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Chart of the most commonly searched connector types
Navitas showcasing advances in GaN and SiC technologies at PCIM, including first production-released 650V bi-directional GaNFast ICs
Navitas showcasing advances in GaN and SiC technologies at PCIM, including first production-released 650V bi-directional GaNFast ICs
Infineon showcasing power device solutions at PCIM
Portable power station battery capacity extension: Curious coordination
I’m still awaiting an opportunity, when I have spare time, the snow’s absent from the deck and winds are calm, to test out those two 220W solar panels I already mentioned I bought last year:
for parallel-combining and mating with my EcoFlow DELTA 2 portable power station:
While I remain on more-favorable-conditions standby, I’ve got two other pieces of EcoFlow gear also in the queue to tell you about. One, the 800W Alternator Charger that I mentioned in a more recent piece, isn’t an installation high-priority right now, so hands-on results prose will also need to wait.
But the other (and eventually also its replacement; hold that thought), which I pressed into service as soon as it arrived, is the topic of today’s post. It’s the DELTA 2 Smart Extra Battery, which mates to the DELTA 2 base unit over a thick dual-XT150-connectors-inclusive cable and combo-doubles the effective subsequently delivered storage capacity:
Here’s what my two identical-sized (15.7 x 8.3 x 11 in/400 x 211 x 281 mm) albeit different-weight (DELTA 2 base unit: 27 lbs/12 kg, DELTA 2 Smart Extra Battery: 21 lbs/9.5 kg) devices look like in their normal intended stacked configuration:
And here’s my more haphazard, enthusiastic initial out-of-box hookup of them:
In the latter photo, if you look closely, you can already discern why I returned the original Smart Extra Battery, which (like both its companion and its replacement) was a factory-refurbished unit from EcoFlow’s eBay storefront. Notice the brightness difference between it and the more intense DELTA 2’s displays. I should note upfront that at the time I took that photo, both devices’ screens still had the factory-installed clear plastic protectors on them, so there might have been some resultant muting. But presumably it would have dimmed both units’ displays equally.
The displays are odd in and of themselves. When I’d take a screen protector off, I’d see freakish “static” (for lack of a better word) scattered all over it for a few (dozen) seconds, and I could also subsequently simulate a semblance of the same effect by rubbing my thumb over the display. This photo shows the artifacts to a limited degree (note, in particular, the lower left quadrant):
My root-cause research has been to-date fruitless; I’d welcome reader suggestions on what core display technology EcoFlow is using and what specific effect is at play when these artifacts appear. Fortunately, if I wait long enough, they eventually disappear!
As for the defective display in particular, its behavior was interesting, too. LCDs, for example, typically document a viewing angle specification, which is the maximum off-axis angle at which the display still delivers optimum brightness, contrast and other attributes. Beyond that point, typically to either side but also vertically, image quality drops off. With the DELTA 2 display, it was optimum when viewed straight on, with drop-off both from above and below. With the original Smart Extra Battery display, conversely, quality was optimum when viewed from below, almost (or maybe exactly) as if the root cause was a misaligned LCD polarizer. Here are closeups of both devices’ displays, captured straight on in both cases, post-charging:
After checking with Reddit to confirm that what I was experiencing was atypical, I reached out to EcoFlow’s eBay support team, who promptly and thoroughly took care of me (and no, they didn’t know I was a “press guy”, either), with Fedex picking up the pre-paid return-shipping defective unit at my front door:
and a replacement, quick-shipped to me as soon as the original arrived back at EcoFlow.
That’s better!
The Smart Extra Battery appears within the app screens for the DELTA 2, vs as a distinct device:
Here’s the thick interconnect cable:
I’d initially thought EcoFlow forgot to include it, but eventually found it (plus some documentation) in a storage compartment on top of the device:
Here are close-ups of the XT150 connectors, both at-device (the ones on the sides of the DELTA 2 and Smart Extra Battery are identical) and on-cable (they’re the same on both ends):
I checked for available firmware updates after first-time connecting them; one was available.
I don’t know if it was related to the capacity expansion specifically or was just timing-coincidental, and if it was for the DELTA 2 (with in-progress status shown in the next photo), Smart Extra Battery or both…but it completed uneventfully and successfully.
