BBK dk925S Service Manual

CONTENTS
1. SAFETY PRECAUTIONS
2. PREVENTION OF ELECTRO STATIC DISCHARGE(ESD)TO ELECTROSTATICALLY
SENSITIVE(ES)DEVICES
3. CONTROL BUTTON LOCATIONS AND EXPLANATIONS
4. PREVERTION OF STATIC ELECTRICITY DISCHARGE
5. ASSEMBLING AND DISASSEMBLING THE MECHANISM UNIT
5.1 OPTICAL PICKUP UNIT EXPLOSED VIEW AND PART LIST
5.2 MISCELLANEOUS
6.1 VIDEO OUTPUT (LUMINANCE SIGNAL) CONFIRMATION
6.2 VIDEO OUTPUT(CHROMINANCE SIGNAL) CONFIRMATION
7. MPEG BOARD CHECK WAVEFORM
1
1
2
3
4
4
6
7
7
8
9
8. IC BLOCK DIAGRAM & DESCRIPTION
8.1 MT1336 10
8.2 MT1379
8.3 AM29LV160D 34
8.4 HY57V641620HG
9. SCHEMATIC & PCB WIRING DIAGRAM
10. SPARE PARTS LIST 57
10
18
39
42
1.1 GENERAL GUIDELINES
1. SAFETY PREAUTIONS
2.PREVENTION OF ELECTRO STATIC DISCHARGE(ESD)TO  ELECTROSTATICALLY SENSITIVE(ES)DEVICES
1
1. When servicing, observe the original lead dress. if a short circuit is found, replace all parts which have been overheated or damaged by the short circuit.
2. After servicing, see to it that all the protective devices such as insulation barrier, insulation papers shields are properly installed.
3. After servicing, make the following leakage current checks to prevent the customer from being exposed
to shock hazards.
Some semiconductor(solid state)devices can be damaged easily by static electricity. Such components commonly are called Electrostatically Sensitive(ES)Devices. Examples of typical ES devices are integrated circuits and some field-effect transistors and semiconductor chip components. The following techniques should be used to help reduce the incidence of component damage caused by electro static discharge(ESD).
1. Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any ESD on your body by touching a known earth ground. Alternatively, obtain and wear a commercially availabel discharging ESD wrist strap, which should be removed for potential shock reasons prior to applying power to the unit under test.
2. After removing an electrical assembly equipped with ES devices,place the assembly on a conductive surface such as alminum foil, to prevent electrostatic charge buildup or exposure of the assembly.
3. Use only a grounded-tip soldering iron to solder or unsolder ES devices.
4. Use only an anti-static solder removal device. Some solder removal devices not classified as anti-static (ESD protected)can generate electrical charge sufficient to damage ES devices.
5. Do not use freon-propelled chemicals. These can generate electrical charges sufficient to damage ES devices.
6. Do not remove a replacement ES device from its protective package until immediately before you are ready to install it. (Most replacement ES devices are packaged with leads electrically shorted together by conductive foam, alminum foil or comparable conductive material).
7. Immediately before removing the protective material from the leads of a replacement ES device, touch the protective material to the chassis or circuit assembly into which the device will be installed. Caution Be sure no power is applied to the chassis or circuit, and observe all other safety precautions.
8. Minimize bodily motions when handling unpackaged replacement ES devices. (Otherwise harmless motion such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity(ESD).
notice (1885x323x2 tiff)
Fr ont Panel I l l u s t r at i o n
2
2
Power indicator
2
IR SENSOR
3
4
OPEN/CLOSE button
5
PLAY/PAUSE button
546 7 9
7
PREV button
8
8
NEXT button
3
Display window
6
STOP button
9
POWER switch
The laser diode in the traverse unit (optical pickup)may brake down due to static electricity of clothes or human
body. Use due caution to electrostatic breakdown when servicing and handling the laser diode.
Some devices such as the DVD player use the optical pickup(laser diode)and the optical pickup will be damaged
by static electricity in the working environment.Proceed servicing works under the working environment where
1. Put a conductive material(sheet)or iron sheet on the area where the optical pickup is placed,and ground the
3. The flexible cable may be cut off if an excessive force is applied to it.Use caution when handling the cable.
3
4.PREVENTION OF STATIC ELECTRICITY DISCHARGE
4.1.Grounding for electrostatic breakdown prevention
grounding works is completed.
