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BA6387K
Optical disc ICs
Preservo amplifier for CD players
BA6387K
The BA6387K is a preservo amplifier for CD players. By using this paired with a ROHM DSP, a servo and main signal system can be configured with few external components and low power consumption.
!Applications CD players
!Features 1) Internal RF and AGC circuits. 2) Internal APC circuit. 3) Internal auto asymmetry circuit.
4) Internal disc defect detector. 5) Internal focus protect function against disc defects.
!Absolute maximum ratings (Ta = 25C)
Parameter Power supply voltage Power dissipation Operating temperature Storage temperature Symbol VCC Pd Topr Tstg Limits 9 400* -25~+75 -55~+125 Unit V mW C C
* Reduced by 4mW for each increase in Ta of 1C over 25C.
!Recommended operating conditions (Ta = 25C)
Parameter Power supply voltage Symbol VCC Limits 2.4~5.5 Unit V
BA6387K
Optical disc ICs
!Block diagram
CAGC RFO ASY PLH BLH RFRFI VCC
24
23
22
21
20
19
18 18
17
45
-
+
20k
B 2k 25 2k 60k
EFM
20k
-
+
DET BLOCK
16
20k
A 26
20k
- +
10k 44.7k
PS PL
BL BS MIRR
20k
20k
20k
20k
2k 2k
- +
60k
10k
+ -
15
39k
C 27
39k
+
-
44.7k 0.6V
+
DEFECT 14
+
-
30p
160k
28
30p
FOK HOLD BLOCK SCRATCH CONTROL FOK LOOP ON
29
10k
FEB
VB
+
100k 100k
-
FOCUS BIAS FOCUS SWITCH GAIN 6dB 5p TEO 20k BL 20k
- + + -
30
0.2V
FE' 31
10k 50k 12p
- +
2k 32 2k
402k 10k 12p
+
50k 5p
18
100k
E
20k
PL 20k
1M
- +
260k 1 2 3 4 5 6 7
F
FO
AGND
FI
CAPC
LD
PD
R/H
-
D
160k
+
-
FE 13
+
-
FOK 12
FON RAMP OSC 11
+
-
-
+
-
TE TEO 13.3k 10
SC 9
2.64k MUTE High=off 8
BA6387K
Optical disc ICs
!Pin descriptions
Pin No. 1 2 3 4 5 6 7 8 Pin name F FO AGND FI CAPC LD PD R/H F input F output Analog GND F gain adjustment feedback For capacitor for APC phase compensation APC amplifier output APC amplifier input For capacitor for ramp wave/ loop off For resistor for scratch depth adjustment Tracking error output Focus on control Focus OK comparator output Focus error output 1 Defect signal output Mirror signal output EFM signal output
23 24 25 26 27 28 29 30 31 32 RFO RFB A C D FEB VB FE' E
Function
Pin No. 17 18 19 20 21 22
Pin name ASY CAGC BLH PLH VCC RFI
Function Auto-asymmetry control input For capacitor for AGC constant For capacitor for bottom long For capacitor for peak long Power supply RF output capacity coupling reinput RF summing amplifier output RF summing amplifier feedback input B input A input C input D input Focus error bias input Bias amplifier output Focus error output 2 E input
9 10 11 12 13 14 15 16
SC TE FON FOK FE DEFECT MIRR EFM
BA6387K
Optical disc ICs
!Electrical characteristics (unless otherwise noted, Ta = 25C and VCC = 2.5V)
