WP1518 A case against discretes Rev. 1 — 2 June 2016 1 White paper Introduction Power conversion and its management are critical part of a system design. Power is one of the most vulnerable parts of the system as it is exposes the system to the outside world and handles high-power electrical signals. Complex hardware designs based on applications processors and communications processors require multiple numbers of power rails. Accuracy of stabilized voltage levels and their timing is critical for reliable system boot-up. Most of the time the power designs are not given enough attention, and project managers tend to cut corners with this critical function. For example, the perceived cost saving of discrete implementation of power solution may actually end up costing more than the specialized power solution using PMICs. The hidden cost of discrete implementation and NXP’s robust, reliable PMICs, which effectively reduce the project costs, are discussed in the paper. 2 Complex power map for multimedia application and network infrastructure device A typical multimedia system consists of a high-performance i.MX 6Dual or i.MX 6Quad processor with 2D, 3D graphic processing unit, 3D 1080p video processing block, multiple interfaces including DDR, WLAN, Bluetooth®, GPS, audio amplifier, various sensors, flash and camera control and drive units, SD, eMMC memory control, various communication interfaces like USB, HDMI, SATA, LVDS and mPCIe (Figure 1). PF0100 SW1A 1.375 V, 2.5 A SW2 SW3A VDD_SOC 1.375 V, 2.0 A Vin Coin cell SWBST VGEN1 VGEN2 VGEN3 VGEN4 VGEN5 VGEN6 VSNVS VREFDD 1 GB DDR3 VSNVS VREFDDR 3.3 V, 2 A 1.5 V, 2.5 A SW3B SW4 i.MX6 VDD_HIGH SW1B SW1C VDD_ARM 4.2 V 1.8 V, 1 A Audio 3.3 V Light sensor 5 V, 0.6 A 1.5 V, 100 m 1.5 V, 250 mA SD Slot 3.3 V eMMC Memory 3.3 V 2.5 V HDMI 3.3 V 2.5 V SATA 5.0 V 3.3 V 1.5 V GPS 3.3 V Barometer 2.5 V, 100 mA 1.8 V, 350 mA 2.8 V, 100 mA 3.3 V 1.8 V 3.3 V NOR Flash 3.3 V USB 5.0 V 3.3 V LVDS 1.5 V 3.3 V mPCIe 3-Axis accelerometer 3.3 V, 200 mA Ethernet 3.0 V, 400 μA 0.75 V, 10 mA 1.5 V 1.8 V 2.8 V 3.3 V Camera x2 3.3 V eCompass Figure 1. Complex power map for applications processors – i.MX 6 and MMPF0100 WP1518 NXP Semiconductors A case against discretes Similarly, a networking equipment like IoT gateway includes power efficient, highperformance dual core LS1021x processor, audio block, integrated flash, DDR memory, display control and multiple SerDes lanes for high speed peripheral interfaces like PCI express, Sata, and SGMI-II. All these interface circuits within the processors and the peripherals need various voltage levels and currents (Figure 2). MC34VR500 LS102x VDD SW1 SW2 Power Control Logic 3.3 Vin Bus LDO2 LDO4 LDO5 SW3 SW4 REFOUT LDO1 LDO3 1.0 V, (4.5 A peak) 1.0 V, (1 A peak) 1.8 V, 100 mA 2.5 V, 100 mA 1.8 V, 200 mA 1.35 V, (2.5 A peak) 0.675 V, (1.0 A peak) 0.675 V, 10 mA 1.2 V, 250 mA 2.5 V, 350 mA Light sensor TA_BB_VDD VDDC OVDD1/2 L1VDD OVDD GVDD DDR3 1.5 GB VTT HDMI Ethernet Figure 2. Complex power map for communication processors – LS1021x and MC34VR500 Moreover, they all need to be powered up in a proper sequence for successful system boot up (Figure 3), and must be monitored for faults during the normal operation. This kind of complex power system design with discrete power devices is impractical without sacrificing the product quality. For example, the glitches associated with improper boot up or unexpected system failure can badly suffer user experience. It may even cost an equipment recall event. The situation gets even worse when the input black out or brown out happens. The turning off of the rails due to sudden loss of power may not be as big of a concern as recovering back the rails in a disciplined manner. WP1518 White paper All information provided in this document is subject to legal disclaimers. Rev. 1 — 2 June 2016 © NXP B.V. 2016. All rights reserved 2/8 WP1518 NXP Semiconductors A case against discretes LICELL UVDET VIN td1 tr1 1V VSNVS td2 tr2 td3 PWRON tr3 SW1A/B td4 SW1C tr3 SW2 td4 VGEN2 tr3 SW3A/B SW4 VREFDDR VGEN4 VGEN5 td5 VGEN6 tr4 RESETBMCU Figure 3. Complex power sequence (default) – MMPF0100 The PMIC’s ability to centrally monitor all the LDOs, DDR and switching regulator blocks for over-voltage, over-current and over-temperature fault conditions along with its ability to control the operation of these rails, allows smooth power down of the system. The uncertainty of the power recycling behavior is resolved when using NXP’s PMICs like PF0100, PF3000 and VR500. The MMPF0100 is a high-efficiency, quick-turn programmable 14-channel, 11.7 A system power management solution targeting i.MX 6 applications processor family. The MC34PF3000 is a high-performance, quick-turn programmable, 12-channel, 7.2 A power solution targeting i.MX 6UL, i.MX 7. The MC34VR500 is a quad buck regulator with 4.5 A peak current, five user programmable LDOs targeting low power communications processors like LS1 and T1. 