Free tools Windows power users keep installed
One-click scans. No signup required.
Choose the discharge method for the actual X-capacitor, safety target and standby-power budget—not by searching for a supposedly interchangeable “discharge IC.” In an offline AC/DC supply, X-capacitor discharge is usually integrated into a switching controller or implemented as a system-level circuit. The controller’s topology, disconnect sensing and exact variant must fit the complete converter.
Start with the capacitor and the compliance target
An X-rated capacitor is connected across the AC input, commonly as part of the EMI filter. After the supply is unplugged, it can retain voltage at the plug. The discharge circuit must bring that voltage to the required level within the time applicable to the product and market.
As an Amazon Associate I earn from qualifying purchases.
Texas Instruments’ UCC25640x datasheet, Rev. F (revised August 2026), summarizes IEC 60950 and IEC 60065 as requiring a discharge time constant below one second. The same datasheet summarizes IEC 62368 as requiring the X-capacitor voltage to be below 60 V two seconds after AC unplug for capacitance of 300 nF or more. These are the datasheet’s descriptions of the standards, not a substitute for checking the currently applicable standard edition, product scope and compliance interpretation for a particular design. Read the UCC25640x datasheet.
Quick wins for a faster PC:
Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Record the maximum capacitance in the finished input filter, including tolerances and any configurations that change it. Then establish the required residual voltage and discharge time for the product’s applicable safety requirements. A controller feature rating is useful only if it covers those actual conditions.
#1 Best Overall
- High Voltage 1000V Capacitor Discharge Pen：This capacitor discharge tool enables the safe and fast discharging of capacitors with a 2V-1000V range, safely handling all capacitors at 1000V and below. Preventing electric shocks and protecting sensitive equipment. A must-have discharge tool for electronic maintenance and repairs.
- Compact & Ergonomic for Easy One-Handed Use：The Capacitor Discharge Tool design is portable and easy to handle, ensuring comfort and convenience for one-handed operation. Ideal for various spacings and use in tight spaces.The capacitor discharge pen enables safe and fast discharging of all high-voltage capacitors in automotive LED lights, HVAC systems, household appliances , digital camera , camcorder , TV, car, consoles and other equipment.
- LED Indicator for Easy Monitoring：Our Capacitor Discharge tool built-in LED light indicates when discharging occurs, ensuring safe and accurate usage. Note: This discharge tool is not designed for battery discharging.
- Polarity-Free, Spark-Free, Safe：The intelligent discharge pen operates safely with no polarity, Suitable for AC/DC capacitor discharge. This capacitor discharge pen provides maximum safety protection and reduces the risk of accidents during capacitor discharge & maintenance.
- Capacitor Discharge tool for Home Maintenances：Quickly discharges residual energy from capacitors to protect operators and products. Essential capacitor discharge tool for electrical maintenance and repair and power capacitor DIY enthusiasts.
Choose between a passive bleeder and active discharge
Passive bleeder resistor
A resistor or resistor string placed in parallel with the X-capacitor provides a simple, continuously available discharge path. Its trade-off is that it also draws current while AC remains connected, creating standing power loss. TI describes this as a concern when aiming for very low standby power.
TI’s UCC25640x datasheet gives a worked example for a typical 60–100 W supply with a typical 330 nF X-capacitor: 3 MΩ total discharge resistance dissipates 17.63 mW at nominal high line of 230 V. This is a manufacturer example, not a universal resistor value or sizing recommendation. The same datasheet states, in its own design context, “For every 100 nF of capacitance, add a maximum bleed resistor of 10 MΩ in parallel.” Do not apply that guidance outside its stated context without checking the full design and applicable requirements.
Rank #2
- Discharge capacitors safely, without the risk of electrical shock | For professional use only
- LED indicator to let you know if capacitor is charged | Standard magnetic connector or alligator clip adapter
- Maximum voltage: 440 VAC
- Dimensions: 6-1/2 x 1 Inches | Lead length: 14 Inches
- SD products come in Supplying Demand packaging.
Active switched discharge
An active scheme detects that AC has been disconnected and then switches on a discharge path. It can reduce the continuous loss associated with a bleeder, but depends on reliable disconnect detection and a suitable switched path. Check how the candidate behaves during brownout, brief line interruptions and transients, not only after a clean unplug.
The UCC25640x implementation is a specific example, not a general description of all active-discharge controllers: it monitors AC zero crossings through its HV pin and uses a staircase test current for detection. Its datasheet says four missed zero crossings at the highest test-current setting confirm disconnect; the controller then enables discharge current for 350 ms. Those thresholds and timing describe this device behavior and should not be assumed for another part.