Parameter Quiescent current Bias amplifier Bias voltage Maximum output high level voltage Maximum output low level voltage RF amplifier Output offset voltage Voltage gain Maximum output high level amplitude Maximum output low level amplitude Cutoff frequency FE amplifier Output offset voltage Voltage gain AC Voltage gain BD Voltage gain difference Maximum output high level amplitude Maximum output low level amplitude Frequency characteristics TE amplifier Output offset voltage Voltage gain E Voltage gain F Voltage gain difference Maximum output high level amplitude Maximum output low level amplitude Frequency characteristics FOK comparator Threshold voltage Output high level voltage Output low level voltage Maximum operating frequency Asymmetry amplifier Output offset voltage Voltage gain 1 Voltage gain 2 Maximum output high level amplitude Maximum output low level amplitude VOFAS G1AS G2AS VOHAS VOLAS -60 3 8.5 0.90 6 11.5 1.10 -1.10 60 9 14.5 -0.90 mV dB dB V V Input pin 22, 80mVP-P, 1kHz Input pin 17, 80mVP-P, 1kHz V7 = VB 0.8 V6 = VB 0.4
* *
Symbol IQ
Min. -
Typ. 8.7
Max. 12.7
Unit mA
Conditions -
VB IOH IOL
1.12 3.0 3.0
1.25 -
1.38 -
V mA mA
Bias fluctuation below 200mV Bias fluctuation below 200mV
VOFRF GRF VOHRF VOLRF FCRF
-1.02 21.0 0.90 -
-0.90 24.0 1.10 -1.10 6
-0.78 27.0 -0.90 -
V dB V V MHz V8 = 0.8V, SG5 = 30mVP-P, 1kHz Simultaneous AC and BD input V9 = VB + 0.25V, VB-0.05V -3dB point
*
*
VOFFE GFEAC GFEBD GFE VOHFE VOLFE FCFE
-80 26 26 -3 0.90 19
0 29 29 0 1.10 -1.10 22
80 32 32 3 -0.90 25
mV dB dB dB V V dB SG5 = 30mVP-P, 1kHz SG6 = 30mVP-P, 1kHz Measurement with AC and BD input V9 (V10) = VB 0.15V SG5 (SG6) = 60mVP-P, 60kHz
*
*
VOFTE GTEE GTEF GTE VOHTE VOLTE FCTE
-80 27 27 -3 0.90 19
0 30 30 0 1.10 -1.10 22
80 33 33 3 -0.90 25
mV dB dB dB V V dB V1 = VB + 0.1V V2 = VB + 0.1V SG1 (SG2) = 60mVP-P, 60kHz Input pin 22 SG1 = 30mVP-P, 1kHz SG2 = 30mVP-P, 1kHz -
*
* *
VTHFK VOHFK VOLFK FMXFK
-0.42 2.0 45
-0.30 -
-0.18 0.5 -
V V V kHz V7 = VB-0.42V V7 = VB-0.18V -
*
BA6387K
Optical disc ICs
Parameter APC Output voltage 1 Output voltage 2 Reference voltage Frequency characteristics AGC Reference voltage 1 Reference voltage 2 Attack time Recovery time Mirror detector Output high level voltage Output low level voltage Minimum operating frequency Maximum operating frequency Minimum input operating voltage Maximum input operating voltage Defect detector Output high level voltage Output low level voltage Minimum operating frequency Maximum operating frequency Minimum input operating voltage Maximum input operating voltage Scratch depth Ramp wave generator circuit Period High level limit voltage Low level limit voltage FON pin Inflow current Input threshold voltage Loop on unit Loop off delay time FZC comparator Input sensitivity level Zero cross sensitivity level * Standards are with VB reference.
** When FON is LOW, 8 voltage is VB. ** The ramp wave begins at the bottom. ** The loop will not turn on when the ramp wave is at the bottom. ** Pin 8 is charged rapidly when the loop turns on.
Symbol
Min.
Typ.
Max.