Returning to the original unit, as that’s what I’d predominantly photo-documented, it initially arrived only 30% “full”:
With the DELTA 2 running the show, first-time charging of the Smart Extra Battery was initially rapid and high power-drawing; note the incoming power measured at it:
and flowing both into and out of the already-fully-charged DELTA 2:
As the charging process progressed, the current flow into the Smart Extra Battery slowed, eventually to a (comparative) trickle:
until it finished. Note the high reported Smart Extra Battery temperature immediately after charge completion, both in an absolute sense and relative to the normal-temperature screenshot shown earlier!
In closing, allow me to explain the “Curious Coordination” bit in the title of this writeup. I’d upfront assumed that if I lost premises power and needed to harness the electrons previously collected within the DELTA 2/Smart Extra Battery combo instead, the Smart Extra Battery would be drained first. Such a sequence would theoretically allow me to, for example, then disconnect the Smart Extra Battery and replace it with another already-fully-charged one I might have sat around to further extend the setup’s total usable timespan prior to complete depletion.
In saying this, I realize that the feasibility of such a scenario isn’t likely, since the Smart Extra Battery can’t be charged directly from AC (or solar, for that matter) but instead requires an XT150-equipped “smart” source such as a (second, in this scenario) DELTA 2. That said, what I discovered to be the case when I finally got the gear in my hands was the exact opposite; the DELTA 2 battery drained first, down to a nearly (but not completely) empty point, then the discharge source switched to the extra battery. And that said, further research has educated me that actual behavior varies depending on how much current is demanded by whatever the combo is powering; in heavy-load scenarios, the two devices’ battery packs drain in parallel.
What are your thoughts on this behavior, and/or anything else I’ve mentioned here? Share them with your fellow readers (and me!) in the comments!
—Brian Dipert is the Editor-in-Chief of the Edge AI and Vision Alliance, and a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the company’s online newsletter.
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- EcoFlow’s Delta 2: Abundant Stored Energy (and Charging Options) for You
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EPC launches laser driver evaluation board for indirect time-of-flight applications
Continental Group Sector Automotive will be Named Aumovio in the Future
- Aumovio combines tradition and a strong market position in the automotive industry with the ambition to shape the mobility of the future
- With the announcement of the new name at Auto Shanghai 2025, Automotive underlines the importance of the growth market of China and its “in the market for the market” approach
- Philipp von Hirschheydt, Member of the Executive Board of Continental and CEO Automotive: “We have consistently aligned automotive with future technologies and are picking up on market developments quickly, innovatively and from a strong competitive position. This means that we are consistently on our way to becoming an adaptive automotive powerhouse. Our future brand also reflects this ambition”
Continental group sector Automotive presented its future name at Auto Shanghai. The independent automotive company will be named Aumovio. The name of the new company combines the strong market position, heritage and technological expertise in the automotive industry with the ambition to shape the mobility of the future with innovations. Aumovio will offer electronic products and advanced mobility solutions for the software-defined vehicle and safe, exciting, connected and autonomous mobility to a wide range of global customers. According to a market analysis by Berylls, Automotive expects the value of solutions per vehicle in these segments to grow by an average of 4.7 percent annually until 2029 – and more dynamically than the number of passenger cars and light commercial vehicles produced worldwide (based on market forecast by S&P Global Mobility). At the Auto Shanghai this year, the group sector also presented its “in the market for the market” approach and several innovative technologies for Chinese customers and the Chinese market. Following the expected approval at the Continental Annual Shareholders’ Meeting on April 25, 2025, Aumovio is scheduled to list on the Frankfurt Stock Exchange in September 2025.
“As an independent company, we gain significantly more creative power and speed. Aumovio will be characterized by a triad of technologically leading products, a consistent value creation strategy and a global synergetic network, combined with a strong local presence for our customers. Our aim is to further expand our position in the future fields and growth markets of mobility. This strategy is particularly evident in China. Among other things, we are relying on our strong local presence by producing and developing locally for the Chinese market,” says Philipp von Hirschheydt, Member of the Executive Board of Continental and CEO of Automotive.
Continental’s group sector Automotive has been present in China for 30 years and employs around 10,000 people there. In the 2024 financial year, Automotive generated around 14 percent of its global sales in China. At Auto Shanghai, Automotive presented the Luna and Astra driver assistance systems, among others. Both were developed in the joint venture Horizon Continental Technology, for the Chinese market. Luna is an assistance system and supports active safety as well as basic driving and parking functions to increase safety and comfort. Astra is an advanced assistance system and enables, among other things, assisted driving without a high-resolution map and parking assistance with memory function.
