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Rockchip RK32 Series Hardware Design Manual

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RK3288 Hardware Design Guide
RK3288
Hardware
Design Guide
Revision 1.2
Jun.18, 2014

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Summary of Contents for Rockchip RK32 Series

  • Page 1 RK3288 Hardware Design Guide RK3288 Hardware Design Guide Revision 1.2 Jun.18, 2014...
  • Page 2 RK3288 Hardware Design Guide Revision History Date Revision Description 2014-12-15...

  • Page 3: Table Of Contents

    RK3288 Hardware Design Guide Table of Contents Table of Contents ..................... 3 Warranty Disclaimer ....................5 1 RK3288 Brief Introduction ..................6 1.1 Chip Overview ................... 6 1.2 Chip Feature ....................7 2 Selection of Reference Schematic ................10 3 PCB Design ......................14 3.1 Structure....................
  • Page 4 RK3288 Hardware Design Guide 19.2 PCB Layout ..................... 88 20 eFUSE ......................90 20.1 Schematic ....................90 21 MAC ........................ 91 21.1 Schematic ....................91 21.2 PCB Layout ..................... 94 22 2G/3G/4G ......................99 22.1 Schematic ....................99 22.2 PCB Layout ................... 100 23 WIFI &...

  • Page 5: Warranty Disclaimer

    Rockchip Electronics Co., Ltd’s product could create a situation where personal injury or death may occur, should buyer purchase or use Rockchip Electronics Co., Ltd’s products for any such unintended or unauthorized application,...

  • Page 6: Rk3288 Brief Introduction

    RK3288 Hardware Design Guide 1 RK3288 Brief Introduction 1.1 Chip Overview RK32xx is a high-performance processor for high-end tablet, laptop and intelligent monitor, and it is also one of the most powerful solution for 4Kx2K TV box. RK3288 integrates quad-core Cortex-A17 with separately Neon and FPU coprocessors, shared 1 MB L2 Cache.
  • Page 7 RK3288 Hardware Design Guide 1.2 Chip Feature Quad-core Cortex-A17  Separately Integrated Neon and FPU per CPU  32KB/32KB L1 ICache/DCache per CPU  Unified 1MB L2 Cache  LPAE (Large Physical Address Extensions) , Support up to 8GB address space ...
  • Page 8 RK3288 Hardware Design Guide Dual-channel input for front and rear camera  Dual-channel MIPI-CSI2 interface with 4-lane per channel  8/10/12 bits standard DVP interface  Maximum 5Mpixel for front camera  Maximum 13Mpixel for rear camera with high-performance ISP ...
  • Page 9 RK3288 Hardware Design Guide 100M/1000M RMII/RGMII Ethernet interface  Dual channel TS stream interface, descramble and demux support  Smart Card interface  GPS baseband interface  PS/2 master interface  5 UART, 3 SPI (master or slave), 6 I2C(up to 4Mbps), 5 PWM ...

  • Page 10: Selection Of Reference Schematic

    RK3288 Hardware Design Guide 2 Selection of Reference Schematic RK3288 integrates multiple function modules, basically each module has its own power supply, and power pins of each module should be packaged within its own domain. In order to avoid too many schematic versions as well as repeated corrections, function modules is designed separated pages and groups, and add some options in common use, as shown in Fig 2-1.
  • Page 11 RK3288 Hardware Design Guide For example, customer has below requirement: RK3288 Sample Plan One DC 5V Fire bull Charger USB Charger Battery 1-Cell DRAM 1GB,4 x 16bit DDR3 FLASH 8GB,Emmc 10.05'' eDP,2560 x 1600 Front Camera OV2659 Rear Camera MIPI FX288A R2.0(OV8825) HDMI Yes(Type C) USB OTG 2.0...
  • Page 12 RK3288 Hardware Design Guide Fig 2-2 Tips: If 9.7’’ eDP screen is adapted, please chose 2-cell battery to ensure stability of system and display. For other screens, suggest to use 1-cell battery for lower cost. Another example, customer raises below request: RK3288 Sample Plan Two DC 5V Fire Bull Charger USB Charger...
  • Page 13 RK3288 Hardware Design Guide TF Card Audio Codec Microphone Audio Jack Vibration G-Sensor Gyroscope WIFI Module 802.11 a/b/g/n, BT 4.0 Efuse Based on this requirement, complete schematic can be finalized by omitting unnecessary parts as shown in below Fig 2-3. Fig 2-3...

  • Page 14: Pcb Design

    RK3288 Hardware Design Guide 3 PCB Design 3.1 Structure PCB design is quite crucial to ensure stability and performance of product, more attention should be paid to this part. To ensure higher performance of RK3288, it is recommended to use 6 layers or above PCB stack structure design with double-faced SMT. Suggest to take 1oz copper foil to maximize PCB thermal dissipation.

