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15 Jul 2015

mosfet

Turn loads on and off with your Arduino! Use 5V to control up to 100V. Add a motor, solenoid, or get creative! P channel or N Channel.

This is version 2.0 of the previously successful kickstarter project I launched last year. I have a ton of these PCB boards left over and it got me thinking. Why not find a P channel MOSFET with the same pinout and use it to control the direction of the motor also. I looked around and found the IRF5210. I ordered up a batch and tested them out. All thats left to do now is order a large quantity for the price break and assemble the rest of the boards.

Super Simple Arduino Load Driver V2.0 – [Link]

2 Jul 2015

solderingstation-600x224

MatthiasW over at DebuggingLab posted his DIY Weller station clone project, that is available at Github:

At the fpv-community.de Forum I read about a DIY Weller station. Basically an Arduino shield to drive a Weller soldering tip. As there is not much to it, the board simply contains an precision OpAmp, a power MOSFET, 2 buttons for adjusting the temperature and a display to show the current values. This design looks like a good starting point for my own advanced project. As I have lately discovered a 1,8 inch SPI TFT at banggood.com for an amazing price ( ~ 4.60 $ / 3,70 €), I started using them regularly in my projects. So I surely wanted to use it with this soldering station as well.

DIY soldering station – [Link]

2 Jun 2015

Dave explains how BJT and MOSFET transistors work at the silicon chip level.
How does a BJT transistor actually amplify current?
P and N type doping, charge carriers, conduction channel, field effect, holes and electrons, all the other good stuff.

EEVblog #748 – How Do Transistors Work? – [Link]

27 May 2015

600-mA-Constant-On-Time-Buck-Regulator-1432517217

The LM5017 is a 600 mA constant on-time synchronous buck regulator with built-in high side and low side MOSFETs. This device has a wide input voltage range from 7. 5 V to 100 V. The constant on-time control scheme used in this device doesn’t need loop compensation, delivers excellent transient response, and enables very high step-down ratios. The on-time varies inversely with the input voltage resulting in nearly constant frequency over the input voltage range. A high voltage startup regulator provides bias power for internal operation of the IC and for integrated gate drivers.

600 mA Constant On-Time Buck Regulator – [Link]


26 May 2015

In a DC motor, the stator is a permanent magnet and the rotor has the windings, which are excited with a current. The current in the rotor is reversed to create a rotating or moving electric field by means of a split commutator and brushes. On the other hand, in a BLDC motor, the windings are on the stator and the rotor is a permanent magnet, hence the term inside-out DC motor is coined.

To make the rotor turn, there must be a rotating electric field, typically a three-phase BLDC motor has three stator phases that are excited two at a time to create a rotating electric field. This method is fairly easy to implement, but to prevent the permanent magnet rotor from getting locked with the stator; the excitation on the stator must be sequenced in a specific manner while knowing the exact position of the rotor magnets. Position information can be gotten by hall effect sensors that detect the rotor magnet position.

The dsPIC30F2010 is a 28-pin 16-bit MCU specifically designed for embedded motor control applications. The six MCPWM pin outputs are connected to three MOSFET driver pairs (IR2101S), which in turn are connected to six MOSFETs (IRFR2407). These MOSFETs are connected in a three-phase bridge format to the three BLDC motor windings. MOSFET drivers also require a higher voltage (15V) to operate, the motor is a 24V BLDC motor so the DC+ to DC- bus voltage is 24V and a regulated 5V is provided to drive the dsPIC30F2010. The three Hall effect sensor inputs are connected to input pins that have Change Notification circuits associated with them. These inputs are enabled along with their interrupt. If a change occurs on any of these three pins, an interrupt is generated. To provide a speed demand, a potentiometer is connected to an ADC input (RB2).

To start and stop the motor, a push button switch is provided at RC14. To provide some current feedback to the motor, a low value resistor (25 milliohms) is connected between the DC- bus voltage and ground or Vss. The voltage generated by this resistor is amplified by an external op amp (MCP6002) and fed to an ADC input (RB1).

