Overview
Online design
Sample & Buy
Solutions
Documentation
CAD Resources
Tools & Software
Quality & Reliability
Get Started
Partner products
Sales Briefcase

Product overview

Description

The UC284xB family of control ICs provides the necessary features to implement off-line or DC to DC fixed frequency current mode control schemes with a minimal external parts count. Internally implemented circuits include a trimmed oscillator for precise DUTY CYCLE CONTROL under voltage lockout featuring start-up current less than 0.5mA, a precision reference trimmed for accuracy at the error amp input, logic to insure latched operation, a PWM comparator which also provides current limit control, and a totem pole output stage designed to source or sink high peak current. The output stage, suitable for driving N-Channel MOSFETs, is low in the off-state. Differences between members of this family are the under-voltage lockout thresholds and maximum duty cycle ranges. The UC2842B and UC2844B have UVLO thresholds of 16V (on) and 10V (off), ideally suited off-line applications The corresponding thresholds for the UC2843B and UC2845B are 8.5V and 7.9V. The UC2842B and UC2843B can operate to duty cycles approaching 100%. A range of the zero to < 50 % is obtained by the UC2844B and UC2845B by the addition of an internal toggle flip flop which blanks the output off every other clock cycle.
  • All features

    • LOW START-UP AND OPERATING CURRENT
    • UNDERVOLTAGE LOCKOUT WITH HYSTERESIS
    • INTERNALLY TRIMMED REFERENCE WITH UNDERVOLTAGE LOCKOUT
    • CURRENT LIMITING
    • TRIMMED OSCILLATOR FOR PRECISE FREQUENCY CONTROL
    • CURRENT MODE OPERATION TO 500kHz
    • OSCILLATOR FREQUENCY GUARANTEED AT 250kHz
    • LATCHING PWM FOR CYCLE-BY-CYCLE
    • HIGH CURRENT TOTEM POLE OUTPUT
    • AUTOMATIC FEED FORWARD COMPENSATION

Circuit Diagram

Recommended for you

EDA Symbols, Footprints and 3D Models

STMicroelectronics - UC3845B

Speed up your design by downloading all the EDA symbols, footprints and 3D models for your application. You have access to a large number of CAD formats to fit with your design toolchain.

Symbols

Symbols

Footprints

Footprints

3D model

3D models

Quality and Reliability

Part Number Marketing Status Package Grade RoHS Compliance Grade Material Declaration**
UC3845BD1
Active
SO-8 Industrial Ecopack2
UC3845BD1013TR
Active
SO-8 Industrial Ecopack2
UC3845BN
Active
DIP-8 Industrial Ecopack2

UC3845BD1

Package:

SO-8

Material Declaration**:

PDF XML

Marketing Status

Active

Package

SO-8

Grade

Industrial

RoHS Compliance Grade

Ecopack2

UC3845BD1013TR

Package:

SO-8

Material Declaration**:

PDF XML

Marketing Status

Active

Package

SO-8

Grade

Industrial

RoHS Compliance Grade

Ecopack2

UC3845BN

Package:

DIP-8

Material Declaration**:

PDF XML

Marketing Status

Active

Package

DIP-8

Grade

Industrial

RoHS Compliance Grade

Ecopack2

(**) The Material Declaration forms available on st.com may be generic documents based on the most commonly used package within a package family. For this reason, they may not be 100% accurate for a specific device. Please contact our sales support for information on specific devices.

Sample & Buy

Part Number
Order from Distributors
Order from ST
Marketing Status
ECCN (US)
ECCN (EU)
Packing Type
Package
Temperature (°C) Country of Origin
Budgetary Price (US$)*/Qty
min
max
UC3845BN Available at 7 distributors

Distributor availability ofUC3845BN

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 92 1 Order Now
RS COMPONENTS EUROPE 40 10 Order Now
FUTURE WORLDWIDE 697 1 Order Now
Newark Element14 AMERICA 254 0 Order Now
MOUSER WORLDWIDE 5141 1 Order Now
Farnell Element14 EUROPE 1899 1 Order Now
ANGLIA Live EUROPE 3100 50 Order Now

Distributor reported inventory date: 2021-05-11

Distributor Name

DIGIKEY

Stock

92

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

40

Min.Order

10

Region

EUROPE Order Now

FUTURE

Stock

697

Min.Order

1

Region

WORLDWIDE Order Now

Newark Element14

Stock

254

Min.Order

0

Region

AMERICA Order Now

MOUSER

Stock

5141

Min.Order

1

Region

WORLDWIDE Order Now

Farnell Element14

Stock

1899

Min.Order

1

Region

EUROPE Order Now

ANGLIA Live

Stock

3100

Min.Order

50

Region

EUROPE Order Now

Distributor reported inventory date: 2021-05-11

Buy Direct
Active
EAR99 NEC Tube DIP-8 - - CHINA 0.2772 / 1k
UC3845BD1 Available at 5 distributors

Distributor availability ofUC3845BD1

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 178 1 Order Now
RS COMPONENTS EUROPE 19 1 Order Now
Newark Element14 AMERICA 164 0 Order Now
MOUSER WORLDWIDE 365 1 Order Now
Farnell Element14 EUROPE 557 1 Order Now

