B43700A5687M
680µF 400V snap-in aluminum electrolytic capacitor, high capacitance for DC link and energy storage applications.
Product Overview
Description
The B43700A5687M is a high-capacitance snap-in aluminum electrolytic capacitor designed for DC link and bulk energy storage applications. With 680µF capacitance and 400V rating, this capacitor is ideal for medium-power inverters and motor drives.
This capacitor features a robust snap-in terminal design for secure PCB mounting and reliable electrical connection. The advanced electrolyte formulation provides good low-temperature performance down to -40°C.
The 35mm diameter x 50mm length case provides high volumetric efficiency for applications requiring significant energy storage in a compact footprint. The pressure relief vent ensures safe operation under abnormal conditions.
Product Series
B
Primary Application
DC link capacitors for inverters
Key Features
- High capacitance: 680µF in compact package
- High ripple current: 3.5A rms
- Low ESR for reduced heating
- Wide temperature range: -40°C to +105°C
- Snap-in terminals for secure mounting
- Pressure relief vent
Specifications
| Capacitance | 680µF ±20% |
|---|---|
| Rated Voltage | 400V DC |
| Temperature Range | -40°C to +105°C |
| Lifetime | 5,000 hours at 105°C |
| Ripple Current | 3.5A rms @ 100Hz, 105°C |
| ESR | 0.35Ω max @ 100Hz |
| Case Size | 35mm D x 50mm L |
| Termination | Snap-in |
Applications
DC link capacitors for inverters
Electronic system design
Motor drive power supplies
Motor drive and control systems
UPS systems
Electronic system design
Renewable energy inverters
Renewable energy systems
Industrial power supplies
Industrial automation and control
FAE Expert Insights
"The B43700A5687M is a solid choice for DC link applications in 5-15kW motor drives and inverters. The 680µF capacitance provides good energy storage for handling load transients, while the 400V rating is well-suited for 380-480VAC three-phase systems after rectification. The 3.5A ripple current rating handles the switching ripple from modern IGBT and SiC inverters effectively. I've used this capacitor in several solar inverter designs with good results. One tip: for high-vibration environments, use additional mechanical support beyond the snap-in terminals to prevent PCB stress. The -40°C rating also makes it suitable for outdoor applications in cold climates."
Excellent capacitance density for DC link applications in motor drives
— Robert Kim, BeiLuo
Frequently Asked Questions
What is the surge voltage rating of this capacitor?
The B43700A5687M has a surge voltage rating of 450V (1.125 x rated voltage) for short-duration transients up to 1000 cycles. This allows the capacitor to handle occasional voltage spikes above the normal 400V rating without damage. However, sustained operation above the rated voltage will accelerate aging and reduce lifetime. For applications with frequent voltage transients, consider using a higher voltage rated capacitor or adding external protection such as TVS diodes or metal oxide varistors. The capacitor also features a pressure relief vent that opens if internal pressure becomes excessive, preventing catastrophic failure.
Use surge rating for occasional transients only; consider higher voltage rating for sustained overvoltage conditions.
How many charge/discharge cycles can this capacitor withstand?
Aluminum electrolytic capacitors are not typically rated for a specific number of charge/discharge cycles like batteries or supercapacitors. However, they can withstand frequent voltage variations within their rated specifications. The B43700A5687M is designed for continuous operation in switching applications where the voltage varies at the switching frequency (typically 1-20kHz for IGBT inverters). The limiting factor is the ripple current and resulting thermal stress, not the number of cycles. With proper thermal management and operation within ripple current ratings, this capacitor can operate for its entire rated lifetime (5,000+ hours) with continuous switching. Rapid, deep discharge cycles are not recommended as they can stress the dielectric.
Design for continuous operation within ripple current and temperature ratings for maximum reliability.
What is the self-discharge rate of this capacitor?
The B43700A5687M has a typical self-discharge time constant of several hours due to its high capacitance and insulation resistance. After charging to rated voltage and then disconnected, the capacitor will retain approximately 63% of its charge after one time constant (typically 2-4 hours), 37% after two time constants, and so on. The exact self-discharge rate depends on temperature (faster at higher temperatures) and the capacitor's insulation resistance. For safety, always assume capacitors may retain dangerous voltages for extended periods after power-off. Use appropriate discharge resistors or procedures before handling. The high capacitance (680µF) and voltage (400V) is significant stored energy (54 joules) that can cause injury or damage if discharged rapidly.
Always discharge capacitors before handling; use discharge resistors in designs requiring rapid discharge.
Can this capacitor be used outdoors?
The B43700A5687M can be used in outdoor applications with proper enclosure and thermal management. The -40°C to +105°C temperature range covers most outdoor environments. However, the capacitor is not sealed against moisture and requires protection from direct exposure to rain, humidity, and corrosive atmospheres. For outdoor installations, use an IP54 or better enclosure with adequate ventilation for heat dissipation. Consider temperature cycling effects - daily temperature variations can cause pressure changes inside the capacitor, potentially accelerating seal aging. In high-humidity environments, conformal coating of the PCB assembly is recommended to prevent corrosion of the snap-in terminals and surrounding circuitry.
Use appropriate enclosure and conformal coating for outdoor applications; ensure adequate thermal management.
What is the ESR at different frequencies?
The ESR of the B43700A5687M varies significantly with frequency due to the dielectric and electrolyte properties. At 100Hz (standard measurement frequency), maximum ESR is 0.35Ω. At 120Hz (typical rectifier ripple), ESR is similar to 100Hz. At higher frequencies: 1kHz approximately 0.25Ω, 10kHz approximately 0.15Ω, and 100kHz approximately 0.10Ω. This frequency-dependent ESR characteristic is important for switching applications - the effective ESR at inverter switching frequencies (5-20kHz) is significantly lower than the 100Hz specification. Lower ESR at switching frequencies means reduced heating from ripple current and better filtering performance. TDK provides ESR vs frequency curves in the detailed datasheet.
Use frequency-specific ESR data for thermal calculations in switching power supply applications.