Long express opto launched low-cost DC-LED drive -CYT34065

Committed to power supply and LED driver design integrated circuit design company long express Optoelectronics Technology Co., Ltd., recently released the best economic DC-LED drive -CYT34065.

Route analysis of DC-LED driving technology:

The LED drive circuit controls the power supply circuit of LED (light emitting diode) to light up the required power. The forward voltage drop (VF) of LED is changed with the error of manufacture and the ambient temperature. Therefore, it is necessary to use constant current drive, so that the current supply to the LED remains constant. LED drive circuit structure and the ordinary switching regulator (DC-DC converter) is basically the same, there is not much difference. But LED drivers have special requirements, roughly two different.

The first difference is that the feedback voltage is low (Figure). Feedback voltage refers to the output voltage, the voltage feedback to the switching regulator IC. LED driver IC using constant current control, the output current is converted into a voltage as a feedback voltage.

Typically, the switching regulator IC sets the feedback voltage to approximately 1.2V. But for LED driver IC, 1.2V is too large. Because the output current is converted into a voltage of hundreds of M resistors (current sense resistors) need to be connected in series with the LED. For the use of lighting appliances, such as high brightness LED, through the 1.5A and 2A and other large current. If the 500m current is detected by a resistor in the current through the 1.5A, only this one will produce a 0.75W power loss. Thus, the LED driver IC sets the feedback voltage at a very low 0.2V. In this way, not only can the use of a smaller current detection resistor, but also in the large current through the power loss can also be controlled at a low level.

The second difference is to achieve a more accurate constant current control improvements. It is difficult to compensate the change of input voltage, the variation of LED forward voltage drop, the characteristic change of inductor and capacitor because of the feedback of the output current.

The representative improvement of each LED driven IC manufacturer in order to achieve a more accurate constant current control is "constant pulse mode". After the above changes, the amplitude of the fluctuating components overlapped with the current supplied to the LED will also be changed, resulting in the change of LED brightness. In general, the amplitude of the ripple component is determined by the input voltage, output voltage, inductance, and the turn-on time of the switch. To this end, the constant pulse mode is to detect the input voltage and output voltage, according to the voltage to adjust the conduction time. That is, through the precise control of the switch frequency, to achieve more accurate constant current control.

Long express photoelectric DC-LED design route:

Long express optoelectronics has been operating CYT34063 for many years, the market share in the forefront. On the basis of this theory, combined with the understanding of the LED driver technology, the design of the Gao Heng flow accuracy of the DC driver, officially launched a large number of DC-LED drive -CYT34065.

CYT34065 is a LED driver based on CYT34063 and improved design. CYT34065 continue to retain the excellent features of CYT34063, but also efficient drive LED. CYT34065 is designed for high power LED and a DC driver, you can choose to boost, or step-down applications, the maximum output value of 1A, the efficiency of up to 85%. CYT34065 in the design of DC storage battery has a high performance price ratio, high reliability, high stability, excellent constant current effect.

CYT34065 is particularly suitable for the design of 3-12V boost design, output above 12-24V. The 36V-24V can also be designed to 1.25V even lower than the 12V drive line, CV or CC mode, and buck down to the output voltage above. CYT34065 still meet the output DC constant voltage mode design, fully compatible with CYT34063 applications. The output sampling reference needs to be recalculated, without the need to modify the original design of the PCB line. And can also be designed under 1.25V or lower voltage range.

The launch of CYT34065 28V and 40V two specifications, design, step-down constant current LED driver circuit, built-in 1A power transistor, switch type converter, lighter type SOP8 or DIP8 package, the frequency at 100KHz, 300mV to the low sampling efficiency up to 85%, to achieve a cost-effective design of constant current DC driver.

CYT34065 design has opened up, CV and CC mode compatible applications precedent, to find a new way of CV compatible with CC DC output applications. Long express Photoelectric Technology Co., the company has been committed to the research of LED driver based on IC design, DC design of IC power supply company for many years, to find a new design direction, then express photoelectric technology company will launch a full range of DC and CV application circuit, and CC compatible.