My Inquiry
My Account
Texas Instruments UC2844AN
- Part No.:
- UC2844AN
- Manufacturer:
- Texas Instruments
- Category:
- DC DC Switching Controllers
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
UC2844AN.pdf
- Description:
- IC CUR-MODE PWM CONT 8-DIP
- Quantity:
- Payment:
- Shipping:
Inventory:801
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
UC2844AN from STMicroelectronics is a high-performance current-mode PWM controller IC designed for fixed-frequency off-line and DC-DC power supplies. It features internal toggle flip-flop limiting maximum duty cycle to <50%, 5V ±1% trimmed reference, 8.3mA oscillator discharge current, under-voltage lockout (16V ON / 10V OFF), and ±1A totem-pole output capable of directly driving N-channel MOSFET gates - used in flyback and forward converters requiring precise cycle-by-cycle current limiting.
For engineers reviewing the UC2844AN datasheet, UC2844AN pinout, UC2844AN application, or UC2844AN equivalent, this device is selected for cost-sensitive AC-DC adapters, industrial auxiliary supplies, and isolated DC-DC modules where duty-cycle clamping, low start-up current (<0.5mA), and integrated UVLO hysteresis are critical design requirements.
Technical Context
The UC2844AN implements current-mode control using an error amplifier, PWM latch, and current-sense comparator with 3V/V gain and 150ns propagation delay. Its oscillator uses RT/CT programming with 47–57kHz nominal frequency and trimmed 8.3mA discharge current for stable timing across temperature.
Internal UVLO (16V turn-on, 10V turn-off) ensures reliable startup and brownout recovery; the toggle flip-flop architecture enforces ≤50% max duty cycle by blanking every other clock cycle - distinguishing it from UC2842AN/UC2843AN variants.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 47–57 kHz at 25°C - sets switching frequency for flyback/forward topologies with RT/CT tuning |
| Max Duty Cycle | <50% - enforced by internal toggle flip-flop, prevents transformer saturation in single-ended topologies |
| VREF Output | 5.00 V ±1% - provides stable 1mA reference for CT charging and feedback scaling |
| UVLO Threshold | 16 V (ON), 10 V (OFF) - enables robust startup from bulk rectified AC and graceful shutdown during line sag |
| Output Drive | ±1 A peak - directly switches medium-power N-MOSFETs without external buffer stages |
| Start-up Current | <0.5 mA - reduces auxiliary winding losses and enables high-impedance bias networks |
| Current Sense Gain | 3.0 V/V - converts sense resistor voltage to precise 1V trip point for accurate peak-current limiting |
Pinout & Package
DIP-8 package with through-hole mounting; 0.3" wide body, 0.1" lead pitch, and 0.2" row spacing - compatible with legacy PCB layouts and manual soldering processes.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (COMP) | Error amplifier output | Provides open-collector node for loop compensation network (type II/III) connecting to VFB |
| 2 (VFB) | Error amp inverting input | Receives scaled output voltage via resistive divider; sets regulation setpoint at 2.5V |
| 3 (ISENSE) | Current sense input | Accepts voltage from primary-side sense resistor; triggers PWM latch at 1V threshold |
| 4 (RT/CT) | Oscillator timing interface | Connects RT to VREF and CT to GND to program frequency and discharge slope |
| 5 (GROUND) | Signal & power return | Single-point ground for control logic, error amp, and current sense - critical for noise immunity |
| 6 (OUTPUT) | Gate drive output | Totem-pole stage sourcing/sinking up to 1A; low-state impedance <0.4V @ 200mA |
| 7 (VCC) | Supply input | Operates from 10–30V; self-limiting current above 30mA prevents damage during overvoltage |
| 8 (VREF) | 5V reference output | Supplies 1mA typical for RT/CT network; short-circuit protected to 180mA |
Key Features
| Feature | Design Value |
|---|---|
| Latching PWM with cycle-by-cycle current limit | Prevents MOSFET failure during overload or short-circuit by disabling gate drive within one switching cycle |
| Internally trimmed 5V reference | ±1% accuracy over temperature eliminates need for external trimming in most applications |
