FAIRCHILD KA3842AC, KA3842AE Service Manual

KA3842AC/KA3842AE SMPS Controller

March 2006

Features

 Low start current 0.2mA (Typ.)  Operating range up to 500kHz  Cycle by cycle current limiting  Under Voltage Lock Out (UVLO) with hysteresis  Short shutdown delay time: Typ.100ns  High current totem-pole output  Output swing limiting: 22V

Ordering Information

Operating

Part Number

KA3842AC -0 to +70°C Yes 8-DIP Tube

KA3842AE

Temp. Range Pb-Free Package Packing Method

Description

The KA3842AC/KA3842AE are fixed PWM controllers for Off Line and DC to DC converter applications. The internal circuits include UVLO, low start up current, temperature compensated reference, high gain error amplifier, current sensing comparator, and high current totem pole output for driving a POWER MOSFET. Also KA3842AC/KA3842AE provides low start up current below 0.3mA and short shutdown delay time, typically 100ns. The KA3842AC/KA3842AE has a UVLO threshold of 16V(on) and 10V(off). The KA3842AC/KA3842AE can operate within a 100% duty cycle.

1

8-DIP

KA3842AC/KA3842AE Rev. 1.0.1

Internal Block Diagram

8

V

REF

Internal

Bias

1/2 V

REF

2

V

FB

R

C.S

T/CT

1

3

4

COMP

5V

V

REF

Error Amp

+

-

OSCILLATOR

SET/

RESET

Good LOGIC

1/3

1V

C.S Comp.

UVLO

PWM LATCH

R

S

T

29V

22V

7

V

5

GND

PWR

7

V

6

OUTPUT

PWR

5

GND

KA3842AC/KA3842AE SMPS Controller

CC

C

KA3842AC/KA3842AE Rev. 1.0.1

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KA3842AC/KA3842AE SMPS Controller

Absolute Maximum Ratings

The “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. The device should not be operated at these limits. The parametric values defined in the Electrical Characteristics tables are not guaranteed at the absolute maximum ratings. The “Recommended Operating Conditions” table will define the conditions for actual device operation.

Symbol Parameter Value Unit

V

CC

I

O

V

I(ANA)

I

SINK(EA)

P

D

Rθja Thermal Resistance, Junction-to-Air

Supply Voltage 30 V

Output Current ±1 A

Analog Inputs (Pins 2, 3) -0.3 to 6.3 V

Error Amp. Output Sink Current 10 mA

Power Dissipation 1 W

(4)

95 °C/W

Electrical Characteristics

(VCC = 15V, RT = 10k¾, CT = 3.3nF, TA = 0°C to +70°C, unless otherwise specified)

Symbol Parameter Conditions Min. Typ. Max. Unit

REFERENCE SECTION

V

REF

ΔV

REF

I

SC

OSILLATOR SECTION

F

OSC

Voltage Stability VCC = 12V to 25V – 0.2 1 %

ST

V

OSC

I

DISCHG

CURRENT SENSE SECTION

GV Gain

V

I(MAX)

PSRR PSRR

I

BIAS

T

D

ERROR AMPLIFIER SECTION

Input Voltage T

V

I

BIAS

G

VO

GBW Unity Gain Bandwidth

PSRR PSRR

I

SINK

I

SOURCE

V

OH

V

OL

Output Voltage TJ = 25°C, IO = 1mA 4.9 5.0 5.1 V

Line Regulation VCC = 12V to 25V – 6 20 mV

Load Regulation I

= 1mA to 20mA – 6 25 mV

O

Output Short Circuit TA = 25°C – -100 -180 mA

Initial Accuracy TJ = 25°C 47 52 57 kHz

Amplitude V

, Peak to Peak – 1.7 – V

PIN4

Discharge Current TJ = 25°C, Pin 4 = 2V 7.8 8.3 8.8 mA

(2)(3)

Maximum Input Signal

(1)(2)

(2)

V

= 5V 0.9 1.0 1.1 V

PIN1

VCC = 12V to 25V – 70 – dB

2.85 3 3.15 V/V

Input Bias Current – -2 -10 µA

Delay to Output

(1)

V

= 0 V to 2V – 100 200 ns

PIN3

= 2.5V 2.42 2.50 2.58 V

PIN1

Input Bias Current – -0.3 -2 µA

Open Loop Gain

(1)

V

Output Sink Current V

Output Source Current V

Output High Voltage V

Output Low Voltage V

(1)

V

(1)

T

= 2V to 4V 65 90 – dB

O

= 25°C 0.7 1 – MHz

J

= 12V to 25V 60 70 – dB

CC

= 2.7V

PIN2

V

= 1.1V

PIN1

= 2.3V

PIN2

V

= 5.0V

PIN1

= 2.3V, R1 = 15k¾ to GND 5 6 – V

PIN2

= 2.7V

PIN2

2 6 – mA

-0.5 -0.8 – mA

– 0.8 1.1 V

R1 = 15k¾ to Pin 8

KA3842AC/KA3842AE Rev. 1.0.1

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KA3842AC/KA3842AE SMPS Controller

