ADP2386
High-efficiency synchronous buck regulator with 20V input, 6A output, programmable frequency 200kHz-1.2MHz.
Product Overview
Description
The ADP2386 is a synchronous buck regulator with an integrated high-side MOSFET and low-side driver for external MOSFET. It operates from a 4.5V to 20V input voltage and provides up to 6A continuous output current.
The switching frequency is programmable from 200kHz to 1.2MHz via an external resistor, allowing optimization between efficiency and solution size. The device features precision enable input, power good output, and adjustable soft-start.
With peak current-mode control architecture, the ADP2386 provides fast transient response and excellent loop stability. The device operates at up to 95% efficiency and is available in a compact 4mm × 4mm LFCSP package.
Product Series
ADP
Primary Application
Industrial and instrumentation
Key Features
- Integrated high-side MOSFET (35mΩ)
- Synchronous rectification support
- Programmable switching frequency
- Precision enable and power good
- Adjustable soft-start time
- Pre-bias startup capability
- Overcurrent and thermal protection
- Compact 4mm × 4mm package
Specifications
| Input Voltage | 4.5V to 20V |
|---|---|
| Output Voltage | 0.6V to 18V |
| Output Current | 6A continuous |
| Switching Frequency | 200kHz to 1.2MHz |
| Efficiency | Up to 95% |
| Quiescent Current | 0.8mA |
| Shutdown Current | 12μA |
| Feedback Voltage | 0.6V ±1% |
| Package | LFCSP-24 (4mm × 4mm) |
| Temperature Range | -40°C to +125°C |
Applications
Industrial and instrumentation
Industrial automation and control
Telecommunications equipment
Communication and interface
Medical devices
Medical electronics
Server and storage systems
Electronic system design
Point-of-load regulation
Power conversion and supply
Battery-powered systems
Battery and charging management
FAE Expert Insights
"The ADP2386 is an excellent workhorse for industrial power applications. The 20V input range handles 12V and 24V industrial buses with margin. I've used it in multiple designs delivering 5V at 4A from 12V input with > 93% efficiency. The integrated high-side MOSFET saves board space and reduces component count. The programmable frequency is useful - I typically run at 600kHz for good balance of efficiency and inductor size. The external low-side MOSFET allows optimization for cost or performance. One nice feature is the pre-bias startup - it doesn't pull the output low when starting into a charged capacitor. The compensation is straightforward with standard Type II network. For 6A operation, ensure adequate copper area for heat dissipation - I recommend 4-layer board with thermal vias. Overall, a reliable, high-performance buck regulator for demanding industrial applications."
20V input handles industrial buses; >93% efficiency at 5V/4A; pre-bias startup prevents output discharge
— David Liu, BeiLuo
Frequently Asked Questions
What is the maximum output current of ADP2386?
The ADP2386 is rated for 6A continuous output current under the following conditions: Input voltage 4.5V to 20V, ambient temperature up to 85°C with proper thermal design (4-layer PCB with thermal vias and adequate copper area). The actual maximum current depends on thermal constraints - junction temperature must not exceed 125°C. At 6A output with 12V input and 5V output, efficiency is approximately 93%, resulting in about 2.1W power dissipation. With thermal resistance θja of 30°C/W (typical for LFCSP-24 with good layout), junction temperature rise is 63°C. At 25°C ambient, Tj = 88°C, well within limits. For higher ambient temperatures or poor thermal design, derating may be required. The current limit is typically 8A, providing headroom above the 6A rating. For reliable operation, design for 80% of maximum (4.8A) under worst-case conditions.
Rated for 6A continuous with proper thermal design; ensure Tj < 125°C; current limit is 8A typical.
How do I select the switching frequency?