4.1.1. Worktable grounding
sheet.
4.1.2.Human body grounding
1 Use the anti-static wrist strap to discharge the static electricity from your body.
safety_3 (1577x409x2 tiff)
4.1.3.Handling of optical pickup
1. To keep the good quality of the optical pickup maintenance parts during transportation and before installation, the both ends of the laser diode are short-circuited.After replacing the parts with new ones, remove the short circuit according to the correct procedure. (See this Technical Guide).
2. Do not use a tester to check the laser diode for the optical pickup .Failure to do so willdamage the laser diode due to the power supply in the tester.
4.2. Handling precautions for Traverse Unit (Optical Pickup)
1. Do not give a considerable shock to the traverse unit(optical pickup)as it has an extremely high-precise structure.
2. When replacing the optical pickup, install the flexible cable and cut is short land with a nipper. See the optical pickup replacement procedure in this Technical Guide. Before replacing the traverse unit, remove the short pin for preventingstatic electricity and install a new unit.Connect the connector as short times as possible.
4. The half-fixed resistor for laser power adjustment cannot be adjusted. Do not turn the resistor.
5.1 Optical pickup Unit Explosed View and Part List
5. Assembling and disassembling the mechanism unit
4
Pic (1)
Materials to Pic (1)
5
No. PARTS CODE PARTS NAME Q ty
14692200 SF-HD60 1
1
1EA0311A06300 ASSY, CHASSIS, COMPLETE 1
2
Or
3
4
5
6
7
8
9
10
11
21
Or
31
32
1EA0M10A15500 ASSY, MOTOR, SLED 1
1EA0M10A15501 ASSY, MOTOR, SLED 1
1EA2451A24700 HOLDER, SHAFT 3
1EA2511A29100 GEAR, RACK 1
1EA2511A29200 GEAR, DRIVE 1
1EA2511A29300 GEAR, MIDDLE, A 1
1EA2511A29400 GEAR, MIDDLE, B 1
1EA2744A03000 SHAFT, SLIDE 1
1EA2744A03100 SHAFT, SLIDE, SUB 1
1EA2812A15300 SPRING, COMP, TYOUSEI 3
1EA2812A15400 SPRING, COMP, RACK 1
1EA0B10B20100 ASSY, PWB 1
1EA0B10B20200 ASSY, PWB 1
SEXEA25700--- SPECIAL SCREW BIN+-M2X11 3
SEXEA25900--- SPECIAL SCREW M1.7X2.2 2
33
34
35

Note : This parts list is not for service parts supply.
SFBPN204R0SE- SCR S-TPG PAN 2X4 2
SFSFN266R0SE- SCR S-TPG FLT 2.6X6 1
SWXEA15400--- SPECIAL WASHER 1.8X4 X0.25 2
2 MISCELLANEOUS
6
5.
5.2.1 Protection of the LD(Laser diode)
Short the parts of LD circuit pattern by soldering.
5.2.2 Cautions on assembly and adjustment
Make sure that the workbenches,jigs,tips,tips of soldering irons and measuring instruments are
grounded,and that personnel wear wrist straps for ground.
Open the LD short lands quickly with a soldering iron after a circuit is connected.
Keep the power source of the pick-up protected from internal and external sources of electrical noise.
Refrain from operation and storage in atmospheres containing corrosive gases (such as H2S,SO2,
NO2 and Cl2)or toxic gases or in locations containing substances(especially from the organic silicon,cyan,
formalin and phenol groups)which emit toxic gases.It is particularly important to ensure that none of the
above substances are present inside the unit.Otherwise,the motor may no longer run.
6.1. Video Output (Luminance Signal) Confirmation
6.Electrical Confirmation
7
DO this confirmation after replacing a P.C.B.
Measurement point
Video output terminal
Measuring equipment,tools
200mV/dir,10 sec/dir
Purpose:To maintain video signal output compatibility.
1.Connect the oscilloscope to the video output terminal and terminate at 75 ohms.
2.Confirm that luminance signal(Y+S)level is 1000mVp-p±30mV
PLAY(Title 46):DVDT-S15 PLAY(Title 12):DVDT-S01
Mode Disc
Color bar 75%
Confirmation value
1000mVp-p±30mV
DVDT-S15
or
DVDT-S01
Do the confirmation after replacing P.C.B.
