Freescale Semiconductor Application Note Document Number: AN3462 Rev. 1.1, 01/2010 Power Distribution for the MMM6007 Module by: Power Management and Audio Application Team 1 Introduction The purpose of this application note is to provide general guidelines for the implementation of the Melody Vdd core voltage (VMelody core) on a radio design. The Melody core voltage supplies the following: • Approximately 700k gate equivalents of digital standard cell logic. This includes Rx, Tx, and synthesizer sections. Approximately 12 mA of current in full duplex mode at 1.2 V or 18 mA at 1.6 V, forcing large digital switching current impulses. • A 26 MHz clock synthesizer TCXO input buffer. Supply noise significantly contributes to spur induced deterministic jitter. This clock is used as reference for 92.16 MHz PLL, which is the main clock source for all blocks within the design. • All level shifters that interface between the 1.2 V digital and 2.7 V analog design blocks. This includes the Tx modulation sigma delta DACs that are very sensitive to supply noise induced deterministic jitter. © Freescale Semiconductor, Inc., 2007–2010. All rights reserved. Contents 1 2 3 4 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . PCB Layout Recommendation . . . . . . . . . . . Selection of Bypass Capacitors . . . . . . . . . . VDig Regulator Decoupling Capacitor Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Buck Switcher 2 Decoupling Capacitor Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 3 4 5 PCB Layout Recommendation 2 PCB Layout Recommendation Routing is always the top priority for any trace. The same should be isolated from noisy traces like clocks and RF lines. Adequate amount of decoupling capacitors should be placed as close as possible to the source and destination pins. Wide trace should be used for the DC distribution to provide current flow capability with minimal resistive loss. The source for the Melody Vdd core voltage should not be used to power any other circuit as to avoid adding any noise to the line. Additional decoupling consideration will be required to suppress any electrical noise unique to a product implementation. Figure 1 shows the recommended implementation of the PCB and Figure 2 shows the implementation concerns. Recommended Implementation To any circuit To any circuit To any circuit Each circuit should have bypass capacitors from main supply MMM6007 Each circuit should source from main supply MC13783 Trace should connect to bypass capacitors before connecting to IC pins VMelody core VDIG Place capacitors as close as possible to symphony module pins. Place capacitors as close as possible to MC13783 pins. Figure 1. Recommended PCB Layout Power Distribution for the MMM6007 Module Application Note, Rev. 1.1 2 Freescale Semiconductor Selection of Bypass Capacitors Implementation Concerns To any circuit To any circuit To any circuit AVOID - Each circuit should have bypass capacitors from main supply Avoid power loop Each circuit should source from main supply MMM6007 MC13783 AVOID - Trace should connect to bypass capacitors before connecting to IC pins VMelody core VDIG Avoid connecting any other circuit to VDIG To any circuit Figure 2. PCB Implementation Concerns 3 Selection of Bypass Capacitors Refer to Freescale’s MC13783 Data Sheet (Document Number: MC13783) for the recommended minimum bypass capacitance value for each regulator and buck switchers. Table 1 is a list of the power supplies used by the MMM6007 and the Freescale recommended implementation. All effort must be made to minimize variations of ceramic capacitors. Variations of ceramic capacitors depend of three main parameters: • Tolerance (generally 10% or 20%). Avoid using 20% parts since these parts will force the implementation of additional parts to meet minimum required capacitance value. • Temperature (15% for X5R and X7R). • DC Bias (from 0% up to 80%). Since DC bias is mostly a function of physical size it is recommended that the largest possible parts are used. Table 1. MC13783 Recommended Capacitor Implementation DTS Value (uF) Block Case Freescale Recommendation Typical Minimum VIOHI 1 0.65 0402 C1005X5R0J105K VRFREF 1 0.65 0402 C1005X5R0J105K or C1608X5R0J225M To increase noise performance VRFCP Power Distribution for the MMM6007 Module Application Note, Rev. 1.1 Freescale Semiconductor 3 VDig Regulator Decoupling Capacitor Study Table 1. MC13783 Recommended Capacitor Implementation (continued) DTS Value (uF) Block Case Freescale Recommendation Typical Minimum 2.2 1.43 0603 C1608X5R0J225K or C2012X5R1A225K 2.2 1.43 0805 C2012X5R1A225K or C1608X5R0J475M SWxA 22 + 2.2 14.3 0805 C2012X5R0J226MTJ in // C1608X5R0J225M or only one C3225X5R1C226M SWxB 22 + 2.2 14.3 0805 C2012X5R0J226MTJ in // C1608X5R0J225M or only one C3225X5R1C226M 2 x 22 + 2.2 28.6 0805 and 0603 C2012X5R0J226MTJ in // C1608X5R0J225M VDIG VREFDIG VRF1 VRF2 SW1 or SW2 Parallel 4 VDig Regulator Decoupling Capacitor Study Table 2 shows the minimum bypass capacitor value at the MC13783 pin for the VDIG regulator is 2.2 uF (-35%) = 1.43 uF. There are several choices