  • Page 15: Design Rule

    RK3288 Hardware Design Guide FR-4 Signal2 core FR-4 Gnd2 Adjust according to FR-4 thickness Power core FR-4 Signal3 FR-4 Signal4 FR-4 Bottom Gnd3 Plating to 1oz 3.2 Design Rule In the product planning state, recommend to choose the design in which capacitors ...
  • Page 16 RK3288 Hardware Design Guide Main components(CUP,DDR) and signal traces are mainly placed on TOP or BOTTOM  layer; Small components like filter capacitor are mainly placed on TOP or BOTTOM layer; big  components can be placed on these two layers as well if structure is allowed. Shielding: ...
  • Page 17 RK3288 Hardware Design Guide Fig 3-3 The width of copper trace is recommended to be 4mils;  The signal fan from CPU pins should be in alignment and reasonable as shown in  below Fig: Fig 3-4 Tips： 3W Principle：Guarantee enough clearance to reduce trace to trace crosstalk. If the ...

  • Page 18: Test Point

    RK3288 Hardware Design Guide 3.3 Test Point Add test points on EMMC_CLKO, FLASH_CLE signal for eMMC, Nand Flash, it will be  more convenient to enter maskrom burning mode for debugging. Fig 3-5 Suggest to add signal test points to interfaces like camera, TP, LCM which is ...

  • Page 19: Silk-Screen And Decal

    RK3288 Hardware Design Guide 3.4 Silk-screen and Decal Add PCB name and layout data for searching and debugging;  Add components labels as many as possible for debugging;  Add silk-screen for key signals such as battery solder pins, connector pins, etc. ...

  • Page 20: Thermal Dissipation

    RK3288 Hardware Design Guide 4 Thermal Dissipation CPU is the maximum heat component on RK3288 production which is the main object for thermal dissipation processing. Other main heating components are PMIC, charger IC and its inductors, backlight IC and power inductors. In addition, power traces with large currents (trace from DC socket to charger IC, battery to VCC_SYS of PMU) will have thermal effect for whole machine.
  • Page 21 RK3288 Hardware Design Guide Place the thermal dissipation material on TOP surface of CUP and its corresponding  bottom area could transfer CPU heat to rear cover and LCD screen or middle frame, it will sharply reduce temperature of CPU. But for transfer heat to LCD screen, trade-off is necessary.
  • Page 22 RK3288 Hardware Design Guide Fig 4-3 Fig 4-4...
  • Page 23 RK3288 Hardware Design Guide Fig 4-5...

  • Page 24: Power

    RK3288 Hardware Design Guide 5 POWER 5.1 Schematic VDD_CPU and VDD_GPU are main power supply for CPU, the current peak will be up  to 4.4A/3.6A (CPU@1.6GHz, CPU@400MHz). Don't reduce the number of filter capacitors in reference design (capacitor value of VDD_CPU is 145uF, capacitor value of VDD_GPU is 66uF), and the large value capacitors should be placed on the reverse side or near CPU to ensure power ripple within 100mV, in case that power ripple is too large in condition of heavy load, as shown in Fig 5-1.
  • Page 25 RK3288 Hardware Design Guide Coupling capacitor of chip in schematic should be placed close to the pin of chip, as  shown in Fig 5-3, 5-4; Fig 5-3 Fig 5-4...

  • Page 26: Pcb Layout

    RK3288 Hardware Design Guide 5.2 PCB Layout Please fully comply with RK power layout design as it is really crucial to the stability and performance of products. A large area of power copper between PMIC power output and CPU power pin can enhance the current capacity and reduce the trace impedance, as shown in Fig 5-5.
  • Page 27 RK3288 Hardware Design Guide Lighted trace in the figure connected to the FB end of DC/DC, is the feedback trace which should be routed in parallel with power layer without any interference by other high-speed signal traces in the same layer or other layers. Fig 5-7 The large capacitors should be located in far-end（load end）of VDD_CPU, VDD_GPU, VDD_LOG, VCC_DDR power;...
  • Page 28 RK3288 Hardware Design Guide Placing enough GND vias with cross-link connection under CPU can improve the quality of power supply, enhance thermal dissipation and stability of system. The size of vias under CPU is 0.2mm/0.35mm (inner/outer diameter), as shown in Fig 5-9. Fig 5-9 Tips：...