Modern mobility solutions from Automotive
The future Aumovio offers highly developed electronic products and modern mobility solutions. In addition to its strong market position with innovative sensor solutions, displays, and technologically leading braking and comfort systems, Aumovio has significant expertise in software, architecture platforms and assistance systems for the rapidly growing future market of software-defined and autonomous vehicles. The Automotive group sector employs around 92,000 people and generated sales of around 19.4 billion Euros in the 2024 financial year.
The post Continental Group Sector Automotive will be Named Aumovio in the Future appeared first on ELE Times.
Bosch presents new software and hardware for assisted and automated driving
New radar sensor with Bosch’s own computing chip (SoC) and flexible ADAS solution packages
- The Bosch ADAS product family is a flexible modular system for driver assistance. Bosch is to equip the first passenger cars in China from mid-2025.
- Bosch is the first Tier 1 supplier to present a new radar sensor with a complete in-house design and its own system-on-chip (SoC).
- The future portfolio for driver assistance and automated driving is rounded off by a next-generation multi-purpose camera and inertial sensor unit.
Bosch is presenting its extensive portfolio of solutions for assisted and automated driving and parking. It includes software features and hardware components that the technology group is aligning with the expectations of local drivers and can be easily customized for different customer needs. With its radar sensor, Bosch is the first Tier 1 supplier worldwide to break new ground and develop and manufacture the entire product in-house. The special feature: The sensor has a computing chip specially developed by Bosch–known as an SoC–which combines high computing power with the smallest possible footprint. The radar sensor fits into Bosch’s newly designed modular system for assisted and automated driving: The Bosch ADAS product family (Advanced Driver Assistance Systems) offers a kind of ecosystem of software, sensors and services as well as the appropriate high-performance computers. Customers can make use of this and flexibly utilize the comprehensive solutions for various markets and vehicle segment – from low-cost small cars to high-performance premium models. The goal: Bosch wants to enable manufacturers worldwide to bring driver assistance functions to the mass market more easily, quickly, and cost-effectively. A new generation of the multi-purpose camera and the inertial sensor unit for the precise localization of assisted and automated vehicles complement the sensor portfolio.
“With our new Bosch ADAS product family, we are offering cost-efficient solutions for assisted and automated driving to the usual high standards of quality and safety. We have the right software and hardware for driver assistance functions, from small cars to mid segment and premium vehicles. This enables car manufacturers to integrate functions quickly and easily into their vehicles and bring them to market very fast.”
Christoph Hartung, President of the Cross-Domain Computing Solutions division at Robert Bosch GmbH.
“With our new Bosch ADAS product family, we are offering cost-efficient solutions for assisted and automated driving to the usual high standards of quality and safety. We have the right software and hardware for driver assistance functions, from small cars to mid segment and premium vehicles. This enables car manufacturers to integrate functions quickly and easily into their vehicles and bring them to market very fast,” says Christoph Hartung, President of the Cross-Domain Computing Solutions division at Robert Bosch GmbH
New Bosch ADAS product family in three equipment variants
Advanced driver assistance systems help to increase safety and comfort on the road. For example, by providing the driver with targeted support during monotonous and tiring driving tasks. Bosch has many years of experience with driver assistance systems, their development and integration into the vehicle. A deep understanding of each vehicle area is required for optimum implementation. With this expertise, Bosch is repositioning the ADAS product family. It enables assisted driving and parking up to SAE level 2, thus meeting the prevailing demand on the market. Bosch offers the ADAS product family in three variants: for the entry segment, the mid segment and the high segment. The variants differ depending on the scope of the software, the number and combination of sensors, and the required computing power. Seamless harmonization of these individual components facilitates system integration. Bosch gives car manufacturers swift and uncomplicated access to driver assistance systems, enabling them to significantly accelerate the development time of their vehicles. Bosch brings its hardware and software components to the market both as a complete systemic solution and separately from each other, as is the case in modern vehicle development. This provides further scope, as individual components of the three variants can be exchanged and flexibly combined as required. Accordingly, manufacturers have further freedom to integrate the driver assistance systems into their cars on a brand-specific basis. Artificial intelligence can be found throughout the Bosch ADAS product family. Bosch uses it, for example, for perception and driving planning. Thanks to AI, the vehicle thinks ahead, pays attention to what other road users might be doing, and calculates the next steps to safely reach the destination.
