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Rohm BD71837MWV, Design Manual

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Application Note 

BD71837MWV Platform Design Guide 

© 2018 ROHM Co., Ltd.

 

No. 61AN002E Rev.001

 

May.2018

 

 

Figure 4.11 BD71837MWV Reference Board Outline (Layer 6) 

 

 

 

 

 

WDOG_B 

SD_VSELECT 

RTC_RESET_B 

Layer 6 is used for routings of each feedback line and I/Os. 

IRQ_B 

POR_B 

C32K_OUT 

Summary of Contents for BD71837MWV

Page 1: ...ied BD71837MWV Platform Design Guide provides the guideline for designing PCB including recommendation for the PCB layer stack up the components placement and the PCB routings To reduce the risk that...

Page 2: ...Layout Guideline 20 5 2 1 Overall Component Placement 20 5 2 2 Large Current Loop 21 5 2 3 Power GND 22 5 2 4 VSYS Power supply for BD71837MWV analog circuit 22 5 2 5 Other Signal Pattern Precautions...

Page 3: ...mple 36 5 3 8 2 Schematic Checklist 36 5 3 8 3 Layout Example 37 5 4 LDOs 38 5 4 1 LDO1 NVCC_SNVS 38 5 4 2 LDO2 VDD_SNVS 38 5 4 3 LDO3 VDDA_1P8 VDDA_DRAM 38 5 4 4 LDO4 VDDA_0P9 38 5 4 5 LDO5 1P8_PHY 3...

Page 4: ...ation Note BD71837MWV Platform Design Guide 2018 ROHM Co Ltd No 61AN002E Rev 001 May 2018 2 Revision History Table 2 1 Revision History Revision Number Description Revision Date 001 Initial release Ma...

Page 5: ...Circuit FET Field Effect Transistor I2C Inter Integrated Circuit IRQ Interrupt ReQuest LDO Low Drop Out Regulator OCP Over Current Protection OVP Over Voltage Protection SoC System On a Chip 3 2 Refer...

Page 6: ...Buck2 0 7V 1 3V 10mV step DVS IOMAX 4 0A Buck3 0 7V 1 3V 10mV step DVS IOMAX 2 1A Buck4 0 7V 1 3V 10mV step DVS IOMAX 1 0A Buck5 0 7V 1 35V 8 steps IOMAX 2 5A Buck6 3 0V 3 3V 100mV step IOMAX 3 0A Bu...

Page 7: ...N002E Rev 001 May 2018 4 General Design Considerations This chapter provides general PCB design guidelines such as BD71837MWV general parts placement 4 1 Package Dimension of BD71837MWV Figure 4 1 The...

Page 8: ...LX BUCK7_VIN BUCK7_FB IRQ_B POR_B C32K_OUT DVDD EXP PAD EXP PAD LDO3_FB VIN_3P3 LDO3_VOUT VSYS3 BUCK4_FB BUCK4_VIN BUCK4_LX BUCK3_LX BUCK3_LX BUCK3_VIN BUCK3_FB AGND INTLDO1P5 LDO7_VOUT VSYS1 XIN XOUT...

Page 9: ...Mils thick copper It is recommended I2C signals to have the reference versus solid planes over the length of their routing and not to cross plane splits Ground should be the ideal reference The extra...

Page 10: ...ability and electrical characteristics Type 3 PCB technology employs plated through hole PTH vias for breakout routing The dimension of PTH vias may vary as necessary Table 2 1 shows the recommended v...

Page 11: ...issue it is highly recommended to keep the positons of PTHs away from the edge of the exposed pad by 500 m or more and PTHs should be placed not to disrupt the current flows between each GND of the o...

Page 12: ...tom layer are shown in Figure 4 6 to Figure 4 11 The layout is designed supposing the position of the SoC as Figure 4 6 1st pin of SoC is positioned at lower right BUCK8 BUCK5 BUCK1 MUXSW BUCK7 BUCK2...

Page 13: ...td No 61AN002E Rev 001 May 2018 Figure 4 7 BD71837MWV Reference Board Outline Layer 2 GND Layer 2 is used as power GND It s better to secure the wide plane for large switching currents The parasitic i...

