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STMicroelectronics E-UC2844BD1
- Part No.:
- E-UC2844BD1
- Manufacturer:
- STMicroelectronics
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
E-UC2844BD1.pdf
- Description:
- IC REG CTRLR BST FLYBK ISO 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,503
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Product details
Overview
E-UC2844BD1 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 at 250 kHz, 50% maximum duty cycle (due to internal toggle flip-flop), UVLO thresholds of 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 E-UC2844BD1 datasheet, E-UC2844BD1 pinout, E-UC2844BD1 application, or E-UC2844BD1 equivalent, key selection criteria include its 50% duty-cycle limitation, precise 5 V reference (±10 mV initial accuracy), 0.5 mA start-up current, current-sense gain of 3 V/V, and SO8 package compatibility with board-level thermal management requirements.
Technical Context
The E-UC2844BD1 implements current-mode control with cycle-by-cycle current limiting via a latched PWM comparator and internal 1 V threshold on the current-sense input. Its oscillator uses RT/CT programming with discharge current of 7.5–8.8 mA, supporting operation up to 500 kHz. The internal toggle flip-flop blanks the output every other clock cycle, enforcing ≤50% duty cycle - distinguishing it from UC2842B/3B.
It integrates a 5 V ±1% trimmed reference with 0.2 mV/°C temperature stability, an error amplifier with 90 dB open-loop gain and 1 MHz unity-gain bandwidth, and UVLO with 6 V hysteresis. The totem-pole output delivers 13.5 V high-level and 0.4 V low-level (at 20 mA), optimized for driving power MOSFET gates without external buffers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 250 kHz guaranteed at 25°C; supports up to 500 kHz with RT/CT tuning - sets switching frequency and timing resolution for loop control. |
| Max Duty Cycle | 47–50% due to internal toggle flip-flop - enforces safe operation in forward/flyback topologies requiring limited conduction time. |
| VREF Output | 5.00 V ±10 mV at 1 mA; supplies stable bias for RT/CT network and external circuitry - eliminates need for external reference. |
| Current Sense Gain | 3.0 V/V (2.85–3.15 V/V); converts sensed resistor voltage to precise 1 V trip point - enables accurate peak-current limiting. |
| UVLO Thresholds | 16 V turn-on / 10 V turn-off (6 V hysteresis); ensures reliable startup and brown-out protection in unregulated AC/DC inputs. |
| Start-up Current | <0.5 mA at 6.5 V - minimizes auxiliary winding losses and enables high-impedance VCC startup circuits. |
| Output Drive | ±1 A peak sink/source; drives MOSFET gates directly - avoids gate driver ICs in cost-sensitive SMPS designs. |
Pinout & Package
Package: SO8 (Small Outline Integrated Circuit, 150 °C/W junction-to-ambient thermal resistance). Pin numbering follows standard SO8 top-view layout with 1.27 mm pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - COMP | Error amplifier output | Provides access to EA output for Type II/III compensation networks - critical for loop stability in current-mode converters. |
| 2 - VFB | Inverting input of error amplifier | Receives feedback voltage from output divider - sets regulation setpoint and closed-loop bandwidth. |
| 3 - ISENSE | Current-sense comparator input | Accepts voltage from sense resistor; triggers PWM latch at 1 V - implements cycle-by-cycle overcurrent protection. |
| 4 - RT/CT | Oscillator timing node | Connects external RT to VREF and CT to GND - determines switching frequency and slope compensation ramp amplitude. |
| 5 - GROUND | Power and signal reference | Single-point ground for control logic, oscillator, and current-sense - requires star grounding to minimize noise coupling. |
| 6 - OUTPUT | Totem-pole gate driver | Sources/sinks up to 1 A; low-state voltage ≤0.4 V at 20 mA - directly switches N-MOSFETs with minimal dead-time risk. |
| 7 - Vi (VCC) | Supply input | Operates from 10–30 V; self-limiting above 30 V - powers internal bias, reference, and gate driver stages. |
| 8 - VREF | 5 V precision reference output | Supplies 5 V ±1% at up to 20 mA; charges CT through RT - serves as stable timing and bias source. |
Key Features
| Feature | Design Value |
|---|---|
| Latched PWM with cycle-by-cycle current limit | Prevents transformer saturation and MOSFET failure by disabling output after each overcurrent event until next clock cycle. |
| Internally trimmed 5 V reference | ±10 mV initial accuracy and 0.2 mV/°C drift - reduces calibration overhead and improves output voltage tolerance across temperature. |
| Automatic feed-forward compensation | Uses input voltage variation (via RT/CT bias) to adjust oscillator ramp slope - maintains constant current limit across line changes. |
| Low-startup current (<0.5 mA) | Enables use of high-value startup resistors - cuts standby power and simplifies auxiliary supply design in offline adapters. |
| High-current totem-pole output | ±1 A peak drive capability - eliminates external buffer stages and supports fast MOSFET switching with <150 ns rise/fall times. |
Applications
| AC-DC Adapter | Flyback Power Supply |
|---|---|
|
Use Scenario: 12 V/2 A isolated wall adapter for consumer electronics with universal AC input (85–265 VAC). IC Role / Device Role / Timing Role: Primary-side PWM controller providing current-mode regulation, soft-start, and overcurrent protection. Use Value: 50% duty cycle limit prevents transformer core saturation during line transients; 250 kHz operation enables compact magnetics and EMI filtering. |
Use Scenario: 5 V/3 A medical-grade isolated power module meeting IEC 60601 creepage and leakage requirements. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller managing primary switch timing, feedback loop, and fault response. Use Value: Trimmed 5 V reference ensures ±1% output regulation; latch protection meets safety-critical single-point-failure requirements. |
