JAJSFD3G August 2016 – March 2019 DRA780 , DRA781 , DRA782 , DRA783 , DRA785 , DRA786 , DRA787 , DRA788
PRODUCTION DATA.
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Maximum acceptable PCB resistance (Reff) between the PMIC and Processor input power balls should not exceed 33mΩ per Table 7-3 and (7).
Maximum decoupling capacitance loop inductance (LL) between Processor input power balls and decoupling capacitances should not exceed 2.5nH per Table 7-3 and (7) (ESL NOT included).
Impedance target for key frequency of interest between Processor input power balls and PMIC’s SMPS output power balls should not exceed 54mΩ per Table 7-3 and (7).
Parameter | Recommendation | Example PCB |
---|---|---|
OPP | OPP_NOM | |
Clocking Rate | 500 MHz | |
Voltage Level | 1 V | 1 V |
Max Current Draw | 1 A | 1 A |
Max Effective Resistance: Power Inductor Segment Total Reff | 13 mΩ | 11.4 mΩ |
Max Loop Inductance | < 2.5 nH | 0.73 - 1.58 nH |
Impedance Target | 54 mΩ for F < 20 MHz | 28.8 mΩ for F < 20 MHz |
Figure 7-15 shows a PCB layout example and the resulting PI analysis results.
Vaule [uF] | Size | Qty | Capacitance [uF] |
---|---|---|---|
Cap Type: Automotive GCM series, X7R | |||
22 | 1206 | 1 | 22 |
4.7 | 805 | 1 | 4.7 |
2.2 | 603 | 1 | 2.2 |
1 | 603 | 1 | 1 |
0.47 | 603 | 1 | 0.47 |
0.22 | 603 | 1 | 0.22 |
0.1 | 402 | 6 | 0.6 |
Totals | 12 | 31.19 |
IR Drop: vdd_dspeve
Dynamic analysis of this PCB design for the CORE power domain determined the vdd_dspeve decoupling capacitor loop inductance and impedance vs frequency analysis shown below. As you can see, the loop inductance values ranged from 0.68 –1.79nH and were less than maximum 2.0nH recommended.
Cap Reference Description | Loop Inductacne at 50MHz [nH] | Footprint Types | PCB Side | Distance to Ball-Field [mils] | Value | Size |
---|---|---|---|---|---|---|
C5101 | 0.73 | 2vWEE | Bottom | 82 | 0.1 | 0402 |
C5100 | 0.78 | 2vWEE | Bottom | 107 | 0.1 | 0402 |
C5085 | 0.84 | 2vWEE | Bottom | 35 | 0.1 | 0402 |
C5019 | 1.09 | 4vWE | Top | 631 | 0.47 | 0603 |
C5111 | 1.09 | 4vWE | Bottom | 681 | 0.1 | 0402 |
C5030 | 1.11 | 4vWE | Top | 738 | 4.7 | 0805 |
C5037 | 1.11 | 4vWE | Top | 563 | 2.2 | 0603 |
C5018 | 1.14 | 4vWE | Top | 681 | 1 | 0603 |
C5021 | 1.17 | 4vWE | Top | 761 | 0.22 | 0603 |
C5026 | 1.18 | 4vWE | Top | 792 | 22 | 1206 |
C5079 | 1.32 | 4vWE | Bottom | 542 | 0.1 | 0402 |
C5080 | 1.58 | 4vWE | Bottom | 602 | 0.1 | 0402 |
Figure 7-17 shows vdd_dspeve Impedance vs Frequency characteristics.