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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > DC DC Switching Controllers

STMicroelectronics E-UC3842BD1013TR

Name: E-UC3842BD1013TR
Brand: STMicroelectronics
SKU: E-UC3842BD1013TR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: E-UC3842BD1013TR

Manufacturer:: STMicroelectronics

Category:: DC DC Switching Controllers

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

Datasheet:: E-UC3842BD1013TR.pdf

Description:: IC REG CTRLR BST FLYBK ISO 8SOIC

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Product details

Overview

E-UC3842BD1013TR 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 with 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-UC3842BD1013TR datasheet, E-UC3842BD1013TR pinout, E-UC3842BD1013TR application, or E-UC3842BD1013TR equivalent, key selection criteria include UVLO threshold compatibility, duty cycle range (up to 96%), oscillator programming flexibility (RT/CT), current sense gain (3 V/V), and SO8 thermal performance (R_{th j-amb} = 150 °C/W).

Technical Context

The UC3842B implements current-mode control via a high-speed current-sense comparator that terminates switch conduction when sensed inductor current reaches the error amplifier's output voltage level. Its oscillator uses an external RT/CT network to set frequency up to 500 kHz, with internal discharge current trimmed to 7.5–8.8 mA for stable timing.

Internal circuitry includes a precision 2.5 V error amplifier input reference, latch logic ensuring single-pulse per cycle operation, and a 5 V reference output with ±25 mV load regulation over 1–20 mA - all operating across –40 °C to +150 °C junction temperature.

Key Specifications

Parameter	Value and Actual Design Meaning
Oscillator Frequency	Guaranteed 250 kHz at T_J = 25 °C; supports 50–500 kHz via RT/CT tuning
Current Sense Gain	3.0 V/V (±5%) - enables accurate 1 V threshold current limit with 0.33 Ω sense resistor
UVLO Threshold	16 V turn-on / 10 V turn-off - ensures reliable start-up and brown-out recovery in AC-DC adapters
Output Drive Capability	±1 A peak sink/source - directly drives gates of ≤1 nF MOSFETs without buffer stage
Reference Voltage	5.00 V ±100 mV (0–70 °C) - provides stable CT charging and feedback reference
Error Amp GBW	1 MHz unity-gain bandwidth - supports stable compensation in CCM flyback and forward topologies
Start-up Current	<0.5 mA at V_CC = 6.5 V - minimizes auxiliary winding losses in low-power SMPS

Pinout & Package

Package: SO8 (Small Outline Integrated Circuit, 150 °C/W thermal resistance, JEDEC MS-012AC compliant).

Pin/Terminal	Circuit Role	Design Meaning
1 - COMP	Error amplifier output	Provides access to EA output for Type II/III loop compensation networks
2 - VFB	Inverting input of error amplifier	Receives scaled output voltage via resistive divider for regulation feedback
3 - ISENSE	Current sense comparator input	Accepts voltage proportional to primary-side current; trip threshold = EA output / 3
4 - RT/CT	Oscillator timing node	Connects external R (to VREF) and C (to GND) to set f_OSC and max duty cycle
5 - GROUND	Signal and power ground reference	Single-point return for control logic, oscillator, and current sense circuits
6 - OUTPUT	Totem-pole gate driver output	Sources/sinks up to 1 A; low-state during UVLO and fault latch
7 - VCC	Supply input (30 V max)	Power source for internal bias; self-limiting above 30 mA; zener clamped at 36 V
8 - VREF	5 V reference output	Supplies precise 5 V ±2% for RT/CT timing and external circuitry; 20 mA max load

Key Features

Feature	Design Value
Latching PWM control	Ensures one switching pulse per clock cycle - prevents multiple pulses during overload or short-circuit events
Trimmed 5 V reference	±100 mV accuracy over temperature eliminates need for external reference in cost-sensitive designs
Automatic feed-forward compensation	Uses VCC ripple to modulate oscillator timing - improves line regulation without extra components
Low start-up current	<0.5 mA enables use of high-value startup resistors - reduces standby power in offline converters
High-current totem-pole output	Eliminates need for external driver in sub-100 W applications - simplifies BOM and layout

Applications

AC-DC Adapter

Flyback SMPS

Use Scenario: 12 V / 2 A wall adapter for consumer electronics with universal AC input (85–265 V_AC).

IC Role / Device Role / Timing Role: Primary-side PWM controller implementing current-mode flyback regulation with fixed 65 kHz switching.

Use Value: UVLO thresholds (16 V/10 V) match bulk capacitor recharge profile; 5 V reference powers optocoupler bias and TL431 shunt regulator.

Use Scenario: Isolated 5 V / 3 A industrial power supply with reinforced insulation and <100 mV output ripple.

IC Role / Device Role / Timing Role: Current-mode controller managing primary MOSFET gate drive and cycle-by-cycle current limiting.

Use Value: 3 V/V current sense gain enables precise 1 A peak current limit using 0.33 Ω sense resistor; SO8 package supports 1.5 W dissipation at 50 °C ambient.

DC-DC Boost Converter

Forward Converter

Use Scenario: 12 V to 24 V boost converter for automotive LED lighting with input dropout protection.

IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller regulating output via duty cycle adjustment and sensing input inductor current.