The ADP2386 switching frequency is set by a resistor (RT) connected from RT pin to ground: RT (kΩ) = 100000 / fsw (kHz). Common values: 500kHz: RT = 200kΩ; 600kHz: RT = 167kΩ; 800kHz: RT = 125kΩ; 1MHz: RT = 100kΩ. Frequency selection involves trade-offs: Lower frequency (200-400kHz): better efficiency (lower switching losses), larger inductor and capacitors, slower transient response. Higher frequency (800kHz-1.2MHz): smaller inductor and capacitors (reduced solution size), faster transient response, slightly lower efficiency (higher switching losses). I recommend 600kHz as a good starting point for most applications - it provides reasonable efficiency with moderate component sizes. For battery-powered applications where efficiency is critical, use 300-400kHz. For space-constrained applications, use 1MHz. Always verify inductor ripple current stays within acceptable range (20-40% of Iout) at your selected frequency.
Use 600kHz for general applications; use 300-400kHz for efficiency; use 1MHz for small solution size.
What external components are required for ADP2386?
The ADP2386 requires the following external components: 1) Input capacitor: 10μF ceramic + 100μF electrolytic for bulk storage, placed close to VIN pin; 2) Inductor: 2.2μH to 10μH depending on frequency and current, rated for saturation current > Iout_max + ΔIL/2; 3) Output capacitor: 22μF to 100μF ceramic for low ESR, plus optional electrolytic for bulk; 4) Low-side MOSFET: N-channel with VDS > Vin_max and RDS(on) < 10mΩ for best efficiency; 5) Bootstrap capacitor: 0.1μF ceramic between BST and SW; 6) Feedback resistors: divider from Vout to FB pin to set output voltage; 7) Compensation network: Type II network (2 resistors, 2 capacitors) for loop stability; 8) Soft-start capacitor: sets startup time; 9) Frequency resistor: sets switching frequency. Total BOM is approximately 15-20 components. ADI provides a design tool and reference designs with optimized component selections.
Requires inductor, input/output caps, low-side MOSFET, feedback divider, compensation network; total ~15-20 components.
How do I set the output voltage?
The ADP2386 output voltage is set by a resistor divider from VOUT to FB pin to ground. The feedback threshold is 0.6V. The output voltage equation is: Vout = 0.6V × (1 + Rtop / Rbottom). Choose Rbottom in the range 10kΩ to 100kΩ (typically 10kΩ). Then calculate Rtop: Rtop = Rbottom × (Vout / 0.6V - 1). Example for 3.3V output: Rbottom = 10kΩ, Rtop = 10k × (3.3/0.6 - 1) = 45kΩ. Use standard 1% resistor values. For adjustable outputs, a potentiometer can be used for Rtop. The feedback node is sensitive to noise - keep the divider close to the IC and minimize trace length to FB pin. Add a 10pF-100pF feedforward capacitor across Rtop to improve transient response. For precision applications, use 0.1% resistors. The output voltage accuracy is primarily determined by the 1% feedback reference tolerance plus resistor tolerances.
Use divider: Vout = 0.6V × (1 + Rtop/Rbottom); Rbottom typically 10kΩ; add feedforward cap for better transient response.
What protection features does ADP2386 include?
The ADP2386 includes comprehensive protection features: 1) Overcurrent protection - cycle-by-cycle current limit with hiccup mode during sustained overload; current limit threshold is typically 8A; 2) Thermal shutdown - shuts down when junction temperature exceeds 150°C, with 25°C hysteresis for restart; 3) Overvoltage protection - if Vout exceeds 120% of setpoint, the low-side MOSFET turns on to discharge the output; 4) Undervoltage lockout (UVLO) - disables switching if Vin drops below 4.0V, prevents erratic operation; 5) Pre-bias startup - prevents discharging output capacitor when starting into a pre-charged load; 6) Soft-start - programmable startup ramp prevents inrush current. These protection features make the ADP2386 robust for industrial applications. The hiccup mode prevents excessive heating during sustained short circuits. The power good output can be used to sequence downstream regulators or signal fault conditions to a microcontroller.
Includes OCP (8A limit), thermal shutdown (150°C), OVP, UVLO, pre-bias startup, and soft-start for robust operation.