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STMicroelectronics UC3844BD1013TR
- Part No.:
- UC3844BD1013TR
- Manufacturer:
- STMicroelectronics
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
UC3844BD1013TR.pdf
- Description:
- IC REG CTRLR BST FLYBK ISO 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,831
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Product details
Overview
UC3844BD1013TR from STMicroelectronics is a high-performance current-mode PWM controller IC designed for fixed-frequency DC-DC and off-line power supplies. It features a trimmed oscillator (250 kHz guaranteed), 47–50% maximum duty cycle, 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 UC3844BD1013TR datasheet, UC3844BD1013TR pinout, UC3844BD1013TR application, or UC3844BD1013TR equivalent, key selection criteria include its internal toggle flip-flop limiting duty cycle to <50%, precise 5.0 V reference (±20 mV), low 0.5 mA start-up current, and SO8 package compatibility with standard PCB layouts.
Technical Context
The UC3844BD1013TR implements current-mode control via a high-speed current-sense comparator (150–300 ns delay) and latching PWM logic that enforces cycle-by-cycle current limiting. Its oscillator uses an external RT/CT network with internal discharge current (7.5–8.8 mA) to achieve stable frequency up to 500 kHz.
It integrates a precision 5.0 V bandgap reference (±0.2 mV/°C drift), error amplifier with 65–90 dB open-loop gain and 0.7–1 MHz unity-gain bandwidth, and under-voltage lockout with 6 V hysteresis - ensuring reliable start-up and brown-out protection in unregulated input applications.
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 - enables compact magnetics and EMI optimization. |
| Max Duty Cycle | 47–50% - enforced by internal toggle flip-flop; prevents transformer saturation in single-ended topologies. |
| VREF Output | 5.00 V ±20 mV at 1 mA; supplies stable bias for RT/CT timing and feedback divider - eliminates need for external reference. |
| UVLO Thresholds | 16 V turn-on / 10 V turn-off (6 V hysteresis); ensures clean start-up from bulk capacitors in AC-DC adapters. |
| Output Drive | ±1 A peak sink/source; directly drives N-MOSFET gates without buffer - reduces BOM count and layout complexity. |
| Start-up Current | <0.5 mA at 6.5 V - minimizes auxiliary winding losses and enables high-efficiency no-load operation. |
| Error Amp GBW | 0.7–1 MHz - provides sufficient phase margin for stable loop compensation in current-mode flyback designs. |
Pinout & Package
UC3844BD1013TR is housed in a standard 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 convection-cooled industrial power supplies.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (COMP) | Error amplifier output | Provides access to EA output for Type II/III loop compensation networks - critical for stability across line/load transients. |
| 2 (VFB) | Inverting input of error amplifier | Connects to output voltage divider; sets regulation point - referenced to internal 2.5 V threshold for accurate feedback. |
| 3 (ISENSE) | Current sense input | Accepts voltage proportional to primary current; triggers PWM latch at 1.0 V threshold - enables precise overcurrent protection. |
| 4 (RT/CT) | Oscillator timing node | Connects external resistor to VREF and capacitor to GND; programs frequency and controls max duty cycle via discharge current. |
| 5 (GROUND) | Signal and power ground | Single-point return for control circuitry and power stage - requires star grounding to minimize noise coupling into sensitive analog nodes. |
| 6 (OUTPUT) | Totem-pole gate driver | Sources/sinks ±1 A; drives MOSFET gate directly - rise/fall times ≤150 ns into 1 nF load ensure fast switching transitions. |
| 7 (Vi / VCC) | Supply input | Operates from 10–30 V; powers internal bias circuits and output stage - includes UVLO hysteresis to prevent chatter during brown-out. |
| 8 (VREF) | 5.0 V reference output | Supplies 50 mA max; used to bias RT/CT network and optional feedback components - regulated independently of VCC variations. |
Key Features
| Feature | Design Value |
|---|---|
| Latched PWM with cycle-by-cycle current limit | Prevents secondary failure during overload or short-circuit by disabling output until next clock cycle - enhances system robustness. |
| Internally trimmed 5.0 V reference | ±20 mV accuracy over temperature eliminates calibration in production - reduces test time and improves batch consistency. |
| Low 0.5 mA start-up current | Enables use of high-value startup resistors - cuts standby power loss and extends hold-up time in energy-efficient adapters. |
| Automatic feed-forward compensation | Compensates for input voltage variations in real time - simplifies loop design and improves transient response without extra components. |
| High-current totem-pole output | ±1 A drive capability supports fast MOSFET switching with minimal external buffering - lowers gate charge delay and conduction loss. |
Applications
| AC-DC Adapter | Flyback SMPS |
|---|---|
|
Use Scenario: 12 V / 3 A wall adapter for consumer electronics with universal AC input (85–265 VAC). IC Role / Device Role / Timing Role: Primary-side PWM controller implementing current-mode flyback regulation with fixed 250 kHz switching. Use Value: 47–50% duty cycle prevents transformer core saturation; low start-up current enables <300 mW no-load consumption. |
