Calculation tool
UCC25661X-CALC — UCC25661X Design Calculator
The purpose of this tool is to aid in the design of the main power stage components of a LLC Resonant Converter along with component calculations using UCC25661x controller.
Data sheet
UCC25661
- Full-load switching frequency: 50kHz to 750kHz
- Input Power Proportional Control (IPPC) for wide LLC
- Enhanced light load management (standby power and audible noise):
- High frequency and audible frequency pulse skip
- Low frequency burst (all except UCC256616)
- Integrated PFC on/off (UCC256614)
- Soft in and out of burst mode (UCC256610)
- Internal resonant-capacitor voltage synthesizer for signal reliability and high frequency start-up
- Zero current switching (ZCS) avoidance to eliminate capacitive region operation
- Adaptive soft start with minimized inrush current and eliminating reverse recovery at start-up
- Integrated gate drive: +0.6/-1.2A
- Integrated high-voltage start-up (UCC25661x family except UCC256613)
- X-capacitor discharge (UCC256610, UCC256611, and UCC256614)
- Extended Gain Range (UCC256611 and UCC256614)
- 50ns overcurrent protection (OCP), cycle-by-cycle current limit
- Overvoltage protection (OVP), OVP latch (UCC256611 and UCC256616)
- Internal and external OTP
- Input and VCCP UVLO with internal 19V VCCP Clamp
- Independently configured OCP and overload protection (OLP/OPP) (UCC25661x family except UCC256616)
- SOIC-14 package with removed pins for high-voltage clearance
The UCC25661x family is a high-frequency LLC controller implementing input-power proportional control (IPPC) scheme, along with enhanced light-load management and multiple protection features. IPPC widens the control range of the LLC converter and simplifies the design of wide input or output-voltage range applications such as LED drivers and battery chargers. IPPC works without a PFC for non-universal input applications.
The UCC25661x family has enhanced light-load management that improves the efficiency while minimizing audible noise. To minimize standby power, the UCC25661x family directly disables the PFC controller when operating in burst mode.
The automatic capacitive region avoidance scheme along with the adaptive soft start with reverse recovery avoidance scheme verifies that the device never works in a mode where there is a potential to damage the FETs. The automatic capacitive region avoidance scheme makes the controller appropriate for working with a prebiased load.
The UCC25661x family comes with robust protection to help users design a reliable power supply. The UCC25661x family has options supporting high-voltage start-up, X-capacitor (X-cap) discharge, OVP, and extended gain range (EGR). See details in the Device Comparison table.
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Technical documentation
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View all 6 | Type | Title | Date | ||
|---|---|---|---|---|
| * | Data sheet | UCC25661x Family 750kHz Wide VIN /VOUT Range LLC Controller Optimized for Light-Load Efficiency datasheet (Rev. B) | PDF | HTML | 21 Jan 2026 |
| White paper | High Efficiency by Leveraging GaN FET in an LLC Resonant Converter Design | PDF | HTML | 24 Sep 2025 | |
| Product overview | UCC25661(-Q1) Selection Guide | PDF | HTML | 04 Sep 2025 | |
| Technical article | LLC 토폴로지를 이용해 자동차 설계자가 전력 밀도와 안정성을 강화 하도록 지원 | PDF | HTML | 19 May 2025 | |
| Technical article | 幫助汽車設計師藉由 LLC 拓撲結構提升功率密度與系統可靠性 | PDF | HTML | 19 May 2025 | |
| Technical article | Enabling automotive designers to increase power-density and reliability with LLC topology | PDF | HTML | 02 May 2025 |
Design & development
For additional terms or required resources, click any title below to view the detail page where available.
Evaluation board
UCC25661EVM-128 — UCC25661 evaluation module
The UCC25661 evaluation module (EVM) assists designers to evaluate the operation and performance of the UCC25661x LLC Resonant controller (16-pin SOIC package with removed pins for high voltage clearance). This evaluation module demonstrates how UCC25661x controls the LLC resonant half bridge DC-DC (...)
Reference designs
PMP23558 — 240W AC/DC PSU Using GaN reference design
This reference design is a transition-mode, boost power factor correction (PFC) and half bridge LLC that accepts universal AC input and generates an isolated 24V, 10A output. The design utilizes LMG3622 GaN module on the primary side with integrated driver and current sense emulation for improved (...)
Test report: PDF
Reference designs
PMP23454 — Universal input, 430W power tool charger reference design
This reference design is a universal input, 430W constant current (CC), constant voltage (CV) charger for power tool applications. The reference design supports output voltage ranges of 0V to 12.5V in trickle-charge mode and 7.5V to 22.5V in fullcharge mode. The power factor correction (PFC) is (...)
Test report: PDF
| Package | Pins | CAD symbols, footprints & 3D models |
|---|---|---|
| SOIC (DDB) | 14 | Ultra Librarian |
Ordering & quality
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