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STMicroelectronics UC3842BD1013TR
- Part No.:
- UC3842BD1013TR
- Manufacturer:
- STMicroelectronics
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
UC3842BD1013TR.pdf
- Description:
- IC REG CTRLR BST FLYBK ISO 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,858
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Product details
Overview
UC3842BD1013TR from STMicroelectronics is a high-performance current-mode PWM controller IC designed for fixed-frequency off-line and DC-DC power supplies. It features a trimmed oscillator (guaranteed 250 kHz), latching PWM for cycle-by-cycle current limiting, internally trimmed 5.0 V reference with UVLO (16 V on / 10 V off), and a totem-pole output capable of ±1 A peak drive - enabling direct N-channel MOSFET gate control in flyback and forward converters.
For engineers reviewing the UC3842BD1013TR datasheet, UC3842BD1013TR pinout, UC3842BD1013TR application, or UC3842BD1013TR equivalent, key selection criteria include its 250 kHz oscillator guarantee, 96% max duty cycle, 0.5 mA start-up current, and SO8 package compatibility with standard PCB layouts for AC-DC adapters and industrial SMPS designs.
Technical Context
The UC3842BD1013TR implements current-mode control using an internal error amplifier, PWM latch, and current-sense comparator referenced to a 1 V threshold. Its oscillator uses RT/CT programming with discharge current of 7.8–8.8 mA and supports operation up to 500 kHz via external component selection.
UVLO hysteresis (16 V ON / 10 V OFF) ensures reliable start-up and brown-out recovery. The totem-pole output delivers 13.5 V high-level and 0.4 V low-level at 20 mA, with rise/fall times ≤150 ns into 1 nF load - optimized for fast MOSFET switching with minimal dead-time uncertainty.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | Guaranteed 250 kHz at Tj = 25°C; enables precise timing control without external trimming. |
| Max Duty Cycle | 96% typical; supports high-voltage flyback designs requiring extended conduction periods. |
| Start-up Current | <0.5 mA at Vi = 14 V; reduces auxiliary winding losses in offline adapters. |
| Reference Voltage | 5.00 V ±10 mV at 1 mA; provides stable feedback reference for ±1% output regulation. |
| Output Drive | ±1 A peak sink/source; directly drives gate capacitance of MOSFETs up to 1 nF without buffer. |
| Current Sense Threshold | 1.0 V ±0.1 V; sets accurate overcurrent trip point with 3 V/V gain for shunt-based sensing. |
| UVLO Thresholds | 16 V (turn-on) / 10 V (turn-off); prevents erratic operation during input dips in universal AC inputs. |
Pinout & Package
UC3842BD1013TR is housed in an SO8 (Small Outline 8-pin) package per JEDEC MS-012, with 1.27 mm pitch and gull-wing leads. Thermal resistance is 150 °C/W (junction-to-ambient), suitable for surface-mount reflow assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (COMP) | Error amplifier output | Provides access to EA output for loop compensation networks (e.g., Type II/III filters). |
| 2 (VFB) | Inverting input of error amplifier | Connects to output voltage divider; sets regulated output voltage via feedback ratio. |
| 3 (ISENSE) | Current sense input | Accepts voltage from primary-side current sense resistor; terminates switch conduction when ≥1 V. |
| 4 (RT/CT) | Oscillator timing node | RT to VREF and CT to GND set frequency and max duty cycle; supports 500 kHz operation. |
| 5 (GROUND) | Signal and power ground | Single-point return for control circuitry and power stage; critical for noise immunity. |
| 6 (OUTPUT) | PWM output driver | Totem-pole stage sinks/sources up to 1 A; drives N-MOSFET gates directly. |
| 7 (Vi / VCC) | Supply input | Accepts 10–30 V; powers internal bias circuits and output stage; UVLO protected. |
| 8 (VREF) | 5 V reference output | Supplies charging current for CT via RT; can power small external circuitry (≤20 mA). |
Key Features
| Feature | Design Value |
|---|---|
| Latching PWM with cycle-by-cycle current limit | Prevents transformer saturation and MOSFET failure during overload or short-circuit events. |
| Internally trimmed 5.0 V reference | Eliminates need for external reference IC; maintains ±2% accuracy across temperature and load. |
| Automatic feed-forward compensation | Compensates for input line variations in real time, improving transient response in offline SMPS. |
| Low start-up current (<0.5 mA) | Reduces dissipation in startup resistors and enables smaller auxiliary windings in flyback designs. |
| High-current totem-pole output | Drives 1 nF gate capacitance with <150 ns rise/fall; avoids external drivers in medium-power applications. |
Applications
| AC-DC Adapter | Flyback SMPS |
|---|---|
|
Use Scenario: 5–24 V, 10–65 W universal-input AC-DC adapter for consumer electronics. IC Role / Device Role / Timing Role: Primary-side PWM controller generating gate drive for power MOSFET; sets 65–100 kHz switching frequency via RT/CT. Use Value: Enables compact design with <0.5 mA start-up current and integrated 5 V reference, reducing BOM count by two components. |
Use Scenario: Isolated 12 V/2 A flyback converter in industrial power modules. IC Role / Device Role / Timing Role: Current-mode controller regulating output via optocoupler feedback to VFB; provides cycle-by-cycle overcurrent protection. Use Value: Latching shutdown prevents secondary rectifier stress during output short; 96% duty cycle supports wide input range (85–265 VAC). |