The entry segment version already incorporates key safety and comfort functions into the vehicle. The car uses this to regulate its speed and distance from the vehicle in front depending on the situation and keeps in lane when lane markings are clearly visible. This variant can be implemented as a purely camera solution with the new multi-purpose camera from Bosch, but can also be supplemented with up to five radar sensors depending on the safety requirements (of a country). The variant for the mid segment unlocks even more extensive functions. For example, an extended lane keeping assist that can also cope with lane markings that are not visible in places. In this variant, Bosch combines its camera heads for perception with additional sensors. The computing power no longer takes place in the camera itself, but in a more powerful central vehicle computer, as is becoming standard in software cars. Thanks to Bosch, the vehicle masters more complex traffic scenarios, which further increases driving comfort and safety on freeways and in heavy traffic. The system also pays attention and supports the driver. Bosch is already introducing hands-free driving on the freeway in this variant, provided the legal framework in the respective country permits it. This means that the driver can take their hands off the steering wheel at times, but still remains responsible. The variant for the high segment represents the pinnacle of Bosch driving assistance. It uses a 360-degree video belt and impresses with even greater computing power, so that the vehicle can handle urban junctions with ease and safely enter and exit roundabouts. Hands-free driving is extended to urban traffic in this version, provided that the legal requirements in the markets allow it. Bosch takes into account the various regulatory requirements and safety assessments
Bosch ADAS product family goes into serial production in mid-2025
The equipment variant for the mid-range segment will go into serial production with a Chinese manufacturer in the middle of this year. Users of this system will benefit from an assistance system linked to the navigation system, which is particularly popular among Chinese customers. The vehicle then independently carries out driving maneuvers along the route entered, such as changing lanes on freeways. The driver remains responsible and must be ready to intervene at any time. This function makes driving in the heavy traffic of Chinese cities more convenient and safer. Bosch has also already secured its first orders for the high segment version, with serial production expected to start in summer 2025. Bosch has already acquired half a dozen new customers for the ADAS product family for mid- and high segment in China, including BAIC, Dongfeng and Jetour. Bosch is thus continuously strengthening its leading position in the global ADAS market.
New radar sensor with Bosch SoC
Radar sensors are key components of driver assistance systems and modern vehicles would be inconceivable without them. For the new generation of its radar sensor, Bosch has developed and manufactured all core elements in-house, including the computing chip (SoC). The new Bosch radar sensor uses “RF CMOS technology,” which enables the efficient integration of high-frequency and digital circuits on a single chip. The structure size of the transistors of only 22 nanometers makes the chip particularly powerful and efficient despite its small footprint. Bosch is the first Tier 1 supplier on the market to introduce this technology in serial production.
New generation of the multi purpose camera
With the increasing market penetration of more extensive driver assistance functions in the lower price segments, high-performance yet affordable camera solutions are steadily gaining in importance. The new multi purpose camera from Bosch enables assisted driving and parking functions (up to SAE level 2) from the entry segment. Serial production is scheduled to start in 2026, initially in the Chinese market. Bosch’s own optical image processing module in the new camera generation ensures optimum sharpness and precision over the entire product service life, even in highly fluctuating temperatures. The camera is particularly durable, with consistently stable functional performance.
With its 8 megapixel image sensor, a horizontal field of vision of 120 degrees, and a detection range of up to 300 meters, the camera enables safety and convenience functions for assisted driving. These include adaptive cruise control and distance control, emergency braking within your own lane, lane keeping in urban areas, and detection and stopping at red lights
The new multi purpose camera is the central interface for the fusion of various sensor data. This means that the camera combines the data from its own image sensor and additionally from up to five radars and other sensors such as driver monitoring cameras or interior sensors. This integrated approach enables OEMs to reliably comply with mandatory ADAS regulations (e.g. General Safety Regulation), improve driving safety, and support the driver on the freeway (e.g. with assisted lane changes).