Sensored BLDC Motor Control – [Link]

21 Apr 2015

3887

by Susan Nordyk @ edn.com:

The LTC3887 dual-output synchronous step-down DC/DC converter from Linear Technology differs from its predecessor, the LTC3880, by offering an enhanced feature set that includes a faster 70-ms power-up time, higher output voltage, and a speedy ADC mode that provides an 8-ms update rate for one parameter. Housed in a 40-pin, 6×6-mm QFN package, the LTC3887 occupies the same board footprint as the previous version and operates over a temperature range of -40 C to +125 C.

Gate drivers integrated within the LTC3887 drive all N-channel MOSFETs from input voltages of 4.5 V to 24 V. The converter can regulate two independent outputs or can be configured for a two-phase single output. Up to six phases can be interleaved and paralleled for accurate sharing among multiple ICs, minimizing input and output filtering requirements for high current and/or multiple-output applications. The LTC3887 provides output voltages from 0.5 V to 5.5 V, accurate to within +/-0.5%, with output currents of up to 30 A per phase over the full operating temperature range.

Buck converter starts up in just 70 ms – [Link]

20 Apr 2015

P1090837a

by berryjam.eu:

I used specialized triple half bridge IC L6234 (~ 8$). You can make the same spending less money (but more time) with MOSFET transistors or other IC.

L6234 datasheet is surprisingly useless. Go straight to Application Note AN1088 instead.

I added current limiting resistors (1kΩ) to all INputs and ENable pins, a bunch of capacitors recommended in application note and current sensing shunt resistor 0.6Ω (big blue one).

Spining BLDC motors at super Slow speeds with Arduino and L6234 – [Link]

7 Apr 2015

 

7860

The LTC7860 is a high efficiency switching surge stopper with overvoltage and overcurrent protection for high availability systems. During normal operation the LTC7860 turns on an external Pchannel MOSFET continuously to pass the input voltage through to the output with minimum conduction loss. During an input overvoltage condition, the LTC7860 controls the external MOSFET to operate as a high efficiency switching DC/DC regulator to protect critical downstream components by limiting the output voltage and current. The LTC7860 has an input voltage operating range of 3.5V to 60V, which can be extended with external circuitry up to 200V and higher. In MIL-STD-1275 applications the LTC7860 protects devices operating from a 28V vehicle power bus which can reach as high as 100V for up to 500ms. The LTC7860 is ideal for industrial, avionics and automotive power applications including ISO7637, as well as positive high voltage distributed power Hot Swap systems.

LTC7860 – High Efficiency Switching Surge Stopper – [Link]

 

4 Mar 2015

DN523f1

by DAVID BURGOON @ edn.com:

There are several ways to produce a negative voltage from a positive voltage source, including using a transformer or two inductors and/or multiple switches. However, none are as easy as using the LTC3863, which is elegant in its simplicity, has superior efficiency at light loads and reduces parts count compared to alternative solutions.

The LTC3863 can produce a –0.4V to –150V negative output voltage from a positive input range of 3.5V to 60V. It uses a single-inductor topology with one active P-channel MOSFET switch and one diode. The high level of integration yields a simple, low parts-count solution.

AppNote: Inverting DC/DC controller converts a positive input to a negative output with a single inductor – [Link]

26 Feb 2015

Di5484f2

by sajjad Haidar @ edn.com:

A simple blocking oscillator circuit can be used to step up voltage using properties of coil inductance (V = L di/dt). Such a circuit is shown in Figure 1, which is more commonly called a Joule thief.

The output will be pulses of voltage that can be filtered using a diode and capacitor. As there is no regulation, the output voltage will vary with the input voltage or load. As this circuit uses a BJT, the supply voltage needs to be at least 0.7V to work, and with enhancement-mode MOSFETs, the supply voltage must usually be even higher.

MOSFET-based Joule Thief steps up voltage – [Link]



 
 
 

 

 

 

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