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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Power Supply Controllers, Monitors

Texas Instruments UC2843D8TRG4

Name: UC2843D8TRG4
Brand: Texas Instruments
SKU: UC2843D8TRG4
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: UC2843D8TRG4

Manufacturer:: Texas Instruments

Category:: Power Supply Controllers, Monitors

Package:: 8-SOIC (0.154", 3.90mm Width)

Datasheet:: UC2843D8TRG4.pdf

Description:: IC REG CTRLR MULT TOPOLOGY 8SOIC

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Product details

Overview

UC2843D8TRG4 from Texas Instruments is a current-mode PWM controller IC designed for fixed-frequency DC-DC converters with regulated input. It features 8.4 V turn-on/7.6 V turn-off UVLO hysteresis, ≤1 mA start-up current, up to 500 kHz oscillator frequency, and 100% maximum duty cycle-enabling compact, high-efficiency buck or flyback topologies in industrial power supplies.

For engineers reviewing the UC2843D8TRG4 datasheet, UC2843D8TRG4 pinout, UC2843D8TRG4 application, or UC2843D8TRG4 equivalent, key selection criteria include its DC-DC–optimized UVLO thresholds, internal 5-V reference accuracy (±1%), totem-pole output capable of ±1 A peak drive, and SOIC-8 package compatibility with space-constrained board layouts.

Technical Context

The UC2843D8TRG4 implements a current-mode control architecture with a dedicated ISENSE input feeding a PWM comparator that terminates gate drive based on primary-side current sensing. Its error amplifier (2.5 V input threshold, 90 dB PSRR) interfaces with optocoupler feedback via VFB, while COMP provides Type II/III compensation node access.

Oscillation is set by external RT/CT components using the formula f_OSC = 1.72/(R_RT × C_CT), supporting 100–500 kHz operation. The device integrates undervoltage lockout with hysteresis, pulse-by-pulse current limiting, and double-pulse suppression logic to ensure stable latched operation under transient conditions.

Key Specifications

Parameter	Value and Actual Design Meaning
UVLO Turn-on / Turn-off	8.4 V / 7.6 V - optimized for regulated DC input, avoids false triggering during brownout recovery
Max Duty Cycle	100% - supports continuous conduction mode (CCM) in buck, forward, and flyback converters
Oscillator Frequency	100–500 kHz - enables small magnetics and EMI filtering; set precisely via RT/CT network
VREF Output	5.0 V ±1% - powers timing circuitry and provides stable bias for external components
Output Drive	±1 A peak - directly drives N-channel MOSFET gates without external buffer stages
Start-up Current	<1 mA - minimizes auxiliary supply losses in high-voltage DC-DC startup circuits
Error Amp Input Threshold	2.5 V ±0.05 V - defines regulation point for voltage feedback loop; matched to optocoupler CTR

Pinout & Package

UC2843D8TRG4 is housed in an 8-pin SOIC (D) package measuring 4.90 mm × 6.00 mm, with gull-wing leads and standard JEDEC MS-012AC footprint.

Pin/Terminal	Circuit Role	Design Meaning
1 - COMP	Error amplifier output	Compensation node for Type II/III feedback networks; internally current-limited to force zero duty cycle when pulled to GROUND
2 - VFB	Inverting error amp input	Connects to optocoupler emitter or resistor divider; sets regulation setpoint at 2.5 V
3 - ISENSE	Current sense input	Terminates OUTPUT pulse when sensed voltage reaches 1 V; supports slope compensation via injected ramp
4 - RT/CT	Oscillator timing	Accepts R_RT from VREF and C_CT to GROUND; determines switching frequency per f_OSC = 1.72/(R_RT×C_CT)
5 - GROUND	Analog & power return	Single ground pin serving both signal and power paths; requires careful PCB layout separation from high di/dt loops
6 - OUTPUT	MOSFET gate driver	Totem-pole stage sinks/sources up to 1 A; actively held low during UVLO; compatible with N-channel MOSFETs
7 - VCC	Supply input	Bias rail (12–28 V); includes 34 V internal clamp; requires 0.1 µF ceramic bypass close to pin
8 - VREF	5-V reference output	Stable 5 V source for RT/CT charging and external circuitry; requires ≥0.1 µF ceramic bypass to GROUND

