1 Decoupling Capacitors Requirements Intel - Microprocessor power levels in the past have increased exponentially, which has led to increased complexity and cost of both power delivery and power removal. In particular, it has led to a need to exponentially lower the impedance of decoupling capacitors (lower inductance and resistance and higher capacitance).

2 Powering high-slew-rate transient loads (such as LSI - microprocessors) require high frequency decoupling and typically uses parallel connection bank of capacitors (usually MLCCs, and low ESL Polymer Electrolytic caps) to provide low impedance up to several hundred MHz Decoupling Capacitors Requirements

3 Capacitors reach their minimum impedance (Z = ESR) at their resonant frequency (F os ), which is determined by the capacitance value and the ESL of the capacitor. F os - Resonant Freq (  500KHz)

4 PCB pad layout design & Inductance (nH - nanoHenry) The 'mounted inductance'(PCB) and ESL of a capacitor both contribute to the total inductance loop that current must flow within. The larger the loop, the more the inductance, and the slower the response. Reduction in total inductance is achieved by reducing the size of the current loop. The figure below shows a comparative study of various pad layout designs. Decoupling Capacitors Requirements Low Inductance Pad Layout

5 ESL  ESL impacts the speed of the capacitor response in transferring energy to the load Ideal capacitor Real world capacitor ESR  Limits current rating  Impacts ripple voltage  Energy loss Insulation Resistance ‘IR’  DC leakage current  Energy loss Parameter Guide Parasitic Inductance (ESL)  Lower is better Parasitic Resistance (ESR)  Lower is better Insulation Resistance (IR)  Higher is better An ideal capacitor can transfer all its stored energy to a load instantly. A real capacitor has parasitic inductance (ESL) that prevent instantaneous transfer of a capacitor’s stored energy. The ESL of a capacitor determines the speed of energy transfer from the capacitor to the load. Decoupling Capacitors Requirements

6 Reverse Geometry Low ESL Ceramic Chip Capacitors – MLCCs  Reduces ESL up to 60%!  Decoupling and noise suppression in high-speed circuits  Improved response time in power circuits  Reduce the number of decoupling components used  Reduce PCB size - costs and component placement costs!  0204, 0306, 0508, 0612 case sizes  TCC: (Operating Temp) X7R (-55C to +125C) & X5R (-55C to +85C)  Capacitance Range 0.01uF (10nF) to 1.0uF  Rated Voltage Range: 6.3V to 50V Reverse geometry low ESL (Equivalent Series ‘L’ Inductance) MLCCs are ideal for use as high speed decoupling capacitors, mounted in close proximity or adjacent to microprocessors Low inductance (low ESL) surface mount ceramic capacitors are connected directly to the power supply pins of the IC. Short traces or vias are required for this connection to minimize additional series inductance (ESL). Eight Low ESL MLCCs used In microprocessor decoupling Eight Low ESL MLCCs used In microprocessor decoupling Decoupling Capacitors Requirements

12/21/ NMC-R Series Performance Advantage Equivalent Series Inductance (L) Decoupling Capacitors Requirements

12/21/ NMC-R Series Performance Advantage Equivalent Series Inductance (L) Increased Fos ESL ≤ 0.20nH Decoupling Capacitors Requirements

9 Low ESL Solid Polymer Aluminum Electrolytic Capacitors  3-Terminal construction reduces Series Inductance ‘ESL’ by  50%  Decoupling and noise suppression in high-speed circuits  Improved response time in power circuits  Reduce the number of decoupling components used  Reduce PCB size - costs and component placement costs!  Operating Temperature Range: -55°C to +105°C  Capacitance Range 68uF to 560uF  Rated Voltage Range: 2.0V, 2.5V, 4.0V & 6.3VDC  +260°C Reflow Soldering Compatible ADVANTAGES:  Stable with voltage, temperature and time  No voltage derating  No DC bias (weakness of MLCC)  Reduce ripple voltage  Eliminates piezoelectric ringing & singing  Reduce number of capacitors used Bottom view of component Top view of component Decoupling Capacitors Requirements

10 ESL Reduction by 3-Terminal Structure (+) Anode 2-terminal NSP series ESL in loop impedance is represented by L x T W ESL = k x where k is a constant loop impedance 3-terminal NSPL has  50% lower ESL than standard 2-terminal NSP series 3-terminal NSPL has  50% lower ESL than standard 2-terminal NSP series 3-terminal NSPL series Bottom view of component (+) Anode (-) Cathode Bottom view of component ESL The smaller the capacitor ESL, the smaller the impedance loop, and the faster the capacitor response in transferring energy to the load, and the better the high frequency noise suppression ability Decoupling Capacitors Requirements

11 Typical ESL comparison between NSPL, NSP and MLCC  3-Terminal NSPL has low ESL, close to ESL of 0603 size MLCC 0603 Size MLCC X5R 6.3V 22uF NSPL181M2.5D5YATRF 2.5V 180uF NSP181M2.5D6ZATRF 2.5V 180uF Frequency (MHz) ESL (nH) Decoupling Capacitors Requirements

12 Frequency (MHz) Impedance (Ohm) Typical Impedance (Z) comparison between NSPL, NSP and MLCC  3-Terminal NSPL has low Impedance (Z) over wide frequency range 0603 Size MLCC X5R 6.3V 22uF NSPL181M2.5D5YATRF 2.5V 180uF NSP181M2.5D6ZATRF 2.5V 180uF Decoupling Capacitors Requirements

Frequency (MHz) ESL (nH) Typical ESL example for each thickness: 1.1mm, 1.4mm and 1.9mm NSPL471M2D6YATRF 2.0V 470uF, 1.9mmT NSPL331M2D1YATRF 2.0V 330uF, 1.4mmT NSPL221M2D5YATRF 2.0V 220uF, 1.1mmT Decoupling Capacitors Requirements

14 Low ESR performance for NSPL series; 220uF, 330uF & 470uF Frequency (MHz) ESR (Ohm) NSPL471M2D6YATRF 2.0V 470uF, 1.9mmT NSPL331M2D1YATRF 2.0V 330uF, 1.4mmT NSPL221M2D5YATRF 2.0V 220uF, 1.1mmT Decoupling Capacitors Requirements

15 Better: lower noise Best: lowest noise NSPL Lowest ESL High ESL High frequency noise Decoupling Capacitors Requirements

16 Summary  All decoupling capacitors should connect to a large area low impedance ground plane through a via or short trace to minimize inductance.  Reducing the ESL of the capacitor bank, results in better ‘faster’ capacitor bank that speeds energy transfer to the load.  The strategy is to place the 'fastest' low ESL capacitors as close to the load as possible, as physically close to the power pins of the chip as is possible  Mounted inductance is minimized by locating Vdd and Gnd vias close to each other and minimizing the length of via from the pad to the power planes. Decoupling Capacitors Requirements - Summary

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