Distributor reported inventory date: 2021-05-10

Distributor Name

DIGIKEY

Stock

178

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

19

Min.Order

1

Region

EUROPE Order Now

Newark Element14

Stock

164

Min.Order

0

Region

AMERICA Order Now

MOUSER

Stock

365

Min.Order

1

Region

WORLDWIDE Order Now

Farnell Element14

Stock

557

Min.Order

1

Region

EUROPE Order Now

Distributor reported inventory date: 2021-05-10

Buy Direct
Active
EAR99 NEC Tube SO-8 - - MOROCCO 0.2772 / 1k
UC3845BD1013TR Available at 3 distributors

Distributor availability ofUC3845BD1013TR

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 3687 1 Order Now
MOUSER WORLDWIDE 23 1 Order Now
Farnell Element14 EUROPE 4250 1 Order Now

Distributor reported inventory date: 2021-05-10

Distributor Name

DIGIKEY

Stock

3687

Min.Order

1

Region

WORLDWIDE Order Now

MOUSER

Stock

23

Min.Order

1

Region

WORLDWIDE Order Now

Farnell Element14

Stock

4250

Min.Order

1

Region

EUROPE Order Now

Distributor reported inventory date: 2021-05-10

Buy Direct
Active
EAR99 NEC Tape And Reel SO-8 - - MOROCCO 0.2772 / 1k

UC3845BN

Marketing Status

Active

ECCN (US)

EAR99

Budgetary Price (US$)*/Qty

0.2772 / 1k

Distributor availability ofUC3845BN

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 92 1 Order Now
RS COMPONENTS EUROPE 40 10 Order Now
FUTURE WORLDWIDE 697 1 Order Now
Newark Element14 AMERICA 254 0 Order Now
MOUSER WORLDWIDE 5141 1 Order Now
Farnell Element14 EUROPE 1899 1 Order Now
ANGLIA Live EUROPE 3100 50 Order Now

Distributor reported inventory date: 2021-05-11

Distributor Name

DIGIKEY

Stock

92

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

40

Min.Order

10

Region

EUROPE Order Now

FUTURE

Stock

697

Min.Order

1

Region

WORLDWIDE Order Now

Newark Element14

Stock

254

Min.Order

0

Region

AMERICA Order Now

MOUSER

Stock

5141

Min.Order

1

Region

WORLDWIDE Order Now

Farnell Element14

Stock

1899

Min.Order

1

Region

EUROPE Order Now

ANGLIA Live

Stock

3100

Min.Order

50

Region

EUROPE Order Now

Distributor reported inventory date: 2021-05-11

ECCN (EU)

NEC

Packing Type

Tube

Package

DIP-8

Operating Temperature (°C)

(min)

-

(max)

-

Budgetary Price (US$)* / Qty

0.2772 / 1k

Country of Origin

CHINA

UC3845BD1

Marketing Status

Active

ECCN (US)

EAR99

Budgetary Price (US$)*/Qty

0.2772 / 1k

Distributor availability ofUC3845BD1

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 178 1 Order Now
RS COMPONENTS EUROPE 19 1 Order Now
Newark Element14 AMERICA 164 0 Order Now
MOUSER WORLDWIDE 365 1 Order Now
Farnell Element14 EUROPE 557 1 Order Now

Distributor reported inventory date: 2021-05-10

Distributor Name

DIGIKEY

Stock

178

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

19

Min.Order

1

Region

EUROPE Order Now

Newark Element14

Stock

164

Min.Order

0

Region

AMERICA Order Now

MOUSER

Stock

365

Min.Order

1

Region

WORLDWIDE Order Now

Farnell Element14

Stock

557

Min.Order

1

Region

EUROPE Order Now

Distributor reported inventory date: 2021-05-10

ECCN (EU)

NEC

Packing Type

Tube

Package

SO-8

Operating Temperature (°C)

(min)

-

(max)

-

Budgetary Price (US$)* / Qty

0.2772 / 1k

Country of Origin

MOROCCO

UC3845BD1013TR

Marketing Status

Active

ECCN (US)

EAR99

Budgetary Price (US$)*/Qty

0.2772 / 1k

Distributor availability ofUC3845BD1013TR

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 3687 1 Order Now
MOUSER WORLDWIDE 23 1 Order Now
Farnell Element14 EUROPE 4250 1 Order Now

Distributor reported inventory date: 2021-05-10

Distributor Name

DIGIKEY

Stock

3687

Min.Order

1

Region

WORLDWIDE Order Now

MOUSER

Stock

23

Min.Order

1

Region

WORLDWIDE Order Now

Farnell Element14

Stock

4250

Min.Order

1

Region

EUROPE Order Now

Distributor reported inventory date: 2021-05-10

ECCN (EU)

NEC

Packing Type

Tape And Reel

Package

SO-8

Operating Temperature (°C)

(min)

-

(max)

-

Budgetary Price (US$)* / Qty

0.2772 / 1k

Country of Origin

MOROCCO

(*) Suggested Resale Price per unit (USD) for BUDGETARY USE ONLY. For quotes, prices in local currency, please contact your local ST Sales Office  or our Distributors