3 Hidden costs of discrete solution There are many apparent and hidden costs associated with the discrete solutions. Mere cost of individual components are usually very low. This is because they’re commonly used across multiple platforms and enjoy volume discounts. However, use of generic components comes with its inherent drawbacks. Firstly, they’re not a perfect fit for the application and that they’re not proven to work with the target processors. For example, WP1518 White paper All information provided in this document is subject to legal disclaimers. Rev. 1 — 2 June 2016 © NXP B.V. 2016. All rights reserved 3/8 WP1518 NXP Semiconductors A case against discretes some discrete regulators’ output voltage accuracy and settling time do not even meet the processor tolerance requirements. Use of less than perfect power solution impacts device quality and the manufacturer’s reputation. The solution size is another important factor to be considered when designing the hardware (Figure 4). Figure 4. Typical component placement – Discrete vs. equivalent NXP PMIC Solution A typical discrete DC/DC switching regulator uses up to 20 discrete passives (resistors and capacitors) in total. They’re used for programming various parameters like Vout, softstart, frequency, input/output filtering, sequencing delays, closed loop compensation, and synchronization. And each LDO regulator uses up to four components including input/ output capacitors, soft-start, start-up delays. The number of components quickly adds up for four to six buck regulators and six LDOs. And they become expensive to manage. The following are the various hidden costs of using discrete solution: 1. Assembly and PCB cost: The placement cost per component may be insignificant but if we add hundreds of components, they become a significant portion of assembly. Many times the cost of insertion exceeds the component cost itself. Multi-layer PCBs with tight tolerance are expensive. Increased PCB cost of up to 25 cents per square inch must not be neglected when deciding on the discrete implementation. 2. Cost of carrying inventory: Keeping and managing hundreds of different part numbers becomes a logistical nightmare. Additional resources for managing the inventory to ensure uninterrupted production line is not free. 3. Solution size: Any discrete implementation inherently increases the solution size. Depending on the frequency of operation and type of passive filter components, the discrete implementation could take three to five times larger PCB real estate in comparison with that of the PMIC implementation. Larger equipment size means bigger packaging, higher cost of storage, shipping and the installation. 4. Failure rate (MTBF): Failure rate of the equipment is seriously impacted by the part counts and the number of joints. According to the part count reliability prediction method, an equipment failure rate depends on part complexity, their quality levels, equipment environment and number of parts itself. Adding 100 components to WP1518 White paper All information provided in this document is subject to legal disclaimers. Rev. 1 — 2 June 2016 © NXP B.V. 2016. All rights reserved 4/8 WP1518 NXP Semiconductors A case against discretes the BOM when using discrete solution affects MTBF significantly (refer to MILHDBK-217F). 4 Apparent advantages of PMIC solution The need for an extreme integration arises from the requirement of multiple voltage rails as well as functions while simultaneously shrinking equipment size. High power processor systems like high-end networking switches and routers require distributed power architecture to ensure that the point of load regulators (POL) are physically located near the electronic loads. However, in case of low power, compact devices like wireless access points, or e-book readers, a small PCB size mandates a highly 2 integrated solution. A typical 2 to 3 A buck regulator needs about 100 to 150 mm PCB area depending on the operating frequency and selection of passive components type. 2 The most size optimized (up to 120 mm ) solution uses relatively higher