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STMicroelectronics UC3843AD1013TR
- Part No.:
- UC3843AD1013TR
- Manufacturer:
- STMicroelectronics
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
UC3843AD1013TR.pdf
- Description:
- IC REG CTRLR BOOST/FLYBACK 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,857
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Product details
Overview
UC3843AD1013TR from STMicroelectronics is a high-performance current-mode PWM controller IC designed for off-line and DC-DC fixed-frequency switching power supplies. It features an internally trimmed 5V reference, UVLO with 8.4V turn-on/7.9V turn-off hysteresis, 500kHz oscillator capability, latching PWM for cycle-by-cycle current limiting, and a totem-pole output capable of ±1A peak drive - enabling direct gate control of N-channel MOSFETs in flyback, forward, and boost converters.
For engineers reviewing the UC3843AD1013TR datasheet, UC3843AD1013TR pinout, UC3843AD1013TR application, or UC3843AD1013TR equivalent, key selection criteria include its 8.4V UVLO threshold (optimized for low-input-voltage DC-DC designs), 96% max duty cycle, ±1A output drive strength, 8-pin SOIC package, and compatibility with standard current-mode compensation networks.
Technical Context
The UC3843AD1013TR implements a current-mode control architecture where the error amplifier output modulates the PWM comparator's trip point via the ISENSE input, enabling automatic feed-forward compensation and improved line regulation. Its oscillator uses RT/CT programming to set frequency up to 500kHz, with trimmed discharge current (8.3mA typ.) ensuring stable timing across temperature.
Internal circuitry includes a precision 5.00V ±10mV reference (0.2mV/°C drift), a rail-to-rail error amplifier with 90dB open-loop gain and 1MHz bandwidth, and UVLO logic with hysteresis that guarantees clean start-up below 0.5mA supply current - critical for low-power auxiliary supplies and battery-backed systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply UVLO Threshold | 8.4V (on) / 7.9V (off) - enables reliable start-up from low-voltage rails like 12V or 5V-derived supplies |
| Max Duty Cycle | 96% - supports high step-up ratio topologies such as boost and flyback without external duty clamp |
| Oscillator Frequency | 47–57kHz (typ. 52kHz at RT=10kΩ, CT=3.3nF) - programmable up to 500kHz for compact magnetics and EMI optimization |
| Output Drive Capability | ±1A peak sink/source - directly drives medium-size MOSFET gates without external buffer stages |
| Reference Voltage Accuracy | 5.00V ±10mV at 25°C, ±180mV over full temp range - ensures tight output voltage regulation in feedback loops |
| Error Amp Gain-Bandwidth | 90dB open-loop gain, 1MHz unity-gain bandwidth - provides sufficient phase margin for stable Type II/III compensation |
| Start-up Current | <0.5mA at 6.5V - reduces auxiliary winding losses and enables operation from high-impedance bias sources |
Pinout & Package
UC3843AD1013TR is housed in an 8-pin SOIC (SO-8) package with 1.27mm pitch, 5.00mm × 4.00mm body size, and thermal resistance RθJA = 150°C/W - suitable for surface-mount reflow assembly and moderate-power applications up to ~30W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (COMP) | Error Amplifier Output | Provides high-impedance node for loop compensation network (Type II/III); connects to feedback divider and optocoupler |
| 2 (VFB) | Inverting Input of Error Amp | Receives scaled output voltage; sets regulation point when referenced to internal 2.5V threshold |
| 3 (ISENSE) | Current Sense Input | Accepts voltage proportional to primary-side current; triggers PWM latch shutdown at 1.0V threshold |
| 4 (RT/CT) | Oscillator Timing Node | Connects external resistor (RT) to VREF and capacitor (CT) to GND to program frequency and max duty cycle |
| 5 (GROUND) | Signal & Power Ground | Single-point return for control logic, reference, and current sense - requires star grounding for noise immunity |
| 6 (OUTPUT) | PWM Output Driver | Totem-pole stage sourcing/sinking up to 1A; drives N-MOSFET gate directly with fast 50–150ns rise/fall times |
| 7 (VCC) | Supply Input | Operates from 8.5–30V; self-limited current draw; powers internal bias and gate driver circuits |
| 8 (VREF) | 5V Reference Output | Stable 5.00V ±10mV source; supplies charging current for CT and can power optocoupler LED or sensing circuitry |
Key Features
| Feature | Design Value |
|---|---|
| Trimmed Oscillator Discharge Current | 8.3mA typical - ensures precise duty cycle control and minimal frequency drift over temperature |
| Automatic Feed-Forward Compensation | Integrated into current-mode architecture - improves line transient response without additional components |
| Latching PWM with Cycle-by-Cycle Limiting | Hard-shutdown on each overcurrent event - prevents MOSFET failure during short-circuit or overload conditions |
| Internally Trimmed 5V Reference | ±10mV accuracy at 25°C - eliminates need for external voltage reference in most regulated SMPS designs |
| Low Start-up Current | <0.5mA at 6.5V - enables use with high-value startup resistors or capacitive dropper supplies |
Applications
| AC-DC Adapter | Industrial DC-DC Converter |
|---|---|
|
Use Scenario: 12V/24V input AC-DC adapter powering IoT gateways and industrial sensors. IC Role / Device Role / Timing Role: Primary-side PWM controller regulating output via optocoupler feedback; generates 52kHz gate drive synchronized to transformer reset. Use Value: 8.4V UVLO allows reliable start-up from brownout-prone 12V bus; ±1A output drives 500V/1Ω MOSFET without buffer. |
Use Scenario: Isolated 48V-to-12V DC-DC converter in PLC backplane power distribution. IC Role / Device Role / Timing Role: Current-mode controller implementing forward topology with synchronous rectification timing. Use Value: 96% max duty cycle supports wide input variation (36–75V); 1MHz error amp bandwidth enables fast load-step response. |
| LED Driver Supply | Telecom Power Module |