  • Page 29: Syr827, Syr828 Pcb Layout Guide

    RK3288 Hardware Design Guide PCB trace area need 312.5mil, bigger copper width is necessary to further reduce temperature rise. How to calculate vias amount in connection between power layers?  Above formula applies to calculate current capability for single via as well, but the copper width should be: L=πR, "R"...
  • Page 30 RK3288 Hardware Design Guide Fig 5-11 Reference value of SYR82X DCDC inductor: inductance is 0.22uH, saturation current is greater than 5A, DC current resistance is less than 20mR; In order to improve output power, suggest to use inductor the value of which ranges from 0.22uH to 0.24uH. In actual test, if 0.22uH inductor is used, power ripple is 20mV less than 0.33uH Fig 5-12 (Model: SYR827, the corresponding power is VDD_CPU)

  • Page 31: Pmic Rc5T620

    RK3288 Hardware Design Guide 5.4 PMIC RC5T620 Suggest to use RC5T620 in 1-cell battery solution, as the cost is lower. However, try to avoid using it in the system of which the max current is over 5A (For 9.7'' eDP screen display in 1-cell battery solution, internal resistance of cell is 70mR, sample resistance from Coulomb Counting IC is 20mR, internal resistance of route management is 60mR, the total volume will easily exceed 150mR, 150mR*3.5A=0.525V, which means the huge voltage will be lost in...
  • Page 32 RK3288 Hardware Design Guide Fig 5-15 RC5T620 has two sample resistors: one of them is sample resistor of charging current as shown in Fig 5-16, both ends of R2166 should be differentially routed to pads of C4 and C5, as shown in blue trace in Fig 5-17, notice don't connect C5 to B5, otherwise charging current will be too small.
  • Page 33 RK3288 Hardware Design Guide Fig 5-17 Another sample resistor is R2119 on battery terminal as shown in Fig 5-18, R2120 must be placed close to R2119 in Layout, R2120 can't be connected to GND, and it should be separated from GND copper by keepout and be routed to pad of R2119 separately. ICP and ICM will be differentially routed to pads of E3 and D3, as shown in Fig 5-19.
  • Page 34 RK3288 Hardware Design Guide 32.768KHz Crystal should be surrounded by GND, take the second layer as reference ground plane, make sure no other traces will be routed on this plane in case of interference to clock, as shown in Fig 5-20. 。...
  • Page 35 RK3288 Hardware Design Guide Sampling point FB of DCDC should be located on the end of capacitor, don't place it on both ends of inductor, as OUT3 trace shown in Fig 5-22. Fig 5-22 Place charger IC close to battery to reduce internal resistance to shorten charging time. 5.5 PMIC ACT8846 There is two sample resistors in RK818, one is the current sample resistor R2340 close to battery, and the other one is sample resistor R2342 on differential lines, as shown in Fig 5-23.
  • Page 36 RK3288 Hardware Design Guide Fig 5-24 To improve the sampling accuracy of battery, capacitor C2363 in feedback circuit should be placed close to the pin of RK818, as shown in Fig 5-25. Fig 5-25...
  • Page 37 RK3288 Hardware Design Guide To guarantee the performance and heat dissipation of RK818, please connect it to GND well, and the GND pins should be connected to ePAD under the chip, and enough via holes should be placed around ePAD, as shown in Fig 5-26. Fig 5-26 The clearance between inductors SW5 and SW6 should be more than 1.6 mm, or high voltage caused by mutual-inductance between inductors will lead to RK818 failure.
  • Page 38 RK3288 Hardware Design Guide Fig 5-28 The traces of power feedback lines must be surrounded by output power plane, or crosstalk from other signals will cause voltage instability and oscillation，as shown in Fig 5-29. Fig 5-29 All input and output capacitors should be placed close to RK818, and enough via holes should be placed around them to guarantee the signal return path, especially to input and output capacitors of large current power supply.
  • Page 39 RK3288 Hardware Design Guide Fig 5-30...

  • Page 40: Gpio

    RK3288 Hardware Design Guide 6 GPIO 6.1 Schematic In actual produce design, if GPIO defined by RK need to be revised, notice to match IO level with GPIO pull-up and pull- down features, otherwise it may cause abnormal operation.RK3288 GPIO can be pulled up or down as an input, and it can be configurable and closed after power on, as shown in figure 6-1, “_d”...
  • Page 41 RK3288 Hardware Design Guide All function controllers with their own power domain could be supplied either power or no power, in order to allocate resources on demand and reduce power consumption. No power supplied to the module which is not in using to reduce power consumption except API02_VDD, as shown in Fig 6-3.

  • Page 42: Cpu&Pmu

    RK3288 Hardware Design Guide 7 CPU&PMU 7.1 Schematic RK3288 only need an external 24MHz crystal as shown in Fig 7-1. This crystal Y1100 requires frequency offset =<±20ppm, temperature offset =<±30ppm. The value of load capacitors C1101, C1102 should be selected according to actual load capacitance of crystal. 8pF is the corresponding value of crystal selected by us, it is not the common value.

