IRS25751LTRPBF - 480V High-Voltage Start-Up PMIC | Infineon
MPN: IRS25751LTRPBF β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.85 | $1.85 |
| 10 | $1.62 | $16.20 |
| 100 | $1.38 | $138.00 |
| 500 | $1.15 | $575.00 |
| 1,000 | $0.92 | $920.00 |
| 3,000 | $0.78 | $2,340.00 |
IRS25751LTRPBF Overview
A high-voltage start-up IC is a specialized power management device that provides a small, regulated bias current to a switching converter's controller during cold start-up when no auxiliary winding voltage is yet available. After the converter begins switching and its auxiliary rail comes up, the start-up IC turns off to achieve micro-amp standby current. This category sits within the broader PMIC (power management integrated circuit) family and bridges high-voltage rectification rails to low-voltage control logic - functionally complementary to but distinct from DC-DC converters, linear regulators, and gate drivers.
Key features of the IRS25751L include programmable upper turn-off threshold, an active-low ENN enable input, integrated over-temperature protection, and Infineon's proprietary HVIC (high-voltage integrated circuit) technology rated for 480 V bus operation. The part uses Infineon's junction-isolation HVIC process that integrates a 480 V-capable JFET input with low-voltage CMOS control, eliminating external bleed resistors and high-voltage transistors.
Designed for IGBT and MOSFET half-bridge driver supplies, the IRS25751L is most commonly used as the start-up source for PFC + LLC combo controllers, single-stage flyback converters, and industrial motor drives. The 4.5 mA constant-current behavior is sufficient to charge the VCC capacitor of typical driver ICs within a few hundred milliseconds.
When designing with this device, ensure VCC is decoupled with at least 1 uF of low-ESR ceramic capacitance and verify the upper turn-off threshold matches the downstream controller's UVLO release point. The ENN pin allows synchronization with PFC_OK signals or sequential turn-on in multi-stage converters, while the over-temperature protection engages at approximately 145 C junction.
Drop-in alternatives for IRS25751LTRPBF β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
IRS25752LTRPBF
β Drop-Inπ Reference alternative (not in catalog)
IRS2452D
β Drop-Inπ Reference alternative (not in catalog)
IRS25751LTRPBF Maximum Ratings & Electrical Characteristics
| Product Type | High-Voltage Start-Up PMIC / Start-Up Gate Driver Support IC |
| Topology | Constant-current start-up with auto switch-over to standby |
| Maximum Input Voltage | 480 V (high-voltage bus) |
| Regulated Output Current | 4.5 mA (typical, during start-up phase) |
| Source Current | 0 A (typical) |
| Sink Current | 0 A (typical) |
| Standby (Off) Current | Ultra-low (per Infineon datasheet) |
| Upper Turn-Off Threshold | Programmable (per Infineon datasheet) |
| Enable Input | ENN (active-low) |
| Protection Features | Over-temperature protection (OTP) |
| Technology | Infineon proprietary HVIC (high-voltage integrated circuit) |
| Target Switches | IGBTs and MOSFETs (driver supply bias) |
| Package | SOT-23-5 (5-lead) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
IRS25751LTRPBF Pin Configuration
| Pin 1 | HV β High-voltage bus input (480 V max) - connect to rectified high-voltage DC bus |
| Pin 2 | GND β Ground reference for control logic and VCC return |
| Pin 3 | VCC β Regulated output / VCC bypass - 4.5 mA constant current during start-up |
| Pin 4 | ENN β Active-low enable input - tie to GND to enable, tie to VCC to disable |
| Pin 5 | TH β Threshold programming - resistor to VCC sets upper turn-off threshold |
Typical Applications
IRS25751LTRPBF is suitable for 6 applications: PFC + LLC Combo Converter Start-Up Bias, Single-Stage Flyback AC/DC Converter Start-Up, Industrial Motor Drive VCC Bias, Solar Inverter Auxiliary Supply Start-Up, EV Charging Station Power Supply Start-Up, LED Driver High-Voltage Start-Up.
PFC + LLC Combo Converter Start-Up Bias
The IRS25751LTRPBF's 480 V input rating and regulated 4.5 mA output current make it ideal for charging the VCC capacitor of PFC + LLC combo controllers during cold start-up directly from rectified 230/400 VAC mains, without an auxiliary winding. Placed between the high-voltage DC bus and the VCC pin, it eliminates the discrete bleed resistor, Zener diode, and high-voltage transistor traditionally required - reducing BOM count by 3-4 components and shrinking standby power below 50 mW once the converter takes over. Unlike a passive bleed resistor, the IRS25751 automatically switches to micro-amp standby current after the auxiliary winding comes up, achieving ErP and ENERGY STAR standby compliance in single-stage AC/DC adapters and LED driver power supplies.
Recommended
Single-Stage Flyback AC/DC Converter Start-Up
The IRS25751LTRPBF is well-suited for single-stage flyback AC/DC converters where the VCC of the primary-side PWM controller must be biased from the rectified mains before the auxiliary winding becomes active. Its 480 V HVIC input stage eliminates external high-voltage dropper components, allowing direct connection to the 325 VDC rectified mains of 230 VAC supplies. The programmable upper turn-off threshold lets designers match VCC switch-over to the controller's UVLO release point - typically 12-15 V - while the ENN active-low enable allows synchronization with PFC_OK or fault signals. This integration reduces PCB area and improves overall system reliability versus discrete resistor-Zener start-up circuits.