Screwdriver,Oscilloscope
6.2 Video Output(Chrominance Signal) Confirmation 
8
Measurement point
Video output terminal
Measuring equipment,tools Confirmation value
200mV/dir,10 sec/dir
Purpose:To maintain video signal output compatibility.
1.Connect the oscilloscope to the video output terminal and terminate at 75 ohme.
2.Confirm that the chrominance signal(C)level is 621 mVp-p±30mV
PLAY(Title 46):DVDT-S15 PLAY(Title 12):DVDT-S01
Mode Disc
Color bar 75%
621mVp-p±30mV
DVDT-S15
or
DVDT-S01
7.MPEG BOARD CHECK WAVEFORM
7.1 27MHz WAVEFORM 
7.2 IC TEA1523 PIN.8 WAVEFORM DIAGRAM
9
8.1 MT1336
8. IC BLOCK DIAGRAM & DESCRIPTION
10
PRELIMINARY, SUBJ ECT TO CHANGE WITHOUT NOTICE MTK CONFIDENTIAL, NO DISCLOSURE
MT1336
GENERAL DESCRIPTION
MT1336 is a high performance CMOS analog front-end IC for both CD_ROM driver up to 48XS and
DVD-ROM driver up to 16XS. It also supports DVD-RAM read up to 4XS Version 2. It contains servo amplifiers to generate focusing error, 3-beam tracking error, 1 beam radial push-pull signal, RF level and SBAD for servo functions. It also includes DPD tracking error signal for DVD_ROM application. For DVD- RAM disks, there are also Differential Push-Pull (DPP) method for generating tracking signal and Differential Astigmatic Detection (DAD) for processing focusing signal. Programmable equalizer and AGC circuits are also incorporated in this chip to optimize read channel performance. In addition, this chip has dual automatic laser power control circuits for DVD- ROM (DVD-RAM) and CD -ROM seperately and reference voltage generators to reduce external components. Programmable functions are implemented by the access of internal register through bi-directional serial port to configure modes selection.
FEATURES
n RF equalizer with programmable
13dB.
n MT1336 supports at least eight different kinds of pick-up heads with versatile input configuration for
both RF input stages and servo signal blocks.
n Versatile on -line AGC.
n 3 beams tracking error signal generator for CD_ROM application.
n One beam differential phase tracking error (DPD) generator for DVD_ROM application.
n Differential push pull tracki ng error (DPP) generator for DVD_RAM application.
n Focusing error signal generator for CD-ROM, DVD-ROM and DVD-RAM (DAD method).
n RF level signal generator.
n Sub-beam added signal for 3 beams CD_ROM.
n One beam push-pull signal generator for central servo application.
n High speed RF envelop detection circuit with bandwidth up to 400KHz for CD-ROM.
n Defect and Blank detection circuits.
from 3MHz to 70 MHz and programmable boost from 3dB to
f
c
n Dual automatic laser power control circuits with programmable level of LD monitor voltage.
n Vref=1.4V voltage and V2ref=2.8V voltage generators.
n V20=2.0V voltage for pick-up head reference.
n Bi-directional serial port to access internal registers.