Unit
Conditions
VO1AP VO2AP VAPR FAP
1.90 190 -5
2.30 1.0 200 -1
1.4 210 3
V V mV dB
230mV input at pin 7 170mV input at pin 7, I2 = 1mA SG7 = 40mVP-P, 500Hz
VAGC1 VAGC2 RATT RRCV
0 180 70 0.7
195 100 1.0
100 210 130 1.3
mV mV k M
V8 = 0.8V, RFO = 1.2VP-P V8 = 0.8V, RFO = 0.7VP-P Measurement of internal R
VOHMR VOLMR FMNMR FMXMR VMNMR VMXMR
2.0 30 1.2
-
0.5 600 0.2 -
V V Hz kHz VP-P VP-P
RL = 15k -
VOHDF VOLDF FMNDF FMXDF VMNDF VMXDF VSC
2.0 2 1.2 0.13
0.20
0.5 1 0.5 0.27
V V kHz kHz VP-P VP-P V
RL = 15k -
ISIRA VLHRA VLLRA
220 80 -168
340 124 -124
460 168 -80
ms mV mV FEO output value
-
*
IIFON VTHFO
10.4 1.10
13.5 1.45
16.6 1.80
A V
-
tOFLO
4.0
6.6
10.0
ms
-
VFZH VFZL
320 120
400 200
480 280
mV mV
-
BA6387K
Optical disc ICs
!Measurement circuit
SW11 A OFF B SG4 N VCC I1 C A SW3 V11 10k
3300p
A
SW10
B
OFF CB A SW4 SW9 A C 91k
V
O
V7 SW21
V V
T
3300p
A
1
B
OFF
10k
SW12
20k
SG3 V6
SG5
V8 A B C 27k 25 SW15 SW13 27k 26 A B
24
RF-
23
RFO
22
RFI
21
VCC
20
PLH
19
BLH
18
CAGC
17
ASY
M
SW8 16 SW23 15k
V
EFM
V9
10k MIRR 15
V V
SW24
L K 15k f1
SG6
27k OFF A B 27k 28 C SW14 SW17 SW16 30 VB FON 11 29 FEB D FE 13 27 C DEFECT 14
f
SW7
V10
BA6387K
FOK 12
SW25 100k J I
V
82k
V
SW18 B 33k OFF A
I2
V
P SW22 V12 62k
31
FE'
TE
10 H
A V
SW6 10k
S V5
AGND
R/H
32
E
FO F
CAPC
V
Q SC 9
PD LD FI
1
2
3
4
5
6
7
8 SW26
G
V
22k
62k SW1 C B SG1 V1 SG2 A B SW2 C
13k
SW20 A B
B
SW19
A
B
A
D V3
C A B SW5
A
A
A B
26k
C 1
A
E V4
V
F
V2
V
C 1 I2 470p 4.7
V
V
1k 47 U
V
1 SG7
Fig.1
10k
BA6387K
Optical disc ICs
!Circuit operation (1) RF amplifier, FOK comparator
20k 24 23 0.01 22
- + 45
20k
10k 10k 60k 25 2k 28 2k + -
20k + - 20k
20k
60k 26 2k 27 2k + 0.6V - - 12 +
Fig.2 RF and FOK block
RFO is shifted downwards from VB by 0.9V. However, the resistance between pins 23 and 24 is set to 20k and if this resistance is changed use external components to adjust the shift back to 0.9V. Have the feedback resistance 10k or greater. If the DC component of RF rises 0.3V, then FOK becomes high.
BA6387K
Optical disc ICs
(2) FE amplifier and focus search
30p ON 160k - 160k + 10k + LOOP ON - OFF 20k - + 13
44.7k
44.7k
20k
30p
11 FOK ON OFF x3 I I / 10 I
60k 25 2k 28 2k + -
60k 26 2k 27 2k 29 31 + - 8 1F
Fig.3 Focus error block
The voltage for focus search is obtained by the charging and discharging of the capacitor attached to pin 8. The charging current is I / 10 and the discharging current is I. The FEO output amplitude (VSERCH) at this time is determined by the formula given below. VSERCH = I x 15k x 2 (VB reference) Moreover, from Fig.3, I can be approximated by the formula given below.
Set R11 so that I becomes 2A or greater. Apply biasing to the focus error signal from pin 29. If no adjustment occurs, pin 29 = VB . The timing charts when the focus loop turns ON or OFF are given on the next page.
I=
VCC - 1.4 65k + R11
x
1 3
65k
R11
BA6387K
Optical disc ICs
(1) LOOP ON timing When FOK turns high, the fall of FE' is detected and the FOCUS LOOP turns ON.
