Catalog Introduction

1.Series model

2.Main characteristics3.in function4.Parameters5.Application Circuit6.Application products7.Precautions

   XBLW LM2576SThe series is a 3A current output step-down switch type voltage stabilizing integrated circuit designed and produced by Xinbole. After several improvements and optimizations by the design team, it is now fully launched on the market. It contains a fixed frequency oscillator (52kHz) and a reference regulator (1.23V), and has a complete protection circuit, includingCurrent LimitreachThermal shutdown circuitclass，This device can be constructed with very few peripheral componentsEfficient voltage regulator circuit。

①Series model

XBLW LM2576SThe maximum input voltage of the series is 40V, and the series products provide3.3V,5V,12V以及ADJThe voltage version, in addition, the chip also provides external control pins for the working status.

②Main features

XBLW LM2576SThe main features of the series of switch stabilized integrated circuits are as follows:

    (1)Maximum output current: 3A;

(2)Maximum input voltage limit：XBLW LM2576S is 45V;

(3)Output voltage：3.3V、5V、12V、15Vand ADJ (adjustable) are available for selection;

(4)Vibration frequency：52kHz;

(5)Conversion efficiency：75%~88% (efficiency varies at different voltage outputs);

(6) Control mode: PWM;

(7)Working temperature range: -40 ℃~+125 ℃

(8)Working mode: Both normal modes can be externally controlled;

(9)Working mode control: TTL level compatible;

(10)Required external components: only four (non adjustable) or six (adjustable);

(11)Chip protection: thermal shutdown and current limitation

(12)Packaging form: TO-220 or TO-263-5L

③pin function

XBLW LM2576Spin function

④Parameters

   XBLW LM2576SInternally containing a 52kHz oscillator、1.23VReference voltage regulator circuit, thermal shutdown circuit, current limiting circuit, amplifier, comparator, and internal voltage regulator circuitWait. In order to generate different output voltages, the negative terminal of the comparator is usually connected to a reference voltage (1.23V), and the positive terminal is connected to a voltage divider resistor network. This allows different resistance values to be selected according to the different output voltages, where R1=1k Ω (open circuit when adjustable - AJ), R2 are 1.7 k Ω (3.3V), 3.1 k Ω (5V), 8.84 k Ω (12V), 11.3 k Ω (15V), and 0 (- AJ), respectively. The above resistors have been precisely adjusted inside the chip according to different models, so there is no need for users to consider them. Compare the output of the voltage divider resistor network with the internal reference voltage of 1.23V. If there is a deviation in voltage, an amplifier can be used to control the output ratio of the internal oscillator to maintain stable output voltage.

⑤Application Circuit

Fixed voltage output circuit+5V

Negative voltage output circuit

Undervoltage reduction circuit lock circuit

⑥Application Products

XBLW LM2576S-5.0High current DC motor drive board

XBLW LM2576S ADJAdjustable switch power supply

XBLW LM2576S-5.0Power module

⑦note

   The layout of the printed circuit board is crucial in any switching regulator. Due to the effect of lead inductance, fast switching current can causeTransient voltage，Causing many problems.To minimize inductance and grounding circuit, Use thick lines to mark the leads as short as possible. To obtainBest results，Single point grounding or grounding plane structure should be used. When using adjustable voltage regulators, the regulating resistor should be adjusted as much as possibleApproaching the voltage regulator,，Keep sensitive feedback wiring as short as possible.