Page 14: ...HM Co Ltd No 61AN002E Rev 001 May 2018 Figure 4 8 BD71837MWV Reference Board Outline Layer 3 VSYS Layer 3 is used as VSYS power Input for each VR It s better to secure the wide plane for large input c...

Page 15: ...Design Guide 2018 ROHM Co Ltd No 61AN002E Rev 001 May 2018 Figure 4 9 BD71837MWV Reference Board Outline Layer 4 Layer 4 is used as power traces for each VR It s better to secure the enough width to r...

Page 16: ...M Co Ltd No 61AN002E Rev 001 May 2018 Figure 4 10 BD71837MWV Reference Board Outline Layer 5 LDO4 LDO1 LDO2 LDO7 LDO3 LDO5 LDO6 Layer 5 is used as the power traces for each LDO It s better to secure t...

Page 17: ...Platform Design Guide 2018 ROHM Co Ltd No 61AN002E Rev 001 May 2018 Figure 4 11 BD71837MWV Reference Board Outline Layer 6 WDOG_B SD_VSELECT RTC_RESET_B Layer 6 is used for routings of each feedback l...

Page 18: ...in Table 5 1 Table 5 1 The Maximum Design Powers for BUCK convertors LDOs and the Load Switch Voltage Rail Type Input Voltage Default Output Voltage V Max Current mA Over Current Protection Min mA BU...

Page 19: ..._OUT BUCK6 3 0A 3 0 to 3 3V 0 1V step BUCK7 1 5A 1 6V to 2 0V 8steps NVCC_DRAM VDD_SOC VDD_ARM VDD_GPU VDD_VPU VDD_DRAM NVCC_SNVS 3P3_PHY GPIO_3V3 VDD_SNVS VDDA_1P8 1P8_PHY GPIO_1V8 VDDA_0P9 0P9_PHY i...

Page 20: ...ion of the stability for the input level for each buck convertor so the design for each input should be also taken care It is highly recommended to follow the all guidelines in this section 5 2 1 Over...

Page 21: ...e minimize the impedance of the each loop Figure 5 3 shows the current loops to be designed carefully As Figure 5 4 shows the patterns which handle the heavy currents should be routed as much shortly...

Page 22: ...t can be referred to for your reference 5 2 5 Other Signal Pattern Precautions Make sure to leave adequate space between noisy lines of voltage rail and serial interface I2C 5 2 6 Feedback Sense Lines...

Page 23: ...8 5 2 7 AGND layout AGND is recommended not to be connected to PGND for PMIC exposed pad directly to avoid noise effect It s better to short AGND to a GND at inner GND plane stable GND through PTH The...

Page 24: ...the system As a decoupling capacitor use one 10 F Select the input capacitor with the capacitance 3 5 F including the DC bias effect at VSYS 5 0V The recommended part of capacitor is shown below A LMK...

Page 25: ...be connected to near output capacitors Figure 5 8 BUCK1 Layout Example Top Layer 5 3 2 BUCK2 VDD_ARM BUCK2 is a high efficiency buck converter which converts VSYS 2 7V to 5 5V voltage to a regulated...

Page 26: ...d area and cost restrictions The recommended part of inductor is shown below A HMLE32251E R47MSR size 3225 Rated DC Current 7 2A As output capacitors use two 22 F capacitors Select the output capacito...

Page 27: ...tance 1 88 F including the DC bias effect at VSYS 5 0V The recommended part of capacitor is shown below A LMK107BJ475MA size 1608 capacitance 4 7 F tolerance 10V BUCK3_LX 1 0 O Connect to BUCK3 via th...

Page 28: ...y 2018 5 3 3 3 Layout Example About the parts placement for each capacitor around BUCK3 the below reference layout can be referred to BUCK3_FB should be connected to near output capacitors Figure 5 12...

Page 29: ...capacitance 1 88 F including the DC bias effect at VSYS 5 0V The recommended part of capacitor is shown below A LMK107BJ475MA size 1608 capacitance 4 7 F tolerance 10V BUCK4_LX O Connect to BUCK3 via...

Page 30: ..._FB should be connected to near output capacitors Figure 5 14 BUCK4 Layout Example Top Layer 5 3 5 BUCK5 VDD_DRAM BUCK5 is a high efficiency buck converter which converts VSYS 2 7V to 5 5V voltage to...