0.2V 0.4V FE' (pin31)
pin8
FZC (internal)
RFO (pin23) 0.3V
FOK (pin12)
FOCUS LOOP ON (internal)
Fig.4 LOOP ON timing
(2) LOOP OFF timing After FOK turns low, the FOCUS LOOP turns OFF after the delay T (s) shown in the figure below.
RFO (pin23) 0.3V
FOK (pin12)
pin8
VB
T
T=14E3 C In (1+1.5 / VCC) [S]
FOCUS LOOP ON (internal)
Fig.5 LOOP OFF timing
BA6387K
Optical disc ICs
(3) APC block and AGC block
lagc=50A MUTE 20k 20k BL 20k PL
20k
11 FON High-off
- + Tr1
13.3k V1
100k
- V-I 2.64k +
1M
18 1F
5 1F
6
7
10H
200
PD LD 1F
1k
Fig.6 APC and AGC blocks
The initial setting for V1 is 1.2V. When PL-BL (the RF AC amplitude) exceeds a certain value (VAGC), then AGC lowers V1 and suppresses the laser power. The value of VAGC is (50A x 20k) = 1V. When defect turns high, Tr1 turns OFF. When FON (pin 11) is low, the LD output (pin 6) becomes high.
4.7
BA6387K
Optical disc ICs
(4) DET block
37k RFO Bottom hold (long) Charging current 0.1A 1.2V 9 19 3300p Bottom hold (short) Charging current 1A 17.8p
88k -
Peak hold (long) Discharging current 0.1A
Peak hold (short) Discharging current 1A 30p
200
20 3300p
R9
Fig.7 DET block
Peak hold (long) (PL) Bottom hold (long) (BL) Peak hold (short) (PS) Bottom hold (short) (BS)
PL-VSC
BL + (PL - BL) 37k (37k + 88k)
Mirror
Defect
Fig.8 Defect and mirror generation
When defect is high, the bottom hold (long) charging current is 50A. The scratch depth (VSC) can be adjusted by changing the resistance at pin 9.
VSC =
12 R9 + 200
x 4k
The peak hold voltage will not go below (GND + 0.9V) and the bottom hold voltage will not go below (VCC - 0.9V).
+
+ 15 vsc 14 -
BA6387K
Optical disc ICs
!Application example
33
3300p
3300p
20k
0.01
1 0.47
100k EFMO
24
23
22
21
20
19
18
17
RFO
RF-
RFI
VCC
PLH
BLH
CAGC
27k B 27k A 27k C 27k D 28 D 27 C 26 A 25 B
ASY
EFMI 16 MIRR
EFM
MIRR
15 DEF To DSP
DEFECT
14 FE
FE
13 FOK
BA6387K
50k 10 30 VB FON 11 33k TE FE' 62k 31 FE' TE 10 29 FEB FOK 12 FON
R/H
32
E
CAPC
E
AGND
SC
9 22k
FO
1 62k F 22k
2
3
4
5
6
PD
7
LD
FI
F
8
1
1
20k
10
10H 200 PD 1 1k LD
Fig.9
BA6387K
Optical disc ICs
!Electrical characteristics curves
50 180 GAIN GAIN 50 180
PHASE (deg)
0
PHASE
0
0 PHASE
0
-180 -50 1k 10k 100k 1M 10M 100M -50 100 1k 10k 100k
-180 1M
FREQUENCY : f (Hz)
FREQUENCY : f (Hz)
Fig.10 RF amplifier frequency characteristics
50 180 GAIN
Fig.11 FE amplifier frequency characteristics
0 PHASE
0
-180 -50 100 1k 10k 100k 1M
FREQUENCY : f (Hz)
Fig.12 TE amplifier frequency characteristics
!External dimensions (Units : mm)
9.00.3 7.00.2 24
9.00.3 7.00.2
17 16 9
0.4
25 32 1 8
0.150.1
1.450.1 0.05
0.8
0.40.1
0.15
QFP32
PHASE (deg)
GAIN (dB)
PHASE (deg)
GAIN (dB)
GAIN (dB)

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