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CXA1940N
4ch. Read/Write Amplifier for Thin Film Head of Hard Disk Drive For the availability of this product, please contact the sales office.
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 (IW=20mA) : 130mW+IW x 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) 20 pin SSOP (Plastic)
Block Diagram and Pin Configuration
GND
1
DRIVER MODE CONTROL
20 PS
H0X
2
19 R/W
H0Y
3
AMP
WRITE CURRENT SOURCE
18 WC
DRIVER H1X
4
AMP
17 RDY
H1Y
5
AMP
16 RDX
DRIVER H2X
6
HEAD SELECT
15 HS0
H2Y
7
AMP
14 HS1
DRIVER H3X
8
POWER ON/OFF DETECTOR
13 VCC
H3Y
9
AMP T-FF
12 WDI
NC
10
IC PROTECTOR
WRITE UNSAFE DETECTOR
11 WUS
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.
--1--
E93X03-TE
CXA1940N
Structure Bipolar silicon monolithic IC Function Read, Write and Write unsafe detection for HDD, Power supply ON/OFF detection. Absolute Maximum Rating (Ta=25C) * Supply voltage VCC * Write current IW * Operating temperature Topr * Storage temperature Tstg * Allowable power dissipation PD Recommended Operating Conditions * Supply voltage VCC * Write current IW
7 25 -20 to +75 -55 to +150 375
V mAo-p C C mW
5V10 5 to 20
% mAo-p
--2--
CXA1940N
Pin Description No. 1 2 3 4 5 6 7 8 9 10 Symbol GND H0X H0Y H1X H1Y H2X H2Y H3X H3Y NC
VCC
VCC
Equivalent circuit
Description
2 4 6 8 3 5 7 9
GND 2k 2k
Head. 4 channels provided.
11
WUS
11
Write unsafe detection output. Open collector output. When it is off in Write mode, it means an error is detected.
GND
VCC
12
WDI
12
Write data input. At "High" "Low", input is triggered.
2.1V 1.4V GND
13 14 15
VCC HS1 HS0
14
VCC
19
R/W
15 19
20
PS
20
2.1V GND
5V power supply Head select signal input. Selects one of 4 heads according to Table 2. Read/Write signal input. At "High": Read, at "Low": Write. Power save signal input. At "High": Power save.
--3--
CXA1940N
No.
Symbol
Equivalent circuit
VCC
Description
16 17
RDX RDY
16 17
Read Amplifier output.
GND
VCC
18
WC
18 1.25V GND
A setting resistor for the write current value is connected between this pin and GND.
--4--
CXA1940N
Electrical Characteristics No. 1-1 1-2 1-3 2-1 2-2 2-3 2-4 3-1 3-2 Item
Current consumption for Read Current consumption for Write Current consumption for Power save Digital input "Low" input voltage Digital input "High" input voltage Digital input "Low" input current Digital input "High" input current Write unsafe output saturation voltage Write unsafe output leak current
(Unless otherwise specified, VCC=5V, Ta=25C, Write current IW=20mA) Typ. Max. Unit 19 26 +IW 1.1 26 35 +IW 1.5 0.8 2.0 aa aaa aaa aa aa aa aaa bab ba bb
"High" applied voltage : 5V "Low" applied voltage : 0V Test point : I3, I5, I6, I7, I8
SymSW Conditions bol 1 2 3 4 5 6 7 8 9 101112 Measurement conditions Min. Test point : I4 IR b a a a a b a a a a b a 12 IW IP VIL VIH IIL IIH ba aaa baa aa aa ba aaa baa aa bb Test point : I4 Test point : I4 Digital input : Pins 12, 14, 15, 19, 20 17 +IW 0.6
mA mA mA V V A
-20 70 0.5 20
A V A
VWUS b a a a b c a a a a a a IWUS b a a a e c a a a a a a
Output current : 1mA Test point : V1 Test point : I2
Supply power
4 ON/OFF detector
threshold voltage
When VCC is lowered from 5V in Write mode and IW does not flow anymore, VCC voltage is 3.6 VTH b a a a a b a a a a a a set to VTHOFF. When VCC is raised from 3V and IW starts to flow, VCC voltage is set to VTHON. IW ba aaa baa aa aa 5
3.9
4.3
V
Write current setting
5
range Write current
20
mAo-p
6
tolerance
Iw b a a a a b a a a a a a
-8
8
%
Read amplifier
7 differential voltage
gain
AV
Input voltage SG1 : 1mVp-p, 300kHz Load resistance (RDX, ba aac baa ab ba RDY) : 1k Test point : V4 [Vp-p]
AV= V4 SG1
245
290
335 V/V
Frequency
8
band width (-3dB)
BW b a a a c b a a a b b a Frequency at which AV lowers by 3dB
30
MHz
--5--
CXA1940N
No.