| DC-DC Forward Converter | LED Driver Supply |
|
Use Scenario: 48 V input to 5 V/10 A forward converter for telecom shelf power. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller driving synchronous rectification gate signals via OUTPUT pin. Use Value: Totem-pole output delivers 1 A peak current to drive high-side MOSFET gate, eliminating need for dedicated gate driver IC. |
Use Scenario: Constant-current LED driver for architectural lighting (36 V, 700 mA). IC Role / Device Role / Timing Role: PWM controller regulating LED current via primary-side sensing at ISENSE pin; operates at 250 kHz for EMI compliance. Use Value: Guaranteed 250 kHz oscillator simplifies EMI filter design; 1 V current sense threshold enables accurate ±3% current regulation. |
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 |
|---|---|---|---|
| UC3842N | DIP-8 package; higher Rth j-amb (100 °C/W); no moisture sensitivity level rating. | Suitable for prototyping or through-hole production; less thermally efficient in high-density layouts. | Select when manual soldering or breadboarding is required; avoid for high-temperature SMT volume production. |
| TL494CN | Fixed 200 kHz oscillator; dual-output push-pull; no built-in current-sense comparator or UVLO hysteresis. | Requires external current sensing and start-up circuitry; better suited for half-bridge or push-pull topologies. | Choose only if dual-output capability or adjustable dead time is needed; not drop-in compatible for flyback designs. |
Compared with UC3842N and TL494CN, the UC3842BD1013TR offers superior thermal performance in SO8, guaranteed 250 kHz timing, and integrated current-limiting architecture - making it optimal for space-constrained, high-reliability flyback and forward converters where start-up robustness and regulation accuracy are critical.
Availability
UC3842BD1013TR is available at Aetrix Electronics and suitable for AC-DC adapters, flyback SMPS, and industrial DC-DC converters requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for UC3842BD1013TR 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.
The UC384xB series was developed specifically for cost-sensitive, high-efficiency current-mode switch-mode power supplies - targeting offline AC-DC, DC-DC conversion, and LED driver applications demanding precision timing and robust fault protection.
FAQ
What is the maximum operating frequency of UC3842BD1013TR?
The UC3842BD1013TR supports current-mode operation up to 500 kHz via external RT/CT selection. Its oscillator frequency is guaranteed at 250 kHz under standard test conditions (Tj = 25°C, RT = 6.2 kΩ, CT = 1 nF), with typical variation of ±3% across temperature and supply voltage.
Does UC3842BD1013TR require an external current-sense resistor?
Yes - the ISENSE pin (Pin 3) requires an external current-sense resistor placed in series with the primary-side MOSFET source or transformer winding. The controller trips when voltage across this resistor reaches 1.0 V, corresponding to peak primary current determined by Ipk ≈ 1.0 V / Rsense.
Can UC3842BD1013TR drive a P-channel MOSFET directly?
No - the OUTPUT pin is a totem-pole stage that sources current when high and sinks when low, optimized for driving N-channel MOSFET gates. Driving a P-channel device would require level-shifting circuitry or an external inverter, as the output does not provide high-side gate drive capability.
Is the 5 V reference on Pin 8 internally current-limited?
Yes - the VREF pin (Pin 8) delivers up to 20 mA while maintaining regulation within ±2% across load and temperature. Electrical characteristics show short-circuit current of –30 to –180 mA, confirming active current limiting to protect the bandgap reference circuitry.
UC3842BD1013TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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 (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
UC3842BD1013TR FAQ
1.How can I place an order for UC3842BD1013TR through Aetrix?
Please submit a Request for Quotation (RFQ) for UC3842BD1013TR 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 UC3842BD1013TR reliable?
The price and inventory of UC3842BD1013TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC3842BD1013TR is usually 5 days.
3.What payment methods are accepted for UC3842BD1013TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC3842BD1013TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UC3842BD1013TR?
UC3842BD1013TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UC3842BD1013TR 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 UC3842BD1013TR?
For technical support, including UC3842BD1013TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC3842BD1013TR requirements.
6.How does Aetrix verify that UC3842BD1013TR is sourced from the original manufacturer or authorized distributors?
All UC3842BD1013TR 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 UC3842BD1013TR meets industry standards.
7.What is the process for return or replacement of UC3842BD1013TR?
All UC3842BD1013TR units undergo pre-shipment inspection (PSI). If there is an issue with UC3842BD1013TR, 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 UC3842BD1013TR part is unused and in its original packaging.
Return procedure for UC3842BD1013TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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