frequency operation, small ceramic capacitors and high density inductor. A typical 200 to 300 mA 2 LDO needs about 25 mm PCB area. That means the MMPF0100 type of PMIC (4 to 2 6 DCDC, 6 LDOs) equivalent discrete solution would need about 800 mm of PCB real 2 estate. In comparison, the MMPF0100 based solution can fit in 350 mm (60 % saving) PCB area saving significant cost of 6 to 8 layer PCB. NXP PMICs offer size optimization by design. NXP’s state of the art 130 nm BCD process technology along with clever architecture makes the power solution exceptionally small. The PF0100/PF3000 series PMICs operate multiple DC/DC converters at the same frequency but in an out-of-phase manner. Out of phase operation effectively increases the switching frequency seen by input capacitor. For example, the PF0100’s four DCDC regulators switching at 2 MHz, operating 90 degrees out of phase, effectively increase the input capacitor ripple frequency to 8 MHz (Figure 5). Cin_Ripple SW1A/B SW2 SW3 SW4 Figure 5. Ripple phase operation reduces required input capacitor Higher ripple frequency significantly reduces the input capacitor need and shrinks the solution size further. Note that the ripple phase operation is not feasible when using discrete solution without adding a significant cost and complexity of clock generator and synchronization. 2 The I C based central control and monitoring is an essential feature when powering the complex systems using high performance processors like i.MX applications processors WP1518 White paper All information provided in this document is subject to legal disclaimers. Rev. 1 — 2 June 2016 © NXP B.V. 2016. All rights reserved 5/8 WP1518 NXP Semiconductors A case against discretes and Layerscape communications processors. Highly integrated power regulators and 2 PMICs with I C capability make the control and monitoring operation ubiquitous with the 2 system. I C works seamlessly between numerous internal blocks including all DCDCs, LDOs, thermal sensor, UV/OV detection circuit and the main processor load. Again, the discrete implementation makes it very difficult to monitor and control major functions from individual DCDC and LDO regulator. Figure 6. i.MX 7-PF3000 Saber board, LS1021-VR500 IoT Gateway module 5 Conclusion There is a good reason why the rise of PMICs coincided with the popularity of small hand held gadgets like flip phone, smart phones and tablets with cramped processing power and connectivity. The PMICs are evolved from its relatively simple predecessor called multi-output regulators. They were widely used to power portable devices like notebooks. Adoption of PMICs has become necessary for equipment manufacturers to keep up with the customer demand of reliable devices. NXPs line of robust, reliable PMICs such as PF0100, PF0200, PF3000 and VR500 substitute the discrete for the quick time to market solutions. WP1518 White paper All information provided in this document is subject to legal disclaimers. Rev. 1 — 2 June 2016 © NXP B.V. 2016. All rights reserved 6/8 WP1518 NXP Semiconductors A case against discretes Figures Fig. 1. Fig. 2. Fig. 3. Complex power map for applications processors – i.MX 6 and MMPF0100 ................ 1 Complex power map for communication processors – LS1021x and MC34VR500 .......... 2 Complex power sequence (default) – MMPF0100 ........................................................ 3 WP1518 White paper Fig. 4. Fig. 5. Fig. 6. Typical component placement – Discrete vs. equivalent NXP PMIC Solution ......................... 4 Ripple phase operation reduces required input capacitor ...................................................5 i.MX 7-PF3000 Saber board, LS1021VR500 IoT Gateway module ............................. 6 All information provided in this document is subject to legal disclaimers. Rev. 1 — 2 June 2016 © NXP B.V. 2016. All rights reserved 7/8 NXP Semiconductors WP1518 A case against discretes Contents 1 2 3 4 5 Introduction ......................................................... 1 Complex power map for multimedia application and network infrastructure device ................................................................... 1 Hidden costs of discrete solution ..................... 3 Apparent advantages of PMIC solution ............ 5 Conclusion ...........................................................6 © NXP B.V. 2016. All rights reserved For more information, please visit: http://www.nxp.com For sales office addresses, please send an email to: [email protected] Released on 2 June 2016