Safe localization in all driving situations
For assisted and automated driving, it is essential that vehicles can locate themselves precisely and safely at all times. Even in difficult visibility conditions and in the absence of lane markings or if the signal from the global navigation satellite system (GNSS) fails – for example, when driving through a tunnel – it is essential that the vehicle’s location can be determined reliably. This is the only way to guarantee a high level of functional availability. At the largest automotive trade fair in China, Bosch is presenting for the first time the new generation of its high-performance inertial measurement unit (IMU), which has been specially designed for ADAS and vehicle dynamics applications. Vehicles pitch when braking, lean to one side (roll) or lurch (swerve) when taking corners. In addition to these movements, the inertial sensor unit measures the vertical, longitudinal and lateral acceleration of the vehicle. From this, it can precisely calculate the relative change in position of the vehicle, enabling it to maintain the originally planned route with only minimal deviation. With various product variants, Bosch offers a high degree of scalability, from the cost-effective entry segment variant for assisted driving to the high-performance sensor for automated driving up to SAE level 4. Bosch uses sensor modules that are manufactured in the company’s own production facilities and, in addition to an in-depth understanding of the system, can draw on a comprehensive range of experience from over three decades of developing such inertial sensors.
The post Bosch presents new software and hardware for assisted and automated driving appeared first on ELE Times.
OMNIVISION Launches 1.5-Megapixel Global Shutter Sensor for Automotive Driver Monitoring Systems
The new OX01N1B is designed to be a cost-effective solution for DMS cameras and features industry-leading QE, MTF and low power
OMNIVISION, a leading global developer of semiconductor technology, including advanced digital imaging, analog and display solutions, announced the new OX01N1B image sensor for in-cabin automotive driver monitoring systems. The device is the newest addition to OMNIVISION’s industry-leading Nyxel near-infrared technology family of automotive sensors and is a 1.5-megapixel RGB-IR or monochrome BSI global shutter (GS) sensor with a pixel size of 2.2 microns (µm) and an optical format of 1/4.51-inch. OMNIVISION will showcase the OX01N1B sensor with eco-system partners at Auto Shanghai, taking place April 23-May 2, 2025.
Key features of the OX01N1B include industry-leading NIR quantum efficiency at 36% for excellent low-light performance, a high modulation transfer function for better image quality and resolution, low power consumption, and an optical format that enables extremely compact camera module design. The OX01N1B uses OmniPixel 4-GS technology for simultaneous image detection in all pixels to accurately reproduce rapid motion without any distortions.
“Driver monitoring systems will be mandatory for all new cars in Europe starting in 2026; the entire global automotive industry is experiencing greater adoption rates of DMS as well, in an effort to improve road safety. As a result, OMNIVISION is introducing the new OX01N1B, which is the ‘sweet spot’ among performance, size and cost for mainstream DMS applications,” said Dr. Paul Wu, head of automotive product marketing, OMNIVISION. “The OX01N1B chip size is even smaller than the previous OX01H1B and it can reuse the same optical path since the pixel size and optical array size is identical. We’ve also added image signal processing to the OX01N1B device.” Dr. Wu adds, “There are many design considerations for DMS. With our expanded portfolio, we offer automotive OEMs a variety of cost and performance options and greater flexibility to place the DMS camera into different locations in their next-generation vehicle designs.”
“OMNIVISION’s new OX01N1B sensor delivers exceptional performance in a remarkably compact format, which makes it a perfect fit for our latest innovation, the All-In-One camera AI ONE,” said Martin Krantz, CEO and Founder of Smart Eye. “With this sensor at its core, we’ve been able to build the integrated DMS we’ve always envisioned, bringing together camera, sensor, processing, and software in a single, self-contained unit.”
The OX01N1B has integrated ASIL-B and cybersecurity that meet the latest industry standards. It comes in an OMNIVISION a-CSP package, allowing for higher-performance image sensors in tighter camera spaces. It is available in a reconstructed wafer option for designers who want to assembly a bare die imager into their camera module.
The post OMNIVISION Launches 1.5-Megapixel Global Shutter Sensor for Automotive Driver Monitoring Systems appeared first on ELE Times.
Renesas Debuts New Group in Popular RA0 Series with Best-in-Class Power Consumption and Extended Temperature Range
Low-Cost RA0E2 Devices Target Consumer Electronics, Small Appliances, Industrial System Control and Building Automation
Renesas Electronics Corporation, a premier supplier of advanced semiconductor solutions, today introduced the RA0E2 microcontroller (MCU) Group based on the Arm Cortex -M23 processor. The new, cost-competitive devices offer extremely low power consumption, extended temperature range, and a wide variety of peripheral functions and safety features.