  • Page 43: Pcb Layout

    RK3288 Hardware Design Guide 7.2 PCB Layout No traces are allowed on surface layer and second layer right under 24MHz crystal. If OSC_XVSS is used as clock ground, crystal should be placed close to CPU, and it is reference plane for crystal route, as shown in Fig 7-2. Fig 7-2 If GND is used as clock ground, crystal should be placed close to CPU and more via holes need to be placed around crystal pin and load capacitor, as shown in Fig 7-3.

  • Page 44: Schematic

    RK3288 Hardware Design Guide 8 DDR Controller & DRAM 8.1 Schematic RK3288 has dual channel 32bits DDR controllers, DDR0 and DDR1. They share the  same configuration. Taking DDRO channel for example: Four groups of data cables （DATA0—DATA31） , four DATA MASKS （DQM0--DQM3） ， ...
  • Page 45 RK3288 Hardware Design Guide Fig 8-1 For DDR3, four groups data (GROUP A, B, C, D) can be exchanged in group. Moreover,  each data in GROUP A/B/C/D (eg. DDR0_D0~D7) also can be exchanged with each other, as shown in Fig 8-2：...
  • Page 46 RK3288 Hardware Design Guide Fig 8-2 For LPDDR2/3, DDR0 channel GROUP A can’t be exchanged in group, and each data in  it (DDR0_D0~D7) also cannot be exchanged with each other. DDR0 channel GROUP A (DDR0_D0~D7) must match A or B channel (DDR0_D0~D7) in LPDDR2/3, meanwhile DDR0_D0~D7 is one-to-one correspondence.
  • Page 47 RK3288 Hardware Design Guide DDRIO_RETLE is the input pin of enabled signal for DDR controller retention latch.  DDR PHY can run into self-refresh module to reduce the power consumption, and the voltage level of the DDR_RETLE should be keep the same with VCC_DDR. Match the voltage level by two divider resistors R1204 (120K) and R1206 (120K) for DDR3 mode, as shown in Fig 8-4.
  • Page 48 RK3288 Hardware Design Guide For the topological structure which has branches, such as DDR3, place a NC resistor  0402 between DDR_CLK and DDR_CLKn, and it should be placed close to the branch point of DDR clock trace as possible. Fig 8-6 VCC_DDRC is turned off by MOS Transistor in order to reduce power consumption in ...

  • Page 49: Pcb Layout（Ddr0 Channel,Ddr1 Channel

    RK3288 Hardware Design Guide Fig 8-8 8.2 PCB Layout（DDR0 channel, DDR1 channel） Please follow below recommendations strictly to get the better performance: Trace width and safe clearance  The trace width of all signals related to DDR should be set to 4mils. ...
  • Page 50 RK3288 Hardware Design Guide Make sure that a complete layer must be applied to reference for all DDR signals,  in order to get the minimum return path impedance, and get the continuity of impedance. Prohibit all DDR signals bridge on different power layers. ...
  • Page 51 RK3288 Hardware Design Guide Fig 8-9 Ensure vias in signal trace connection between layers are evenly distributed, and  safe clearance between two vias should be equal to or more than 32mils. The size of vias is 0.2mm for drill, and 0.4mm for diameter. ...

  • Page 52: Flash Control & Memory

    RK3288 Hardware Design Guide 9 Flash control & Memory 9.1 Schematic RK3288 supports Nand Flash, eMMC and tSD, etc. If Nand Flash, tSD Flash is used, controller and its power supply VCC_FLASH should be 3.3V (R1300 is NC as shown in Fig 9-1). For eMMC in different versions, controller and its power supply VCC_FLASH may be 1.8V (eMMC4.1 above version) or 3.3V, please adjust it based on Datasheet, and verify FLASH0_VOLTAGE_SEL pull-up and pull-down status as shown in Table 9-1.
  • Page 53 RK3288 Hardware Design Guide Fig 9-1 If Nand Flash is in use, schematic diagram is shown as Fig 9-2. For Nand Flash mode in Toshiba and SanDisk DDR, VCCQ1 and VCCQ4 need to be connected to VCC_IO for power supply, which means R4001, R4003, R4004, R4005 should be SMT with OR resistor. Fig 9-2 If eMMC Flash is in use as shown in below Fig 9-3.
  • Page 54 RK3288 Hardware Design Guide Fig 9-3 eMMC LDO power supply is 1.8V as default, as shown in Fig 9-4, it can be compatible with components below eMMC 4.1, which means product materials have more choices. Fig 9-4 For better to enter MaskRom hardware burning mode(need update LOADER) in Developing stage, FLASH_CLE should reserve test point when Nand Flash is used, same for EMMC_CLKO when eMMC Flash is used as shown in Fig 9-5, 9-6.
  • Page 55 RK3288 Hardware Design Guide Fig 9-6 9.2 PCB Layout Nand Flash and eMMC Flash could be switched through double Layout. Keep-out frame should be added to pads when pouring copper under eMMC chip, in order to avoid pseudo soldering due to fast thermal dissipation through GND copper, as shown in Fig 9-7. All eMMC Flash data traces are required to be surrounded by GND, and eMMC signal traces should be equal-length with difference between any two limited in 400mil, or else it will restrain frequency in high-speed mode.
  • Page 56 RK3288 Hardware Design Guide Fig 9-7 Fig 9-8...

