Tag Archives: app notes

App note: How to measure the power consumption of a peripheral

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Application note from NXP Semiconductors on MCU peripheral power consumption measurement. Link here (PDF)

This Application Note outlines the steps to measure the power consumption of a peripheral and figure out some key points in the measurement. The document takes low-power timer (LPTMR) and LPUART as examples to introduce the method to measure the power consumption of peripheral. The test code is developed in IAR and FRDM-KE15Z board.

App note: TEA1938T GreenChip SMPS control IC

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TEA1938T SMPS control IC application note from NXP Semiconductors. Link here (PDF)

The TEA1938T is a high-featured low-cost DCM and QR mode flyback converter controller. It provides high efficiency at all power levels and very low no-load power consumption at nominal output voltage in burst mode operation.

To minimize ripple, the burst mode uses a small hysteresis scheme. The TEA1938T is designed to support multiple-output-voltage applications like USB PD (Type C) power supplies. Typical applications include notebooks and tablet adapters, fast charging, and direct charging adapters.

App note: Using trench technology MOSFETs in hot swap applications

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Safely use trench MOSFETs on hot swap application by determining its operation within its SOA in a limited time, app note from International Rectifier. Link here (PDF)

Hot Swap circuits are used to allow for “Hot Plugging” of circuit boards into back planes. The applications that require such functionality are mission critical, such as servers and communications equipment that must operate continuously. These circuit boards are usually employed in a rack mount system which consists of an array of boards that cannot be powered down. Thus hot swapping allows for a bad board in the array to be replaced without powering down the entire system.

In essence the Hot Swap circuit, which is between the board input rail and the rest of the board’s circuitry, is an inrush current limiter that allows for charging of the bulk capacitance in a controlled manner. Also faults, such as over current and overvoltage are managed by Hot Swap circuits.

App note: Class D audio amplifier performance relationship to MOSFET parameters

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Application note from International Rectifier on MOSFET paremeters to consider when designing a Class D audio amplifier. Link here (PDF)

Class D audio amplifier is a switching amplifier that consists in a pulse width modulator (with switching frequency in order of several hundred kHz), a power bridge circuit and a low pass filter. This type of amplifier has demonstrated to have a very good performance. These include power efficiencies over 90%, THD under 0.01%, and low EMI noise levels that can be achieved with a good amplifier design.

Key factors to achieve high performance levels in the amplifier are the switches in power bridge circuit. Power losses, delay times, and voltage and current transient spikes should be minimized as much as possible in these switches in order to improve amplifier performance. Therefore, switches with low voltage drop, fast on and off switching times and low parasitic inductance are needed in this amplifier.

MOSFET have proved to be the best switch option for this amplifier because of its switching speed. It is a majority carrier device, its switching times are faster in comparison with other devices such as IGBT or BJT, resulting in better amplifier efficiency and linearity.

App note: 12Vac LED Driving without smoothing capacitors

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Application note from Diodes Incorporated on driving 12Vac LED without smoothing capacitors with their Zetex ZXLD1360 LED driver IC and SBR2A40P1 super barrier rectifier. Link here (PDF)

LED based architectural lighting is now coming of age, but there are still some problems to be considered when designing luminaires to be fitted into existing installations.

This Application Note discusses some of the challenges and shows that the omission of the traditional smoothing capacitors has advantages in saving cost, space and PFC problems.

App note: CAN Bus – Common high speed physical layer problems

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App note from Vector on three commonly encountered high speed CAN physical layer problems – bus termination, signal levels, and ground. Link here (PDF)

Determining the exact cause of a CAN problem is not at all simple.

Is the problem in hardware or software? Is the problem on the circuit board or on the CAN network wiring?
Sometimes the problem may not be at the module level – perhaps the cause is up at the system level.

This application note discusses methods used to investigate serveral of the more common CAN Physical Layer problems typically encountered when debugging high-speed CAN.