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STMicroelectronics E-UC2843BD1
- Part No.:
- E-UC2843BD1
- Manufacturer:
- STMicroelectronics
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
E-UC2843BD1.pdf
- Description:
- IC REG CTRLR BOOST/FLYBACK 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,625
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Product details
Overview
E-UC2843BD1 from STMicroelectronics is a high-performance current-mode PWM controller IC designed for fixed-frequency DC-DC and off-line power supplies. It features an internally trimmed 5V reference, under-voltage lockout with 8.5V turn-on/7.9V turn-off thresholds, latching PWM for cycle-by-cycle current limiting, oscillator frequency guaranteed at 250kHz (up to 500kHz), and a totem-pole output capable of ±1A peak drive-enabling direct N-channel MOSFET gate control in flyback and forward converters.
For engineers reviewing the E-UC2843BD1 datasheet, E-UC2843BD1 pinout, E-UC2843BD1 application, or E-UC2843BD1 equivalent, key selection criteria include UVLO threshold compatibility with low-input-voltage systems, duty cycle range (0–100%), current-sense gain (3 V/V), oscillator timing flexibility (RT/CT programmable), and SO8 package thermal performance (Rth j-amb = 150°C/W).
Technical Context
The E-UC2843BD1 implements current-mode control via a high-gain (3 V/V) current-sense comparator that terminates switch conduction when sensed inductor current reaches the error amplifier's output voltage. Its oscillator uses an external RT/CT network to set frequency and maximum duty cycle, supporting operation up to 500kHz with precise ramp generation.
Internal circuitry includes a trimmed 5.00V ±50mV reference (±0.2mV/°C drift), a rail-to-rail error amplifier (65dB open-loop gain, 0.7MHz bandwidth), and UVLO with hysteresis-ensuring reliable start-up at 8.5V and hold-on down to 7.9V. The output stage delivers fast rise/fall times (50–150ns into 1nF) and sustains ±200mA at <2.2V low-level saturation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 250 kHz guaranteed at 25°C; programmable up to 500 kHz via RT/CT network for flexible switching speed design. |
| UVLO Threshold | 8.5 V (turn-on) / 7.9 V (turn-off); enables stable operation in low-input-voltage DC-DC applications like 12V input adapters. |
| Current Sense Gain | 3.0 V/V (±5%); provides accurate, temperature-stable current-to-voltage conversion for precise cycle-by-cycle limiting. |
| Reference Voltage | 5.00 V ±50 mV at 1 mA load; internally trimmed for <0.2 mV/°C drift, eliminating need for external reference in feedback loop. |
| Output Drive | ±1 A peak sink/source; directly drives N-MOSFET gates without buffer, reducing BOM count and layout complexity. |
| Max Duty Cycle | 100% (UC2843B variant); supports continuous conduction mode in boost and flyback topologies without internal toggle flip-flop limitation. |
| Start-up Current | <0.5 mA at 6.5 V; minimizes auxiliary supply burden during initial power-up in energy-constrained systems. |
Pinout & Package
Package: SO8 (Small Outline Integrated Circuit, 150°C/W junction-to-ambient thermal resistance).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - COMP | Error Amplifier Output | Open-collector node for external compensation network; sets loop stability and transient response in voltage-mode feedback path. |
| 2 - VFB | Inverting Input of Error Amp | Connects to resistor divider from output; compares regulated output voltage against internal 2.5V threshold for closed-loop control. |
| 3 - ISENSE | Current-Sense Input | Receives voltage proportional to primary-side current; triggers PWM latch when ≥1.0 V, enabling cycle-by-cycle overcurrent protection. |
| 4 - RT/CT | Oscillator Timing Node | RT resistor to VREF and CT capacitor to ground set fOSC and max duty cycle; supports wide frequency tuning range (100kHz–500kHz). |
| 5 - GROUND | Signal & Power Ground | Common return for control logic, error amp, and current sense; requires star grounding near pin 5 to minimize noise coupling. |
| 6 - OUTPUT | Totem-Pole Gate Driver | Drives N-MOSFET gate directly; sinks/sources up to 1A peak, with 0.4V low-level saturation at 20mA for efficient switching. |
| 7 - VCC | Supply Input | Accepts 7.9–30V; powers internal bias circuits; UVLO monitors this pin to enable/disable controller based on input availability. |
| 8 - VREF | 5V Reference Output | Supplies 5.00V ±50mV at up to 20mA; powers RT resistor and optionally feeds optocoupler or sensing circuitry in isolated designs. |
Key Features
| Feature | Design Value |
|---|---|
| Latching PWM with cycle-by-cycle current limit | Prevents transformer saturation and MOSFET failure during overload or short-circuit by disabling output until next clock cycle reset. |
| Internally trimmed 5V reference with <0.2 mV/°C drift | Eliminates external reference IC and reduces component count while maintaining ±1% output regulation across temperature. |
| Low start-up current (<0.5 mA) | Reduces auxiliary winding size and losses in flyback converters, improving light-load efficiency and simplifying startup circuitry. |
| High-current totem-pole output (±1 A) | Enables direct drive of medium-power MOSFETs (e.g., 500V/2A), avoiding gate driver ICs and associated PCB area and cost. |
| Automatic feed-forward compensation | Uses VCC ripple to modulate oscillator ramp slope, inherently compensating for input voltage variations without external components. |
Applications
| AC-DC Adapters | Flyback SMPS |
|---|---|
Use Scenario: 5–24V output AC-DC wall adapters for consumer electronics and IoT devices. IC Role / Device Role / Timing Role: Primary-side PWM controller implementing current-mode feedback, providing isolation via optocoupler-linked VFB and regulating output voltage through duty cycle modulation. Use Value: UVLO thresholds (8.5V/7.9V) match typical 12V DC bus derived from rectified AC, enabling reliable start-up and brownout recovery without auxiliary bias winding. | Use Scenario: Isolated 12V/1A flyback converter in industrial sensors and PLC I/O modules. IC Role / Device Role / Timing Role: Core timing and current-limiting controller; generates gate drive signal synchronized to oscillator, with ISENSE monitoring primary current for inherent overcurrent protection. Use Value: 100% max duty cycle supports continuous conduction mode operation, improving efficiency at medium loads while maintaining tight regulation via 3 V/V current-sense gain. |