Key Features

Feature	Design Value
DC-DC–optimized UVLO	8.4 V turn-on / 7.6 V turn-off hysteresis prevents chatter during low-input transients in regulated bus applications
Pulse-by-pulse current limiting	Hardware-based overcurrent protection resets each cycle-enables robust short-circuit response without latch-up
Internally trimmed 5-V reference	±1% accuracy at 25°C ensures precise oscillator timing and stable feedback bias across temperature
High-current totem-pole output	±1 A peak drive capability eliminates need for external gate drivers in ≤100 W DC-DC designs
Automatic feedforward compensation	Input voltage feedforward path improves line transient response without additional external components
Enhanced load-response characteristics	Fast error amplifier (1 MHz GBW) and low-output-impedance COMP enable tight regulation under dynamic load steps

Applications

Industrial DC-DC Power Supply	Telecom Intermediate Bus Converter
Use Scenario: 24 V or 48 V intermediate bus stepped down to 3.3 V/5 V/12 V for FPGA, ASIC, or DSP loads in base station equipment. IC Role / Device Role / Timing Role: Primary-side current-mode PWM controller generating gate drive signals synchronized to internal 200–300 kHz oscillator. Use Value: 8.4 V/7.6 V UVLO matches telecom bus hold-up requirements; ±1 A OUTPUT drives 500 V MOSFETs directly, reducing BOM count.	Use Scenario: Isolated 48 V-to-12 V converter powering fan controllers, sensors, and interface ICs in optical line terminals. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller implementing optocoupler-coupled voltage feedback loop with COMP compensation. Use Value: 2.5 V VFB threshold aligns with common PC817 CTR range; 500 kHz max frequency enables compact transformer design.
Programmable Logic Controller (PLC) Power Module	Factory Automation Sensor Hub Supply
Use Scenario: 24 V input converted to isolated 5 V and ±15 V rails for analog I/O modules requiring high noise immunity. IC Role / Device Role / Timing Role: Core controller in forward or flyback topology managing duty cycle via ISENSE feedback and VFB regulation. Use Value: ≤1 mA start-up current reduces auxiliary supply burden; 100% duty cycle supports high step-down ratios in discontinuous mode.	Use Scenario: Compact 12 V-to-3.3 V non-isolated buck converter powering microcontrollers and digital sensors on modular I/O cards. IC Role / Device Role / Timing Role: Voltage-mode-capable controller (via ISENSE ramp injection) delivering fast transient response to burst-mode sensor loads. Use Value: RT/CT programmability allows tuning to 350 kHz for optimal efficiency/noise trade-off; SOIC-8 footprint fits dense PCB layouts.

Industrial DC-DC Power Supply

Telecom Intermediate Bus Converter

Use Scenario: 24 V or 48 V intermediate bus stepped down to 3.3 V/5 V/12 V for FPGA, ASIC, or DSP loads in base station equipment.

IC Role / Device Role / Timing Role: Primary-side current-mode PWM controller generating gate drive signals synchronized to internal 200–300 kHz oscillator.

Use Value: 8.4 V/7.6 V UVLO matches telecom bus hold-up requirements; ±1 A OUTPUT drives 500 V MOSFETs directly, reducing BOM count.

Use Scenario: Isolated 48 V-to-12 V converter powering fan controllers, sensors, and interface ICs in optical line terminals.

IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller implementing optocoupler-coupled voltage feedback loop with COMP compensation.

Use Value: 2.5 V VFB threshold aligns with common PC817 CTR range; 500 kHz max frequency enables compact transformer design.

Programmable Logic Controller (PLC) Power Module

Factory Automation Sensor Hub Supply

Use Scenario: 24 V input converted to isolated 5 V and ±15 V rails for analog I/O modules requiring high noise immunity.

IC Role / Device Role / Timing Role: Core controller in forward or flyback topology managing duty cycle via ISENSE feedback and VFB regulation.

Use Value: ≤1 mA start-up current reduces auxiliary supply burden; 100% duty cycle supports high step-down ratios in discontinuous mode.

Use Scenario: Compact 12 V-to-3.3 V non-isolated buck converter powering microcontrollers and digital sensors on modular I/O cards.

IC Role / Device Role / Timing Role: Voltage-mode-capable controller (via ISENSE ramp injection) delivering fast transient response to burst-mode sensor loads.

Use Value: RT/CT programmability allows tuning to 350 kHz for optimal efficiency/noise trade-off; SOIC-8 footprint fits dense PCB layouts.