|
Use Scenario: Constant-current LED driver for street lighting using flyback topology with analog dimming. IC Role / Device Role / Timing Role: Regulates LED current by sensing secondary-side sense resistor voltage through auxiliary winding. Use Value: ISENSE input threshold of 1.0V ±100mV enables accurate current sensing with low-loss shunt; COMP pin supports analog dimming interface. |
Use Scenario: -48V telecom intermediate bus converter supplying 3.3V/5V to line cards. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller managing high-efficiency forward converter with active clamp. Use Value: 500kHz programmability reduces magnetic size; 150ns output fall time minimizes switching loss in high-frequency operation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar current-mode PWM controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UC3843BD1TR | Same pinout and function; tighter VREF tolerance (±5mV vs ±10mV) and lower Istart (0.35mA typ.) | Better suited for precision 5V-output supplies requiring <±1% regulation | Select when reference stability and low-startup-current margin are critical; otherwise functionally interchangeable |
| NCP1200DR2G | Fixed 65kHz frequency, no RT/CT programming; integrated soft-start; lower UVLO (10.5V/9.0V) | Targeted at cost-sensitive, low-power adapters (<15W); lacks programmable frequency and high-duty-cycle support | Choose for simplified BOM and reduced layout complexity in low-power universal-input designs |
Compared with UC3843BD1TR and NCP1200DR2G, the UC3843AD1013TR offers superior flexibility in frequency/duty-cycle tuning and higher drive strength, making it optimal for medium-power, variable-input industrial and telecom converters where design adaptability outweighs ultra-tight reference specs or lowest-cost integration.
Availability
UC3843AD1013TR is available at Aetrix Electronics and suitable for AC-DC adapters, industrial DC-DC converters, LED drivers, and telecom power modules requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for UC3843AD1013TR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power management, analog, microcontrollers, and automotive ICs - with over 40 years of innovation in energy-efficient power conversion solutions.
The UC384x family was developed specifically for cost-effective, high-reliability current-mode switching power supplies in industrial, telecom, and consumer applications - emphasizing minimal external parts count, robust fault protection, and wide operating voltage range.
FAQ
What is the maximum recommended operating junction temperature for UC3843AD1013TR?
The UC3843AD1013TR has a specified junction operating temperature range of –40°C to +150°C. For continuous reliability in SO-8 package, derating is required above +105°C ambient due to its 150°C/W thermal resistance; maximum sustained power dissipation should remain ≤400mW above +70°C ambient to maintain TJ < 125°C.
Can UC3843AD1013TR be used in discontinuous conduction mode (DCM) flyback designs?
Yes - UC3843AD1013TR supports DCM flyback operation via its current-mode architecture and 96% max duty cycle. The ISENSE input detects primary current zero-crossing indirectly through slope compensation or auxiliary winding sensing, and the latching PWM ensures stable operation even at light loads when paired with proper snubber and compensation.
Does UC3843AD1013TR support external clock synchronization?
Yes - pin 4 (RT/CT) accepts an external sync signal when configured with a diode clamp (to limit negative swing to –300mV) and appropriate biasing. This allows multiple UC3843AD1013TR units to operate in phase, reducing input ripple and EMI in multi-phase or parallel power supply designs.
Is there a built-in soft-start function in UC3843AD1013TR?
No - UC3843AD1013TR does not integrate soft-start. However, it supports external soft-start via a capacitor on the COMP pin charged through a resistor from VREF, or via dedicated circuits using pin 1 (COMP) and pin 8 (VREF) as shown in Figure 26 of the datasheet - enabling controlled ramp-up of duty cycle during power-up.
UC3843AD1013TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Output Type:
- Transistor Driver
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Boost, Flyback
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 10V ~ 30V
- Frequency - Switching:
- Up to 500kHz
- Duty Cycle (Max):
- 96%
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Frequency Control
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
UC3843AD1013TR FAQ
1.How can I place an order for UC3843AD1013TR through Aetrix?
Please submit a Request for Quotation (RFQ) for UC3843AD1013TR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for UC3843AD1013TR reliable?
The price and inventory of UC3843AD1013TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC3843AD1013TR is usually 5 days.
3.What payment methods are accepted for UC3843AD1013TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC3843AD1013TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UC3843AD1013TR?
UC3843AD1013TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UC3843AD1013TR order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for UC3843AD1013TR?
For technical support, including UC3843AD1013TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC3843AD1013TR requirements.
6.How does Aetrix verify that UC3843AD1013TR is sourced from the original manufacturer or authorized distributors?
All UC3843AD1013TR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that UC3843AD1013TR meets industry standards.
7.What is the process for return or replacement of UC3843AD1013TR?
All UC3843AD1013TR units undergo pre-shipment inspection (PSI). If there is an issue with UC3843AD1013TR, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The UC3843AD1013TR part is unused and in its original packaging.
Return procedure for UC3843AD1013TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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