Renesas introduced the RA0 MCU series in 2024 and it has quickly become very popular with a wide range of customers due to its affordability and low power consumption. RA0E1 devices have already been adopted in consumer electronics, appliance and white goods, power tools, industrial monitoring and other applications.
RA0E2 MCUs are fully compatible with RA0E1 devices, offering pin-expansion while maintaining the same peripherals and ultra-low power. This compatibility lets customers re-use existing software assets. The new devices deliver industry-leading power consumption of only 2.8mA current in active mode, and 0.89 mA in sleep mode. In addition, an integrated High-speed On-Chip Oscillator enables the fastest wake-up time for this class of microcontroller. The fast wake-up enables the RA0 MCUs to stay in Software Standby mode more of the time, where power consumption drops to a minuscule 0.25 µA.
Renesas’ RA0E1 and RA0E2 ultra-low power MCUs deliver an ideal solution for battery-operated consumer electronics devices, small appliances, industrial system control and building automation application.
Feature Set Optimized for Low Cost
The RA0E2 devices have a feature set optimized for cost-sensitive applications. They offer a wide operating voltage range of 1.6V to 5.5V so customers don’t need a level shifter/regulator in 5V systems. The RA0 MCUs also integrate timers, serial communications, analog functions, safety functions and security functionality to reduce customer BOM cost. A wide range of packaging options is also available, including a tiny 5mm x 5mm 32-lead QFN.
In addition, the new MCU’s high-precision (±1.0%) HOCO improves baud rate accuracy and enables designers to forego a standalone oscillator. Unlike other HOCOs in the industry, it maintains this precision in environments from -40°C to 125°C. This wide temperature range enables customers to avoid costly and time-consuming “trimming,” even after the reflow process.
“The market reception for our RA0 Series has exceeded even our own high expectations,” said Daryl Khoo, Vice President of the Embedded Processing Marketing Division at Renesas. “The RA0E2 Group MCUs deliver the same ultra-low power and price point that have been so popular with our customers. The addition of extended temperature range and more memory opens up even more applications and use cases. We plan to further expand the RA0 product lineup, delivering optimal solutions for 8-16 bit MCU users transitioning to 32-bit MCUs.”
Key Features of the RA0E2 Group MCUs
- Core: 32MHz Arm Cortex-M23
- Memory: Up to 128KB integrated Code Flash memory and 16KB SRAM
- Extended Temperature Range: Ta -40°C to 125°C
- Timers: Timer array unit (16b x 8 channels), 32-bit interval timer (8b x 4 channels), RTC
- Communications Peripherals: 3 UARTs, 2 Async UART, 6 Simplified SPIs, 2 I2C, 6 Simplified I2Cs
- Analog Peripherals: 12-bit ADC, temperature sensor, internal reference voltage
- Safety: SRAM parity check, invalid memory access detection, frequency detection, A/D test, output level detection, CRC calculator, register write protection
- Security: Unique ID, TRNG, AES libraries, Flash read protection
- Packages: 32- and 48-lead QFNs, 32-, 48-, and 64-pin LQFP
The new RA0E2 Group MCUs are supported by Renesas’ Flexible Software Package (FSP). The FSP enables faster application development by providing all the infrastructure software needed, including multiple RTOS, BSP, peripheral drivers, middleware, connectivity, networking, and security stacks as well as reference software to build complex AI, motor control and cloud solutions. It allows customers to integrate their own legacy code and choice of RTOS with FSP, thus providing full flexibility in application development. Using the FSP will ease migration of RA0E1 designs to larger RA0E2 devices.
The post Renesas Debuts New Group in Popular RA0 Series with Best-in-Class Power Consumption and Extended Temperature Range appeared first on ELE Times.
Amplification of transfer function by 53.98 dB
 | submitted by /u/Kotsaros [link] [comments] |
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LM4041 voltage regulator impersonates precision current source
The LM4041 has been around for over 20 years. During those decades, while primarily marketed as a precision adjustable shunt regulator, this classic device also found its way into alternative applications. These include voltage comparators, overvoltage protectors, voltage limiters, etc. Voltage, voltage, voltage, must it always be voltage? It gets tedious. Surely this popular precision chip, while admittedly rather—um—“mature”, must have untapped potential for doing something that doesn’t start with voltage.