| Industrial DC-DC Converter | LED Driver (Constant Current) |
|
Use Scenario: 24 V input to ±15 V dual-output converter for PLC I/O modules operating in -40°C to +85°C ambient. IC Role / Device Role / Timing Role: Core PWM engine implementing current-mode control with feed-forward line compensation. Use Value: UVLO hysteresis (16 V/10 V) ensures clean startup under brownout; SO8 package supports industrial reflow profiles. |
Use Scenario: 36 V input, 350 mA constant-current LED driver for street lighting with analog dimming interface. IC Role / Device Role / Timing Role: Current-regulated PWM controller using ISENSE feedback to maintain LED string current. Use Value: 3 V/V current-sense gain enables precise 1 V threshold detection with 0.1 Ω sense resistor - minimizing power loss. |
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 |
|---|---|---|---|
| UC3844BN | Same functional block diagram and pinout; wider temperature range (0°C to 70°C vs. –40°C to 105°C for UC2844B variants). | Targeted at commercial-grade power supplies; lacks extended industrial temperature qualification. | Select when cost sensitivity outweighs extended temperature or automotive qualification needs. |
| TL494CN | Fixed-frequency voltage-mode controller; dual-output, adjustable dead time, no integrated current-sense comparator or 5 V reference. | Requires external current sensing and reference; suited for push-pull or half-bridge topologies needing complementary outputs. | Choose only if dual-output drive or voltage-mode control is mandatory - not a drop-in replacement. |
Compared with UC3844BN, E-UC2844BD1 offers broader industrial temperature support and tighter reference accuracy; versus TL494CN, it provides integrated current-mode control and simplified BOM but lacks dual-output flexibility - making it optimal for cost-constrained, single-switch flyback designs.
Availability
E-UC2844BD1 is available at Aetrix Electronics and suitable for AC-DC adapters, flyback power supplies, industrial DC-DC converters, and LED drivers requiring stable component supply, long-term lifecycle assurance, and SO8-compatible manufacturing flow.
Supply support for E-UC2844BD1 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 power conversion IP development.
The UC284xB family was engineered specifically for cost-sensitive, high-efficiency current-mode SMPS in consumer, industrial, and telecom power supplies - emphasizing minimal external components, robust fault handling, and production-ready thermal performance.
FAQ
What is the maximum recommended switching frequency for E-UC2844BD1?
The E-UC2844BD1 supports operation up to 500 kHz per datasheet specifications, contingent on proper RT/CT selection and PCB layout. At 500 kHz, oscillator discharge current remains within 7.5–8.8 mA, and propagation delays (150 ns max) ensure reliable PWM timing. Thermal derating must be applied above 250 kHz in SO8 packages due to 800 mW power dissipation limit.
Can E-UC2844BD1 drive a P-channel MOSFET directly?
No - the E-UC2844BD1 OUTPUT pin is a totem-pole stage referenced to ground and designed to sink/source current into an N-channel MOSFET gate. Driving a P-channel device would require level-shifting circuitry or an external high-side driver, as the IC lacks floating output capability or bootstrap support.
How does the internal toggle flip-flop affect duty cycle in E-UC2844BD1?
The internal toggle flip-flop forces the OUTPUT pin inactive every other oscillator cycle, limiting maximum duty cycle to 47–50%. This prevents transformer saturation in forward converters and improves stability in discontinuous conduction mode flybacks - a deliberate architectural distinction from UC2842B/3B's near-100% capability.
Is external slope compensation required when using E-UC2844BD1 in continuous conduction mode?
Yes - for CCM operation with duty cycles >50% (even though internal limit is 50%, margin exists), external ramp injection at the ISENSE pin is recommended to prevent subharmonic oscillation. The datasheet Figure 18 shows RC-based slope compensation tied to the RT/CT node, synchronized to oscillator frequency.
E-UC2844BD1 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):
- 48%
- 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-UC2844BD1 FAQ
1.How can I place an order for E-UC2844BD1 through Aetrix?
Please submit a Request for Quotation (RFQ) for E-UC2844BD1 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-UC2844BD1 reliable?
The price and inventory of E-UC2844BD1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for E-UC2844BD1 is usually 5 days.
3.What payment methods are accepted for E-UC2844BD1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for E-UC2844BD1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for E-UC2844BD1?
E-UC2844BD1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your E-UC2844BD1 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-UC2844BD1?
For technical support, including E-UC2844BD1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your E-UC2844BD1 requirements.
6.How does Aetrix verify that E-UC2844BD1 is sourced from the original manufacturer or authorized distributors?
All E-UC2844BD1 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-UC2844BD1 meets industry standards.
7.What is the process for return or replacement of E-UC2844BD1?
All E-UC2844BD1 units undergo pre-shipment inspection (PSI). If there is an issue with E-UC2844BD1, 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-UC2844BD1 part is unused and in its original packaging.
Return procedure for E-UC2844BD1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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