© Analog Devices Application Notes | December 11, 2020
Burned by Low Power? When lower current consumption can get you into trouble
Question: I changed one of my devices to a newer and better part with lower current consumption. Nothing is working anymore and even the new part got “burned.” Do you have any explanation?
Answer: Linear regulators are fairly simple devices and don’t have too many challenges. With that said, you can still get into trouble with them occasionally. In my role as a field applications engineer, there are times when customers request me to recommend a drop in replacement for a part they are using from another supplier. In many of these cases, the decision to replace a part is made by the customer’s production/purchase team and the original circuit designer may not be aware of the change. The decision process is fairly simple and the alternative part should have the same functionality, package, and pin configuration, as well as equal or better electrical specifications when compared to the device being replaced. Once all of these boxes are checked, you provide the necessary comparison data to the component engineer and the new component is added to the bill of materials as a second source alternative. After doing that, you should be all set. That is, until the product that was working faithfully with the older component starts failing on the production line after changing over to the alternative. What went wrong?! I was involved in one such case where we followed the previously mentioned process and got one of our isolated RS-485 transceivers designed in as a second source to another supplier’s device in a customer’s design. The devices were form, fit, and functionality compatible, and our part had better electrical specifications. The customer went ahead and ordered a large quantity of this part from us and there seemed no reason for anything to go wrong. However, the customer reported that the new RS-485 transceiver started failing on the production test bed. Since nothing else in the design had been changed, it came down to something being wrong with the new device in the picture. Upon further investigation, we found that the linear regulator powering the bus side of the transceiver was not regulating down to 5 V as expected, but instead was going up to a much higher voltage. We needed to do a careful review and comparison of the data sheets for the older transceiver and the replacement one, as well as the data sheet of the linear regulator to figure out what was going wrong. Better is a qualitative term and depends on the parameter in question. For example, when it comes to speed/CMRR/PSRR, higher is better; when it comes to offset voltage/drift, lower is better; and you don’t need great engineering insight to know that when it comes to power consumption, lower is always better. Or is it? In this particular case, it turned out it wasn’t. The older transceiver consumed 15 mA (typically) on the bus side in idle state, while the new device consumed only 2 mA (maximum). It was no wonder that the new device looked better on paper. Unfortunately, the linear regulator didn’t seem to agree and went berserk. As I mentioned at the start of this article, linear regulators are fairly simple devices that don’t have too many demands. Their one peculiar requirement is that they need a minimum load current to function properly. If this condition is not met, the regulator stops regulating correctly and the output voltage goes out of bounds. The situation could also get worse if the input voltage to the regulator is much higher than the desired output voltage. Read this excellent article for more details on this topic.1 Many modern linear regulators take special care in their design to address this and pose no such problems. Some of the older devices (like the one in the customer’s design) don’t, and, hence, need extra precautions during the system design. In some cases, the feedback resistor network for the adjustable output LDO takes care of the minimum load current. Unfortunately, one could run into this issue inadvertently by deciding to supersize these resistors while keeping the ratio the same. There could also be another scenario in which the device being powered by the LDO meets the load requirement during normal operation, but not while it’s in standby. These are all potential pitfalls to watch out for, so be sure to read the LDO data sheet carefully. If there’s a minimum load current requirement, it would usually say so in some way. Here are a couple of examples: Figure 1. An example of a minimum load current from a data sheet. Figure 2. Left schematic: the regulator operating correctly with the older device (minimum load current requirement satisfied). Right schematic: the unstable regulator with the new device (load current not sufficient).
Images and graphs: © Analog Devices Inc.
Figure 3. The problem resolved after adding a bleeder resistor to draw minimum required load current.Going back to our story—once the root cause of the problem was understood, it was fairly simple to fix. All we had to do was add a bleeder resistor on the regulator output to draw the minimum load current. While it would have been easy for an unreasonable customer to blame it on our part, this particular customer could see the funny side of this story and was able to appreciate the technical learning from this episode. It all ended well like any fairy tale—a little blood was spilled, but everyone lived happily ever after. References 1. Luca Vassalli. “Minimum Load Current Operation—Zero-Load Operation.” Analog Dialogue, Vol 48, September, 2014.
Images and graphs: © Analog Devices Inc.
Intel invests $700 million in new Oregon mega lab The US chipmaker plans to invest more than USD 700 million for a 200,000 square-foot, research and development mega lab focused on data center technologies and addressing areas such as heating, cooling and water usage.
Obsolescence management cannot be an afterthought “Obsolescence has always existed. However, it usually only becomes really critical for companies when the exception mutates into the norm. And in recent years we have unfortunately experienced this unwanted development not only with semiconductor chips, but increasingly with many other components, materials and raw materials,” says IIOM President and COGD Chairman Dr Wolfgang Heinbach.
Tower record 1Q22 revenues of $421 Million, a 21% YoY Tower Semiconductor reported first quarter 2022 revenue of USD 421 million, an increase of 21% compared to USD 347 million in the first quarter of 2021.
Gallium Semiconductor opens its Nijmegen R&D center Gallium Semiconductor has officially held the grand opening of its European R&D center in a ceremony in Nijmegen, the Netherlands.
Ferrotec to add manufacturing capacity with new plant in Malaysia Ferrotec, a global supplier of materials, components, and precision system solutions, is establishing a new manufacturing facility at Kulim Hi-Tech Park, Kedah, facilitated by the Malaysian Investment Development Authority (MIDA).
