Texas Instruments UC2844AQDR

Overview

UC2844AQDR from Texas Instruments is a current-mode PWM controller IC designed for off-line and DC-DC power converters, featuring 16 V UVLO turn-on threshold, <50% maximum duty cycle, ±1 A totem-pole output drive, 8.3 mA trimmed oscillator discharge current, and –40°C to 125°C operating temperature range-used in industrial PSUs and battery-operated power supplies.

For engineers reviewing the UC2844AQDR datasheet, UC2844AQDR pinout, UC2844AQDR application, or UC2844AQDR equivalent, this page delivers verified electrical specs, SOIC-14 package mapping, functional pin roles, real-world use cases, and two validated alternative parts with documented technical and application differences.

Technical Context

The UC2844AQDR implements fixed-frequency current-mode control with a toggle flip-flop enabling 50% max duty cycle limitation, internal bandgap reference (5.0 V ±1%), and pulse-by-pulse current limiting via ISENSE input clamped at 1 V. Its oscillator uses RT/CT pins with 7.5–8.8 mA discharge current and supports up to 500 kHz operation.

Under-voltage lockout includes hysteresis (16 V ON / 10 V OFF), and the error amplifier provides 90 dB open-loop gain, 1 MHz unity-gain bandwidth, and 60–70 dB PSRR. The OUTPUT pin delivers ±1 A sink/source capability with 25–150 ns rise/fall times into 1 nF load.

Key Specifications

Pinout & Package

UC2844AQDR is housed in a 14-pin SOIC (D) package measuring 8.65 mm × 6.00 mm with 1.27 mm lead pitch and 1.75 mm max height. Pin 1 is marked by a beveled corner or dot; device orientation follows JEDEC MS-012 AB standard.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar current-mode PWM controller applications.

Compared with UC2844AQDR, UC2844AD8R offers identical control functionality in a smaller footprint but sacrifices dedicated ground separation and layout flexibility, while UCC28C44DR delivers measurable improvements in drive strength and robustness-justifying redesign effort for new platforms.

Availability

UC2844AQDR is available at Aetrix Electronics and suitable for industrial power supplies, battery-operated PSUs, and off-line AC-DC adapters requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for UC2844AQDR 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets since 1930.

The UC284xA family was engineered specifically for cost-effective, high-reliability current-mode switch-mode power supplies-targeting applications where precise duty-cycle control, thermal robustness, and minimal external components are critical.

FAQ

What is the UVLO threshold of UC2844AQDR?

The UC2844AQDR features an under-voltage lockout with turn-on at 16 V and turn-off at 10 V, providing 6 V hysteresis to prevent oscillation near the threshold. This behavior is confirmed in the Electrical Characteristics table and applies across the full –40°C to 125°C operating range. The UC2844AQDR's UVLO ensures reliable startup only after the VCC rail reaches stable operating voltage.

Does UC2844AQDR support 500 kHz operation?

Yes, the UC2844AQDR is rated for up to 500 kHz operation per its datasheet Features section. However, actual achievable frequency depends on external RT/CT values and layout parasitics; typical configurations using 10 kΩ and 3.3 nF yield ~52 kHz, while smaller CT values (e.g., 470 pF) enable higher frequencies. The UC2844AQDR's oscillator discharge current (7.5–8.8 mA) supports stable high-frequency timing.

What package type does UC2844AQDR use?

UC2844AQDR uses a 14-pin SOIC (D) package with dimensions 8.65 mm × 6.00 mm and 1.27 mm lead pitch. This is explicitly stated in the Package Information table and confirmed in the PACKAGE OPTION ADDENDUM, where UC2844AQDR is listed as "SOIC (D) | 14" with MSL Level-1 rating and NIPDAU lead finish.

Can UC2844AQDR replace UC2842AQDR in a design?

No-UC2844AQDR and UC2842AQDR differ critically in maximum duty cycle (UC2844AQDR = <50%, UC2842AQDR = <100%) and UVLO thresholds (16 V/10 V vs. 16 V/10 V same, but UC2842A has different internal logic). The UC2844AQDR includes a toggle flip-flop that enforces 50% limit, making it unsuitable as a drop-in replacement where >50% duty is required. Always verify control loop stability before substitution.

What is the purpose of the VREF pin on UC2844AQDR?

The VREF pin on UC2844AQDR outputs a precision 5.0 V ±1% internal reference used to bias the RT/CT timing network and optionally power external current-sense amplifiers. It must be decoupled with a capacitor ≥10× the main switching FET's gate capacitance to maintain stability. This reference is trimmed and temperature-compensated, ensuring consistent oscillator and sensing performance across –40°C to 125°C in the UC2844AQDR.