Juchen Semiconductor Co., Ltd. announced recently that it is a controller designed for AC-DC LED lighting, charger, adapter, household appliances power supply and auxiliary power supply application. GT5010 has been formally mass-produced. Juchen Semiconductor GT5010 is another main product of power supply product line after EERPOM memory series and smart card series.

GT5010 adopts the latest PSR control mode of transformer and full current feedback control technology with independent patent; drives highly reliable external MOSFET power devices; its constant current and constant voltage characteristics meet the range of less than +5%; standby power consumption for mobile phone charger is less than 30 mW; conversion efficiency fully meets the latest "EPS 2.0"; GT5010 is packaged in SOT 23-6; and can work in - 40 to + 85 degrees. Temperature range, at the same time with over-temperature protection characteristics such as perfect protection characteristics. These characteristics make GT5010 one of the most cost-effective control chips in the best isolation and non-isolation of 3W, 5W and 7W high-performance, low-cost MR16, E14, E27 and GU10 LED lighting schemes.

Transformer primary edge control

The AC/DC control technology based on original side feedback is a new AC/DC control technology developed in recent 10 years. Compared with the traditional structure of side feedback optocoupler plus 431, its greatest advantage is that the two chips and a group of components cooperating with them are omitted, which saves the space on the system board, reduces the cost and improves the reliability of the system. Because of the high cost and pressure of LED driver, it has broad application prospects in the market with high volume requirement.

GT5010 LED lighting scheme is based on this original feedback mode. As shown in Fig. 1, the scheme eliminates the peripheral devices such as optocoupler and regulator 431 with original side feedback. The circuit volume will be smaller and the production cost will be more competitive.

Fig. 1. Circuit sketch of Juichen GT5010 LED.

Driving External High Reliability MOSFET Power Devices

Typical transmission characteristics can usually be found in MOSFET data tables. It is noted that there is an intersection point between the two curves at 25 and 175 C, which corresponds to the corresponding VGS voltage and ID current values. If the VGS of this intersection point is called the turning voltage, we can see that when the VGS voltage is fixed in the lower left part of the curve, the higher the temperature is, the greater the current flowing through, and the positive feedback of temperature and current is formed. That is, the RDS (ON) of MOSFET is the negative temperature coefficient, which can be called the negative temperature coefficient region of RDS (ON).

Fig. 2. Transfer characteristics of MOSFET.

In the upper right part of the VGS transition voltage curve, when the VGS voltage is constant, the higher the temperature, the smaller the current flowing through, and the negative feedback between temperature and current is formed. That is, the RDS (ON) of MOSFET is a positive temperature coefficient, which can be called the RDS (ON) positive temperature coefficient region. When MOSFET is used as power switch, VGS is larger when it is turned on, so it works in the negative temperature coefficient region of RDS (ON). As the temperature increases, the current decreases. It has self-limiting property. Therefore, it has higher reliability than BJT (RDS (ON) positive temperature coefficient in high temperature environment.

Depending on the power required to drive the LED, the scheme can choose to match the 1A and 2A MOSFET of the Juchen brand. This scheme guarantees the stable operation in the high temperature environment inside the LED lamp body.

Constant Current and Constant Pressure Characteristic in (+5%) Range

After eliminating these components, in order to achieve high-precision CC/CV characteristics, Juchen GT5010 adopts a new technology to monitor the real-time changes of load, power supply and temperature as well as the same batch tolerance of components. The original side adjustment technology, transformer tolerance compensation, cable compensation and EMI optimization technology are adopted. Therefore, GT5010 provides a constant current accuracy of up to (+5%) range. It can well match the production consistency requirements of different materials of LED.

Fig. 3. Constant current characteristics of GT5010 at 85-264V input.

Meeting the latest Energy Star 5.0 standard

The scheme can support 3W, 5W, 7W LED lighting at present. And meet the American Energy Star 5.0 and UL 8750 LED lighting safety standards. The energy efficiency of this scheme is 78% under 6.3W LED power consumption. At the same time, with appropriate peripheral devices, its PFC value can stay at 0.8.