  • Page 57: Tf Card

    RK3288 Hardware Design Guide 10 TF Card 10.1 Schematic The memory card socket adopted by reference diagram published by RK is TF card. If need to be changed to SD card, please note the package of socket. TF card is compatible with SD 2.0/3.0, module power supply VCCIO_S is configurable and the default voltage of VCCIO_SD and VCC_SD is 3.3V.
  • Page 58 RK3288 Hardware Design Guide 10.2 PCB Layout Capacitor C8106/C8107 should be placed close to SD socket pin VCC_SD. All SD data traces are required to be surrounded by GND, the same for CLK, which should be routed respectively. On the RK3288 platform, traces length of TF card should be limited within 12.4 inch. In order to improve stability and compatibility of SDIO, suggest to use the adaptive algorithms of driven strength and Timing Tuning.

  • Page 59: Usb & Hsic

    RK3288 Hardware Design Guide 11 USB & HSIC 11.1 Schematic RK3288 has 3 sets of USB interface in total, one of them is USB OTG, and the other two are USB HOST, as shown in Fig 11-1. USB OTG can detect USB_VBUS/USB_ID signal, support both Host and Device ...
  • Page 60 RK3288 Hardware Design Guide To reduce EMI, consider to reserve a common mode choke on signal traces. Choosing common mode choke or resister can be according to actual needs in debugging, as shown in Fig 11-2. Fig 11-2 11.2 PCB Layout Below points need to be considered on USB PCB Layout：...
  • Page 61 RK3288 Hardware Design Guide shown in Fig 11-4; If the trace is on PCB surface layer, it should be surrounded by GND, as shown in Fig 11-5; Fig 11-4 Fig 11-5 Take as less vias between different layers as possible, which will cause ...
  • Page 62 RK3288 Hardware Design Guide Fig 11-7...

  • Page 63: Saradc & Key

    RK3288 Hardware Design Guide 12 SarADC & Key 12.1 Schematic RK3288 adapt SARADC ADC_IN1 as input key-value sampling port, RECOVER mode is available ( don't need to update LOADER) as shown in Fig 12-1.Under the premise of system has a hardware, system will start up after pressing SW1500, and ADC_IN1 will keep OV level(maximum will not exceed 100mV), RK3288 will enter Rockusb burning mode.
  • Page 64 RK3288 Hardware Design Guide 12.2 PCB Layout Recommendations for Key PCB Layout: ESD protective component should be placed close to Key to fulfill electrostatic  protection as shown in Fig 12-2; Key-buffeting eliminated capacitor C1501 should be placed close to Chip; ...

  • Page 65: Dvp Interface & Camera

    RK3288 Hardware Design Guide 13 DVP Interface & Camera 13.1 Schematic DVP interface power domain supply DVPIO_VDD, in actual product design, IO power supply requirement (1.8V or 2.8V)should be based on Camera, chose a corresponding power supply and keep it in the same level with I2C pull-up level, otherwise it will cause Camera abnormal or disabled working status as shown in Fig 13-1.
  • Page 66 RK3288 Hardware Design Guide Fig 13-2 Recommendations for DVP SOC Camera Sensor usage: Suggest to connect Sensor output YUV data bit0-bit7 to RK3288 DVP interface  bit0-bit7; If front and back cameras are not requested to be working at the same time, suggest ...

  • Page 67: Pcb Layout

    RK3288 Hardware Design Guide Tips: MIPI 1Lane and 2Lane will directly affect the preview frame rate and the speed of  camera; If MIPI Camera Sensor need to be used ,it is recommended to refer to RK Verification  list: RK_Camera_Verification_List.xlsx, to make sure debugs have been passed at first;...

  • Page 68: Schematic

    RK3288 Hardware Design Guide 14 Display Interface 14.1 Schematic RK3288 support many video output mode such as Parallel RGB, LVDS, MIPI, eDP,  HDMI, etc. 1% accuracy reference resistor should be taken for MIPI, LVDS, HDMI PHY, as shown in Fig 14-1 to Fig 14-5. Fig 14-1...
  • Page 69 RK3288 Hardware Design Guide Fig 14-2 Fig 14-3...
  • Page 70 RK3288 Hardware Design Guide Fig 14-4 Fig 14-5 MIPI_TX_AVDD_1V8 and MIPI_TX/RX_AVDD_1V8 are the same group of power, they  share same power supply; When LVDS and RGB are using, LVDS_AVDD_1V0, LVDS_AVDD_1V8 and  LVDS_AVDD_3V3 need power supply; otherwise no power supply is needed, as shown in Fig 14-6;...
  • Page 71 RK3288 Hardware Design Guide Fig 14-6 In the RK3288, each display module has its own power supply, and power pins of each  module should be packaged within its own domain. No power supplied to the module which is not in using to reduce power consumption, as shown in Fig 14-7, 14-8; Fig 14-7...
  • Page 72 RK3288 Hardware Design Guide Fig 14-8 Make sure LCDC_VDD has regular power supply, or HDMI will not display, as pin V20  shown in Fig 14-9; Fig 14-9 As shown in Fig 14-10, decoupling capacitor of each module power should be placed ...

