg2 : 100mvp-p, 5mhz when the read amplifier output is v cm [mvp-p], test point : v 4 ripple voltage sg3 : 100mvp-p, 5mhz when the read amplifier output is v p [mvp-p], test point : v 4 selected head input voltage : 0mv p-p unselected head input voltage sg1 : 100mvp-p, 5mhz when the read amplifier output is v cs [mvp-p], test point : v 4 v offr =v 2 ? 3 test point : v 2 , v 3 e n = 100 ?av ? 15 10 6 v n cmrr=20 log +20 log a v 100 v cm psrr=20 log +20 log 100 v p cs=20 log +20 log a v 100 v cs 1 2 3 4 5 6 7 8 9 101112 9 10 11 12 13 input referred noise common mode rejection ratio power supply rejection ratio channel separation read data output offset voltage for read e n cmrr psrr cs v offr 0.55 0.7 50 db 50 db 50 db ?00 200 mv nv hz aa aaa baa ab ba ba aad baa ab ba aa aaa bba ab ba ab aac baa ab ba ba aaa baa aa ba no. item measurement conditions min. typ. max. unit sym- sw conditions bol
? CXA1940N unless otherwise specified, v cc =5v, ta=25?, f wd (write data frequency)=5mhz, i w =20ma, l h (head inductance)=1?, r h (head dc resistance value)=30 refer to fig. 2 to fig. 4 4.4 5.2 vp-p 280 1000 khz 0.6 ? 0.6 ? 3 7 11 ? 1.0 ? 1.0 ? 0.6 ? 30 ns 510ns v sw f wus t rw t wr t sa1 t sa2 t pr t h t pd t r/ t f head differential voltage amplitude write unsafe detection max. frequency mode switching time read to write mode switching time write to read mode switching time safe to unsafe mode switching time unsafe to safe mode switching time power save to read head switching time write current propagation delay time write current rise/fall time 14 15 16-1 16-2 17-1 17-2 18 19 20 21 differential voltage between hx pin and hy pin at switching of write current f wus is the max. write data frequency when pin 11 turns ?igh?in write mode. t rw is the time required for write current to turn to 90% after pin 19 changes from ?igh?to ?ow? t wr is the time required for either write current to decrease to 10% or for the read amplifier output * to turn to 90% after pin 19 changes from ?ow?to ?igh? t sa1 is the time required for pin 11 to turn ?igh after the last transition of write data when write data is stopped in write mode. t sa2 is the time required for pin 11 to turn ?ow after the first transition of write in write mode. t pr is the time required for read amplifier output to turn to 90% after pin 20 changes from ?igh?to ?ow? t h is the time required for the read amplifier output * to reach 90% when the selected head switched in read mode. t pd is the time required for write current to reach 90% after the write data falling edge. l h =0?, r h =0 t r is the time required for write current to reach 90% from 10%; t f is the same time required to reach 10% from 90%. l h =0?, r h =0 no. item measurement conditions min. typ. max. unit sym- bol * read amplifier output 100mvp-p 10mhz
? CXA1940N 5v 0v 500khz s12 s11 s10 s9 s8 s7 s6 ab a b ab ab ab ab ab ab ab c d a bc d s1 s2 s3 s4 s5 8.2k 33 i1 sg2 sg1 1 8.2k 5v 1k 1k 5.1k 1 h 100 1k 1k a b i4 v cc 5v v cc 5v amp 1 a ba ba ab ab b ab 5v bc a pg1 5.1k v1 v5 v4 v3 v2 sg3 ee amp a a a a a pg a a v a pg pg pg pg v v 1 h 1 h 1 h 1 1 1 0.1 0.1 0.1 i8 i7 i6 i5 i3 i2 1 1 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 20 19 v v 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 20 19 5v 0v lpf to 15mhz amp test circuit 2 test circuit 1 fig. 2 fig. 1 note) write current is measured with current probe. use an oscilloscope to test items related to time.
? CXA1940N 50% 50% t rw 90% 10% 90% t wr t pr 90% 10% 90% 50% 50% 10% 10% 50% 50% 50% t r t f 90% 90% t sa2 t pd 90% wus i wx i wy wdi t sa1 i wx i wy ps rdx rdy r/w wdi t wr timing chart 2 fig. 3 fig. 4 timing chart 1
?0 CXA1940N description functions read amplifier this is a low noise amplifier amplifying the signals from the head and is an emitter follower output. it outputs to rdx and rdy pins differentially. the head x side and rdx pin, the head y side and rdy pin have the same polarity. rdx, rdy outputs become high impedance in write mode (when these outputs is ac coupled to the load). write circuit write data which is input to wdi pin passes through a t flip-flop and frequency is divided into 1/2. it then drives the write switch circuit and flows write current to the head. write data is triggered where from ?igh?to ?ow?and write current is switched. write current flows from x side when read changes to write. mode control modes are set as shown in table 1 using r/w and ps pins. table 1. mode selection head selection heads are selected as shown in table 2 using hs0 and hs1 pins. table 2. head selection r/w ps mode l l write h l read h h power save hs0 hs1 head ll 0 hl 1 lh 2 hh 3
?1 CXA1940N write unsafe detection circuit abnormal write mode is detected. in normal write mode, wus output turns to ?ow?and in the following other conditions, wus output turns to ?igh? head input is open. head input is shorted to gnd. write data frequency is abnormally low. no write current in read in power save power supply on/off detection v cc is monitored to avoid incorrecting write. recording and playback functions are inhibited as detected as abnormal when v cc decreases below the power supply on/off detector threshold voltage (v th ). when v cc is higher than v th , the above inhibition is released.