Wow the engineering world with your unique design: Design Ideas Submission Guide
The Design Idea (DI) presented in Figure 1 offers the 4041 a usual, possibly weird, maybe even new role to play. It’s a precision current source.
Figure 1 Weirdly, the “CATHODE” serves as the sense pin for active current source regulation.
The above block diagram shows how the 4041 works at a conceptual level:
Sourced current = Is = (V+ – (Vc + 1.24v))/R1
Is > 0, V+ < 15v, Is < 20 mA
The series connection subtracts an internal 1.24-V precision reference from the external voltage input on the CATHODE pin. The internal op-amp subtracts the voltage input on the FB pin from that difference, then amplifies and applies the result to the pass transistor. If it’s positive [(V+ – 1.24) > Vc], the transistor turns on and shunts current from CATHODE to ANODE. Otherwise, it turns off.
When a 4041 is connected in the traditional fashion (FB connected to CATHODE and ANODE grounded), the scheme works like a shunt voltage regulator should, forcing CATHODE to the internal 1.24-V reference voltage. But what will happen if the FB pin is connected to a constant control voltage [Vc < (V+ – 1.24v)] and CATHODE—and instead of being connected to FB—floats freely on current sensing resistor R1?
What happens is the current gets regulated instead of the voltage. Because Vc is fixed and can’t be pulled up to make FB = CATHODE – 1.24, CATHODE must be pulled down until equality is achieved. For this to happen, a programmed current, Is, must be passed that is given by:
Is = (V+ – (Vc – 1.24))/R1.
Figure 2 illustrates how this relationship can be used (assuming a 5-V rail that’s accurate enough) to make a floated-cathode 4041 regulate a constant current source of:
Is = (5v – 2.5 – 1.23)/R1 = 1.27v /R1
It also illustrates how adding a booster transistor Q1 can accommodate applications needing current or power beyond Z1’s modest limits. Notice that Z1’s accuracy will be unimpaired because, with whatever fraction of Is that Q1 causes to bypass, Z1 is summed back in before passing through R1.
Figure 2 The booster transistor Q1 can handle current beyond 4041 max Is and dissipation limits.
Figure 3 shows how Is can be digitally linearly programmed with PWM.
Figure 3 Schematic showing the DAC control of Is. Is = Df amps, where Df = PWM duty factor. The asterisked resistors should be 1% or better.
Incoming 5-Vpp, 10-kHz PWM causes Q2 to switch R5, creating a variable average resistance = R5/Df. Thanks to the 2.5-V Z1 reference, the result is a 0 to 1.22 mA current into Q1’s source. This is summed with a constant 1.22 mA bias from R4 and level shifted by Q1 to make a 1.22 to 2.44 V control voltage, Vc, for current source Z2.
The result is a linear 0- to 1-A output current, Is, into a grounded load where Is = Df amps. Voltage compliance is 0 to 12 V. The 8-bit compatible PWM ripple filtering is 2nd order using “Cancel PWM DAC ripple with analog subtraction.”
R3C1 provides the first-stage ripple filter and R7C2 the second. The C1 and C2 values shown are scaled for Fpwm = 10 kHz to provide an 8-bit settling time of 6 ms. If a different PWM frequency is used, scale both capacitors by 10kHz/Fpwm.
A hot topic is that Q4 can be called on to dissipate more than 10 W, so don’t skimp on heatsink capacity.
Q3 is a safety shutdown feature. It removes Q1 gate drive when +5 falls below about 3 V, shutting off the current source and protecting the load when controller logic is powered down.
Figure 4 adds zero and span pots to implement a single-pass calibration for best accuracy:
- Set Df = 0% and adjust single turn ZERO trim for zero output current
- Set Df = 100% and adjust single turn CAL trim for 1.0 A output
- Done.
Figure 4 Additional zero and span pots to implement a single-pass calibration for best accuracy.
Stephen Woodward’s relationship with EDN’s DI column goes back quite a long way. Over 100 submissions have been accepted since his first contribution back in 1974.
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The post LM4041 voltage regulator impersonates precision current source appeared first on EDN.
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