My Inquiry
My Account
STMicroelectronics UC2844BD1
- Part No.:
- UC2844BD1
- Manufacturer:
- STMicroelectronics
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
UC2844BD1.pdf
- Description:
- IC REG CTRLR BST FLYBK ISO 8-SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,948
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
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 an internally trimmed oscillator (250 kHz guaranteed), 47–50% 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 UC2844BD1 datasheet, UC2844BD1 pinout, UC2844BD1 application, or UC2844BD1 equivalent, key selection criteria include its 50% duty-cycle limitation, precise 5 V reference (±10 mV), low start-up current (<0.5 mA), and compatibility with standard current-sense resistor-based overcurrent protection in isolated AC/DC adapters and industrial SMPS.
Technical Context
The UC2844BD1 implements current-mode control with cycle-by-cycle current limiting via a latched PWM comparator, where the ISENSE input triggers shutdown when voltage exceeds ~1.0 V. Its oscillator uses RT/CT programming and includes automatic feed-forward compensation to reject line-voltage variations.
Unlike UC2842B/3B, the UC2844BD1 integrates a toggle flip-flop that blanks the OUTPUT every other clock cycle - enforcing ≤50% duty cycle for transformer reset safety in forward topologies. The error amplifier features 90 dB open-loop gain, 1 MHz unity-gain bandwidth, and rail-to-rail output swing into 15 kΩ load.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | Guaranteed 250 kHz at 25°C; programmable up to 500 kHz via RT/CT network. |
| Max Duty Cycle | 47–50% - enforced by internal toggle flip-flop for safe transformer reset in forward converters. |
| UVLO Thresholds | 16 V turn-on / 10 V turn-off - optimized for universal-input offline applications with bulk capacitor hold-up. |
| Reference Voltage | 5.00 V ±10 mV at 1 mA - trimmed for accuracy at error amp input; used to bias RT/CT timing network. |
| Output Drive | ±1 A peak sink/source - directly drives N-MOSFET gates without external buffer in sub-100 W designs. |
| Start-up Current | <0.5 mA at 6.5 V - enables high-impedance startup from auxiliary winding or HV resistor. |
| Error Amp Gain | 90 dB typical open-loop gain - supports stable Type II/III compensation in current-mode loops. |
Pinout & Package
UC2844BD1 is housed in an SO8 (Small Outline 8-pin) package per JEDEC MS-012, with 1.27 mm lead pitch and surface-mount footprint. Thermal resistance is 150 °C/W (junction-to-ambient).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (COMP) | Error Amplifier Output | Open-collector node for loop compensation; connects to RC network between COMP and VFB for stability. |
| 2 (VFB) | Error Amp Inverting Input | Receives feedback voltage from output divider; sets regulation point when VFB = 2.5 V. |
| 3 (ISENSE) | Current Sense Input | Terminates switch conduction when sensed voltage ≥1.0 V - enables cycle-by-cycle overcurrent protection. |
| 4 (RT/CT) | Oscillator Timing Node | Connects RT to VREF and CT to GND; sets frequency and max duty cycle; CT also receives 5 V reference charging current. |
| 5 (GROUND) | Power & Signal Reference | Common return for control logic, power stage, and bypass capacitors; requires star grounding near pin 5. |
| 6 (OUTPUT) | PWM Output Driver | Totem-pole stage sourcing/sinking up to 1 A; drives MOSFET gate low during UVLO or fault. |
| 7 (Vi / VCC) | Supply Input | Operates from 10–30 V; powers internal bias, reference, and logic; self-limiting above 30 V. |
| 8 (VREF) | 5 V Reference Output | Supplies stable 5 V ±10 mV; sources up to 20 mA; used to charge CT and bias external circuitry. |
Key Features
| Feature | Design Value |
|---|---|
| Latched PWM with cycle-by-cycle current limit | Prevents runaway under overload or short-circuit by holding OUTPUT low until next clock cycle reset. |
| Internally trimmed 5 V reference | ±10 mV accuracy at 1 mA ensures precise RT/CT timing and stable feedback threshold across temperature. |
| Toggle flip-flop for 50% duty-cycle enforcement | Guarantees transformer core reset in forward converters - eliminates need for external duty-cycle clamp. |
| Low start-up current (<0.5 mA) | Enables high-impedance startup from auxiliary winding, reducing standby losses in energy-efficient adapters. |
| High-current totem-pole output | ±1 A peak drive reduces external gate driver requirements and improves switching speed in 65–100 kHz designs. |
Applications
| AC/DC Adapter | Industrial DC-DC Converter |
|---|---|
|
Use Scenario: 12 V / 3 A universal-input offline adapter for networking equipment. IC Role / Device Role / Timing Role: Primary-side PWM controller implementing current-mode flyback topology with 50 kHz switching and auto-restart on overcurrent. Use Value: Internal 50% duty-cycle limit prevents transformer saturation during line transients; 16 V UVLO ensures reliable startup after brownout recovery. |
Use Scenario: 24 V input to 5 V / 10 A isolated forward converter in PLC power module. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller with synchronous rectification timing and transformer reset assurance. Use Value: Toggle flip-flop enforces safe 48% max duty cycle for core reset; ±1 A output drives 50 nC gate charge MOSFETs without buffering. |
| LED Driver (Constant Current) | Telecom Power Supply |
|