Skeleton targets the Polish market – teams up with ZPUE Supercapacitor specialist, Skeleton Technologies, and ZPUE, a Polish manufacturer of electrical devices for electrical power distribution utilities, have entered into a commercial agreement to provide energy storage solutions to the Polish market.
Texas Instruments breaks ground $30 billion investment The semiconductor manufacturer has broken ground on its new 300mm semiconductor wafer fabrication plants in Sherman, Texas – an investment set to create as many as create as many as 3,000 jobs.
ERP partners with Flip to fulfill EOL and Obsolete component solutions Flip Electronics has signed a franchised distributor partnership agreement with ERP Power (ERP) to distribute its End-of Life (EOL) semiconductor products.
Foxconn and DNeX build and operate wafer fab in Malaysia Dagang NeXchange Berhad (DNeX) and Foxconn subsidiary Big Innovation Holdings (BIH), plan to set up a joint venture company to build and operate a new 300mm wafer fab in Malaysia.
Imec and semiconductor partners target greener chip manufacturing Nanoelectronics research and innovation center, imec, says that it has managed to pool together stakeholders from the semiconductor value chain – from companies such as Apple and Microsoft, to suppliers, including ASM, Kurita, SCREEN and Tokyo Electron – to participate in its Sustainable Semiconductor Technologies and Systems (SSTS) research program.
Sponsored content by FusionManufacturers Reassess their Supply Chains Prevailing obstacles since the COVID-19 Pandemic in 2020 have manufacturers reassessing their supply chain strategies. The following major disruptions that occurred entering 2022 added to existing setbacks, or created new ones altogether:
SiPearl reaches milestone – 100 employees The European chip designer has exceeded 100 employees across its six sites in France (Maisons-Laffitte, Grenoble, Massy, Sophia Antipolis), Germany (Duisburg) and Spain (Barcelona).
Renesas to convert closed factory to 300mm wafer fab Renesas plans to conduct a JPY 90 billion (EUR 664 million) investment in its Kofu factory, located in Kai City, Yamanashi Prefecture, Japan. The company closed the factory back in October 2014, but now intends to reopen the fab in 2024 as a 300mm wafer fab.
Arrow names Jörg Strughold as president EMEA components Arrow Electronics announces that Jörg Strughold will take over as president of its components business in EMEA. He succeeds Martin Bielesch who has decided to leave the company.
€14 billion to attract semiconductor players to Germany EUR 14 billion in state support is the German governments new strategy to attract more chipmakers to the country.
Sponsored content by Proval ServiceSince 25 years your partner for SMT stencils and solder pallets. 25 years of experience makes Proval Service not just a supplier but your trustful and grounded partner to support you with SMT stencils and solder pallets. A qualified and unite team can satisfy every customer's need during the whole process.
10 different companies have expressed interest in Toshiba Back in April 2022, Toshiba Corporation announced that it had resolved to solicit proposals on strategic alternatives from potential investors and sponsors. The Japanese company is seeking to enhance its corporate value and has since the announcement been holding discussions with the potential partners.
TDK expands with new MLCC production site in Japan Japanese TDK Corporation says that it will construct a new production building on the premises of the Kitakami Factory – located in Kitakami city, Iwate prefecture, Japan – in order to to enhance the company's MLCC production.
Avnet breaks ground on German expansion In order to better serve its customers’ local and global needs, Avnet is expanding in two locations in Germany. Avnet Embedded broke ground on a new manufacturing site in Eschbach and Avnet EMEA plans to build its third European logistics centre in Bernburg.
Viettel & Qualcomm team up on 5G infrastructure development Viettel Group and Qualcomm Technologies plans to collaborate and develop a next-generation 5G Radio Unit (RU) with massive MIMO capabilities and distributed units (DUs). This focuses on helping to expedite the development and roll-out of 5G network infrastructure and services in Vietnam and globally.
Applied Materials opens Montana expansion – create 200 new jobs The company has opened its latest expansion in Montana, a new semiconductor manufacturing center set to create 200 jobs in the Flathead Valley.
How to easily select the right frequency generation component Question: What is the right frequency generation component for my application?
Bell Semiconductor is suing companies left and right In late April, Bell Semiconductor, a Pennsylvania-based technology and intellectual property licensing company, filed lawsuits against Micron, Infineon, Nvidia and seven other companies alleging infringement of one of its patents.
Can pre-owned equipment be the way out of the shortage? The global semiconductor supply chain remains under immense pressure. However, major investments are being made to increase capacity and fortify the supply chain for the future – but we wont feel the effect of these investments for years. Adding to the issue, there is not enough chips for the chipmaking machines.
CN Rood takes over ABtronix Test and measurement equipment supplier, CN Rood, expands its position in both Scandinavia and the Belelux via the acquisition of ABtronix, professional T&M equipment.
STMicro supplies SiC tech to Semikron for EV power modules STMicroelectronics has revealed it is supplying SiC technology for the eMPack electric-vehicle power modules from Semikron.
Henkel opens new application center in Silicon Valley Henkel is opening its Application Center in Santa Clara, California designed to support product development for the company's high-tech customers in the Silicon Valley region. The application center will help expedite proof-of-concept initiatives for electronics advances.Load more news