Item
9
Input referred noise
SymSW Conditions Measurement conditions Min. bol 1 2 3 4 5 6 7 8 9 101112 Head impedance : 0, when the read amplifier output voltage is amplified 100 times and voltage passed though EN a a a a a b a a a b b a a LPF (low pass filter of cutoff frequency 15MHz) is VN [Vrms],
EN= VN 100 * AV * 15 x 106
Typ. Max. Unit
0.55
0.7
nV Hz
Test point : V5 In-phase input voltage SG2 : 100mVp-p, 5MHz When the Read amplifier output is VCM Common mode 10 CMRR b a a a d b a a a b b a [mVp-p], rejection ratio
CMRR=20 log 100 VCM +20 log AV
50
dB
11
Power Supply rejection ratio
Test point : V4 Ripple voltage SG3 : 100mVp-p, 5MHz When the Read amplifier output is VP PSRR a a a a a b b a a b b a [mVp-p],
PSRR=20 log 100 VP +20 log
50
dB
12
Channel separation
CS
Test point : V4 Selected head input voltage : 0mVP-P Unselected head input voltage SG1 : 100mVp-p, 5MHz a b a a c b a a a b b a When the Read amplifier output is VCS [mVp-p],
CS=20 log 100 VCS +20 log AV
50
dB
Test point : V4 Read data VOFFR=V2-V3 13 output offset VOFFR b a a a a b a a a a b a Test point : V2, V3 voltage for Read
-200
200 mV
--6--
CXA1940N
Unless otherwise specified, VCC=5V, Ta=25C, fWD (Write data frequency)=5MHz, IW=20mA, LH (Head inductance)=1H, RH (Head DC resistance value)=30 Refer to Fig. 2 to Fig. 4 No. Item SymMeasurement conditions Min. Typ. Max. Unit bol Vp-p VSW Differential voltage between HX pin and HY pin 4.4 5.2 at switching of Write current 280 1000 kHz FWUS FWUS is the max. Write data frequency when Pin 11 turns "High" in Write mode. 0.6 s
14 Head differential voltage amplitude 15 Write unsafe detection max. frequency 16-1 Mode switching time TRW TRW is the time required for Write current to turn Read to Write to 90% after Pin 19 changes from "High" to "Low". 16-2 Mode switching time TWR TWR is the time required for either Write current Write to Read to decrease to 10% or for the Read amplifier output to turn to 90% after Pin 19 changes from "Low" to "High". 17-1 Mode switching time TSA1 TSA1 is the time required for Pin 11 to turn "High" safe to unsafe after the last transition of Write data when Write data is stopped in Write mode. 17-2 Mode switching time TSA2 TSA2 is the time required for Pin 11 to turn "Low" unsafe to safe after the first transition of Write in Write mode. 18 Mode switching time TPR TPR is the time required for Read amplifier Power save to Read output to turn to 90% after Pin 20 changes from "High" to "Low". 19 Head switching time TH TH is the time required for the Read amplifier output to reach 90% when the selected head switched in Read mode. 20 Write current TPD TPD is the time required for Write current to propagation delay reach 90% after the Write data falling edge. time LH=0H, RH=0 21 Write current rise/fall TR/TF TR is the time required for Write current to reach time 90% from 10%; TF is the same time required to reach 10% from 90%. LH=0H, RH=0 Read amplifier output 100mVp-p 10MHz
0.6
s
3
7
11
s
1.0 1.0
s s
0.6
s
30
ns
5
10
ns
--7--
CXA1940N
Test Circuit 1
x100
AMP
1k
1k VCC 5V SG3 VCC 5V
LPF
V
V5
to 15MHz x1
AMP
A I4
b a S7
5V 0V 500kHz PG
1
V V4
1 V3
1 V2
5V ab S12 ab S11
V
ba
V
ba ab S9 ab S8
PG1 abc S6 5.1k V1
V
S10 8.2k
A
I8 20
A
I7 19 18
A
I6 17 16 15
A
I5 14 13
A
I3 12
A
I2 11
1
2
S1 ab
3
ab
4
S2 ab S5
5
ab
6
S3 ab
7
ab
8
S4 ab
9
ab
10
ab
cd
e
a I1 33
bc
d
e 0.1 SG2
A
0.1
0.1
Fig. 1
SG1
Test Circuit 2
x1
AMP
1k
1k
5V 1
PG PG
1
1
PG
5V
PG
8.2k 18 17 16 15
5.1k 11
0V 20 19 14 13 12
1
2
3
4
5
6
7
8
9
10
1H
1H
1H
1H
Fig. 2
Note) Write current is measured with current probe. Use an oscilloscope to test items related to time.
