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Texas Instruments UC2843AD8TRG4
- Part No.:
- UC2843AD8TRG4
- Manufacturer:
- Texas Instruments
- Category:
- Power Supply Controllers, Monitors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
UC2843AD8TRG4.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,933
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Product details
Overview
UC2843AD8TRG4 from Texas Instruments is a current-mode PWM controller IC designed for off-line and DC-DC switch-mode power supplies, featuring 8.4 V UVLO turn-on threshold, ≤0.5 mA start-up current, 500 kHz max switching frequency, 1 A totem-pole output drive, and internal 5 V ±1% bandgap reference. It serves as the core timing and current-sense control unit in flyback, forward, and boost converters.
For engineers reviewing the UC2843AD8TRG4 datasheet, UC2843AD8TRG4 pinout, UC2843AD8TRG4 application, or UC2843AD8TRG4 equivalent, key selection criteria include its 8-pin SOIC (D) package, pulse-by-pulse current limiting, automatic feedforward compensation, undervoltage lockout with hysteresis, and compatibility with TI's WEBENCH® Power Designer for custom SMPS design.
Technical Context
The UC2843AD8TRG4 implements peak-current-mode control using an internal oscillator with trimmed 8.3 mA discharge current, enabling precise duty-cycle programming up to 100%. Its error amplifier delivers 80 dB open-loop gain and 1 MHz unity-gain bandwidth, directly interfacing with opto-isolated feedback networks in isolated topologies.
During undervoltage lockout (UVLO), the device sinks ≥10 mA at <1.2 V on OUTPUT while drawing only 0.3–0.5 mA from VCC - a critical feature for high-voltage start-up in offline AC/DC supplies. The ISENSE input clamps at 1 V and supports cycle-by-cycle current limiting with 150–300 ns propagation delay.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| UVLO Turn-On Threshold | 8.4 V - enables reliable start-up from auxiliary winding in DC-DC or low-input AC/DC converters |
| Start-Up Current | <0.5 mA - reduces power loss in high-voltage start-up resistors, critical for energy-efficient offline designs |
| Oscillator Discharge Current | 8.3 mA (trimmed) - ensures accurate maximum duty cycle and stable 500 kHz operation across temperature |
| Output Drive Capability | ±1 A - directly drives power MOSFET gates without external buffer, supporting fast switching in compact layouts |
| Reference Voltage | 5.0 V ±1% - provides stable, short-circuit protected bias for feedback circuitry and internal comparators |
| Error Amplifier Gain | 80 dB open-loop gain - enables robust loop compensation for stable voltage regulation under dynamic load steps |
| ISENSE Input Clamp | 1 V max - defines precise current limit threshold for magnetic component sizing and overcurrent protection |
Pinout & Package
UC2843AD8TRG4 is housed in an 8-pin SOIC (D) package measuring 4.90 mm × 6.00 mm, optimized for surface-mount assembly and thermal performance in power supply PCBs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - COMP | Error amplifier output | Low-impedance node (80 dB gain, 1 MHz GBW) connecting to PWM comparator; sinks up to 6 mA for loop stability tuning |
| 2 - FB | Voltage feedback input | High-impedance node for opto-isolator emitter or resistor divider; sets output regulation point via 2.5 V internal reference |
| 3 - ISENSE | Current sense input | Direct connection to shunt resistor; clamped at 1 V to define cycle-by-cycle peak current limit and enable slope compensation |
| 4 - RT/CT | Oscillator timing input | Accepts external R (5–100 kΩ) and C (470 pF–4.7 nF) to set 500 kHz fOSC; trimmed discharge current ensures duty-cycle accuracy |
| 5 - GND | Signal ground reference | Common return for error amp, comparators, and logic; must be star-connected to minimize noise coupling into sensitive analog nodes |
| 6 - OUTPUT | Gate driver output | Totem-pole stage sourcing/sinking ±1 A; drives N-channel MOSFET gates directly; low saturation voltage (<0.4 V @ 20 mA) |
| 7 - VCC | Bias supply input | Operates from 11–30 V; powers internal circuitry and gate driver; includes UVLO hysteresis (8.4 V ON / 7.6 V OFF) |
| 8 - VREF | 5 V reference output | Stable 5 V ±1% source for RT/CT timing, feedback dividers, and opto-isolator bias; short-circuit protected (~100 mA) |
