STMicroelectronics E-UC2843BN

Overview

E-UC2843BN from STMicroelectronics is a high-performance current-mode PWM controller IC designed for fixed-frequency DC-DC and off-line power supplies. It features an internally trimmed 5 V reference, under-voltage lockout with 8.4 V turn-on/7.6 V turn-off thresholds, 100% maximum duty cycle capability, and oscillator frequency programmable up to 500 kHz via RT/CT. It drives N-channel MOSFETs directly with ±1 A peak output current and supports cycle-by-cycle current limiting in flyback, forward, and boost topologies.

For engineers reviewing the E-UC2843BN datasheet, E-UC2843BN pinout, E-UC2843BN application, or E-UC2843BN equivalent, key selection criteria include UVLO threshold compatibility (8.4 V/7.6 V), absence of internal toggle flip-flop (enabling full-duty operation), low start-up current (<0.5 mA), and SO8 package suitability for space-constrained board layouts.

Technical Context

The E-UC2843BN implements current-mode control using a high-gain error amplifier (90 dB open-loop gain, 1 MHz bandwidth) and a dedicated current-sense comparator with 3 V/V gain and 1 V input threshold. Its oscillator uses a constant-current discharge scheme with temperature-stable discharge current (7.5–8.8 mA), enabling precise frequency setting independent of supply voltage variation (±1% ∆fOSC/∆V).

Internal logic ensures latched PWM operation with automatic feed-forward compensation and a totem-pole output stage optimized for fast MOSFET gate drive (50–150 ns rise/fall time into 1 nF). The device lacks the internal toggle flip-flop found in UC3844B/45B variants, preserving continuous 0–100% duty cycle control without clock-cycle blanking.

Key Specifications

Pinout & Package

E-UC2843BN is housed in an industry-standard SO8 (Small Outline 8-pin) package with 1.27 mm lead pitch, compliant with JEDEC MS-012. Thermal resistance is 150 °C/W (junction-to-ambient), supporting operation up to 150 °C junction temperature.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UC3843BD1, E-UC2843BN offers identical performance and footprint but distinct ordering branding; versus TL494CN, it delivers integrated current-mode control with lower BOM count and simpler compensation, though lacking dual-output flexibility.

Availability

E-UC2843BN is available at Aetrix Electronics and suitable for AC-DC adapters, industrial DC-DC converters, telecom power supplies, and battery charger controllers requiring stable component supply, long-lifecycle support, and SO8 package compatibility.

Supply support for E-UC2843BN 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-UC2843BN belongs to the UCx84xB family of current-mode PWM controllers, engineered specifically for cost-sensitive, high-reliability off-line and DC-DC power conversion where minimal external components and robust fault protection are essential.

FAQ

What is the minimum recommended RT/CT combination to achieve 250 kHz operation?

The datasheet guarantees 250 kHz at 25°C with RT = 6.2 kΩ and CT = 1 nF. For production designs, RT = 10 kΩ and CT = 3.3 nF is the validated combination delivering 250 kHz across -40°C to 125°C, confirmed by Figure 2 and electrical characteristics tables.

Can E-UC2843BN be used in a boost converter without slope compensation?

Yes - E-UC2843BN supports stable boost operation in discontinuous conduction mode (DCM) without slope compensation. In continuous conduction mode (CCM), external ramp injection at the ISENSE pin is required per Figure 18 to prevent subharmonic oscillation above 50% duty cycle.

How does the UVLO hysteresis affect system restart behavior after brownout?

With 8.4 V turn-on and 7.6 V turn-off thresholds, E-UC2843BN provides 0.8 V hysteresis. After brownout, the IC remains latched off until input voltage rises above 8.4 V, preventing erratic restart attempts and ensuring clean reinitialization of the power stage and feedback loop.

Is the VREF pin capable of sourcing current to external circuitry while maintaining regulation?

Yes - VREF can source up to 50 mA while holding 5.00 V ±25 mV across temperature and load (1–20 mA), as specified in the "Load Regulation" parameter. For loads >10 mA, ensure PCB trace width and thermal relief support adequate heat dissipation to avoid local heating-induced drift.