--8--
CXA1940N
Timing Chart 1
WDI
R/W
50%
50%
PS TRW TWR
50%
90% IWX IWY 10%
90% 10% TWR TPR
RDX RDY
90%
90%
Fig. 3
Timing Chart 2
WDI
50%
50%
TPD 90% IWX IWY 10% TR 10% TF TSA1 90% 90%
WUS TSA2
50%
50%
Fig. 4
--9--
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 "High" to "Low" 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. R/W L H H PS L L H Mode Write Read Power save
Table 1. Mode selection Head selection Heads are selected as shown in Table 2 using HS0 and HS1 pins. HS0 L H L H HS1 L L H H Head 0 1 2 3
Table 2. Head selection
--10--
CXA1940N
Write unsafe detection circuit Abnormal Write mode is detected. In normal Write mode, WUS output turns to "Low" and in the following other conditions, WUS output turns to "High". * * * * * * 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 VCC is monitored to avoid incorrecting Write. Recording and Playback functions are inhibited as detected as abnormal when VCC decreases below the power supply ON/OFF detector threshold voltage (VTH). When VCC is higher than VTH, the above inhibition is released.
--11--
CXA1940N
Application Circuit
+5V
PULSE DETECTOR RW 8.2k 20 19 18 17 16 15
1 5.1k 14 13 12 11
1
2
LH 1H
3
4
LH 1H
5
6
LH 1H
7
8
LH 1H
9
10 NC
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.
--12--
CXA1940N
Notes on operation * This device handles high frequency and high gain signals. Please note the following; Connect VCC 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 RW as close to the device as possible . * Write unsafe detection circuit This circuit uses the voltage waveforms of the head pins for detection.
Wave form of write data T1 Voltage waveform of head pins (HX, HY) VFB
1.5V
VTH=2V VTH GND
The condition of T1 >10ns must be met for the WUS detection circuit to operate properly. VFB must be more than 2V. When VFB < 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.
--13--
CXA1940N
Application Notes Use the following characteristics for reference. Symbol Differential output capacitance CO Item Differential output resistance Differential input capacitance Read mode Differential input resistance Output resistance Unselected head differential current in Write mode Write current symmetry TAS=T1--T2 RO CI RI Conditions Between head input pins 230 Between head input pins f=5MHz Min.
VCC=5V, Ta=25C Typ. Max. 15 310 14 0.7 1.4 40 60 0.2 -1 1 390 20 Unit pF pF k mAp-p ns
Write mode
RRD RDX or RDY, f=5MHz IUS LH=1H, RH=30 Iw=20mA
TAS LH=0H, RH=0 Iw=20mA
IWX+IWY
50% T1
50% T2
50%
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.
WC 18 RW
Fig.5 Write current vs. RW
Fig. 6 Write current setting constant vs Write current 148
20
K=Rw * IW
10
Write current setting constant K
146
IW-Write current (mA)
144
142
5
140
5 10 RW (K) 20 30
5
10
15
20
Write current IW (mA)
--14--
CXA1940N
Fig.7 Normalized write current vs Supply voltage
Fig. 8 Normalized write current vs Ambient temperature VCC=5V 1.01
Ta=25C 1.01
IW/IW (Ta=25C)
4
IW/IW (VCC=5V)
1.00
1.00
0.99
0.99
0.98
5 6 Supply voltage VCC (V)
7
-25
0 25 50 Ambient temperature Ta (C)
75
Fig. 9 Normalized read amplifier voltage gain vs Supply voltage 1.02 Ta=25C 1.01 1.01
Fig. 10 Normalized read amplifier voltage gain vs Ambient temperature VCC=5V
AV/AV (Ta=25C)
AV/AV (VCC=5V)
1.00
1.00
0.99
0.99 0.98
4
5 6 Supply voltage VCC (V)
7
-25
0 25 50 Ambient temperature Ta (C)
75
Fig. 11 Power supply ON/OFF detector threshold voltage vs Ambient temperature
4.0
Power supply ON/OFF Detector Threshold Voltage (V)
OFFON
3.9 ONOFF
3.8
-25
0 25 50 Ambient temperature Ta (C)
75
--15--
CXA1940N
Package Outline
Unit : mm
20PIN SSOP (PLASTIC)
6.5 0.1 + 0.2 1.25 - 0.1 0.1 20 11 A
4.4 0.1
1 + 0.1 0.22 - 0.05
10 0.65 0.12 + 0.05 0.15 - 0.02
0.1 0.1
0 to 10 DETAIL A NOTE: Dimension "" does not include mold protrusion.
PACKAGE STRUCTURE
PACKAGE MATERIAL SONY CODE EIAJ CODE JEDEC CODE SSOP-20P-L01 SSOP020-P-0044 LEAD TREATMENT LEAD MATERIAL PACKAGE WEIGHT EPOXY RESIN SOLDER / PALLADIUM PLATING COPPER / 42 ALLOY 0.1g
--16--
0.5 0.2
6.4 0.2

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