| Low start-up current (<0.5mA) | Enables use of high-value startup resistors, reducing standby power in offline adapters |
| Automatic feed-forward compensation | Compensates for input voltage variations without external circuitry, improving transient response |
| Under-voltage lockout with hysteresis | 16V/10V thresholds prevent erratic operation during brownouts and ensure clean power-up sequencing |
Applications
| AC-DC Adapter | Industrial Auxiliary Supply |
|---|---|
|
Use Scenario: 12W isolated flyback converter powering microcontroller and sensors in factory automation equipment. IC Role / Device Role / Timing Role: Primary-side PWM controller regulating output via optocoupler feedback; generates 50kHz gate drive synchronized to current-sense zero-crossing. Use Value: ≤50% duty cycle prevents transformer core reset issues in universal-input (85–265VAC) designs with minimal BOM count. |
Use Scenario: 5V/1A auxiliary supply derived from 48V DC bus in motor drive control cabinet. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller implementing forward topology with discrete synchronous rectification. Use Value: 8.3mA trimmed oscillator discharge current ensures ±3% frequency stability across -40°C to 125°C junction range. |
| LED Driver (Constant Voltage) | Telecom Power Module |
|
Use Scenario: Constant-voltage LED string driver for signage, powered from 24V DC input. IC Role / Device Role / Timing Role: Secondary-side regulated flyback controller with TL431 shunt reference and opto-isolated feedback path. Use Value: COMP pin allows direct integration of type-II compensation, achieving >60° phase margin without additional op-amps. |
Use Scenario: 3.3V/5A intermediate bus converter in telecom shelf management system. IC Role / Device Role / Timing Role: Primary-side controller managing synchronous forward converter with active clamp reset. Use Value: ±1A output drive eliminates need for external MOSFET driver, reducing layout area and EMI sources. |
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 | Same pinout and electrical specs, but rated for 0°C to 70°C ambient (vs. UC2844AN's –40°C to 85°C) | Not suitable for extended-temperature industrial or automotive environments | Select UC2844AN when operating below 0°C or above 70°C is required |
| TL494CN | Fixed-frequency voltage-mode controller; dual-output, adjustable dead time, no built-in current sense comparator | Requires external current sensing and slope compensation for stable current-mode operation | Choose UC2844AN when integrated current-mode control and minimal external components are prioritized |
Compared with UC3844N, UC2844AN offers wider temperature range and identical functionality; versus TL494CN, it delivers true single-chip current-mode control without external signal conditioning - reducing design risk and component count in compact AC-DC systems.
Availability
UC2844AN is available at Aetrix Electronics and suitable for AC-DC adapters, industrial auxiliary supplies, and telecom power modules requiring stable component supply, long-term lifecycle support, and DIP-8 through-hole compatibility.
Supply support for UC2844AN 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, MCU, and automotive ICs with vertical manufacturing capabilities.
The UC284x/UC384x family was developed for cost-effective, high-reliability current-mode switching power supplies - targeting off-line SMPS, battery chargers, and industrial DC-DC converters where precision timing and robust fault protection are essential.
FAQ
What is the maximum recommended operating frequency for UC2844AN?
The UC2844AN supports oscillator frequencies up to 500kHz per datasheet specification, though typical operation is 47–57kHz using standard RT/CT values. At higher frequencies, propagation delays and gate drive rise/fall times (50–150ns) become limiting factors; thermal dissipation must also be verified given 1.25W DIP-8 power rating.
Can UC2844AN be used in boost converter topologies?
Yes, UC2844AN can control boost converters, but requires external slope compensation on the ISENSE pin to prevent subharmonic oscillation when duty cycle exceeds 50%. The internal 50% limit does not apply to boost operation since current sensing occurs on the switch node, not the inductor.