Use Scenario: Isolated 5 V / 2 A auxiliary supply in industrial PLC I/O modules. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller driving a 650 V N-MOSFET in discontinuous conduction mode. Use Value: Precise 5.0 V reference ensures ±1% output regulation; latch protection avoids MOSFET thermal runaway during output short. |
| Offline Battery Charger | DC-DC Forward Converter |
|
Use Scenario: 24 V lead-acid battery charger powered from 120 VAC mains with constant-current/constant-voltage profile. IC Role / Device Role / Timing Role: Primary-side controller managing transformer reset and current sensing via auxiliary winding. Use Value: UVLO hysteresis (16 V / 10 V) ensures reliable restart after AC dropout; 250 kHz frequency allows small EMI filter design. |
Use Scenario: 48 V to 12 V isolated DC-DC module for telecom shelf power distribution. IC Role / Device Role / Timing Role: Synchronous forward converter controller with external MOSFET drivers and reset winding control. Use Value: Totem-pole output drives high-side gate with minimal dead-time; 500 kHz capability enables high power density and reduced output ripple. |
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 |
|---|---|---|---|
| UC3844N | DIP-8 package; higher RθJA (100 °C/W); same electrical specs and pinout. | Better suited for prototyping or through-hole assembly; less thermally efficient in high-density PCBs. | Select when manual soldering or breadboarding is required; avoid in thermally constrained surface-mount production. |
| TL494CN | Fixed 200 kHz oscillator; dual-output push-pull; no integrated current-sense comparator or 5 V reference. | Requires external current sensing and reference; supports complementary outputs for half-bridge topologies. | Choose for push-pull or full-bridge designs where independent output control is needed - not drop-in for UC3844B-based flyback. |
Compared with UC3844N, the UC3844BD1013TR offers superior thermal performance in SO8 packaging and automated assembly compatibility; versus TL494CN, it delivers integrated current-mode control and simplified flyback implementation at the cost of topology flexibility.
Availability
UC3844BD1013TR is available at Aetrix Electronics and suitable for AC-DC adapters, flyback SMPS, offline battery chargers, and DC-DC forward converters requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.
Supply support for UC3844BD1013TR 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 family was developed specifically for cost-sensitive, high-reliability current-mode switch-mode power supplies - targeting off-line and isolated DC-DC applications where minimal external components and robust fault handling are essential.
FAQ
What is the maximum operating frequency of UC3844BD1013TR?
The UC3844BD1013TR supports oscillator frequencies up to 500 kHz using external RT/CT components. Its trimmed internal oscillator is guaranteed at 250 kHz at 25°C, and frequency stability over temperature is ±0.5% - verified per STMicroelectronics' Electrical Characteristics table on page 2 of the datasheet.
Does UC3844BD1013TR require an external current-sense resistor?
Yes - the ISENSE pin (Pin 3) accepts a voltage signal derived from a series current-sense resistor placed in the MOSFET source path. The IC trips the PWM latch when this voltage reaches 1.0 V, corresponding to a peak primary current determined by RSENSE = 1.0 V / IPEAK.
Can UC3844BD1013TR be used in boost converter topologies?
No - UC3844BD1013TR is optimized for single-ended topologies (flyback, forward) with duty cycle limited to <50% by its internal toggle flip-flop. Boost converters typically require >50% duty cycle for step-up operation, making UC3842B/UC3843B more appropriate alternatives.
What is the purpose of the COMP pin (Pin 1) in loop compensation?
The COMP pin exposes the error amplifier output for external Type II or Type III compensation networks. Connecting RC/CR networks between COMP and VFB sets pole-zero locations to stabilize the current-mode control loop - especially critical for maintaining phase margin in flyback converters with variable duty cycle.
UC3844BD1013TR 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):
- 48%
- 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
UC3844BD1013TR FAQ
1.How can I place an order for UC3844BD1013TR through Aetrix?
Please submit a Request for Quotation (RFQ) for UC3844BD1013TR 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 UC3844BD1013TR reliable?
The price and inventory of UC3844BD1013TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC3844BD1013TR is usually 5 days.
3.What payment methods are accepted for UC3844BD1013TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC3844BD1013TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UC3844BD1013TR?
UC3844BD1013TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UC3844BD1013TR 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 UC3844BD1013TR?
For technical support, including UC3844BD1013TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC3844BD1013TR requirements.
6.How does Aetrix verify that UC3844BD1013TR is sourced from the original manufacturer or authorized distributors?
All UC3844BD1013TR 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 UC3844BD1013TR meets industry standards.
7.What is the process for return or replacement of UC3844BD1013TR?
All UC3844BD1013TR units undergo pre-shipment inspection (PSI). If there is an issue with UC3844BD1013TR, 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 UC3844BD1013TR part is unused and in its original packaging.
Return procedure for UC3844BD1013TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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