MT1336
11
PRELIMINARY, SUBJ ECT TO CHANGE WITHOUT NOTICE MTK CONFIDENTIAL, NO DISCLOSURE
DVDA
CDA
DVDB
CDB
DVDC
CDC
DVDD
CDD
DVDRFIN
DVDRFIP
MA
MB
MC
MD
SA
SB
SC
SD
DPFN
DPFO
IR
DPDMUTE
TPI TNI
CDFOP
CDFON
RFGC
RFGCU
RFGCI
AGC1
AGC2
AGC3
RFSUBO
WOBSO
V20
V2REFO
VREFO
ATTENUATOR
INPUT MUX
WOBBLE
DET
VGA
VGA EQ
AGC
AGC
DPD
SBAD
TE
RF
LEVEL
FE
CENTRAL
SERVO
REF and 2VREF
REF and 2VREF
Voltage Generator
Voltage Generator
ENVELOP
ENVELOP
DETECTOR
DETECTOR
PCS
DVD
APC
CD
APC
SERIAL
PORT
OSP
OSN
RFOP
RFON
LRFRP
DEFECT
HRFRP
CRTP
CRTPLP
CSO
LVL
TEO
FEO
REFCOS
HALLCOS
COSPHI
REFSIN
HALLSIN
SINPHI
MDI2
LDO2
MDI1
LDO1
UDGATE
IDGATE
VFO13
SDATA
SLCK
SDEN
MT1336 FUNCTION BLOCKS DIAGRAM
12
MT1336
PRELIMINARY, SUBJ ECT TO CHANGE WITHOUT NOTICE MTK CONFIDENTIAL, NO DISCLOSURE
WGND
WOBSO
WVDD AGNDX
AGNDX AVDDO
RFOP RFON AGNDO
TM1 TM2 TM3
AGNDT TM4
AVDDT
V2REFO VREFO
V20
FEO
LVL CSO
TEO VDDP DEFECT LRFRP
HRFRP CRTP
CRTPLP TRLPA
TRLP
HTRC GNDP
DPFN DPFO
AGNDX
AGNDX
AGNDX
VDD VFO13
1 2 3 4 5 6 7 8 9 10
11
12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
33 34 35 36 37 38
RFSUBO
LDO2
LDO1
127
126
125
128
3940414243
MDI1
124
WAVDD
MDI2
123
AGC1
AGC2
AGC3
121
120
119
122
MT1336
DVD-ROM
DVD_RAM
454647
44
48
WAGND
TNI
SGND
118
117
116
With
Read
495051
525453
SD
CDFOP
SVDD
TPI
CDFON
115
114
113
112
111
555657585960616263
SASBMC
IR
AVDD
SC
110
109
108
MD
AGND
107
106
105
104
103
102 101 100
99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76 75 74 73 72 71
70 69 68 67 66 65
64
MB MA
DVDA
DVDB DVDC DVDD
DVDRFIP
DVDRFIN
CDA
CDB CDC CDD OSN OSP RFGC
RFGCU RFGCI CEQP CEQN AGNDX AGNDX
MON
MOP
SW1 SW2
SWO
SINPHI
REFSIN
HALLSIN
AGNDM
REFCOS HALLCOS COSPHI AVDDM
AGNDX AVDDF
VCON AGNDF
IO0
GND
UDGATE
HDGATE
IO4
IO1
IO5
IO7
IO8
IO9
IO6
IO3
IO2
IOB
IOA
MT1336 PIN ASSIGNMENT
SCLK
VDDS
XCK16M
RST
SDEN
GNDS
SDATA
AGNDP
AGNDX
AVDDP
DPDMUTE
13
PRELIMINARY, SUBJ ECT TO CHANGE WITHOUT NOTICE MTK CONFIDENTIAL, NO DISCLOSURE
MT1336
MT1336 PIN DESCRIPTIONS
Pin Numbers Symbol Type Description
LQFP128
RF Flag Interface
23 DEFECT Digital Output Flag of bad data output status
RF SIO interface
56 SCLK Digital Input RF serial clock input
58 SDEN Digital Input RF serial data enable
59 SDATA Digital IO RF serial data IO
60 RST Digital input Reset (active high)
55 XCK16M Digital Input 16.9MHz for verification
RF SERVO interface
40 UDGATE Digital Input Con trol signal for DVD-RAM
41 IDGATE Digital Input Control signal for DVD-RAM
38 VFO13 Digital Input DVD -RAM Header signal
RF
100 DVDA Analog input AC coupled DVD RF signal input A
99 DVDB Analog Input AC coupled DVD RF signal input B
98 DVDC Analog Input AC coupled DVD RF signal input C
97 DVDD Analog Input AC coupled DVD RF signal input D
95 DVDRFIN Analog Input AC coupled DVD RF signal input RFIN
96 DVDRFIP Analog Input AC coupled DVD RF signal input RFIP
94 CDA Analog Input AC coupled CD RF signal input A
93 CDB Analog Input AC coupled CD RF signal input B
92 CDC Analog Input AC coupled CD RF signal input C
91 CDD Analog Input AC coupled CD RF signal input D
90 OSN Analog RF Offset cancellation capacitor connecting
89 OSP Analog RF Offset cancellation capacitor connecting
85 CEQP Analog RF Offset cancellation capacitor connecting
84 CEQN Analog RF Offset cancellation capacitor connecting
88 RFGC Analog RF AGC loop capacitor connecting for DVD -ROM
14
PRELIMINARY, SUBJ ECT TO CHANGE WITHOUT NOTICE MTK CONFIDENTIAL, NO DISCLOSURE