Key Features
| Feature | Design Value |
|---|---|
| Pulse-by-pulse current limiting | Enables precise, cycle-resolved overcurrent protection using ISENSE clamp at 1 V - eliminates need for external latch circuits |
| Automatic feedforward compensation | Internally adjusts PWM duty cycle in response to input voltage variations - improves line transient response without external components |
| Enhanced load response characteristics | Combines 1 MHz error amplifier bandwidth and low-output-impedance COMP stage to maintain regulation during rapid load steps |
| Double pulse suppression | Prevents false triggering of output stage during startup or fault recovery - ensures single clean pulse per clock cycle |
| High-current totem pole output | ±1 A drive capability allows direct interface with medium-power MOSFETs (e.g., <500 W flyback), reducing BOM count and layout complexity |
Applications
| Industrial DC-DC Converter | AC/DC Adapter for Consumer Electronics |
|---|---|
|
Use Scenario: Regulated 12 V/5 A output from 24 V industrial bus with wide temperature range (–40°C to +85°C). IC Role / Device Role / Timing Role: Primary-side current-mode controller managing flyback transformer duty cycle and peak current sensing via shunt resistor. Use Value: 8.4 V UVLO ensures reliable start-up from 24 V rail; 0.5 mA start-up current minimizes standby losses; 100% max duty cycle supports high step-down ratios. |
Use Scenario: Universal-input (85–265 VAC) 12 V/48 W adapter for set-top boxes and routers. IC Role / Device Role / Timing Role: Core PWM controller implementing opto-isolated feedback loop with TL431 secondary-side reference. Use Value: Trimmed oscillator discharge (8.3 mA) guarantees stable 500 kHz operation across line/load; VREF pin powers opto-isolator LED directly. |
| Battery-Powered PSU for Portable Equipment | Industrial Power Module for PLC I/O |
|
Use Scenario: 5 V/3 A regulated output from 7.2–16.8 V Li-ion battery pack in handheld test equipment. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller regulating synchronous buck topology with external MOSFETs. Use Value: Low 0.5 mA start-up current extends battery runtime; 1 A gate drive supports efficient 500 kHz switching; SOIC-8 footprint enables compact layout. |
Use Scenario: DIN-rail mounted 24 V/10 A power module supplying I/O cards in programmable logic controllers. IC Role / Device Role / Timing Role: Primary-side controller in forward converter with active clamp, managing duty cycle and current limiting via primary current transformer. Use Value: Pulse-by-pulse limiting protects against short-circuits on distributed I/O lines; enhanced load response maintains 24 V regulation during 10 A step loads. |
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 |
|---|---|---|---|
| UC3843BD1R2G | Wider operating temperature range (0°C to 70°C vs –40°C to 85°C); higher UVLO (16 V ON / 10 V OFF); same pinout and function | Suitable for commercial-grade AC/DC adapters but not industrial environments requiring extended temperature operation | Select UC3843BD1R2G only when ambient temperature stays within 0–70°C and higher UVLO threshold matches system start-up requirements |
| NCP1200DR2G | Fixed-frequency current-mode controller with integrated HV start-up; lower start-up current (25 µA); no VREF output pin | Reduces external component count in offline flyback designs but lacks 5 V reference for opto-isolator biasing | Choose NCP1200DR2G when minimizing BOM and HV start-up integration are priorities, and external 5 V bias is available |
Compared with UC3843BD1R2G and NCP1200DR2G, UC2843AD8TRG4 offers superior industrial temperature support, built-in 5 V reference for simplified feedback, and tighter oscillator discharge trimming - making it optimal for ruggedized, cost-sensitive, and layout-constrained SMPS designs.
Availability
UC2843AD8TRG4 is available at Aetrix Electronics and suitable for industrial DC-DC converters, universal-input AC/DC adapters, and battery-powered power supplies requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for UC2843AD8TRG4 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
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in power conversion ICs.
