• [ CXAC85259 ]"

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Introduction

In the field of industrial power supply, LED driver and battery charger, efficient and reliable PWM controller is the core of the system. As a current-mode PWM controller with an integrated 600V half-bridge drive, CXAC85259 is ideal for medium and high power supply solutions due to its excellent EMI characteristics, complete protection functions and flexible design configuration. This paper will analyze its key technical characteristics and application design points in depth.AaI嘉泰姆

1. core features and benefits

1. Efficient driving capabilityAaI嘉泰姆

A built-in 600V half-bridge drive supports 10A peak pull/sink current (LO: 0.8A/1A, HO: 0.8A/1.2A), which can directly drive high-power MOSFET.AaI嘉泰姆

B. Switching delay as low as 70-150ns (typical) to improve system response speed.AaI嘉泰姆

2. Comprehensive protection mechanismAaI嘉泰姆

A. triple voltage protection: VIN undervoltage protection (open 14V/close 9V), bus undervoltage protection (BO pin <1V trigger), OUT clamp protection (lock 17V when VIN>20V).AaI嘉泰姆

B. cycle-by-cycle current limit (CS pin overcurrent threshold 0.92-1.08V), with 80ns leading edge blanking technology to avoid false triggering.AaI嘉泰姆

c. Optocoupler open circuit protection and 150ms overload delay protection to enhance system robustness.AaI嘉泰姆

3.EMI and energy efficiency optimizationAaI嘉泰姆

A. built-in frequency jitter function (± 4% oscillation frequency), significantly reduce electromagnetic interference.AaI嘉泰姆

B. Ultra-low starting current (18 μA) and working current (2.3mA), reducing power consumption of starting resistor, supporting fast starting.AaI嘉泰姆

C. external resistor flexible setting PWM frequency (up to 500kHz), adapt to different topology requirements.AaI嘉泰姆

2. typical application scenarios

3. Key Design Guide

1. Frequency setting and EMI optimization

Set the frequency via an external resistor on the RI pin:AaI嘉泰姆
f_osc(KHz) = 4300 /R_I(kΩ)AaI嘉泰姆
ExampleWhen RI = 43kΩ, the typical frequency is 100kHz. It is recommended to give priority to the use of chip resistors and close to the RI-AGND pin layout to reduce noise interference.AaI嘉泰姆

2. Soft start and protection circuit design

a. Soft start: SS pin external capacitor (internal 10μA constant current charging), slowly raise the overcurrent threshold to prevent startup shock.AaI嘉泰姆

B. Bus undervoltage protection: The BO pin samples the bus voltage through the voltage divider resistor, turns off the output when <1V, and recovers> 1V (internal 5μA current source control).AaI嘉泰姆

c. Current sampling: CS pin resistance needs to use low-temperature drift devices, and the layout is away from the high-frequency switch node.AaI嘉泰姆

3. PCB layout core principles

a. Nearby placement of the capacitor：AaI嘉泰姆

VIN Capacitor & rarr; VIN/AGND pinAaI嘉泰姆

VCC Capacitor & rarr; VCC/PGND PinAaI嘉泰姆

VB/VS Capacitor & rarr; VB/VS PinAaI嘉泰姆

B. Shorten the drive circuit: HO/LO to MOSFET gate trace length ≤ 20mm.AaI嘉泰姆

c. Power loop minimization: Bus capacitor-transformer-power tube loop area needs to be compressed to reduce radiated EMI.AaI嘉泰姆

Quick Look-up Table of 4. Electrical Characteristics

Note: Limit parameters such as VB(600V) and VCC(25V) cannot exceed the limit, otherwise the chip will be permanently damaged.AaI嘉泰姆

5. Typical Topology Applications

1. Dual-tube forward power supply(Figure 6-1)AaI嘉泰姆

a. Advantages: support high power density, high transformer utilization.AaI嘉泰姆

B. Design points: HO/LO driver needs symmetrical wiring, VS pin needs low impedance grounding.AaI嘉泰姆

2. Double tube flyback power supply(Figure 6-2)AaI嘉泰姆

a. Advantage: Suitable for wide input voltage range.AaI嘉泰姆

B. Key configuration: FB pin feedback network to compensate for loop stability.AaI嘉泰姆

6. packaging and production recommendations

1. Encapsulation: SOP16 (size: 10.0 × 4.0 × 1.5mm), pin pitch 1.27mm.AaI嘉泰姆

2. Welding: Reflow soldering temperature ≤ 300 ℃ (within 10 seconds), storage temperature -65~150 ℃.AaI嘉泰姆

3. Prompt for mass production: RI resistance accuracy is recommended to be 1%,SS capacitor is made of X7R material.AaI嘉泰姆

Conclusion

CXAC85259 greatly simplify the development process for medium and high power supplies through a highly integrated design (requiring only a few peripherals), multiple protection mechanisms and flexible frequency configuration. Its excellent EMI performance and low power consumption characteristics are particularly suitable for industrial scenarios where energy efficiency and reliability are critical. Follow the layout and configuration guidelines in this article to quickly implement a stable and efficient power solution.AaI嘉泰姆

Extended reading：AaI嘉泰姆
[Comparison of Topological Efficiency between Forward and Flyback of Double Tubes] | [EMI Optimization Case] | [SOP16 Welding Process Specification]AaI嘉泰姆

If you need detailed PDF specifications, please scan WeChat and contact us. You can also get free samples and technical support.!AaI嘉泰姆

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   Product packaging diagramAaI嘉泰姆

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   Circuit schematicAaI嘉泰姆

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  Related Chip Selection Guide           More similar products.....AaI嘉泰姆

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