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
UC2843D8G4	Same electrical specs and SOIC-8 package; differs only in tape-and-reel packaging (TRG4 vs G4) and RoHS compliance status	No functional difference; suitable for identical DC-DC designs where reel quantity or Pb-free requirement varies	Select UC2843D8TRG4 for automated SMT assembly; UC2843D8G4 for manual prototyping or legacy inventory use
NCP1200DR2G	Voltage-mode controller with 160 kHz fixed frequency, no ISENSE pin, lower start-up current (100 µA), but lacks 100% duty cycle and VREF output	Better suited for low-power AC-DC adapters; not drop-in for current-mode DC-DC requiring slope compensation or VREF sourcing	Choose only if design prioritizes ultra-low start-up loss over current sensing fidelity and full-duty-cycle flexibility

Compared with UC2843D8G4, UC2843D8TRG4 offers identical performance with optimized packaging for high-volume production; versus NCP1200DR2G, it delivers superior current-mode control precision, wider frequency range, and integrated reference-critical for regulated bus DC-DC stability.

Availability

UC2843D8TRG4 is available at Aetrix Electronics and suitable for industrial DC-DC power supplies, telecom intermediate bus converters, and factory automation sensor hub designs requiring stable component supply and long-term manufacturability.

Supply support for UC2843D8TRG4 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 UC284x series was engineered specifically for cost-sensitive, high-reliability DC-DC and off-line power supplies-delivering integrated current-mode control with minimal external components and robust protection features.

FAQ

What is the UVLO threshold behavior of the UC2843D8TRG4?

The UC2843D8TRG4 features an undervoltage lockout with 8.4 V turn-on and 7.6 V turn-off thresholds, providing 0.8 V hysteresis. This narrow hysteresis is specifically designed for regulated DC input applications like telecom or industrial buses, ensuring reliable startup and shutdown without oscillation during brownout events. The UC2843D8TRG4 remains disabled below 7.6 V and activates only upon crossing 8.4 V.

Can the UC2843D8TRG4 be used in voltage-mode control configurations?

Yes, the UC2843D8TRG4 supports voltage-mode operation by injecting a sawtooth ramp onto the ISENSE pin, overriding its default current-sense function. This allows implementation of classical voltage-mode PWM control while retaining the UC2843D8TRG4's oscillator, error amplifier, and output driver. External ramp amplitude must match the internal current-sense threshold (1 V) for accurate duty-cycle control.

What is the maximum switching frequency supported by the UC2843D8TRG4?

The UC2843D8TRG4 supports oscillator frequencies from 100 kHz to 500 kHz, determined by the external RT/CT network per f_OSC = 1.72/(R_RT × C_CT). At 500 kHz, the UC2843D8TRG4 maintains full 100% duty cycle capability and stable operation-enabling high-density power designs with reduced magnetic size and improved transient response.

How does the UC2843D8TRG4 handle overcurrent conditions?

The UC2843D8TRG4 implements hardware-based pulse-by-pulse current limiting: when the ISENSE voltage exceeds 1 V, the PWM comparator immediately terminates the OUTPUT pulse for that cycle. This cycle-by-cycle protection resets automatically every clock period, allowing continued operation under overload without latching-ideal for handling temporary surges in DC-DC converters powered by stable bus voltages.

Is the UC2843D8TRG4 pin-compatible with other UCx84x variants?

The UC2843D8TRG4 shares identical SOIC-8 pinout and core functionality with UC2842D8TRG4, UC2844D8TRG4, and UC2845D8TRG4-but differs in UVLO thresholds and max duty cycle. While physical pin compatibility exists, substituting UC2843D8TRG4 for UC2842D8TRG4 in off-line AC-DC designs risks premature shutdown due to lower 8.4 V turn-on threshold. Always verify UVLO and duty-cycle requirements before interchange.

UC2843D8TRG4 Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: UCx84x

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:: 12V ~ 28V

Current - Supply:: 11 mA

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-SOIC

UC2843D8TRG4 FAQ

1.How can I place an order for UC2843D8TRG4 through Aetrix?

Please submit a Request for Quotation (RFQ) for UC2843D8TRG4 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 UC2843D8TRG4 reliable?

The price and inventory of UC2843D8TRG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC2843D8TRG4 is usually 5 days.

3.What payment methods are accepted for UC2843D8TRG4?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC2843D8TRG4 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for UC2843D8TRG4?

UC2843D8TRG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your UC2843D8TRG4 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 UC2843D8TRG4?

For technical support, including UC2843D8TRG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC2843D8TRG4 requirements.

6.How does Aetrix verify that UC2843D8TRG4 is sourced from the original manufacturer or authorized distributors?

All UC2843D8TRG4 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 UC2843D8TRG4 meets industry standards.

7.What is the process for return or replacement of UC2843D8TRG4?

All UC2843D8TRG4 units undergo pre-shipment inspection (PSI). If there is an issue with UC2843D8TRG4, 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 UC2843D8TRG4 part is unused and in its original packaging.

Return procedure for UC2843D8TRG4:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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