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STMicroelectronics E-UC3842BD1
- Part No.:
- E-UC3842BD1
- Manufacturer:
- STMicroelectronics
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
E-UC3842BD1.pdf
- Description:
- IC REG CTRLR BST FLYBK ISO 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,128
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Product details
Overview
E-UC3842BD1 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 (250 kHz guaranteed), latching PWM for cycle-by-cycle current limiting, 5 V ±1% internal reference, under-voltage lockout (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, forward, and boost converters.
For engineers reviewing the E-UC3842BD1 datasheet, E-UC3842BD1 pinout, E-UC3842BD1 application, or E-UC3842BD1 equivalent, key selection criteria include UVLO threshold compatibility with 115/230 VAC front-end rectification, duty cycle range up to 96%, oscillator programming via RT/CT, error amplifier compensation flexibility, and SO8 package thermal performance (Rth j-amb = 150 °C/W).
Technical Context
The E-UC3842BD1 implements current-mode control using a single-ended PWM architecture with an internal 5 V reference, voltage-controlled oscillator (VCO) with external RT/CT timing, and a current-sense comparator that terminates each switching cycle when sensed inductor current reaches the error amplifier's output-derived threshold. Its latch ensures single-pulse-per-cycle operation during overcurrent events.
It integrates a high-current totem-pole output stage (1 A sink/source), precision error amplifier (90 dB open-loop gain, 1 MHz GBW), and UVLO with hysteresis - all optimized for stable operation across –40 °C to +150 °C junction temperature. The device supports up to 500 kHz switching via external component selection but guarantees 250 kHz minimum frequency at 25 °C with standard RT/CT values.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | Guaranteed 250 kHz at 25 °C; programmable up to 500 kHz via RT/CT - enables compact magnetics and EMI optimization. |
| Reference Voltage | 5.00 V ±1% at 1 mA load - provides stable feedback reference for output regulation accuracy. |
| UVLO Threshold | 16 V turn-on / 10 V turn-off with hysteresis - ensures reliable start-up after bulk capacitor charging in AC/DC adapters. |
| Output Drive | ±1 A peak source/sink capability - directly drives medium-power MOSFET gates without external buffers. |
| Current Sense Gain | 3.0 V/V ±5% - converts sense resistor voltage to precise PWM trip point for accurate cycle-by-cycle current limiting. |
| Error Amp GBW | 1 MHz unity-gain bandwidth - supports stable loop compensation for wide-load-range regulation. |
| Start-up Current | <0.5 mA at 6.5 V - minimizes auxiliary supply losses in high-efficiency offline designs. |
Pinout & Package
Package: SO8 (Small Outline Integrated Circuit, 150 °C/W thermal resistance). Pin numbering follows standard top-view layout with pin 1 at bottom-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 COMP | Error Amplifier Output | Provides access to EA output for Type II/III compensation network placement - critical for loop stability. |
| 2 VFB | Inverting Input of Error Amplifier | Connected to output voltage divider - sets regulated output level via feedback ratio. |
| 3 ISENSE | Current Sense Input | Receives voltage from primary-side sense resistor - triggers PWM termination per cycle. |
| 4 RT/CT | Oscillator Timing Node | RT to VREF and CT to GND set switching frequency and max duty cycle - defines core timing behavior. |
| 5 GROUND | Power & Signal Reference | Single-point ground for control circuitry and power return - requires low-impedance PCB layout. |
| 6 OUTPUT | PWM Output Driver | Drives MOSFET gate directly - low-state output ensures safe FET turn-off during UVLO or fault. |
| 7 VCC | Supply Input | Accepts 10–30 V DC - powers internal bias, reference, and driver; self-limiting above 30 V. |
| 8 VREF | 5 V Reference Output | Sources up to 50 mA - powers RT resistor and can feed auxiliary circuits or optocoupler LED. |
Key Features
| Feature | Design Value |
|---|---|
| Trimmed Oscillator | 250 kHz guaranteed frequency tolerance eliminates need for post-manufacture calibration. |
| Latching PWM | Ensures one pulse per clock cycle during overcurrent - prevents transformer saturation and MOSFET failure. |
| Automatic Feed-Forward Compensation | Internal scaling of oscillator ramp compensates for input voltage variation - improves line regulation. |
| High-Current Totem-Pole Output | ±1 A peak drive reduces external gate driver requirements and improves switching speed control. |
| Internally Trimmed 5 V Reference | ±1% accuracy over temperature - enables tight output voltage regulation without external references. |
Applications
| AC/DC Adapter | Industrial DC-DC Converter |
|---|---|
Use Scenario: 12 V/2 A isolated flyback supply for IoT gateway power rails. IC Role / Device Role / Timing Role: Primary-side PWM controller generating gate drive signals synchronized to 250 kHz oscillator. Use Value: UVLO thresholds match 115 VAC rectified bulk voltage; 5 V reference enables precise secondary-side feedback via optocoupler. |
Use Scenario: 24 V input to 5 V/10 A forward converter in PLC I/O module. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller managing MOSFET switching and cycle-by-cycle current limit. Use Value: ±1 A output drive handles 10 A peak gate charge; SO8 package supports convection-cooled industrial board layout. |
