UC3843BN STMicroelectronics Integrated Circuit (Dual-In-Line Packages) In Stock
UC3843BN is a current-mode PWM controller by STMicroelectronics designed for fixed-frequency offline and DC-DC power supplies. Key specs: 8.2 V to 30 V input range, up to 500 kHz switching frequency, and 1 A peak gate drive output in an 8-pin PDIP package. Available from stock with worldwide shipping.
- Manufacturer
- STMicroelectronics
- Package
- Dual-In-Line Packages
- Pin Count
- 8
- Lifecycle
- ACTIVE
- Datasheet
- UC3843BN Datasheet PDF
- Category
- Integrated Circuit
- Price
- From $0.3350(MOQ 400)
- Temp Range
- ?°C to 70.0°C
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
Key Features
- Current-mode PWM control with pulse-by-pulse current limiting for inherent overcurrent protection without additional external circuitry
- Up to 500 kHz switching frequency enabling compact magnetics design in flyback, boost, and forward converter topologies
- 1 A peak totem-pole gate drive output for fast, reliable switching of power MOSFETs and IGBTs in industrial SMPS designs
Applications
The UC3843BN is widely used as the control core of offline flyback converters, boost pre-regulators, and forward converters in industrial power supplies, battery chargers, and auxiliary power modules. Its current-mode architecture provides inherent cycle-by-cycle overcurrent protection and excellent line-regulation performance, making it a staple in AC-DC adapters and distributed power architectures. The 8-pin PDIP package simplifies prototyping and low-volume production for motor drive auxiliaries, HVAC controls, and LED driver power stages.
Specifications
| Factory Lead Time | 14Weeks |
| YTEOL | 6 |
| Analog IC - Other Type | SWITCHING CONTROLLER |
| Control Mode | CURRENT-MODE |
| Control Technique | PULSE WIDTH MODULATION |
| Input Voltage-Max | 30V |
| Input Voltage-Min | 8.2V |
| Input Voltage-Nom | 15V |
| JESD-30 Code | R-PDIP-T8 |
| JESD-609 Code | e4 |
| Number of Functions | 1 |
| Output Current-Max | 1A |
| Package Body Material | PLASTIC/EPOXY |
| Package Equivalence Code | DIP8,.3 |
| Package Shape | RECTANGULAR |
| Package Style | IN-LINE |
| Qualification Status | Not Qualified |
| Surface Mount | NO |
| Switcher Configuration | SINGLE |
| Switching Frequency-Max | 500kHz |
| Technology | BIPOLAR |
| Temperature Grade | COMMERCIAL |
| Terminal Finish | Nickel/Palladium/Gold (Ni/Pd/Au) |
| Terminal Form | THROUGH-HOLE |
| Terminal Pitch | 2.54mm |
| Terminal Position | DUAL |
| ## UC3843BN Alternates Showing results | Image |
| Package | Dual-In-Line Packages |
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
| ECCN | EAR99 |
| HTS Code | 8542.39.00.60 |
| Country of Origin | Mainland China |
Alternate & Equivalent Parts
Compatible alternatives and drop-in replacements for UC3843BN:
Rochester Electronics LLC 1 A SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDIP8, GREEN, PLASTIC, DIP-8
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Frequently Asked Questions
What switching frequency can the UC3843BN achieve and how is it set?
The UC3843BN supports switching frequencies up to 500 kHz, programmed by a single external timing resistor-capacitor network connected to the RT/CT pin. Selecting appropriate R and C values per the datasheet nomograph allows designers to optimize the frequency for core size, switching losses, and EMI margin in flyback or boost converter designs targeting a specific power range.
How does current-mode control in the UC3843BN improve power supply performance compared to voltage-mode control?
The UC3843BN's current-mode control loop senses inductor peak current each switching cycle, providing automatic feed-forward line regulation and cycle-by-cycle current limiting without a dedicated overcurrent comparator. This results in faster transient response to input voltage changes, simpler loop compensation using a single-pole error amplifier network, and inherent protection against transformer saturation—advantages over voltage-mode controllers in offline flyback designs.
What is the startup and operating input voltage range of the UC3843BN?
The UC3843BN has an undervoltage lockout (UVLO) with a turn-on threshold of approximately 8.2 V and a turn-off threshold of 7.6 V, and it operates continuously up to 30 V on the VCC pin. This wide range accommodates both bootstrap startup from an auxiliary winding that ramps from 0 V and direct bias from a regulated 12 V or 15 V rail in DC-DC converter applications.
Which converter topologies are best suited for the UC3843BN?
The UC3843BN is optimized for single-ended topologies including flyback, boost, and forward converters where a single power switch is driven at duty cycles up to 100% (UC3843 variant has no duty-cycle clamp). It drives power MOSFETs or IGBTs with a 1 A peak gate drive current, making it practical for designs up to several hundred watts when paired with appropriate output stage components rated at the required voltage and current.
How does the UC3843BN package choice affect prototyping and production?
The UC3843BN is supplied in an 8-pin PDIP package with 2.54 mm pitch, ideal for breadboard prototyping and hand-soldering during early design iterations. For production volumes requiring smaller footprint, STMicroelectronics also offers the UC3843B in SO-8 surface-mount packages. Both variants share the same pinout and electrical characteristics, enabling a direct substitution between package types without schematic changes.
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About STMicroelectronics
STMicroelectronics is a global semiconductor leader serving customers across the spectrum of electronics applications. ST's products are found in a wide range of applications including automotive, industrial, personal electronics, and communications.
| Qty. | Unit Price | Ext. Price |
|---|---|---|
| 400+ | $0.4050 | $162.00 |
| 1000+ | $0.3600 | $360.00 |
| 2000+ | $0.3470 | $694.00 |
| 4000+ | $0.3350 | $1340.00 |
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