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CXSD62685: In-Depth Analysis of a High-Performance Synchronous Buck Power Management ICsLz嘉泰姆

In industrial control systems, fast-charging devices, and PC power supplies, efficient and stable DC-DC step-down solutions are a core requirement. The CXSD62685, a synchronous rectification power management IC with wide input voltage range, stands out as an ideal choice for cost-effective power designs, offering over 20A output current capability and multiple protection mechanisms.sLz嘉泰姆

I. Core Features & AdvantagessLz嘉泰姆

1. Wide Voltage Adaptability:sLz嘉泰姆

   • Input Voltage Range: 10V - 25V, Floating Voltage Tolerance up to 80V.sLz嘉泰姆

   • Built-in VCC Regulator (Recommended 10-15V). For inputs >18V, use an external 78L12 for VCC.sLz嘉泰姆

2. High-Efficiency Synchronous Rectification Architecture:sLz嘉泰姆

   • Synchronous rectification improves efficiency by >15%.sLz嘉泰姆

   • Triple Protection: Cycle-by-cycle current limiting, Short-circuit latch-off protection, 155°C thermal shutdown.sLz嘉泰姆

3. Flexible Adjustable Parameters:sLz嘉泰姆

   • PWM Frequency set via external resistor: Fosc (kHz) = 6150 / RI (kΩ)sLz嘉泰姆

   • Adjustable Dead Time: DT (ns) = 5 * RT (kΩ) (e.g., 51kΩ yields 250ns).sLz嘉泰姆

   • Output Voltage freely set: Vout = (1 + R1 / R2) * 1.3VsLz嘉泰姆

II. Key Circuit Design GuidelinessLz嘉泰姆

1. Power Device Selection:sLz嘉泰姆

   • MOSFETs must feature Low Rds(on) + Low Junction Capacitance.sLz嘉泰姆

   • Peak Current Calculation: Ipeak = 0.19V / R3 (External Sensing).sLz嘉泰姆

2. Inductor & Capacitor Design Formulas:sLz嘉泰姆

   • Inductance: L = Vout × (Vin - Vout) / (Vin × Fs × Iripple)sLz嘉泰姆

   • Output Ripple: ΔVo = ΔI_L × (ESR + 1/(8.5 × Fs × Co)) (Recommended Ripple Current ≤30% Max Output Current).sLz嘉泰姆

3. PCB Layout Essentials:sLz嘉泰姆

   • Place VCC/GND decoupling capacitors and VB/VS bootstrap capacitors close to IC pins.sLz嘉泰姆

   • Use short, wide traces for high-current paths.sLz嘉泰姆

III. Typical Application ScenariossLz嘉泰姆

IV. Safety Protection MechanismssLz嘉泰姆

1. Short-Circuit Protection: Triggers latch-off when Vout < 75% of setpoint; requires cycling EN or VCC to recover.sLz嘉泰姆

2. Smart Gate Drive Control:sLz嘉泰姆

   • HO pin controls High-Side MOSFET (80V withstand).sLz嘉泰姆

   • LO pin drives Low-Side MOSFET (VCC powered).sLz嘉泰姆

3. IS Pin: Real-time MOSFET over-current monitoring; response time <1µs.sLz嘉泰姆

Package & Electrical SpecificationssLz嘉泰姆

1. SSOP16 Package: Dimensions 4.9×6.0mm (typ.), suitable for high-density designs.sLz嘉泰姆

2. Standby Power Consumption:sLz嘉泰姆

   • Active Quiescent Current: 1mA (typ.).sLz嘉泰姆

   • Shutdown Mode Power: 0.6mA.sLz嘉泰姆

Design Tip: For 24V input systems, use the wide-voltage application circuit Fig. 6-2 with external MOSFETs for 20A continuous output. For 12V systems, use Fig. 6-1 with internal sensing to reduce cost.sLz嘉泰姆

The CXSD62685 significantly shortens power development cycles by simplifying the external circuit (only 11 essential components) and offering flexible parameter configuration. Its patented dead-time control technology effectively prevents MOSFET shoot-through. Combined with multi-level protection design, it provides a safe and reliable power solution for industrial equipment.sLz嘉泰姆

Application Design Component Parameters & NotessLz嘉泰姆

1. VCC Supply Voltage: Recommended 10-15V to ensure full turn-on of internal drivers. For inputs >18V, add a 78L12 for VCC regulation.sLz嘉泰姆

2. Switching Frequency Setting: Connect resistor RI between RI pin and GND. Frequency: Fosc (kHz) = 6150 / RI (kΩ).sLz嘉泰姆

3. Dead Time Setting: Connect resistor RT between DT pin and GND. Dead Time: DT (ns) = 5 * RT (kΩ).sLz嘉泰姆

4. PCB Layout: Place VCC/GND caps and VB/VS bootstrap caps close to IC pins. Use short, wide traces for high-current paths.sLz嘉泰姆

5. MOSFET Selection: Choose MOSFETs with low Rds(on) and low capacitance for optimal CXSD62685 performance.sLz嘉泰姆

6. Output Inductor: The CXSD62685 operates in Continuous Conduction Mode (CCM). Inductance: L = Vout × (Vin - Vout) / (Vin × Fs × Iripple). Select Iripple ≤ 30% of max output current.sLz嘉泰姆

7. Output Capacitor: Output capacitor Co filters the output voltage. Use low-ESR capacitors. Value determined by output ripple requirement: ΔVo = ΔI_L × (ESR + 1/(8.5 × Fs × Co)). ΔVo is output voltage ripple, ΔI_L is inductor current ripple, Fs is PWM frequency, ESR is capacitor equivalent series resistance.sLz嘉泰姆

8. Output Voltage Setting: Set via FB pin divider resistors. Internal reference voltage = 1.3V. Vout = (1 + R1 / R2) * 1.3V. (e.g., For Vout=14.3V, use R1=10kΩ, R2=1kΩ: Vout = (1 + 10/1) * 1.3V = 14.3V).sLz嘉泰姆

9. Peak Current Limit Setting: Set by resistor R3. Peak Current: Ipeak = 0.19V / R3.sLz嘉泰姆

10. Short-Circuit Protection: If output is overloaded (Vout < 75% of setpoint), after internal delay, short-circuit protection activates (output MOSFETs off). Requires cycling VCC or toggling EN to recover.sLz嘉泰姆

Technical Datasheet (Product PDF): Please contact us via email for the detailed PDF datasheet. Free samples and technical support are also available! (Note: Replaced "scan WeChat" with more universal "contact us via email")sLz嘉泰姆

Package Diagram: (Note: Indicates graphic would be included)sLz嘉泰姆
Schematic Diagram: (Note: Indicates graphic would be included)sLz嘉泰姆

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