STMicroelectronics E-UC2842BD1

Overview

E-UC2842BD1 from STMicroelectronics is a high-performance current-mode PWM controller IC designed for fixed-frequency off-line and DC-DC power supplies. It features a trimmed 250 kHz oscillator, latching PWM for cycle-by-cycle current limiting, 5 V ±1% internal reference, under-voltage lockout (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, forward, and boost converters.

For engineers reviewing the E-UC2842BD1 datasheet, E-UC2842BD1 pinout, E-UC2842BD1 application, or E-UC2842BD1 equivalent, key selection considerations include UVLO threshold compatibility with bulk capacitor charging profiles, duty cycle range (up to 96%), current-sense gain (3 V/V), oscillator timing flexibility (RT/CT programmable up to 500 kHz), and SO8 package thermal performance (R_{th j-amb} = 150 °C/W).

Technical Context

The E-UC2842BD1 implements true current-mode control via a high-speed current-sense comparator with 150 ns propagation delay and 3 V/V transimpedance gain, enabling precise peak-current limiting. Its error amplifier provides 90 dB open-loop gain and 1 MHz unity-gain bandwidth, supporting stable Type II/III compensation in voltage-mode-derived topologies.

Oscillator frequency is set externally via RT and CT pins, with guaranteed 250 kHz at T_J = 25°C using RT = 6.2 kΩ and CT = 1 nF; operation up to 500 kHz is supported. The internal toggle flip-flop is absent - distinguishing it from UC3844B/45B - allowing continuous duty cycles up to 96%.

Key Specifications

Pinout & Package

E-UC2842BD1 is housed in an SO8 (Small Outline Integrated Circuit, 150 mil width) package with standard 1.27 mm pitch, rated for 800 mW power dissipation at T_amb ≤ 25°C and R_{th j-amb} = 150 °C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UC3842BN, E-UC2842BD1 offers wider temperature qualification and tighter reference tolerance; versus NCP1200DR2G, it provides greater system integration via VREF output and higher output drive, at the cost of slightly higher quiescent current.

Availability

E-UC2842BD1 is available at Aetrix Electronics and suitable for AC-DC adapters, flyback SMPS, DC-DC boost converters, and offline LED drivers requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for E-UC2842BD1 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, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

E-UC2842BD1 belongs to the UCx84xB family of current-mode PWM controllers, developed specifically for cost-effective, high-reliability fixed-frequency switch-mode power supplies where cycle-by-cycle current limiting and integrated reference stability are essential.

FAQ

What is the maximum recommended operating frequency for E-UC2842BD1?

The E-UC2842BD1 supports oscillator frequencies up to 500 kHz per datasheet specifications, enabled by its high-speed current-sense comparator (150 ns delay) and fast output stage (50–150 ns rise/fall). However, practical operation above 300 kHz requires careful PCB layout, minimized parasitic inductance on ISENSE and RT/CT traces, and derating of power dissipation due to increased switching losses.

Can E-UC2842BD1 drive a P-channel MOSFET directly?

No - E-UC2842BD1's OUTPUT pin is a totem-pole stage configured for source/sink operation referenced to GROUND (Pin 5), making it suitable only for N-channel MOSFETs with source tied to ground. Driving a P-channel device would require level-shifting circuitry or an external high-side driver, as the IC lacks floating output capability or dedicated high-side gate drive architecture.

Is external slope compensation required for E-UC2842BD1 in continuous conduction mode?

Yes - slope compensation is mandatory for stable operation in CCM flyback or forward converters. The E-UC2842BD1 does not integrate slope compensation; it must be added externally by injecting a sawtooth waveform (derived from RT/CT or VREF) into the ISENSE node, typically via a resistor network, to prevent subharmonic oscillation when duty cycle exceeds 50%.

How does the UVLO hysteresis affect system behavior during AC line dropout?

The 6 V hysteresis (16 V on / 10 V off) prevents rapid toggling during marginal line conditions. When bulk voltage drops below 10 V, the IC shuts down cleanly and remains off until voltage recovers to ≥16 V - ensuring full restart with proper soft-start behavior and avoiding erratic PWM bursts that could stress magnetics or cause audible noise in transformers.