With the popularity of electronic products such as computers, mobile phones, digital cameras, more and more applications with inter-electronic devices transmit data and fast charging, which makes USB Type-C and Quick Charge (QC) have become new development. trend. The target of the USB TYPE-C interface is to adopt a unified interface between the interconnection of different electronic devices, and can provide power and transfer data, also support audio and customer personalized communication protocols. The Quick Charge is to reduce the loss on the cable and joint by increasing the output voltage to increase the output power, and set the output voltage via the USB signal line D +, D-.
Therefore, in order to meet the two standards of USB Type-C and Quick Charge, a power controller that can be modulated according to the requirements of the electric device. The Single Press inductance H bridge boost power controller NCP81239 is an ideal choice. It can adapt to wide input voltage range and wide output voltage range, and the I2C interface of the chip is integrated with the external microcontroller (MCU) to adjust the step adjustment of the output voltage, and can implement a variety of Type-C ports. The fast charge agreement can also dock the Apple Lighting Interface Fast Charge Agreement, Samsung Interface Feelings Agreement, and more.
Features and working principle of NCP81239
NCP81239 supports wide input voltage range, providing dynamic programmable switching frequencies from 150kHz to 1.2MHz, integrated 4 MOSFET drivers, using two-in-circuit current mode control, support output prefinated start, adaptive dead time control to prevent direct access, Independent input and output current detection, output voltage (range 0 to 20V) can be programmed, integrated overvoltage, undervoltage, overflow, and precise overload protection, etc., but also provides protection for 5V VCONN power supply .
Figure 1: Typical application circuit diagram of NCP81239
The NCP81239 uses bifidal current mode lifting pressure control, which can achieve seamless switching of buck mode to boost mode. The I2C interface only uses two signal lines to achieve bidirectional serial communication, and the open drain connection can be convenient to different logic levels, compatible with 1.8V, 2.5V, 3.3V, and 5V logic levels of MCUs.
The input and output current can be detected by a high-side detection resistor. The detected voltage is divided into two channels of internal and external: the internal current signal is used for loop control and current limiting protection of current mode, and overcurrent protection can be performed by internal registers. Set or mask, the internal fixed gain is 10 times, the internal current value is stored in the corresponding register through the analog-to-digital converter (ADC), and can be read by I2C; the external current signal can be read by the MCU to perform the corresponding software operation, exterior Impedance can set the range of current measurements, and the current detecting the conversion is 5 ms, and the externally can also pass the resistance capacitor to filter the current signal into an average value.
The NCP81239 has a built-in 4-channel 7-bit ADC that implements an input and output A / D conversion, and the corresponding value can be read by reading the internal register by the I2C. The internal feedback reference voltage is set through 9-bit DACs, and the reference voltage ranges from 0V to 2.55V, and the output voltage range can be set by external voltage dividing network. Since the internal step size has 9 ADCs, the step size is relatively small, so it is convenient to set the compensation cable pressure drop with the MCU I2C interface, so that the load voltage can be kept within the error range of the set value, which is very suitable for QC3.0 or The USB PD is required to regulate.
Under the specifications of USB PD, QC2.0, QC3.0, if you need to dynamically set the output voltage, the pressure regulation rate is involved. If the pressure regulating speed is too fast, the inductor current is overshoot, the output voltage is overshoot or downstrap. The NCP81239 built-in register can be set via the I2C interface, thereby controlling the slope of the voltage rise and falling in the regulation.
NCP81239 performs forward overcurrent protection by detecting the peak current of the input in RS1, and the current limiting mode is a hicked mode. Whether in the buck mode or the boost mode, when the overcurrent is detected in one cycle, the Q1 limit input power is turned off immediately. If the time-by-wave limit time reaches 2 ms or FB voltage below 300 millivolts, enter the fast shutdown mode, and turn off 4 switches, and then re-started to the original set output voltage and current. The overcurrent protection value can be set via the I2C or current detection resistor, and the selection of current detecting resistors should ensure that the voltage of CSP1-CSN1 is not exceeding 100 mV of the op amp voltage range. If a 5 milliobic detection resistor is used, the corresponding peak overcurrent protection value is as follows, the default value is 7.6A.
Table 1: 5 MΩ Detection Resistance Corresponding peak overcurrent protection value (forward overcurrent protection)
The lifting pressure of 4 switch synchronous rectification is controlled in light-load mode, overloaded to light load, output overvoltage protection, and outputs from high voltage to low voltage adjustment. CSP2 / CSN2 is used to detect the reverse current, when the reverse current exceeds the current limit setting value, if the output voltage is within the set voltage range, Q4 will immediately turn off to prevent the reverse directional current from continuously increase. If it is in the buck mode, Q4 will be returned when Q2 is turned off. The overcurrent protection value can be set by the I2C or current detection resistor. The selection of current detecting resistors To ensure that the voltage of the CSP2-CSN2 is not exceeding 100 mV of the op amp voltage range. If a 5 milliobic detection resistor is used, the corresponding peak overcurrent protection value is used, and the default value is -8a.
Table 2: 5 MΩ detection resistors corresponding to peak overcurrent protection values (reverse overcurrent protection)
When the output voltage is above the set value of 110%, the time exceeds one switching cycle, the NCP81239 will enter the overvoltage protection mode. When overvoltage protection, S1 is turned off, S2 conduction, S3 and S4 will alternately turn on to discharge the output voltage while preventing the reverse current from exceeding the set reverse protection current value. Under output overvoltage failure, the switching frequency will drop to 50 kHz, prevent inductance saturation, and reduce power consumption on the power tube.
Figure 2: Output overvoltage protection illustration
The traditional synchronous rectification is activated when there is a pre-off voltage, and the output will be discharged first and then rises. When the output is pre-off, the NCP81239 is started, and the non-synchronous rectifier mode is started, and the output discharge is not suitable for the battery load.
The output voltage is within 3.3ms of the set value +/- 5%, will issue a POWER GOOD signal after the delay is 3.3 ms. If the output voltage exceeds the set value +/- 7% exceeds one switching cycle, the Power Good Register is reset, and the interrupt signal is output.
NCP81239 supports 4 I2C addresses, which can be configured before the customer needs, and the default model of I2C address is E8H / E9H.
In addition, the NCP81239 itself has supermoy protection, and the chip junction temperature exceeds 150 degrees, and four switches are turned off, and the temperature will be restarted after 125 degrees.
Reference design
Ansian Semiconductor provides a 60W car charger with NCP81239, laptop external expansion dock, desktop applications, a TYPE-C interface, such as a TYPE-C interface, a small volume, high energy efficiency, satisfaction in USB PD and Quick Charge specifications Different application needs.
Summarize
The TYPE-C interface is becoming a single interface between electronic products, high-power USB PD different voltage and power need to be adjusted to the output voltage. The NCP81239 of the Ansian Semiconductor has a featured function and a complete protection function that makes it ideal for a wide voltage input, a high reliable application of the adjustable voltage output, such as USB PD and Quick Charge, and battery charging, its unique control mode implementation High-efficiency lifting pressure conversion, the maximum design of the highest 1.2 MHz can achieve miniaturization. , Reading the full text, the technology area
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