How does the UC2844AN's UVLO hysteresis improve system reliability?
The 6V hysteresis (16V ON, 10V OFF) prevents chattering during brownout conditions by ensuring the controller remains fully disabled until input voltage recovers sufficiently to guarantee stable internal bias and reference operation - eliminating repeated restart attempts that stress MOSFETs and magnetics.
Is the VREF pin internally decoupled, or does it require an external capacitor?
The VREF pin requires an external 0.1µF ceramic capacitor placed close to pin 8 and pin 5 (GROUND) to suppress high-frequency noise and stabilize the oscillator timing network. This capacitor is mandatory per Figure 4 in the datasheet and prevents frequency jitter caused by coupling from the OUTPUT or ISENSE nodes.
UC2844AN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- UCx84xA
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- -
- Function:
- -
- Output Configuration:
- -
- Topology:
- -
- Number of Outputs:
- -
- Output Phases:
- -
- Voltage - Supply (Vcc/Vdd):
- -
- Frequency - Switching:
- -
- Duty Cycle (Max):
- -
- Synchronous Rectifier:
- -
- Clock Sync:
- -
- Serial Interfaces:
- -
- Control Features:
- -
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
UC2844AN FAQ
1.How can I place an order for UC2844AN through Aetrix?
Please submit a Request for Quotation (RFQ) for UC2844AN 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 UC2844AN reliable?
The price and inventory of UC2844AN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC2844AN is usually 5 days.
3.What payment methods are accepted for UC2844AN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC2844AN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UC2844AN?
UC2844AN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UC2844AN 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 UC2844AN?
For technical support, including UC2844AN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC2844AN requirements.
6.How does Aetrix verify that UC2844AN is sourced from the original manufacturer or authorized distributors?
All UC2844AN 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 UC2844AN meets industry standards.
7.What is the process for return or replacement of UC2844AN?
All UC2844AN units undergo pre-shipment inspection (PSI). If there is an issue with UC2844AN, 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 UC2844AN part is unused and in its original packaging.
Return procedure for UC2844AN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
UC2844AN 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
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
LDO regulator guide covering low dropout voltage, power dissipation, thermal design, PSRR, output noise, capacitor stability, adjustable LDO circuits, LDO vs buck converter and datasheet selection chec…
Conditional Access Module guide covering CAM meaning, CI/CI+ interface, smart card authorization, DVB security workflow, TV and set-top box compatibility, internal electronics, ESD protection, connecto…
Guide to electronic component obsolescence covering EOL risk, PCN/PDN notices, last-time buy planning, replacement options, form-fit-function validation, counterfeit risk and BOM lifecycle management.
18650 battery guide covering lithium-ion cell basics, 3.6V/3.7V voltage, 4.2V charging, mAh and Wh capacity, protected cells, chargers, BMS, series-parallel packs, holders, welding and sourcing checks.…
Hall effect sensor guide covering working principle, linear and digital sensors, Arduino circuits, current sensing, speed detection, automotive applications, A3144 examples, signal filtering and datash…
Product Change Notification guide for electronic components, covering PCN meaning, PCN vs PDN/EOL, common change types, risk levels, form-fit-function review, engineering validation, BOM control, LTB/L…
A practical guide to blend door actuators, covering HVAC function, symptoms, location, AC and heater issues, reset and calibration, replacement cost, electrical diagnosis, compatibility checks, and rep…
Engineering guide to Raspberry Pi alternatives, covering chip-level differences, Orange Pi, ROCK, Jetson, Banana Pi, NanoPi, Compute Module, Pico, GPIO, camera, HAT compatibility, and replacement risks…
Engineering guide to dynamic load response testing for high-current buck converters, covering load step setup, slew rate, Vcore undershoot, overshoot, recovery time, probe location, output capacitors a…