| LED Driver Power Supply | Automotive Auxiliary DC-DC |
Use Scenario: Constant-current 48 V LED string driver with analog dimming interface. IC Role / Device Role / Timing Role: Regulates average inductor current via ISENSE feedback while maintaining fixed 250 kHz switching. Use Value: Current-sense gain of 3.0 V/V allows accurate 100 mΩ shunt use; COMP pin enables dimming voltage injection. |
Use Scenario: 12 V battery-input buck-boost converter powering infotainment USB ports. IC Role / Device Role / Timing Role: Controller managing bidirectional energy flow with robust UVLO for cold-crank conditions. Use Value: 10 V UVLO release point avoids dropout during engine cranking; SO8 package meets AEC-Q200 mounting requirements. |
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; Rth j-amb = 100 °C/W; same electrical specs. | Better thermal performance in through-hole prototyping; larger footprint limits high-density PCBs. | Select for lab validation or low-volume through-hole assembly where heatsinking is feasible. |
| TL494CN | Fixed-frequency dual-output PWM; no integrated 5 V reference; requires external Vref and UVLO. | Supports push-pull and full-bridge topologies; lacks cycle-by-cycle current limiting. | Choose only when dual-output drive or adjustable dead time is required - not a drop-in replacement. |
Compared with UC3842N, E-UC3842BD1 offers superior board-level integration and thermal management in surface-mount production; compared with TL494CN, it delivers simpler current-mode implementation with built-in reference and protection - reducing BOM count and design risk for single-switch topologies.
Availability
E-UC3842BD1 is available at Aetrix Electronics and suitable for AC/DC adapters, industrial DC-DC converters, and LED driver power supplies requiring stable component supply, long-term lifecycle support, and consistent parametric performance across manufacturing lots.
Supply support for E-UC3842BD1 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 high-reliability analog controller development.
E-UC3842BD1 belongs to ST's legacy UC384xB current-mode PWM controller product line, engineered specifically for cost-sensitive, high-volume switch-mode power supply applications demanding minimal external components and robust fault handling.
FAQ
What is the maximum recommended operating frequency for E-UC3842BD1?
The E-UC3842BD1 supports oscillator frequencies up to 500 kHz using external RT/CT components, though ST guarantees 250 kHz minimum at 25 °C. At higher frequencies, propagation delays and gate drive slew rates become limiting factors; practical designs typically operate between 250 kHz and 400 kHz to maintain timing margin and efficiency.
Can E-UC3842BD1 drive a P-channel MOSFET directly?
No - E-UC3842BD1's OUTPUT pin is a totem-pole stage referenced to GROUND and sinks current when low. It is designed to drive N-channel MOSFETs configured in low-side or self-driven high-side (with bootstrap) arrangements. Direct P-channel high-side drive requires inverted logic and level-shifting not supported by this IC.
How does the internal oscillator frequency change with supply voltage?
Frequency variation versus VCC is specified as ±1% over 12 V to 25 V - achieved via internal constant-current discharge of CT. This low sensitivity enables stable switching across wide input ranges without external compensation, unlike RC oscillators vulnerable to supply ripple.
Is slope compensation required when using E-UC3842BD1 in continuous conduction mode?
Yes - for duty cycles exceeding 50% in boost, flyback, or forward converters, external slope compensation must be injected at the ISENSE pin to prevent subharmonic oscillation. ST recommends adding a sawtooth waveform derived from the RT/CT node scaled to ~50% of the sensed current ramp amplitude.
E-UC3842BD1 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Output Type:
- Transistor Driver
- Function:
- 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
E-UC3842BD1 FAQ
1.How can I place an order for E-UC3842BD1 through Aetrix?
Please submit a Request for Quotation (RFQ) for E-UC3842BD1 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 E-UC3842BD1 reliable?
The price and inventory of E-UC3842BD1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for E-UC3842BD1 is usually 5 days.
3.What payment methods are accepted for E-UC3842BD1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for E-UC3842BD1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for E-UC3842BD1?
E-UC3842BD1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your E-UC3842BD1 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 E-UC3842BD1?
For technical support, including E-UC3842BD1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your E-UC3842BD1 requirements.
6.How does Aetrix verify that E-UC3842BD1 is sourced from the original manufacturer or authorized distributors?
All E-UC3842BD1 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 E-UC3842BD1 meets industry standards.
7.What is the process for return or replacement of E-UC3842BD1?
All E-UC3842BD1 units undergo pre-shipment inspection (PSI). If there is an issue with E-UC3842BD1, 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 E-UC3842BD1 part is unused and in its original packaging.
Return procedure for E-UC3842BD1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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