| DC-DC Boost Converters | Offline LED Drivers |
Use Scenario: 12V-to-24V boost converter powering automotive infotainment displays from battery supply. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller regulating output by adjusting MOSFET on-time based on inductor current feedback and VFB error signal. Use Value: Low operating current (12–17 mA) and 5V reference reduce standby power consumption, meeting automotive micro-sleep requirements. | Use Scenario: Constant-current LED driver for commercial signage using universal AC input (85–265VAC). IC Role / Device Role / Timing Role: Off-line flyback controller with primary-side regulation; uses VREF to bias optocoupler and COMP to close current loop via secondary-side shunt regulator. Use Value: Oscillator frequency guarantee (250kHz) ensures EMI compliance in narrow-band conducted emission tests, while ±1A output drives large MOSFETs needed for high-power LED strings. |
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 |
|---|---|---|---|
| UC3843BD1 | Same pinout, identical electrical specs, but rated for 0–70°C ambient (vs. UC2843BD1's –40–105°C industrial grade). | Not qualified for extended temperature environments such as outdoor lighting or automotive under-hood use. | Select UC3843BD1 only for commercial-grade applications where ambient stays within 0–70°C. |
| NCP1200DR2G | Fixed 65kHz frequency, no RT/CT programming; lower start-up current (100µA); integrated soft-start; no VREF output. | Lacks programmable frequency and external reference-unsuitable for designs requiring EMI tuning or optocoupler biasing. | Choose NCP1200DR2G for cost-sensitive, low-power (<15W) applications where fixed frequency and minimal external parts are prioritized. |
Compared with UC3843BD1, E-UC2843BD1 offers wider temperature qualification and identical functionality; versus NCP1200DR2G, it trades integrated soft-start and ultra-low start-up current for full frequency programmability, external reference capability, and higher output drive-making it better suited for robust, flexible, medium-power industrial SMPS designs.
Availability
E-UC2843BD1 is available at Aetrix Electronics and suitable for AC-DC adapters, flyback SMPS, DC-DC boost converters, and offline LED drivers requiring stable component supply, long-term lifecycle support, and industrial-grade temperature performance.
Supply support for E-UC2843BD1 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, delivering innovative analog, power, and microcontroller solutions for industrial, automotive, and consumer markets.
The UC284xB series was developed specifically for high-reliability, cost-effective current-mode PWM control in off-line and DC-DC power supplies-emphasizing minimal external component count, precise oscillator control, and robust fault protection.
FAQ
What is the maximum recommended operating junction temperature for E-UC2843BD1?
The absolute maximum junction operating temperature is 150°C. For reliable long-term operation, STMicroelectronics specifies a recommended maximum of 125°C under continuous load. Thermal design must ensure Rth j-amb × Pdiss + Tamb ≤ 125°C, especially given the SO8 package's 150°C/W thermal resistance.
Can E-UC2843BD1 be used in a boost converter without slope compensation?
Yes-E-UC2843BD1 supports stable boost operation without external slope compensation when operating in discontinuous conduction mode (DCM). In continuous conduction mode (CCM), slope compensation is required to prevent subharmonic oscillation; Figure 18 in the datasheet shows RC-based implementation using the VREF and RT/CT pins.
How does the UVLO hysteresis improve system reliability?
The 0.6V hysteresis (8.5V ON / 7.9V OFF) prevents oscillatory startup/shutdown during marginal input conditions-such as slow-rising AC line or weak battery sources. This avoids repeated MOSFET switching attempts that could cause thermal stress or audible noise in transformers and inductors.
Is the VREF pin intended for powering external circuitry?
Yes-the VREF pin delivers up to 20mA at 5.00V ±50mV and is commonly used to bias optocouplers in isolated feedback paths or power current-sense amplifiers. Load regulation is ±25mV from 1–20mA, so external decoupling (e.g., 1µF ceramic) is recommended near the pin for stability.
E-UC2843BD1 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):
- 7.6V ~ 30V
- Frequency - Switching:
- Up to 500kHz
- Duty Cycle (Max):
- 96%
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Frequency Control
- Operating Temperature:
- -25°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
E-UC2843BD1 FAQ
1.How can I place an order for E-UC2843BD1 through Aetrix?
Please submit a Request for Quotation (RFQ) for E-UC2843BD1 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-UC2843BD1 reliable?
The price and inventory of E-UC2843BD1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for E-UC2843BD1 is usually 5 days.
3.What payment methods are accepted for E-UC2843BD1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for E-UC2843BD1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for E-UC2843BD1?
E-UC2843BD1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your E-UC2843BD1 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-UC2843BD1?
For technical support, including E-UC2843BD1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your E-UC2843BD1 requirements.
6.How does Aetrix verify that E-UC2843BD1 is sourced from the original manufacturer or authorized distributors?
All E-UC2843BD1 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-UC2843BD1 meets industry standards.
7.What is the process for return or replacement of E-UC2843BD1?
All E-UC2843BD1 units undergo pre-shipment inspection (PSI). If there is an issue with E-UC2843BD1, 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-UC2843BD1 part is unused and in its original packaging.
Return procedure for E-UC2843BD1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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