  • Page 73: Pcb Layout

    RK3288 Hardware Design Guide Differential signal is sensitive to traces parasitic capacitance, so low junction  capacitance (less than 1pF) should be selected as ESD protective component which conform to the specification on the signal path. 14.2 PCB Layout Signal connector should be placed close to chip, to shorten trace length; ...
  • Page 74 RK3288 Hardware Design Guide Fig 14-11 Coupling capacitor of eDP data output channel should be placed close to chip, as  shown in Fig 14-12; Fig 14-12...

  • Page 75: Schematic

    RK3288 Hardware Design Guide 15 LCM 15.1 Schematic eDP screen power consumption is big, a big current backlight IC should be used as shown in Fig 15-1. 9.7'' big screen should chose 2-cell battery solution with R5002 SMT; 7.85'' smaller screen can chose 1-cell battery solution with R5003 SMT.
  • Page 76 RK3288 Hardware Design Guide If dual MIPI screen is in use, take MIPI_TX as left output channel and MIPI_TX/RX as right output channel, which cannot be switched as shown in Fig 15-3, 15-4. If MIPI screen channels can be switched, this problem doesn't exist, for more details, please refer to chapter in datasheet about screen.
  • Page 77 RK3288 Hardware Design Guide Reserve CABC control circuit in MIPI, LVDS screen drive circuit is shown as in Fig 15-5. If CABC is not applied, resistor R5107, R5108, R5109, R5110 and inverter U5101 is not necessary in SMT, backlight voltage regulator circuit in Fig 15-6 can be used instead, which is controlled by CPU PWM, and if PWM duty ratio is higher, screen brightness is lower;...

  • Page 78: Pcb Layout

    RK3288 Hardware Design Guide Fig 15-7 15.2 PCB Layout High-speed signal trace design is referenced to section 12 of PCB Layout Backlight current-limiting resistors R5006, R5007 and power capacitor C5004 should be placed close to screen base as shown in Fig 15-8, 15-9. Fig 15-8 Fig 15-9...
  • Page 79 RK3288 Hardware Design Guide...

  • Page 80: Schematic

    RK3288 Hardware Design Guide 16 Debug 16.1 Schematic For convenience of online software debug, RK3288 has reserved a special debug Uart interface（UART2）; In actual product application, this interface is not suggested to be used for other functions, design is shown as in Fig 16-1. Fig 16-1 If level conversion chip RS232 is used, TXD, RXD direction is an important note.

  • Page 81: Audio Codec & Spdif

    RK3288 Hardware Design Guide 17 Audio Codec & SPDIF 17.1 Schematic CODEC I2S interface power supply region feeds APIO4_VDD, in practical produce design, actual IO power supply requirement based on Codec, choose a corresponding supply circuit (1.8V or 3.3V), and remains equal to pull-up level of I2C, otherwise it will cause abnormal working or halt working, as shown in Fig 17-1,17-2.
  • Page 82 RK3288 Hardware Design Guide Divider resistors R7010, R7016 of MIC should be chosen based on electret microphone specification as shown in Fig 17-3. Fig 17-3 If Codec chooses decoupling capacitor for output, in ideal condition, 100uF capacitor can ensure flatness of frequency response test curve. If smaller decoupling capacitors are used for the sake of lower cost, low-frequency response deviation may occur, as EC7000, EC7001 shown in Fig 15-4.
  • Page 83 RK3288 Hardware Design Guide 17.2 PCB Layout Line width of all Codec power supply is requested to be above 15mils，VCC_SPK trace  width should be above 30mils. Each analog signals input/output from Codec, including HP out, LINE in, LINE out, MIC ...

