App note: High-frequency automotive power supplies


Switching power supply used in automotive electronics app note from Maxim Integrated. Link here (PDF)

The combination of high switching frequency and high-voltage capability is difficult to achieve in IC design. You can, however, design an automotive power supply that operates with high frequency if you protect it from temporary high-voltage conditions. High-frequency operation is becoming important as more and more electronic functions are integrated into the modern automobile. This article discusses several ways to protect low-voltage electronic circuits from the harsh effects of the automotive electrical environment. Also included are the results of laboratory tests for noise immunity.

App note: Fan speed control is cool!


App note from Maxim Integrated about their MAX6650 and MAX6651 fan controllers chip. Link here (PDF)

Temperature-based fan control is a necessity in a growing number of systems, both to reduce system noise and to improve fan reliability. When fan control is augmented by fan-speed monitoring, a speed-control loop can be implemented that is independent of manufacturing variances and wear on the fan. In addition, a fan that is about to fail can be identified so that it can be replaced before it fails.

App note: Choose the right power supply for your FPGA


Designing a power supply for FPGA includes multiple voltage, ripple management and power sequencing, here’s an app note from Maxim Integrated. Link here (PDF)

Field-programmable gate arrays (FPGAs) and complex programmable logic devices (CPLDs) require 3 to 15, or even more, voltage rails. The logic fabric is usually at the latest process technology node that determines the core supply voltage. Configuration, housekeeping circuitry, various I/Os, serializer/deserializer (SerDes) transceivers, clock managers, and other functions all have differing requirements for voltage rails, sequencing/tracking, and voltage ripple limits. An engineer must consider all of these issues when designing a power supply for an FPGA.

App note: Current-sense amplifier doubles as a high common mode instrumentation amplifier


Application note from Maxim intergrated on utilizing a boost converter and a current-sense amplifier to form a regulator that derives +5V from -48V without isolation. Link here (PDF)

Instrumentation amplifiers (IAs) are used where gain accuracy and dc precision are important, such as in measurement and test equipment. The downside of IAs is the cost. However, inexpensive current-sense amplifiers handle high common-mode voltages and share some traits with IAs. As a result, in some applications, such as a ground-referenced -48V to +5V power converter, current-sense amplifiers can replace IAs, thereby reducing cost.

App note: Microcontroller Clock – crystal, resonator, RC Oscillator, or silicon oscillator?


App note from Maxim Integrated on clock sources of microcontrollers and their strengths and weaknesses. Link here

The majority of clock sources for microcontrollers can be grouped into two types: those based on mechanical resonant devices, such as crystals and ceramic resonators, and those based on electrical phase-shift circuits such as RC (resistor, capacitor) oscillators. Silicon oscillators are typically a fully integrated version of the RC oscillator with the added benefits of current sources, matched resistors and capacitors, and temperature-compensation circuits for increased stability.

App note: ASIC fixes for noisy analog “Oops”


App note from Maxim Integrated about simple fixes that can solve most issues when designing with ASICs. Link here (PDF)

Noise is a common problem in mixed-signal ASICs, degrading performance and jeopardizing the completion of products. This application note gives hints and tips for adding external circuits that make many of these ASICs operational for prototyping or shippable as final products. Ways to optimize the ASIC by correcting noise in analog circuits, making adjustments, calibrating gain and offset, and cleaning power sources are discussed. The payoff is quicker time to market and even the prevention of an extra ASIC manufacturing spin.

App note: Multiplex boosted class-D without additional external circuitry


An analog switch MAX14689 from MAXIM Integrated let signals that are higher than rail voltage pass. Link here (PDF)

Boosted class-D amplifiers drive speakers with voltages greater than the supply voltage. These amplifiers are becoming more common because they allow higher performance audio from a single lithium ion battery. Most boosted class-D amplifiers, however, do not give the user access to the internal boosted voltage. This makes it difficult to multiplex a speaker to multiple audio sources using common analog switches. This application note discusses how the Beyond-the-Rails capability of the MAX14689 allows it to switch these signals without additional circuitry.