Electrical Characteristics (Continued)

(VCC = 15V, RT = 10k¾, CT = 3.3nF, TA = 0°C to +70°C, unless otherwise specified)

Symbol Parameter Conditions Min. Typ. Max. Unit

OUTPUT SECTION

V

OL

V

OH

t

Rise Time

R

t

Fall Time

F

V

OLIM

UNDER VOLTAGE LOCKOUT SECTION

V

TH

V

TL

PWM SECTION

D

MAX

D

MIN

TOTAL STANDBY CURRENT

I

ST

I

CC

V

Z

* Adjust VCC above the start threshold before setting at 15V

Output Low Level I

Output High Level I

(1)

T

(1)

T

= 20mA – 0.1 0.4 V

SINK

I

= 200mA – 1.5 2.2 V

SINK

SOURCE

I

SOURCE

= 20mA 13 13.5 – V

= 200mA 12 13.5 – V

= 25°C, C1 = 1nF

J

= 25°C, C1 = 1nF – 40 100 ns

J

– 40 100 ns

Output Voltage Swing Limit VCC = 27V, C1 = 1nF – 22 – V

Start Threshold 15 16 17 V

Min. Operating Voltage

9 10 11 V

(After turn on)

Maximum Duty Cycle 94 96 100 %

Minimum Duty Cycle – – 0 %

Start-Up Current – 0.2 0.4 mA

Operating Supply Current V

PIN2

= V

= 0V – 11 17 mA

PIN3

VCC Zener Voltage ICC = 25mA – 29 – V

Notes:

1. These parameters, although guaranteed, are not 100% tested in production.

2. Parameter measured at trip point of latch with V2 = 0V.

3. Gain defined as: G

= ΔV

V

PIN1ΔVPIN3(VPIN3

= 0 to 0.8V)

4. Junction-to-air thermal resistance test environments PCB information: Board thickness; 1.6mm, Board dimension: 76.2 X 114.3mm

2

, Ref.: EIA/JSED51-3 and EIA/JSED51-7

Board structure; Using the single layer PCB.

KA3842AC/KA3842AE Rev. 1.0.1

4 www.fairchildsemi.com

Package Dimensions

8-Pin DIP

KA3842AC/KA3842AE SMPS Controller

Dimensions in millimeters

KA3842AC/KA3842AE Rev. 1.0.1

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TRADEMARKS

The following are registered and unregistered trademarks Fairchild Semiconductor owns or is authorized to use and is not intended to be an exhaustive list of all such trademarks.

ACEx™ ActiveArray™ Bottomless™ Build it Now™ CoolFET™ CROSSVOLT™ DOME™ EcoSPARK™

2

E

CMOS™ EnSigna™ FACT™

FACT Quiet Series™

Across the board. Around the world.™ The Power Franchise Programmable Active Droop™

DISCLAIMER

FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TOMAKE CHANGES WITHOUT FURTHER NOTICE TOANY PRODUCTS HEREINTO IMPROVERELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANYLIABILITY ARISING OUTOF THEAPPLICATION OR USE OFANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT

CONVEYANY LICENSEUNDER ITS PATENT RIGHTS, NOR THERIGHTS OF OTHERS.

LIFE SUPPORT POLICY

®

FAST FASTr™ FPS™ FRFET™ GlobalOptoisolator™ GTO™ HiSeC™

2

I

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QFET

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KA3842AC/KA3842AE SMPS Controller

FAIRCHILDíS PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES ORSYSTEMS WITHOUTTHE EXPRESSWRITTEN APPROVAL OF FAIRCHILDSEMICONDUCTOR CORPORATION. As used herein:

1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, or (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in significant injury to the user.

PRODUCT STATUS DEFINITIONS

Definition of Terms

Datasheet Identification Product Status Definition

Advance Information

Preliminary

No Identification Needed

Formative or In Design

First Production

Full Production

2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or

effectiveness.

This datasheet contains the design specifications for product development. Specifications may change in any manner without notice.

This datasheet contains preliminary data, and supplementary data will be published at a later date. Fairchild Semiconductor reserves the right to make changes at any time without notice in order to improve design.

This datasheet contains final specifications. Fairchild Semiconductor reserves the right to make changes at any time without notice in order to improve design.

Obsolete

KA3842AC/KA3842AE Rev. 1.0.1

Not In Production

This datasheet contains specifications on a product that has been discontinued by Fairchild semiconductor. The datasheet is printed for reference information only.

Rev. I18

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