The UCx84xA family - including UC2843AD8TRG4 - was engineered specifically for cost-effective, high-reliability current-mode switch-mode power supplies targeting industrial, consumer, and computing power applications.
FAQ
What is the UVLO behavior of UC2843AD8TRG4 during power-up?
UC2843AD8TRG4 enters undervoltage lockout below 7.6 V and turns on at 8.4 V with 0.8 V hysteresis. During UVLO, the OUTPUT pin remains low and sinks ≥10 mA at <1.2 V, preventing parasitic MOSFET turn-on. Once VCC exceeds 8.4 V, the 5 V reference stabilizes and PWM operation begins. This behavior is fully specified in the UC2843AD8TRG4 datasheet Section 6.3.4.
Can UC2843AD8TRG4 drive a MOSFET directly without a gate driver IC?
Yes, UC2843AD8TRG4 features a ±1 A totem-pole output stage capable of directly driving medium-power N-channel MOSFETs used in flyback, forward, and boost converters up to ~500 W. Gate resistor selection (typically 10–100 Ω) is required to control slew rate and prevent ringing. The UC2843AD8TRG4 OUTPUT pin specification confirms 0.4 V low-level saturation at 20 mA and 13.5 V high-level output at 20 mA.
How does UC2843AD8TRG4 implement pulse-by-pulse current limiting?
UC2843AD8TRG4 compares the ISENSE voltage - derived from a shunt resistor in series with the power switch - against an internal 1 V clamp. When ISENSE reaches 1 V, the PWM latch resets immediately, terminating that switching cycle. This cycle-resolved action prevents current runaway and enables precise magnetic component sizing. The UC2843AD8TRG4 datasheet Section 6.3.1 and Table 5-5 confirm this 1 V threshold and 150–300 ns response time.
What is the purpose of the VREF pin on UC2843AD8TRG4?
The VREF pin on UC2843AD8TRG4 delivers a precision 5.0 V ±1% output, used to bias the RT/CT timing network, power opto-isolator LEDs in isolated feedback loops, and serve as a reference for external voltage dividers. It is short-circuit protected (~100 mA) and rated for ≤10 mA continuous load. The UC2843AD8TRG4 Electrical Characteristics table (Section 5.5) specifies 4.95–5.05 V output under 1 mA load at 25°C.
Is UC2843AD8TRG4 compatible with TI's WEBENCH® Power Designer?
Yes, UC2843AD8TRG4 is fully supported in TI's WEBENCH® Power Designer tool. Users can enter input/output specifications (e.g., 85–265 VAC to 12 V/5 A), select UC2843AD8TRG4 as the controller, and generate complete schematics, bill-of-materials, thermal simulations, and layout-ready designs. This integration is explicitly referenced in the UC2843AD8TRG4 datasheet Feature list and Section 7.2.2.1.
UC2843AD8TRG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Programmable:
- -
- Applications:
- PWM Controller
- Voltage - Input:
- -0.3V ~ 6.3V
- Voltage - Supply:
- 7.6V ~ 30V
- Current - Supply:
- 11 mA
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
UC2843AD8TRG4 FAQ
1.How can I place an order for UC2843AD8TRG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for UC2843AD8TRG4 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 UC2843AD8TRG4 reliable?
The price and inventory of UC2843AD8TRG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC2843AD8TRG4 is usually 5 days.
3.What payment methods are accepted for UC2843AD8TRG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC2843AD8TRG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UC2843AD8TRG4?
UC2843AD8TRG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UC2843AD8TRG4 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 UC2843AD8TRG4?
For technical support, including UC2843AD8TRG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC2843AD8TRG4 requirements.
6.How does Aetrix verify that UC2843AD8TRG4 is sourced from the original manufacturer or authorized distributors?
All UC2843AD8TRG4 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 UC2843AD8TRG4 meets industry standards.
7.What is the process for return or replacement of UC2843AD8TRG4?
All UC2843AD8TRG4 units undergo pre-shipment inspection (PSI). If there is an issue with UC2843AD8TRG4, 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 UC2843AD8TRG4 part is unused and in its original packaging.
Return procedure for UC2843AD8TRG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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