Page 31: ...8 capacitance 10 F tolerance 10V BUCK5_LX 1 0 O Connect to BUCK5 via the inductor Connect one 0 47 H 20 inductors to BUCK5_LX 1 0 Select the inductor to be used according to board area and cost restri...

Page 32: ...uld be connected to near output capacitors Figure 5 16 BUCK5 Layout Example Top Layer 5 3 6 BUCK6 NVCC_3P3 BUCK6 is a high efficiency buck converter which converts VSYS 2 7V to 5 5V voltage to a regul...

Page 33: ...via the inductor Connect one 1 0 H 20 inductors to BUCK6_LX 1 0 Select the inductor to be used according to board area and cost restrictions The recommended part of inductor is shown below A MAMK2520H...

Page 34: ...itor with the capacitance 1 88 F including the DC bias effect at VSYS 5 0V The recommended part of capacitor is shown below A LMK107BJ475MA size 1608 capacitance 4 7 F tolerance 10V BUCK7_LX O Connect...

Page 35: ...y 2018 5 3 7 3 Layout Example About the parts placement for each capacitor around BUCK7 the below reference layout can be referred to BUCK7_FB should be connected to near output capacitors Figure 5 20...

Page 36: ...h the capacitance 3 5 F including the DC bias effect at VSYS 5 0V The recommended part of capacitor is shown below A LMK107BBJ106MALT size 1608 capacitance 10 F tolerance 10V BUCK8_LX 1 0 O Connect to...

Page 37: ...y 2018 5 3 8 3 Layout Example About the parts placement for each capacitor around BUCK8 the below reference layout can be referred to BUCK8_FB should be connected to near output capacitors Figure 5 22...

Page 38: ...t source will be changed from VSYS to BUCK6 automatically LDO3 output voltage is programmable and its voltage range is from 1 8V to 3 3V by 100mV step 5 4 4 LDO4 VDDA_0P9 VLDO4 converts VSYS 2 7V to 5...

Page 39: ...part of capacitor is shown below A JMK105BJ105MV F size 1005 capacitance 1 0 F tolerance 6 3V LDO2 VDD_SNVS Vout 0 9V 0 8V Iomax 10mA LDO2 O As the output capacitor use one 1 F capacitor Select the ou...

Page 40: ...e 6 3V LDO7 3 3V PHY Vout 1 8V 3 3V Iomax 150mA LDO7 O As the output capacitor use one 2 2 F capacitor Select the output capacitors within the capacitance range defined in the datasheet of BD71837MWV...

Page 41: ...nput for MUXSW and connect to BUCK7 As the input capacitor use one 4 7 F capacitor The recommended part of capacitor is shown below A JMK105BBJ475MV F size 1005 capacitance 4 7 F tolerance 6 3V MUXSW_...

Page 42: ...aluation 5 6 1 1 Schematic Examples Figure 5 25 Crystal Oscillator Driver Schematic Example 5 6 1 2 Schematic Checklist Table 5 12 Schematic checklist of crystal oscillator driver Pin Names Dir Notes...

Page 43: ...l oscillator driver circuit is extremely sensitive to external environment like parasitic capacitance due to the long wirings for XIN and XOUT So it is recommended to position the Crystal oscillator p...

Page 44: ...nd I2C interface Capacitor for decoupling use one 1 0 F 20 size 1005 capacitance 1 0 F tolerance 6 3V SCL I DVDD Pulled up to DVDD with 1kohm Connect to SoC Note If pull up resistor is prepared within...

Page 45: ...hm NC Connect to SoC Note3 If pull up resistor is prepared within SoC the additional pull up resistor is not needed PMIC_STBY_REQ I DVDD Refer to Notes Connect to SoC Note4 PMIC_ON_REQ I DVDD Refer to...

Page 46: ...Pin Names Dir Signal Voltage Level Notes Check MISC AGND GND Connect to PGND at inner GND plane EXP PADs PGND0 4 GND Connect to the inner GND plane with lower impedance Note The package has one pad a...

Page 47: ...hnical information The Products specified in this document are not designed to be radiation tolerant For use of our Products in applications requiring a high degree of reliability as exemplified below...

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