  • Page 84: Schematic

    RK3288 Hardware Design Guide 18 Touch Panel 18.1 Schematic Please pull up resistor from touch panel I2C to TP power supply VCC_TP to avoid increasing extra power consumption by power electric leakage from I2C bus to TP screen. Fig 18-1 Pay attention to the withstand voltage of Charge Pump capacitor of TP IC, and the capacitor should be placed close to IC pins, as shown in Fig 18-2.
  • Page 85 RK3288 Hardware Design Guide 18.2 PCB Layout It is easy to destroy data cables of CPU by ESD of big screen, so sensor signal lines need to be protected. In the design of TP onboard，sensor and driver signals should be separated by GND. Fig 18-3...
  • Page 86 RK3288 Hardware Design Guide 19 Sensor 19.1 Schematic The power domain of VCC Supply and VCCIO Supply of sensor may be different, please make sure the pull-up power of I2C1 bus is in accordance with VCCIO supply of sensor, otherwise voltage matching is required. Fig 19-1 Hall Sensor contains unipolar and all-pole.
  • Page 87 RK3288 Hardware Design Guide Fig 19-2 Motor is inductive device. It's necessary to add diode and pay attention to its direction. Fig 19-3 The gravity sensor includes three compatibility design. SMT can be according to actual needs to meet different compliance requirements.
  • Page 88 RK3288 Hardware Design Guide Fig 19-4 19.2 PCB Layout Users' habits must be considered when the light sensor is placed on PCB, the best  placement zone is near the front camera and don't place any other luminous bodies near it, as shown in Fig 19-5. Fig 19-5 Illumination value received by light sensor is determined by the size of TP silk screen ...
  • Page 89 RK3288 Hardware Design Guide Fig 19-6 Magnetic sensor and Hall sensor should not be placed in the shell cover and should  keep them away from magnetic field, easy magnetization devices, large current devices, etc. such as handset, loudspeaker, motor, camera, large value inductor, etc. Please pay attention to the placement direction of the gravity sensor.

  • Page 90: Efuse

    RK3288 Hardware Design Guide 20 eFUSE 20.1 Schematic If customer need to burn the eFUSE embedded in RK3288, need add eFUSE power supply circuit as shown in Fig 20-1. This parts of circuit can be omitted if it is not essential, Suggest customers to reserve two test points on PCBA so as to complete burning eFUSE through fixture, thus reducing costs.

  • Page 91: Schematic

    RK3288 Hardware Design Guide 21 MAC 21.1 Schematic Ethernet and FLASH1 are reusable, if Ethernet is used, then FLASH1 can't be used at the same time. MAC supports RMII and RGMII these two interfaces, Fig 21-1 is for Gigabit RGMII interface, Fig 21- 2 is for 100M RMII interface.
  • Page 92 RK3288 Hardware Design Guide Fig 21-2 As shown in Fig 21-3, the value of 25MHz crystal load capacitors（C251,C252）should be base on nominal loading capacity of the adopted crystal, 12pF matches the crystal we have chosen, it is not the common value. Fig 21-3 L9 inductor in Fig 21-4 should meet the following conditions: IDC>=600mA；...
  • Page 93 RK3288 Hardware Design Guide Fig 21-4 To pass EMI test, OR resistor concatenating differential line should be considered to be changed to common mode choke (Common mode choke is 90-120ohm), as shown in Fig21-5. Fig 21-5 Suggest to use RJ45 base with metal shield. If RJ45 has LED light, LED0-2 need to be reserved a 100pF capacitor to earth reduce EMI, as shown in Fig 21-6.

  • Page 94: Pcb Layout

    RK3288 Hardware Design Guide Fig 21-7 Network transformer must meet following conditions as shown in Fig 21-8: Fig 21-8 21.2 PCB Layout The whole layout must follow below principles: The closer PHY has been put to RK3288, the EMI will be less, which means RGMII ...
  • Page 95 RK3288 Hardware Design Guide Fig 21-9 If RJ45 and transformer are separate component, 10/100/1000M network  transformer should be placed close to RJ45, and if there is any other transformer besides, the best way is to put them as an 90 degree angle. 4 pairs of MDI differential traces should be equal-length with difference in pair limited ...
  • Page 96 RK3288 Hardware Design Guide Fig 21-10 As shown in Fig 21-11, R146 should be placed close to PHY, and should be surrounded  by GND, with as short trace as possible, and have a complete reference plane. Fig 21-11 RSET resistor R151 must be placed close to PHY(less than 800mil), and keep it far ...
  • Page 97 RK3288 Hardware Design Guide Fig 21-12 As shown in below Fig, concatenating resistor should be located close to PHY to reduce  EMI. MAC_RXCLK must be surrounded by GND.  Distance of all other signals should meet 3W principle as shown in below Fig. ...
  • Page 98 RK3288 Hardware Design Guide Fig 21-13 Take note of internal Switching Regulator LAYOUT：  Capacitors C270, C271 of Power supply VDDREG should be placed close to PIN44  and PIN45, line width should be less than 40mil. Place L9, C260 close to PIN48, line width should be less than 60mil. ...