87 RFGCU Analog RF AGC loop capacitor connecting for DVD -RAM
86 RFGCI Analog RF AGC loop capacitor connecting for DVD -RAM
101 MA Analog Input DC coupled DVD-RAM main-beam RF signal input A
102 MB Analog Input DC coupled DVD-RAM main-beam RF signal input B
103 MC Analog Input DC coupled DVD-RAM main-beam RF signal input C
104 MD Analog Input DC coupled DVD-RAM main-beam RF signal input D
105 SA Analog Input DC coupled DVD -RAM sub-beam RF signal input A
106 SB Analog Input DC coupled DVD-RAM sub-beam RF signal input B
110 SC Analog Input DC coupled DVD-RAM sub-beam RF signal input C
111 SD Analog Input DC coupled DVD-RAM sub-beam RF signal input D
108 IR Analog External current bias resistor (R=20K)
119 AGC1 Analog Wobble AGC loop1 capacitor
121 AGC2 Analog Wobble AGC loop2 capacitor
122 AGC3 Analog Wobble AGC loop3 capacitor
MT1336
127 RFSUBO Analog output Header push-pull RF output signal
1 WOBSO Digital output Wobble signal output
6 RFOP Analog output RF positive output
7 RFON Analog output RF negative output
TRACKING ERROR
32 DPFN Analog DPD amplifier negative input
33 DPFO Analog DPD amplifier output
61 DPDMUTE Digital input DPD mute control input
116 TNI Analog Input 3 beam satellite PD signal negative input
115 TPI Analog Input 3 beam satellite PD signal positive input
21 TEO Analog Output Tracking error output
FOCUSING ERROR & RF LEVEL & CENTRAL SERVO SIGNAL
112 CDFOP Analog Input CD focusing error positive input
113 CDFON Analog Input CD focusing error negative input
18 FEO Analog Output Focusing error output
19 LVL Analog Output RF level output
20 CSO Analog output Central servo signal output
ALPC
15
PRELIMINARY, SUBJ ECT TO CHANGE WITHOUT NOTICE MTK CONFIDENTIAL, NO DISCLOSURE
MT1336
124 MDI1
125 LDO1 Analog Ou tput Laser driver output
123 MDI2
126 LDO2 Analog Output Laser driver output
RF RIPPLE
26 CRTP Analog RF top envelop filter capacitor connecting
27 CRTPLP Analog Defect level filter capacitor connecting
25 HRFRP Analog output High frequency RF ripple output or Blank detector’s output
24 LRFRP Analog output Low frequency RF ripple output
POWER
67, 69 AVDD Power Master PLL Filter power
65, 73 AGND GND GND for Master PLL Filter
64 AVDD Power DPD Power
62 AGND GND DPD GND
109 AVDD Power RF path Power
107 AGND GND RF path GND
Analog Input
Analog Input
Laser power monitor input
Laser power monitor input
114 SVDD Power Servo Power
117 SGND GND Servo GND
2,120 WAVDD Power Wobble Power
128,118 WAGND GND Wobble GND
5 AVDDO Power Power for RF output
8 AGNDO GND GND for RF output
14 AVDDT Power Power for Trimming PAD
12 AGNDT GND GND for Trimming PAD
22 VDDP Power Peak Detection Power
31 GNDP GND Peak Detection GND
37,54 VDD Power Serial I/O Power
39,57 GND GND Serial I/O GND
REFERENCE VOLTAGE
16 VREFO Analog output Reference voltage 1.4V
15 V2REFO Analog output Reference voltage 2.8V
17 V20 Analog Output Reference voltage 2.0V
16
PRELIMINARY, SUBJ ECT TO CHANGE WITHOUT NOTICE MTK CONFIDENTIAL, NO DISCLOSURE
ALPC TRIMMING
9 TM1 Analog input Trimming pin for ALPC1
10 TM2 Analog input Trimming pin for ALPC1
11 TM3 Analog input Trimming pin for ALPC2
13 TM4 Analog input Trimming pin for ALPC2
HIGH SPEED TRACK COUNTING
29 TRLP Analog Low-pass filter capacitor connecting
28 TRLPA Analog Low-pass filter capacitor connecting
30 HTRC Digital output High speed track counting digital output
PCS
74 HALLSIN Analog input Negative input of amplifier for hall sensor signal