for design depending on procurement practice and/or mechanical size requirements. For situations where the procurement part number corresponds to a single vendor part number the designer could specify C1608X5R0J225K (0603 from TDK) or JMK107BJ225KA (0602 from Taiyo Yuden). Taking into account the variations (as shown in Figure 3), the actual capacitance is 1.46 uF or 1.52 uF depending on vendor used. Worst case capacitance in this case would be above the minimum value recommended. For situations where multiple vendor part numbers are associated with a single procurement part number there is the possibility of having a 0603 part below the minimum recommended value such as C1608X5R0J225M (0603 from TDK) or GRM188R61A225M (0603 from Murata). Taking into account the variations (as shown in Figure 3), the actual capacitance range is between 1.30 uF and 1.52 uF depending on vendor used. The performance variation on a product for this range could be interpreted as “lot-to-lot” variations when a reel of parts is changed in production. Worst case capacitance in this case would be below the minimum value recommended. In this case, the designer should specify two 0603 parts or one 0805 part to meet the minimum recommended value. Table 2. MC13783 Regulator General Characteristics Parameter Condition Operating Input Voltage Range Vinmin to Vinmax Min Typ Max Units 4.65 V Vnom + 3% V 0.20 mV/mA 30 µA Vnom + 0.3 Output Voltage Vout Vinmin < Vin < Vinmax ILmin < IL < ILmax Load Regulation 1mA < IL < ILmax For any Vinmin < Vin < Vinmax Active Mode Quiescent Current Vinmin < Vin < Vinmax IL = 0 Vnom - 3% Vnom 20 Power Distribution for the MMM6007 Module Application Note, Rev. 1.1 4 Freescale Semiconductor Buck Switcher 2 Decoupling Capacitor Study Table 2. MC13783 Regulator General Characteristics (continued) Parameter Condition Low Power Mode Quiescent Current Vinmin < Vin < Vinmax IL = 0 PSRR IL = 75% of ILmax 20 Hz to 20 kHz Vin = Vnom + 1V Minimum Bypass Capacitor Value Used as a condition for all other parameters Bypass Capacitor ESR 10 kHz - 1 MHz Min Typ Max Units 5 10 µA 50 60 -35% 2.2 0 dB +35% µF 0.1 Ω Figure 3 gives the minimum capacitor value regarding process (10 or 20%), temperature (15%) and DC bias variation. Figure 3. Summary Capacitor Guide Table 5 Buck Switcher 2 Decoupling Capacitor Study Since Vdig is supplied by buck switcher 2, the similar part specification consideration needs to take place. Table 3 shows the minimum bypass capacitor value at the MC13783 pin per buck switcher is 22 uF (-35%) = 14.3 uF. There are two choices for this implementation based on commercially available parts: one 1210 part or two 0805 parts (one 22 uF and one 10 uF). Taking into account the variations (as shown in Figure 3), the actual capacitance range for a 0805, 22 uF capacitor is between 10.32 uF and 13.61 uF and for a 0805, 10 uF capacitor is between 5.58 uF and 6.32 uF depending on vendor used. Adding worst case of each Power Distribution for the MMM6007 Module Application Note, Rev. 1.1 Freescale Semiconductor 5 Buck Switcher 2 Decoupling Capacitor Study value, the value is 10.32 uF + 5.58 uF = 15.9 uF. Worst case capacitance in this case would be above the minimum value recommended. For applications with SWxA and SWxB connected together, the minimum bypass capacitor value is 2x14.3 uF = 2 8.6 uF. The recommended implementation consists of two 0805, 22 uF capacitors from TDK (C2012X5R0J226MTJ) with a minimum value of 13.61 uF each and one 0603, 2.2 uF capacitor from TDK (C1608X5R0J225K) with minimum value of 1.46 uF. Adding these values: 13.61 uF(x2) + 1.46 uF = 28.68 uF. Worst case capacitance in this case would be at the minimum value recommended. Based on commercially available parts, another implementation is to use three 0805, 22 uF capacitor. Taking into account the variations (as shown in Figure 3), the actual capacitance range for each capacitor is between 10.32 uF and 13.61 uF depending on vendor used. Multiplying this by three, the value range is between 30.96 uF and 40.83 uF. Worst case capacitance in this case would be above the minimum value recommended. Table 3. Buck Switcher Characteristics Parameter Condition Min Typ Max 0.900 V to 1.675 V in 25 m V steps 1.700 V to 2.200 V in 100 V steps Output Voltage 2.8 V < BP < 4.65 V 0 < IL < 500 mA Output Accuracy PWM Mode, including ripple and load regulation Transient Load Response IL from 5 mA to 400 mA in 1μs IL from 400 mA to 5 mA in 1μs Effective Quiescent Current Consumption PWM MODE 50 µA PFM MODE 15 µA External Components Inductor -50 -20% 10 Inductor Resistance Bypass Capacitor -35% Bypass Capacitor ESR 0.005 22 Freescale Semiconductor V +50 mV +/- 25 mV +20% µH 0.16 Ω +35% µF 0.1 Ω Power Distribution for the MMM6007 Module Application Note, Rev. 1.1 6 Units NOTES Power Distribution for the MMM6007 Module Application Note, Rev. 1.1 Freescale Semiconductor 7 How to Reach Us: Home Page: www.freescale.com Web Support: http://www.freescale.com/support USA/Europe or Locations Not Listed: Freescale Semiconductor, Inc. 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