  • Page 99: 3G/4G

    RK3288 Hardware Design Guide 22 2G/3G/4G 22.1 Schematic PIN APIO5_VDD is the power domain for GPIO, in actual product design, IO power is supplied based on 4G module, make sure GPIO level can match 4G module as shown in Fig 22-1, 22-2.
  • Page 100 RK3288 Hardware Design Guide Fig 22-3 22.2 PCB Layout USIM card socket should be placed close to 3G module, and the traces should be short  and thick. The whole trace of the SCLK and SIO signals should be surrounded by GND. The transient current can reach more than 1.8A when the 3G module is transmitting ...
  • Page 101 RK3288 Hardware Design Guide Fig 22-5 Because of the large interference by EMC of switching power supply. Please keep the  power traces and other high-speed signals away from the antenna area. The shield cover needs to be added to PCB if there isn’t a shield cover in the module, ...
  • Page 102 RK3288 Hardware Design Guide Fig 22-7...

  • Page 103: Wifi & Bt

    RK3288 Hardware Design Guide 23 WIFI & BT 23.1 Schematic RK3288 supports WIFI/BT module with SDIO 3.0. If WIFI/BT module with SDIO, UART is used, power supply APIO3_VDD of SDIO, UART controller must keep the same with VIO module, as shown in Fig 23-1, 23-2. Tips：...
  • Page 104 RK3288 Hardware Design Guide Fig 23-3 Fig 23-4 Please note that the ESR of crystal oscillator should be less than 60ohm and its frequency deviation error should be less than 20ppm. Please choose the appropriate value of the matching capacitor of crystal oscillator according to the crystal oscillator specification to avoid frequency deviation is too large to work normally (such as the numbers of hot spots is too little), as shown in Fig 23-5.
  • Page 105 RK3288 Hardware Design Guide Fig 23-6 The range of VBAT power supply voltage of AP6XXX is from 3.0V to 4.8V, and the power supply current is at least 400 mA. Fig 23-7 23.2 PCB Layout WIFI module should keep away from high speed devices, such as DDR, etc. ...
  • Page 106 RK3288 Hardware Design Guide As shown in Fig 23-8, 4.7uF decoupling capacitors C6100, C6111 need to be placed  close to the VBAT and VDDIO power pins of module and to be placed on the same plane with the module as much as possible. Fig 23-8 As shown in Fig 23-9, 23-10 the inductor L6100 and the...
  • Page 107 RK3288 Hardware Design Guide Fig 23-10 The first floor under the module should reserve a complete GND without other signal  traces，as shown in Fig 23-11. Fig 23-11 Reserve a complete GND under the crystal oscillator without other signal traces，and ...
  • Page 108 RK3288 Hardware Design Guide Fig 23-12 Impedance should be considered in the design of the width of antenna and microstrip,  the impedance requirement is Z=50±10ohm. Under the traces, a complete reference plane is needed to serve as a reference GND to RF signal. The longer 3G trace is, the greater energy lose.
  • Page 109 RK3288 Hardware Design Guide Fig 23-13 Fig 23-14...
  • Page 110 RK3288 Hardware Design Guide Fig 23-15 Suggest that the placement of module and antenna can refer to Fig 23-16. Don't put  them in the place where hands hold, and keep them away from the metal devices as far as possible. Impedance matching is required for antenna.
  • Page 111 RK3288 Hardware Design Guide The antenna feeder traces can’t be too long in case of excessive RF energy loss. The feeder length is suggested to be less than 7 cm, and don’t strip too much shielding mesh when stripping feeders, which will cause the discontinuousness of 50ohm impedance, as shown in Fig 23-17.

  • Page 112: Gps

    RK3288 Hardware Design Guide 24 GPS 24.1 PCB Layout GPS belongs to the sensitive device, which is easily interfered by magnetic field .The improper layout of structure and space may affect the performance of GPS, such as loudspeaker, battery, metal device, button, connector, LCD, touchable FPC and all kinds of long fly lines.
  • Page 113 RK3288 Hardware Design Guide Shield cover, conductive fabric and EMI gasket is necessary to ensure the performance of GPS. For the GPS internal layout, place the related devices of the RF circuits as compact as possible, such as LNA, SAW Filter, match circuit, etc. In order to reduce the attenuation and interference, the path between antenna feed and RF_IN in the IC should be as short as possible, as the highlight yellow traces shown in Fig 24-2.

  • Page 114: Schematic

    RK3288 Hardware Design Guide 25 NFC 25.1 Schematic NFC technology uses loop-antenna, the basic sensing distance of which is about 2 cm, and the working current is about 200mA. RSM1 and RSM2 should use the packaging type of 0603. And the trace length of antenna can’t be shorter than 12mil; Fig 25-1 Put the NFC antenna on battery and use special absorbing material between them in order to avoid affecting the sensing distance of antenna.
  • Page 115 RK3288 Hardware Design Guide Fig 25-3...

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