?2 CXA1940N 1 h 1 h 1 h 1 h r w 8.2k 1 l h l h l h l h pulse detector +5v 5.1k nc 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 20 19 application circuit application circuits shown are typical examples illustrating the operation of the devices. sony cannot assume responsibility for any problems arising out of the use of these circuits or for any infringement of third party and other right due to same.
?3 CXA1940N notes on operation this device handles high frequency and high gain signals. please note the following; connect v cc decoupling capacitor of approximately 1000pf near the device. make the gnd area as large as possible. when using as 2-channel, short-circuit the x and y sides of unused head pins or leave them open. write data pulse width set the pulse width to 10ns or more at 1.5v to prevent misoperation. the wc pin is a constant voltage pin. when noise affects this pin, it creates noise in write current. therefore, locate r w as close to the device as possible . write unsafe detection circuit this circuit uses the voltage waveforms of the head pins for detection. the condition of t1 >10ns must be met for the wus detection circuit to operate properly. vfb must be more than 2v. when v fb < 2v, it is possible that write unsafe detection maximum frequency becomes more than 1mhz. the normal operating area of write unsafe detection circuit is changed by head inductance, head dc resistance, write current and other. t 1 v th gnd 1.5v voltage waveform of head pins (hx, hy) w ave form of write data v th =2v v fb
?4 CXA1940N application notes use the following characteristics for reference. unselected head differential current in write mode write current symmetry differential output capacitance differential output resistance differential input capacitance differential input resistance output resistance item conditions min. typ. max. unit write mode read mode c o r o c i r i r rd i us t as * between head input pins between head input pins f=5mhz rdx or rdy, f=5mhz l h =1?, r h =30 iw=20ma l h =0?, r h =0 iw=20ma 15 pf 230 310 390 14 20 pf 0.7 1.4 k 40 60 0.2 map-p ? 1 ns sym- bol * tas=t1?2 t 1 t 2 50% 50% 50% i wx +i wy v cc =5v, ta=25? setting of write current write current can be set with resistor rw (k ) at pin 18. iw=k/rw (ma) refer to fig. 5 and 6. fig.5 w rite current vs. r w 20 10 5 510 20 i w -write current (ma) r w (k w ) 30 fig. 6 w rite current setting constant vs w rite current w rite current setting constant k w rite current i w (ma) 148 146 144 142 140 5101520 k=rw ?i w wc r w 18
?5 CXA1940N fig.7 normalized write current vs supply voltage 4 5 supply voltage v cc (v) 6 0.99 1.00 1.01 ta=25c 7 i w /i w (v cc =5v) supply voltage v cc (v) 4 56 0.99 1.00 1.01 ta=25c 7 fig. 9 normalized read amplifier voltage gain vs supply voltage fig. 8 normalized write current vs ambient temperature ?5 025 0.99 1.00 1.01 50 i w /i w (ta=25c) 75 a v /a v (v cc =5v) ambient temperature ta (c) ?5 025 3.8 3.9 4.0 50 75 power supply on/off detector threshold voltage (v) fig. 11 power supply on/off detector threshold voltage vs ambient temperature off ? on 0.98 1.02 fig. 10 normalized read amplifier voltage gain vs ambient temperature a v /a v (ta=25c) ambient temperature ta (c) ?5 025 0.99 1.00 1.01 50 v cc =5v 75 0.98 on ? off v cc =5v ambient temperature ta (c)
20pin ssop (plastic) sony code eiaj code jedec code package structure package material lead treatment lead material package weight epoxy resin solder / palladium copper / 42 alloy 0.1g ssop-20p-l01 ssop020-p-0044 0.1 0.1 0.5 0.2 0?to 10 detail a plating * 6.5 0.1 * 4.4 0.1 0.22 ?0.05 + 0.1 0.65 0.12 20 11 10 1 a 0.1 + 0.05 1.25 ?0.1 + 0.2 0.15 ?0.02 6.4 0.2 note: dimension * ?does not include mold protrusion. package outline unit : mm CXA1940N ?6

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