Circuits Apmilifier: LM2575

Showing posts with label LM2575. Show all posts

LM2577 and LM2575 Switching Regulators

Switching regulators are available is different circuit configurations including the flyback, feed-forward, push-pull, and non-isolated single-ended or single-polarity types. Also, the switching regulators can operate in any of three modes – step-down, step-up, or polarity inverting.
rovide the active functions for step-down (back) switching regulator, capable of driving a1A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5V, 12V, 15V and an adjustable output version.

Requiring a minimum number of external components, these regulators are simple to use and include internal frequency compensation and a fixed-frequency oscillator. LM 2575 series offers a high-efficiency replacement for popular 3-terminal linear regulators. It substantially reduces the size of the heat sink, and in many cases no heat sink is required. Fixed output voltage version is illustrated in figure.

The National Semiconductor LM 1577/LM 2577 are monolithic ICs that provide all of the power and control functions for step-up (boost), fly back, and forward converter switching regulators. The device is available in three different output voltage versions: 12 V, 15 V and adjustable.

Read more: http://www.circuitstoday.com/switching-regulators-using-lm-2575-and-lm-2577
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5V -1A Power Supply with LM2575

This circuit is derived from an application note of LM2575, It is a Power Switching Regulator from National Semiconductor.

National Semiconductor The details are here
LM2575

An application note by On Semiconductor shows how this chip can be used to generate Negative Voltage Power Supplies from Positive Voltages.

A Power Transistor which is having a drop of 4 Volts across it and passing 3 amps thru it, may dissipate around 12 Watts of Heat, This is the problem in Series Regulators. While a Saturated Transistor or Mosfet with 1 Volts across and 3 Amps Thru will be just 3 Watts. But then a fully on transistor or mosfet cannot be controlled or regulated, for that we turn it ON and OFF very fast so that the right amount of current or voltage is delivered.

The way this is done is PWM – Pulse Width Modulation. In this the mosfet or transistor is switched ON-OFF at say 100 kHz, but the ON duration is varied to control the output. The longer the duration of ON time more energy or punch is transferred. Switching losses will be present depending on how fast the rise and fall times of the pulses are.

The Pulsed AC or Chopped DC can be smoothed to the Average with Inductors and Capacitors. The reactive pulses of the Inductor has to be absorbed by a Schottky Rectifier 1N5817 — 20V-1A fast switching diode with low switching losses.

Source: http://www.electronics-circuits.com/schematics/arc20051113.html
Thank you.

Boost up current to 8 Amps from a LM2575

The LM2575 works a regulator only and don’t deliver any current to the load.
If the regulator switches “ON”, you find a voltage at the output of it. This makes T4 switching on also.
The collector of T4 now is nearly GND and also the Gate of FET T3. This FET switches on (it’s a P-FET!)
For T3 you can take everything what’s called Power P-FET with low RDSON, a IRF9540 is a good choice.
(The lower the higher the price

The “invention” of this circuit is the Gate turn off of T3.
In ON State, The Gate of T3 has nearly GND potential, D9 conducts and T5 is off.
If now the Regulator switch it’s output OFF, then the Base of T4 is pulled low by R12 and no currents flow through T4.
Also the cathode of D9 is connected to Vcc via R13. The stored energy in the Gate capacity of T3 lets now pull T5′s emiter lower then the base. Whats happens if the Base of a NPN transistor has higher voltage than the emiter? It conducts ! Now, T3′s gate is directly connected to the source via T5 and the gate capacity can be discharged very fast.
This happens several times faster than if you only had R13 to discharge the gate capacity !

Read more Source:

http://www.aca-vogel.de/DCDC-Converter/

8AfromLM2575_en.html
Thank you.

8V 1A Switching power supply with LM2575

Here is circuit 8V 1A Switching power supply, Use IC LM2575.
Input Volt 10V-40V DC only.
This Citcuit to become for Car or motorcycle,Use Volt 12V-14.4V 2A.

And Volt Output 2.3V-37V change by R1,R2
Detail see in image circuit and PCB.

Source:

http://www.ngc.pe.kr/bbs/zboard.php?id=data_others&no=28

Power Supply 5V 1.3/3A by LM2575

POWER1 is a switched power supply specially designed for use with modern single board computers. The mechanical dimensions match exactly those of the SBC ZWERG11A. Due to the small mechanical dimensions and the modern design, POWER1 can be used in all applications requiring a regulated voltage of 5 Volts DC, up to 3 Amperes. Voltage regulation is done with a component from National Semiconductor, known as “simple switcher”. Regarding the amount of extra components one can really call the design “simple”, yet resulting in a reliable and low-cost power supply.

Switching power supply dual voltage 5v and 3.3v by LM2575 LM1117

Here is circuit Switching power supply dual voltage, output 5V 1A and 3.3V 1A.
Use IC LM2575 SIMPLE SWITCHER 1A Step-Down Voltage Regulator ,and IC LM1117 is 800mA Low-Dropout Linear Regulator. Volt suppy 9V – 60V
Detail more see to image circuit.

Read more source: http://www.compsys1.com/support/docs/PWRLm25.pdf
Thank you

adjustable switching-regulator using LM2575T

The circuit in Fig 1 fast-charges 500-mAhr AA NiCd cells. Depending on the setting of SW1 and SW2, the circuit handles two to eight cells, providing the circuit’s input voltage is at least 15V; at higher voltages, power IC3 from IC2′s pin 15. Charging starts when you plug in the battery. When the battery is fully charged, LED1 extinguishes, and the charger switches to trickle-charge mode.

Circuit Switching Regulators Using LM2575 and LM2577

Requiring a minimum number of external components, these regulators are simple to use and include internal frequency compensation and a fixed-frequency oscillator. LM 2575 series offers a high-efficiency replacement for popular 3-terminal linear regulators. It substantially reduces the size of the heat sink, and in many cases no heat sink is required. Fixed output voltage version is illustrated in figure.