Use Scenario: 36–72 V DC input constant-current LED driver for street lighting. IC Role / Device Role / Timing Role: Secondary-side regulated flyback controller using optocoupler feedback and primary-side current sensing. Use Value: Precise 5 V reference stabilizes current-sense amplifier bias; low 0.5 mA start-up current enables operation from wide-input auxiliary rail. |
Use Scenario: -48 V telecom rectifier with hold-up and hot-swap capability. IC Role / Device Role / Timing Role: Primary-side controller managing dual-output forward converter with independent regulation and sequencing. Use Value: 10 V UVLO hysteresis prevents oscillation during input sag; 250 kHz guaranteed frequency simplifies EMI filter design for EN55022 Class B compliance. |
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; rated for 0–70°C ambient (vs. UC2844BD1's –40–105°C industrial range). | Not qualified for extended temperature industrial or automotive environments requiring >70°C operation. | Select UC3844BN only for commercial-grade applications with controlled thermal environments. |
| NCP1200DR2G | Fixed-frequency current-mode controller with integrated HV startup, 65 kHz default frequency, no internal toggle flip-flop. | Lacks 50% duty-cycle enforcement; requires external clamp for forward topologies; higher integration reduces BOM count. | Choose NCP1200DR2G when HV startup and lower component count outweigh need for strict duty-cycle limitation. |
Compared with UC3844BN, UC2844BD1 offers wider temperature qualification and tighter oscillator tolerance; versus NCP1200DR2G, it provides deterministic 50% duty-cycle control but requires external HV startup circuitry.
Availability
UC2844BD1 is available at Aetrix Electronics and suitable for AC/DC adapters, industrial DC-DC converters, LED drivers, and telecom power supplies requiring stable component supply, long-term lifecycle support, and industrial-grade temperature performance.
Supply support for 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.
The UCx84xB series was developed for cost-sensitive, high-reliability fixed-frequency current-mode power conversion - targeting offline SMPS, industrial power modules, and telecom infrastructure where precision timing and robust fault handling are critical.
FAQ
What is the maximum operating frequency of UC2844BD1?
The UC2844BD1 supports oscillator frequencies up to 500 kHz via external RT/CT components. Its oscillator is guaranteed at 250 kHz under standard conditions (RT = 6.2 kΩ, CT = 1 nF, TJ = 25°C), with frequency variation ≤±1% over supply voltage and temperature ranges specified in the datasheet.
Why does UC2844BD1 have a 50% maximum duty cycle?
The UC2844BD1 incorporates an internal toggle flip-flop that disables the OUTPUT every other clock cycle - inherently limiting maximum duty cycle to 47–50%. This design ensures safe transformer core reset in forward and push-pull topologies, eliminating risk of saturation during transient conditions or startup.
Can UC2844BD1 drive a P-channel MOSFET directly?
No - UC2844BD1's OUTPUT stage is a totem-pole driver referenced to GROUND, optimized for sinking current into the gate of N-channel MOSFETs. Driving a P-channel device would require level-shifting circuitry or an external high-side driver, as the IC lacks floating or bootstrap gate-drive capability.
How does the UVLO hysteresis benefit system reliability?
The UC2844BD1 features 16 V turn-on and 10 V turn-off UVLO thresholds, providing 6 V hysteresis. This prevents oscillatory startup/shutdown during input voltage sags or brownouts, ensuring clean power-up sequencing and avoiding repeated stress on the power switch and magnetics during marginal line conditions.
UC2844BD1 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- 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):
- 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
UC2844BD1 FAQ
1.How can I place an order for UC2844BD1 through Aetrix?
Please submit a Request for Quotation (RFQ) for 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 UC2844BD1 reliable?
The price and inventory of UC2844BD1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC2844BD1 is usually 5 days.
3.What payment methods are accepted for UC2844BD1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC2844BD1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UC2844BD1?
UC2844BD1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 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 UC2844BD1?
For technical support, including UC2844BD1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC2844BD1 requirements.
6.How does Aetrix verify that UC2844BD1 is sourced from the original manufacturer or authorized distributors?
All 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 UC2844BD1 meets industry standards.
7.What is the process for return or replacement of UC2844BD1?
All UC2844BD1 units undergo pre-shipment inspection (PSI). If there is an issue with 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 UC2844BD1 part is unused and in its original packaging.
Return procedure for UC2844BD1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
UC2844BD1 Tags
-
UCC28C45DR
Texas Instruments
-
UCC28C40DR
Texas Instruments
-
UCC28C43DR
Texas Instruments
-
ZXSC410E6TA
Diodes Incorporated
-
LM3524DMX/NOPB
Texas Instruments
-
LM3489MMX/NOPB
Texas Instruments
-
MIC2102YML-TR
Microchip Technology
-
LM5148RGYR
Texas Instruments
-
TL598CDR
Texas Instruments
-
LM5155DSSR
Texas Instruments
-
LM25085MYX/NOPB
Texas Instruments
-
UCC2813DTR-0
Texas Instruments
Tech Hub
A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