Rank #3
- Discharge capacitor tool Intelligent identification of positive and negative, there is no need to distinguish between positive and negative, because the two LCD lights will be lit
- Discharge tool is suitable for all DC voltage discharge, can put the voltage range 5V-1000V , for discharging household appliances / digital camera / camcorder / TV / car and etc DC voltage or storage capacitor
- Capacitor discharge tools Designed for safety in maintenance operations, discharging high direct current to a safe range to ensure that there is no risk of electric
- Capacitor discharging tool Box made of aluminum alloy plating insulation layer composition, the operation is absolutely safe, drop resistance, compression, available environment is -30 ℃ to +50 ℃
- Discharge the original use: high temperature ceramic surface, high power, high standards, high stability and two warm white 5W LED lamp beads
Compare documented controller candidates
The following TI devices are starting points documented in the cited product material, not interchangeable discharge ICs or a complete market survey. Feature support is variant-specific; confirm it in the current datasheet and for the exact orderable part before committing to a design.
| Candidate | Documented fit | Checks before selection |
|---|---|---|
| UCC256402 / UCC256404 | LLC controller family. The UCC25640x datasheet states active X-capacitor discharge support for feature-enabled variants, for up to 5 µF. | Confirm that the exact variant enables discharge; some variants disable it. Check package, voltage sensing, input range, auxiliary supply and startup needs, capacitance, and compatibility with the complete LLC/PFC design. UCC256403 lacks high-voltage startup and requires an external auxiliary supply. UCC25640x datasheet. |
| UCC28630 / UCC28633 | TI identifies active X-capacitor discharge for these members of its UCC2863x high-power primary-side-regulated flyback family. | Check the precise datasheet and orderable suffix, topology, power range, startup and regulation needs. Do not infer support for UCC28632 from its family membership. UCC2863x product information. |
| UCC28781 | TI’s product page lists X-capacitor discharge for this zero-voltage-switching flyback controller with integrated synchronous-rectifier control. | The product-page listing alone does not establish quantitative discharge limits. Consult the current datasheet and verify complete flyback design compatibility. UCC28781 product information. |
Check the whole converter, not just the feature name
Before choosing a candidate, compare the requirements and implementation details that determine whether it will work in the intended supply:
Rank #4
- ⚡Pen type design and portable size, it is convenient for you to carry and for your daily use.
- ⚡This capacitor discharge pen supports capacitor discharge below 1000V, which can quickly release the remaining of high-voltage capacitor, but cannot for discharge the .
- ⚡The discharge pen can automatically and intelligently identify when discharging, without distinguishing positive and negative electrodes, constant discharge, no sparking.
- ⚡It can quickly release the residual of capacitors generated during production, testing and maintenance of various electronic products (such as switching supplies, digital cameras, mobilephones, TV supplies, etc.) to protects operators from electric shock and products from damage.
- ⚡The discharge pen can automatically and intelligently identify when discharging, without distinguishing positive and negative electrodes, constant discharge, no sparking.
- Capacitance and discharge result: Confirm maximum X-capacitance and the residual-voltage/time performance for the exact part and conditions.
- Standby budget: Compare the passive resistor’s continuous dissipation with the active circuit’s behavior and any associated system-level losses.
- Disconnect detection: Review sensing method, threshold, latency and response to brownout, transient interruptions and line conditions.
- Power topology and input: Match the controller to LLC, flyback or another intended topology, the line-voltage range and the available input-sensing arrangement.
- Variant and surrounding circuitry: Verify discharge support, startup and auxiliary-supply needs, package, protections, layout implications and other required components for the exact orderable part.
- Lifecycle and procurement: Check current part status and availability for the exact ordering code; a family-level product page does not guarantee that a particular variant is orderable.
Use reference designs as evidence, not as a guarantee
TI’s PMP10804 reference design illustrates the active-discharge trade-off in an offline flyback. The page describes a 100–138 V AC input, isolated 24 V/4 A output (96 W), average efficiency over 86% and no-load consumption below 100 mW. These are the reference design’s stated results, not guaranteed performance for a new implementation. TI describes the design as tested and says it includes a test report. See the PMP10804 reference design.
Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minutePC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Use a reference design to understand an implementation and its stated operating conditions; independently check whether its controller, discharge behavior, input range, safety targets and standby performance match the product being designed.
Quick Recap
Best Value
- Our high voltage capacitor discharge pen features a resilient, extendable probe that adjusts easily, ensuring a safe and efficient discharge process. Tailored for both AC/DC applications, this tool is a must-have for electronic repairs and maintenance
- Equipped with a 1000V MOS tube to manage discharges safely - note, the discharging voltage must not exceed 1000V. Dual LED indicators provide immediate feedback during discharging: a red LED for high voltage, and a green LED indicating a safer, lower voltage status
- The transition from red to green LED illuminates at approximately 42V, signaling an on-going discharge. This feature ensures users can monitor the discharge process effectively, enhancing the safety and reliability of electronic repairs
- Fit for electronics production, testing, and repair scenarios, our discharger repair tool rapidly neutralizes residual capacitor voltage, safeguarding both the user and electronic devices from potential harm
- Safety Precautions: Post-discharge, a non-illuminating green LED indicates a completion. A residual voltage of about 6V may remain. When discharging, avoid touching the circuit or exposed metals and ensure sufficient cooling during prolonged use to prevent overheating
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