75 REFSIN Analog input Positive input of amplifier for hall sensor signal
76 SINPHI Analog output Amplifier output for hall sensor signal
MT1336
71 HALLCOS Analog input Negative input of amplifier for hall sensor signal
72 REFCOS Analog input Positive input of amplifier for hall sensor signal
70 COSPHI Analog output Amplifier output for hall sensor signal
FOR MONITOR ONLY
81
80
66 VCON Analog output
77 SWO Analog output Output from mux of SW1 & SW2
78 SW2 Analog input External input for servo input select
79 SW1 Analog input External input for servo input select
FOR SERIAL I/O
42
43 IO1
44 IO2
45 IO3
46 IO4
MON Analog output
MOP Analog output
IO0
47 IO5
17
PRELIMINARY, SUBJ ECT TO CHANGE WITHOUT NOTICE MTK CONFIDENTIAL, NO DISCLOSURE
48 IO6
49 IO7
50 IO8
51 IO9
52 IOA
53 IOB
MT1336
18
8.2 MT1379
Specifications are subject to change without notice
n Super Integration DVD player single chip
§
Servo controller and data channel processing
§
MPEG-1/MPEG-2/JPEG video decoding
§
Dolby AC-3/DTS/DVD-Audio audio decoding
§
Unified track buffer and A/V decoding buffer
§
Video processing for scaling and video quality enhancement
§
OSD & Sub-picture decoding
§
Built-in clock generator
§
Built-in TV encoder
§
Built-in progressive video output
§
Video input port and audio/SPDIF input port
n Speed Performance on Servo and Decoding
§
DVD-ROM up to 8XS
§
CD-ROM up to 24XS
§
Built-in a frequency programmable clock to µP and RSPC Decoder to optimize the performance over power
n Channel Data Processor
§
Provides interface with analog front -end processor
§
Analog data slicer for small jitter capability
§
Built-in high performance data PLL for channel data demodulation
§
EFM/EFM+ data demodulation
§
Enhanced channel data frame sync protection & DVD-ROM sector sync protection
n Servo Control and Spindle Motor Control
§
Programmable frequency error gain and phase error gain of spindle PLL to control spindle motor on CLV and CAV mode
§
Provide a varipitch speed control for CLV and CAV mode
§
Built-in ADCs and DACs for digital servo control
§
Provide 2 general PWM
Progressive Scan DVD Player Combo Chip
§
Tray control can be PWM output or digital output
§
Built-in DSP for digital servo control
n Host Micro controller
§
Built-in 8032 micro controller
§
Built-in internal 373 and 8-bit programmable
MT1379
lower address port
§
1024-bytes on-chip RAM
§
Up to 2M bytes FLASH -programming interface
§
Supports 5/3.3-Volt. FLASH interface
§
Supports power-down mode
§
Supports additional serial port
n DVD-ROM/CD-ROM Decoding Logic
§
Supports CD-ROM Mode 1, CD-ROM XA Mode 2 Form 1, CD-ROM XA Mode 2 Form 2, and CD -DA formats
§
High-speed ECC logic capable of correcting one error per each P -codeword or Q-codeword
§
Automatic sector Mode and Form detection
§
Automatic sector Header verification
§
8-bit counter for decode completion check
§
Programmable descrambling and error correction schemes
§
Automatically repeated error corrections
§
8-bit C2 Pointer counter
§
Decoder Error Notification Interrupt that signals various decoder errors
§
Provide error correction acceleration
n Buffer Memory Controller
§
Supports 16Mb/32Mb/64Mb/128Mb SDRAM
§
Supports 16-bit/32-bit SDRAM data bus interface
§
Build in a DRAM interface programmable clock to optimize the DRAM performance
§
Provide the se lf-refresh mode SDRAM
§
Programmable DRAM access cycle and refresh
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