Recommended
Industrial Motor Drive VCC Bias
The IRS25751LTRPBF provides reliable VCC bias for the gate-driver ICs of 3-phase industrial motor drives operating from rectified 400 VAC industrial mains. Its 480 V input rating provides 80 V of margin above the rectified 565 VDC peak, withstanding line transients and motor regenerative energy events. The 4.5 mA regulated output is sufficient to charge the VCC capacitor of half-bridge gate drivers like the IR2110 family within ~200 ms at typical 10 uF capacitance. Industrial designers benefit from the integrated over-temperature protection which engages at elevated junction temperatures in enclosed motor-drive enclosures where ambient can exceed 85 C during continuous full-load operation.
Recommended
Solar Inverter Auxiliary Supply Start-Up
The IRS25751LTRPBF is appropriate for solar inverter auxiliary supply start-up, particularly for residential and small-commercial string inverters operating from 400-600 VDC photovoltaic arrays. Its 480 V rating covers typical 1500 VDC PV string arrays when paired with external pre-regulation, while its 4.5 mA output charges the VCC rail of gate drivers and digital signal controllers. The ultra-low standby current after switch-over keeps quiescent losses in night-time / grid-disconnected modes below regulatory thresholds. Compared to discrete resistor-based start-up, it dramatically reduces standby power dissipation - critical for meeting CEC and IEC efficiency requirements for grid-tied solar inverters.
Recommended
EV Charging Station Power Supply Start-Up
The IRS25751LTRPBF delivers start-up bias for the auxiliary SMPS of EV charging stations, where the power supply must operate from rectified 400 VAC three-phase mains. Its 480 V rating provides robust transient immunity for the harsh electrical environment of EV charging stations, where PFC boost converters can see voltage spikes from regenerative EV battery loads. The ENN active-low enable input allows sequencing with the PFC_OK signal, ensuring the start-up IC switches off cleanly once the auxiliary winding takes over. This is essential for IEC 61851 and SAE J1772 compliant EVSE designs that require low standby power when no vehicle is connected.
Recommended
LED Driver High-Voltage Start-Up
The IRS25751LTRPBF is well-matched to high-power LED driver power supplies, particularly industrial and horticultural LED drivers operating directly from rectified mains without a step-down transformer. Its 480 V rating covers 230 VAC rectified (325 VDC) and 277 VAC rectified (392 VDC) industrial lighting mains with adequate margin. The regulated 4.5 mA output charges the VCC rail of LED driver controllers such as the XDPL8105 or XDPE12284 within milliseconds, enabling fast start-up without flicker. The integrated OTP protects the device in enclosed luminaires where ambient temperatures may exceed 90 C at full LED output power, ensuring long-term reliability required by DesignLights Consortium (DLC) and ENERGY STAR luminaire standards.
Recommended
Recommended Products Summary
Engineering reference data for IRS25751LTRPBF β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | IRS25752LTRPBF |
|---|---|---|
| Brand | Infineon Technologies | Infineon Technologies |
| Package | SOT-23-5 | SOT-23-5 - same |
| Maximum Input Voltage | 480 V | 480 V |
| Regulated Output Current | 4.5 mA | 4.5 mA (typical) |
| Upper Turn-Off Threshold | Programmable (per Infineon datasheet) | Programmable (marginally different default) |
| Enable Input | ENN active-low | ENN active-low |
| Over-Temperature Protection | Yes (integrated) | Yes (integrated) |
| Technology | Infineon HVIC, 480 V JFET input | Infineon HVIC, 480 V JFET input |
Key Differentiators
- 480 V HVIC input eliminates external high-voltage dropper components (vs Discrete bleed resistor + Zener + high-voltage transistor)
- Programmable upper turn-off threshold via single TH resistor (vs Fixed-threshold competitor parts)
- Integrated over-temperature protection (OTP) (vs Discrete start-up circuits without OTP)
Design Notes
Place the IRS25751LTRPBF's VCC bypass capacitor (typically 1-10 uF low-ESR ceramic) as close as physically possible to pin 3 (VCC) and pin 2 (GND) to minimize parasitic inductance and ensure stable regulation during the constant-current start-up phase. The HV pin (pin 1) trace should be kept short and isolated from low-voltage control traces to comply with 480 V creepage and clearance requirements per IPC-2221 (typically 6.5 mm minimum for 480 V reinforced insulation).
Estimated: during the start-up phase with VCC = 15 V and HV = 400 V, the IRS25751L dissipates approximately (400 V - 15 V) * 4.5 mA = 1.73 W. With SOT-23-5 theta_JA of approximately 200 C/W on a 1 sq-inch 2-oz copper pour, junction temperature rise is ~346 C above ambient - far beyond the 150 C maximum. Therefore the IRS25751 MUST exit start-up mode and switch to ultra-low standby within milliseconds to avoid thermal failure. Verify the downstream VCC capacitor and controller startup time limit IRS25751 active duration to <100 ms in worst case.
Do not use the IRS25751LTRPBF as a continuous high-voltage regulator - it is designed ONLY for start-up bias and must switch off when VCC reaches the upper turn-off threshold. A common mistake is leaving the ENN pin floating; tie ENN to GND via 10 kΞ© to ensure proper enable. Also ensure the threshold programming resistor on pin 5 (TH) is sized per Infineon datasheet - too high a resistance prevents VCC from reaching switch-over and the device will overheat, too low a resistance causes premature switch-off before the downstream controller starts switching.
Compliance Information
Lead-free / RoHS compliant per the 'PBF' suffix in the MPN. Tape-and-reel packaging per the 'TR' suffix. Not AEC-Q100 qualified (industrial/consumer grade). Halogen-free status not explicitly stated in the verified data.
