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  • 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.

    Key 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

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STMicroelectronics - UC3843B

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Quality and Reliability

Part Number Marketing Status Package Grade RoHS Compliance Grade Material Declaration**
UC3843BD1
Active
SO-8 Industrial Ecopack2
UC3843BD1013TR
Active
SO-8 Industrial Ecopack2
UC3843BN
Active
DIP-8 Industrial Ecopack2

UC3843BD1

Package:

SO-8

Material Declaration**:

Marketing Status

Active

Package

SO-8

Grade

Industrial

RoHS Compliance Grade

Ecopack2

UC3843BD1013TR

Package:

SO-8

Material Declaration**:

Marketing Status

Active

Package

SO-8

Grade

Industrial

RoHS Compliance Grade

Ecopack2

UC3843BN

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
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Budgetary Price (US$)*/Qty
min
max
UC3843BD1013TR Available at 7 distributors

Distributor availability ofUC3843BD1013TR

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 6627 1 Order Now
AVNET AMERICA 12500 0 Order Now
FUTURE WORLDWIDE 2500 2500 Order Now
ARROW EUROPE 2500 0 Order Now
Newark Element14 AMERICA 59 0 Order Now
ARROW AMERICA 22549 1 Order Now
Farnell Element14 EUROPE 594 1 Order Now

Distributor reported inventory date: 2021-01-15

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DIGIKEY

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6627

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1

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WORLDWIDE Order Now

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12500

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0

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2500

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2500

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2500

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59

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0

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22549

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1

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AMERICA Order Now

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594

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1

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Distributor reported inventory date: 2021-01-15

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Active
EAR99 NEC Tape And Reel SO-8 - - MOROCCO 0.2772 / 1k
UC3843BD1 Available at 5 distributors

Distributor availability ofUC3843BD1

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 3948 1 Order Now
AVNET AMERICA 4000 0 Order Now
ARROW EUROPE 900 0 Order Now
Newark Element14 AMERICA 316 0 Order Now
Farnell Element14 EUROPE 160 1 Order Now

Distributor reported inventory date: 2021-01-15

Distributor Name

DIGIKEY

Stock

3948

Min.Order

1

Region

WORLDWIDE Order Now

AVNET

Stock

4000

Min.Order

0

Region

AMERICA Order Now

ARROW

Stock

900

Min.Order

0

Region

EUROPE Order Now

Newark Element14

Stock

316

Min.Order

0

Region

AMERICA Order Now

Farnell Element14

Stock

160

Min.Order

1

Region

EUROPE Order Now

Distributor reported inventory date: 2021-01-15

Buy Direct
Active
EAR99 NEC Tube SO-8 - - MOROCCO 0.2772 / 1k
UC3843BN Available at 6 distributors

Distributor availability ofUC3843BN

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 1045 1 Order Now
RS COMPONENTS EUROPE 860 10 Order Now
AVNET AMERICA 620 0 Order Now
ARROW EUROPE 11910 0 Order Now
Farnell Element14 EUROPE 1612 1 Order Now
ANGLIA Live EUROPE 7900 50 Order Now

Distributor reported inventory date: 2021-01-15

Distributor Name

DIGIKEY

Stock

1045

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

860

Min.Order

10

Region

EUROPE Order Now

AVNET

Stock

620

Min.Order

0

Region

AMERICA Order Now

ARROW

Stock

11910

Min.Order

0

Region

EUROPE Order Now

Farnell Element14

Stock

1612

Min.Order

1

Region

EUROPE Order Now

ANGLIA Live

Stock

7900

Min.Order

50

Region

EUROPE Order Now

Distributor reported inventory date: 2021-01-15

Buy Direct
Active
EAR99 NEC Tube DIP-8 - - CHINA 0.2772 / 1k

UC3843BD1013TR

Marketing Status

Active

ECCN (US)

EAR99

Budgetary Price (US$)*/Qty

0.2772 / 1k

Distributor availability ofUC3843BD1013TR

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 6627 1 Order Now
AVNET AMERICA 12500 0 Order Now
FUTURE WORLDWIDE 2500 2500 Order Now
ARROW EUROPE 2500 0 Order Now
Newark Element14 AMERICA 59 0 Order Now
ARROW AMERICA 22549 1 Order Now
Farnell Element14 EUROPE 594 1 Order Now

Distributor reported inventory date: 2021-01-15

Distributor Name

DIGIKEY

Stock

6627

Min.Order

1

Region

WORLDWIDE Order Now

AVNET

Stock

12500

Min.Order

0

Region

AMERICA Order Now

FUTURE

Stock

2500

Min.Order

2500

Region

WORLDWIDE Order Now

ARROW

Stock

2500

Min.Order

0

Region

EUROPE Order Now

Newark Element14

Stock

59

Min.Order

0

Region

AMERICA Order Now

ARROW

Stock

22549

Min.Order

1

Region

AMERICA Order Now

Farnell Element14

Stock

594

Min.Order

1

Region

EUROPE Order Now

Distributor reported inventory date: 2021-01-15

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

UC3843BD1

Marketing Status

Active

ECCN (US)

EAR99

Budgetary Price (US$)*/Qty

0.2772 / 1k

Distributor availability ofUC3843BD1

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 3948 1 Order Now
AVNET AMERICA 4000 0 Order Now
ARROW EUROPE 900 0 Order Now
Newark Element14 AMERICA 316 0 Order Now
Farnell Element14 EUROPE 160 1 Order Now

Distributor reported inventory date: 2021-01-15

Distributor Name

DIGIKEY

Stock

3948

Min.Order

1

Region

WORLDWIDE Order Now

AVNET

Stock

4000

Min.Order

0

Region

AMERICA Order Now

ARROW

Stock

900

Min.Order

0

Region

EUROPE Order Now

Newark Element14

Stock

316

Min.Order

0

Region

AMERICA Order Now

Farnell Element14

Stock

160

Min.Order

1

Region

EUROPE Order Now

Distributor reported inventory date: 2021-01-15

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

UC3843BN

Marketing Status

Active

ECCN (US)

EAR99

Budgetary Price (US$)*/Qty

0.2772 / 1k

Distributor availability ofUC3843BN

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 1045 1 Order Now
RS COMPONENTS EUROPE 860 10 Order Now
AVNET AMERICA 620 0 Order Now
ARROW EUROPE 11910 0 Order Now
Farnell Element14 EUROPE 1612 1 Order Now
ANGLIA Live EUROPE 7900 50 Order Now

Distributor reported inventory date: 2021-01-15

Distributor Name

DIGIKEY

Stock

1045

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

860

Min.Order

10

Region

EUROPE Order Now

AVNET

Stock

620

Min.Order

0

Region

AMERICA Order Now

ARROW

Stock

11910

Min.Order

0

Region

EUROPE Order Now

Farnell Element14

Stock

1612

Min.Order

1

Region

EUROPE Order Now

ANGLIA Live

Stock

7900

Min.Order

50

Region

EUROPE Order Now

Distributor reported inventory date: 2021-01-15

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

(*) 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