UC3843AN Texas Instruments Integrated Circuit (Dual-In-Line Packages) In Stock
The UC3843AN is a high-performance current-mode PWM controller operating from 8.2 V to 28 V, featuring an 8-pin DIP package and 50% maximum duty cycle for single-ended converter topologies. It integrates a precise 5 V reference, oscillator, and current sense comparator for robust flyback and forward converter designs. Available in volume quantity with worldwide shipping.
- Manufacturer
- Texas Instruments
- Package
- Dual-In-Line Packages
- Pin Count
- 8
- Lifecycle
- ACTIVE
- Datasheet
- UC3843AN Datasheet PDF
- Category
- Integrated Circuit
- Price
- From $0.3403(MOQ 226)
- 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 cycle-by-cycle over-current limiting for inherently safe switching power supply designs
- 8.2 V to 28 V wide operating supply range with 15 V nominal suiting a broad range of AC-DC and DC-DC converter inputs
- Integrated 5 V precision reference and totem-pole output capable of 1 A peak drive for direct MOSFET gate driving
Applications
The UC3843AN is one of the most widely deployed current-mode PWM controllers, used in AC-DC flyback power supplies, isolated DC-DC converters, and battery chargers from a few watts up to several hundred watts. Its 50% maximum duty cycle and single-ended output make it the standard choice for flyback and forward converter topologies in consumer electronics, industrial power supplies, and telecom equipment. Designers also use it in boost converters, PFC pre-regulators, and LED driver stages requiring stable peak current control.
Specifications
| Pbfree Code | Yes |
| YTEOL | 15 |
| Analog IC - Other Type | SWITCHING CONTROLLER |
| Control Mode | CURRENT-MODE |
| Control Technique | PULSE WIDTH MODULATION |
| Input Voltage-Max | 28V |
| 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 |
| Output Voltage-Max | 5.1V |
| Output Voltage-Min | 4.9V |
| Output Voltage-Nom | 5V |
| Package Body Material | PLASTIC/EPOXY |
| Package Equivalence Code | DIP8,.3 |
| Package Shape | RECTANGULAR |
| Package Style | IN-LINE |
| Qualification Status | Not Qualified |
| Supply Current-Max (Isup) | 25mA |
| Supply Voltage-Max (Vsup) | 28V |
| Supply Voltage-Min (Vsup) | 8.4V |
| Supply Voltage-Nom (Vsup) | 11V |
| Surface Mount | NO |
| Switcher Configuration | BUCK-BOOST |
| 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 |
| ## UC3843AN Alternates Showing results | Image |
| Package | Dual-In-Line Packages |
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
| ECCN | EAR99 |
| HTS Code | 8542.39.00.90 |
| Country of Origin | Mexico |
Alternate & Equivalent Parts
Compatible alternatives and drop-in replacements for UC3843AN:
suggested
suggested
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Frequently Asked Questions
What supply voltage range does the UC3843AN support and what is the startup threshold?
The UC3843AN operates from 8.2 V minimum to 28 V maximum with a 15 V nominal supply. Its undervoltage lockout (UVLO) turns on at approximately 8.5 V and turns off at 7.9 V, preventing erratic operation during startup from an auxiliary winding before the converter reaches steady-state output. This hysteresis window of about 0.6 V is critical for reliable self-starting flyback designs.
How does current-mode control in the UC3843AN protect the power stage during overload?
The UC3843AN current sense comparator monitors peak switch current each cycle via a low-value shunt resistor. When the sensed voltage exceeds the error amplifier output reference, the PWM pulse terminates immediately, limiting peak current on a cycle-by-cycle basis. This prevents transformer saturation and MOSFET overcurrent in flyback converters experiencing load shorts or transients before the slower voltage feedback loop responds.
What is the maximum duty cycle of the UC3843AN and which topologies benefit from it?
The UC3843AN is internally limited to 50% maximum duty cycle, making it suited for single-ended forward converters, flyback converters, and boost stages where duty cycles above 50% would cause transformer volt-second imbalance or instability. Designs needing up to 100% duty cycle should instead use the UC3842, which shares the same 8-pin DIP pinout with 15 V nominal operation.
Can the UC3843AN directly drive a power MOSFET gate without an external gate drive buffer?
Yes, the UC3843AN totem-pole output stage is rated for 1 A peak source and sink current, sufficient to directly charge and discharge gate capacitances of MOSFETs with up to 10 nC to 15 nC gate charge at switching frequencies up to 500 kHz. For larger MOSFETs with 50 nC or more gate charge, a discrete gate driver with 4 A output is recommended to keep switching losses acceptable.
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About Texas Instruments
Texas Instruments (TI) is a global semiconductor company headquartered in Dallas, Texas. TI designs and manufactures analog and embedded processing chips used in industrial, automotive, consumer, communications, and enterprise systems.
| Qty. | Unit Price | Ext. Price |
|---|---|---|
| 226+ | $1.3300 | $300.58 |
| 250+ | $0.9300 | $232.50 |
| 500+ | $0.8848 | $442.40 |
| 1000+ | $0.3403 | $340.28 |
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