The American Telecom/AT&T fast charging charger adopts the CX7527+CX7538B highly integrated fast charging solution, and the Chengxin Micro 20W PD fast charging solution can enter the supply chain of AT&T such a large enterprise. It can be seen that AT&T recognizes the performance and quality of this solution.

The American Telecom/AT&T 20W PD Fast Charge Charger uses CX7527+CX7538B, while AT&T's 20W PD Fast Charge Charger 06457 is similar in size to Apple's original 20W charger, but comes with foldable pins for better portability. The modified charger is compatible with QC2.0/3.0, AFC, FCP, PD3.0, and PPS fast charging protocols, and has two sets of PPS voltage ranges. Overall, it has good compatibility and can be compatible with Apple iPhone 12/13 series phones, as well as brands such as Xiaomi and Samsung.

American Telecom/AT&T, also known as the American Telephone&Telegraph Company, was founded in 1877 The famous Bell Labs department is part of the company. Today, AT&T has become one of the giants of American mobile phone operators, with a revenue of $181.193 billion in 2020.

AT&T Mini 20W Quick Charge Appearance:

Model: 06457

Input: 100-240V~50/60HZ 0.5A

Output: 5V3A, 9V2.22A, 12V1.67A

PPS: 3.3-5.9V3A, 3.3-11V2.2 (20W Max)

The charger has passed ETL certification and VI level energy efficiency certification.

Equipped with a single USB-C port, white rubber core, supporting up to 20W PD fast charging

The American Telecom/AT&T 20W PD fast charging charger uses CX7527+CX7538B, and uses ChargerLAB POWER-Z KT002 to measure that the USB-C port supports Apple 2.4A, Samsung 5V2A, DCP protocols, as well as QC2.0/3.0, AFC, FCP, PD3.0, and PPS fast charging protocols.

In addition, the PDO message shows that the C port also has three sets of fixed voltage ranges: 5V3A, 9V.22A, and 12V1.67A, as well as two sets of PPS voltage ranges: 3.6-5.9V3A and 3.6-11V1.8A.

This charger adopts a QR switching power supply architecture, and the protocol chip controls the output voltage of the interface.

The main control chip of the switching power supply for the American Telecom/AT&T 20W PD fast charging charger adopts CX7527, which is a current mode PWM control chip with a built-in 650V high-voltage super silicon. It is applied to solutions with power below 20W and operates at a fixed switching frequency in PWM mode. This frequency is precisely set internally, and the working frequency is adjusted internally by the IC during no-load or light load.

CX7527 can operate in green mode to reduce losses during light loads and improve the overall efficiency of the machine. Only a small current is required during startup and operation, and a large resistor can be used in the startup circuit to further reduce power consumption during standby. The chip is equipped with a slope compensation circuit, which avoids the occurrence of subharmonic oscillations and improves system stability when the circuit operates at a large duty cycle.

CX7527 has a built-in Leading edge blanking time, which eliminates the impact of diode reverse recovery current in the buffer network on the circuit. It adopts jitter technology, which can effectively improve the EMI performance of the system. The frequency hopping of the system is set above audio (22KHz), which can avoid system noise during operation.

CX7527 is equipped with various built-in protections, including cycle by cycle current limiting protection (OCP), overvoltage protection (VDD OVP), VDD overvoltage clamping, undervoltage protection (UVLO), over temperature protection (OTP), and secondary transistor short circuit protection. The EMI characteristics of the system can be better improved through the internal soft drive structure.

The secondary synchronous rectifier chip adopts the CX7538B, which is a high-performance switching power supply secondary side synchronous rectifier chip that easily meets 6-level energy efficiency in switching power supplies. It is an ideal replacement solution for Schottky. The CX7538B supports a maximum switching frequency of 150KHz and is equipped with an 11m Ω low conductivity NMOS transistor, which generates much lower heat than Schottky diodes, significantly reducing temperature and improving conversion efficiency.

CX7538B supports the CCM/QR/DCM mode of switch mode power supply, which is very suitable for 3.3-12V fast charging synchronous rectification. It is equipped with a built-in 60V, 11m Ω synchronous rectification tube, which can provide 3A output, with a maximum improvement of 6% compared to Schottky efficiency. The working voltage range is wide, and the peripheral components are very simple. In wide voltage applications, only one capacitor is needed on the periphery.

The American Telecom/AT&T fast charging charger adopts the CX7527+CX7538B highly integrated fast charging solution. The Chengxin Micro 20W PD fast charging solution can enter the supply chain of such a large enterprise as AT&T, and it can be seen that AT&T recognizes the performance and quality of this solution. Its primary and secondary controllers are integrated with MOS transistors, effectively simplifying the peripheral circuits on the primary side, which is very helpful for shortening the production cycle of the charger.