STMicroelectronics E-UC2842BN

Overview

E-UC2842BN 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 oscillator (250 kHz guaranteed), 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 current - enabling direct N-channel MOSFET gate driving in flyback, forward, and boost topologies.

For engineers reviewing the E-UC2842BN datasheet, E-UC2842BN pinout, E-UC2842BN application, or E-UC2842BN equivalent, key selection criteria include UVLO threshold compatibility with 110–240 VAC rectified bus, duty cycle range up to 96%, oscillator programmability via RT/CT, and thermal performance in Minidip (100 °C/W R_{th j-amb}) for cost-sensitive industrial SMPS designs.

Technical Context

The E-UC2842BN implements current-mode control using an internal error amplifier, PWM latch, and comparator that compares sensed inductor current against a voltage derived from the error amp output. Its oscillator uses an external RT/CT network to set frequency (up to 500 kHz) and maximum duty cycle, with discharge current trimmed to 7.8–8.8 mA for precision timing.

Under-voltage lockout incorporates hysteresis (6 V window) and guarantees start-up current < 0.5 mA at 6.5 V, while the 5 V reference provides ±1% accuracy over temperature and load, supporting stable feedback loop compensation. The output stage operates in push-pull configuration with 0.1 V low-level saturation at 20 mA sink, optimized for fast MOSFET switching with minimal dead-time distortion.

Key Specifications

Pinout & Package

E-UC2842BN is housed in an 8-pin Minidip (DIP-8) package with 0.3" body width and 2.54 mm pitch, rated for 1.25 W power dissipation at T_amb ≤ 25°C and R_{th j-amb} = 100 °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-UC2842BN offers extended temperature range and industrial-grade qualification; versus TL494CN, it delivers integrated cycle-by-cycle current limiting and simplified flyback implementation - reducing component count and improving fault resilience.

Availability

E-UC2842BN is available at Aetrix Electronics and suitable for AC-DC adapters, flyback SMPS, LED drivers, and DC-DC boost converters requiring stable component supply, long-term industrial lifecycle support, and consistent Minidip packaging.

Supply support for E-UC2842BN 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, microcontrollers, and automotive ICs.

E-UC2842BN belongs to the UCx84xB family of current-mode PWM controllers, engineered specifically for cost-effective, high-reliability offline and isolated DC-DC power conversion in industrial, consumer, and lighting applications.

FAQ

What is the minimum recommended RT resistor value for stable 250 kHz operation?

The datasheet specifies RT = 10 kΩ with CT = 3.3 nF for nominal 250 kHz operation. Minimum RT is not explicitly defined, but practical lower limit is ~6.2 kΩ (per oscillator characterization at 225–275 kHz). Using RT < 6.2 kΩ risks exceeding 500 kHz upper limit, increasing gate drive losses and EMI - verify stability with scope-based dead-time and jitter measurement.

Can E-UC2842BN drive a P-channel MOSFET directly?

No - the OUTPUT pin is a totem-pole stage with low-state saturation and active pull-down; it cannot provide the high-side gate drive voltage required for P-MOSFETs. It is optimized for N-channel MOSFETs where source is grounded. For high-side N-MOSFETs, a dedicated bootstrap or isolated gate driver is required.

How does the internal oscillator discharge current affect frequency accuracy?

Oscillator frequency depends on CT discharge rate, which is set by internal 7.8–8.8 mA current source. This trimmed current - combined with RT and CT tolerances - determines absolute f_OSC accuracy. At 25°C, frequency tolerance is ±3% (49–55 kHz base range), tightening to ±1% with external calibration of RT/CT values per application notes.

Is soft-start functionality built-in or external?

E-UC2842BN has no internal soft-start circuit. Soft-start must be implemented externally using a capacitor on the COMP pin (Figure 24) or by clamping the error amplifier output with a transistor-controlled voltage ramp. This allows designer-defined rise time and avoids output overshoot during power-up.