Use Value: Oscillator programmability (RT/CT) allows 200 kHz operation to avoid AM band interference; latch protection prevents MOSFET failure during load dump.

Use Scenario: 48 V to 12 V telecom forward converter with synchronous rectification and 300 kHz switching.

IC Role / Device Role / Timing Role: Primary-side PWM generator with precise duty cycle control and current limit monitoring via transformer reset sensing.

Use Value: Totem-pole output drives high-side MOSFET gate directly; 250 kHz guaranteed frequency ensures predictable transformer design and EMI filtering.

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
UC3842N	DIP-8 package; higher R_{th j-amb} (100 °C/W); same electrical specs	Better suited for prototyping or low-volume through-hole assembly	Select when manual soldering or breadboarding is required; not recommended for high-density PCBs
TL494CN	Fixed 2.5 V reference; dual-output push-pull; no integrated current sense comparator	Requires external current sense amp and logic for current-mode operation	Choose only if dual-output or adjustable dead time is needed; adds complexity for basic flyback designs

Compared with UC3842N, E-UC3842BD1013TR offers superior thermal performance in surface-mount layouts; compared with TL494CN, it delivers true integrated current-mode control with fewer external components - reducing design risk and board area in single-output SMPS.

Availability

E-UC3842BD1013TR is available at Aetrix Electronics and suitable for AC-DC adapters, flyback SMPS, and DC-DC boost converters requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for E-UC3842BD1013TR 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.

The UC384xB family was developed specifically for cost-sensitive, high-reliability current-mode switch-mode power supplies - targeting off-line AC-DC and isolated DC-DC conversion where minimal external parts count and robust fault handling are critical.

FAQ

What is the maximum operating frequency of E-UC3842BD1013TR?

The UC3842B supports oscillator frequencies up to 500 kHz using external RT/CT components. The guaranteed minimum frequency is 250 kHz at 25 °C, with typical operation ranging from 50 kHz to 500 kHz depending on RT (6.2 kΩ–500 kΩ) and CT (100 pF–10 nF) values. Frequency stability over temperature is ±0.5%.

Does E-UC3842BD1013TR support continuous conduction mode (CCM) flyback designs?

Yes - the UC3842B's current-mode architecture, 1 MHz error amplifier bandwidth, and 3 V/V current sense gain make it suitable for CCM flyback converters. Stable operation requires proper slope compensation (via RC network on pin 3) to prevent subharmonic oscillation when duty cycle exceeds 50%, as confirmed in ST Application Note AN1052.

How does the under-voltage lockout (UVLO) behave during brown-out conditions?

The UC3842B features hysteresis between 16 V (turn-on) and 10 V (turn-off). During brown-out, the IC remains active until V_CC drops below 10 V, then disables output and resets internal logic. Restart occurs only after V_CC rises above 16 V - preventing erratic switching near threshold and ensuring clean power-up sequencing.

Can E-UC3842BD1013TR drive a MOSFET with 2 nF gate capacitance directly?

Yes - the ±1 A peak output current and 50–150 ns rise/fall times (with 1 nF load) enable direct drive of MOSFETs with ≤2 nF total gate charge (Q_g). For example, a 200 V/2 A MOSFET like STP2NK20Z has Q_g ≈ 1.8 nC at 10 V V_GS, requiring ~180 ns turn-on with 10 mA average gate current - well within the UC3842B's capability.

E-UC3842BD1013TR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Output Type:: Transistor Driver

Function:: Step-Up/Step-Down

Output Configuration:: Positive, Isolation Capable

Topology:: Boost, Flyback

Number of Outputs:: 1

Output Phases:: 1

Voltage - Supply (Vcc/Vdd):: 10V ~ 30V

Frequency - Switching:: Up to 500kHz

Duty Cycle (Max):: 96%

Synchronous Rectifier:: No

Clock Sync:: No

Serial Interfaces:: -

Control Features:: Frequency Control

Operating Temperature:: 0°C ~ 70°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-SOIC

E-UC3842BD1013TR FAQ

1.How can I place an order for E-UC3842BD1013TR through Aetrix?

Please submit a Request for Quotation (RFQ) for E-UC3842BD1013TR 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 E-UC3842BD1013TR reliable?

The price and inventory of E-UC3842BD1013TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for E-UC3842BD1013TR is usually 5 days.

3.What payment methods are accepted for E-UC3842BD1013TR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for E-UC3842BD1013TR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for E-UC3842BD1013TR?

E-UC3842BD1013TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your E-UC3842BD1013TR 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 E-UC3842BD1013TR?

For technical support, including E-UC3842BD1013TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your E-UC3842BD1013TR requirements.

6.How does Aetrix verify that E-UC3842BD1013TR is sourced from the original manufacturer or authorized distributors?

All E-UC3842BD1013TR 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 E-UC3842BD1013TR meets industry standards.

7.What is the process for return or replacement of E-UC3842BD1013TR?

All E-UC3842BD1013TR units undergo pre-shipment inspection (PSI). If there is an issue with E-UC3842BD1013TR, 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 E-UC3842BD1013TR part is unused and in its original packaging.

Return procedure for E-UC3842BD1013TR:

1.Submit a request within 90 days.

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

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