Current Mode Controller B3842/43/44/45A&A1 Description

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Current Mode Controller B3842/43/44/45A&A1 Description

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Linear Inspire Linear Power
Current Mode Controller
B3842/43/44/45A&A1
Description
Linear B3842/43/44/45 fixed frequency currentmode controller. These devices designed OffLine DC-to-DC converter applications with minimum external components. B3842 family Feature trimmed oscillator precise duty cycle control, temperature compensated reference, high gain error amplifier, current sensing comparator, high current totempole output. Ideally suited driving power N-Channel MOSFET's. when stage. Protection circuitry includes built under-voltage lockout current limiting. Major differences between members these series UVLO thresholds maximum duty-cycle ranges. Typical UVLO thresholds (on) (off) B3842 B3844 devices make them ideally suited off-line applications. These corresponding typical thresholds B3842 B3845 devcies 8.4V (on) 7.6V (off). B3842 B3843 devcies operate duty cycles approaching 100%. duty-Cycle range obtained B3844 B3845 addition internal toggle flip-flop, which blanks output every other clock cycle. available SOIC packages.
Features
Start-Up Operating Current Maximum Duty Cycle Operating Frequency 500KHz Under voltage Lockout with Hysteresis Available SOIC Similar industry Standard UC3842
Applications
Switching Power Supply Monitor
Connection
Ordering Information
Devices
B384X(Z)M B384X(Z)P Semi
Package
Temp.
SO-8 8-DIP Z=A1 Fairchild Samsung
8-Pin Surface Mount
COMP
ISENSE RT/CT
OUTPUT
View
Linear,
2478 Armstrong Street, Livermore, 94550 Tel: (925) 989-7144, Fax: (925) 940-9556
www.baylinear.com
B384X
Absolute Maximum Rating
Parameter
Supply Voltage Output Current Analog Input (pin 2,3) Error Output Sink Current Power Dissipation Storage Temperature Range Lead Temperature (Soldering Sec.)
Symbol
V(ANA) ISINK (E.A)
Value
-0.3
Unit
Electrical Characteristics
(VCC 15V;RT 3.3nF, TA=0 +70°C, unless otherwise specified) Parameter Symbol Conditions REFERENCE SECTION
Reference Voltage Line Regulation VREF (line) IREF= 12VVCC25V 1mAIREF20mA 4.90
5.00
5.10
UNIT
Load Regulation
(LOAD)
Short Circuit Output Current
-100
-180
OSCILLATOR SECTION Oscillator Frequency Frequency Change with f/VCC Voltage Oscillator Amplitude VOSC ERROR AMPLIFIER SECTION Input Bias Current IBIAS Input Voltage VI(E>A) Open Loop Voltage Gain Power Supply Rejection PSRR Ratio Output Sink Current ISINK Output Source Current ISOURCE High Output Voltage Output Voltage OUTPUT SECTION Output Voltage High Output Voltage Rise Time Fall Time
12VVCC25V
2.42 -0.6
0.05 -0.1 2.50 -1.0 0.08 13.5 13.0
2.58
VP-P
=2.5V 2VVO4V 12VVCC25V =2.7V, =1.1V V2=2.3, V1=5V V2=2.3, V2=2.7, ISINK 20mA ISINK 200mA Source 20mA Source 200mA CL=1nF (note3) CL=1nF (note3)
Note: Output Switch tests performed under pulsed conditions minimize power dissipation
Linear,
2478 Armstrong Street, Livermore, 94550 Tel: (925) 989-7144, Fax: (925) 940-9556
www.baylinear.com
B384X
Electrical Characteristics
(VCC 15V;RT 3.3nF, TA=0 +70°C, unless otherwise specified) Parameter Symbol Conditions
CURRENT SENSE SECTION Gain (Note Maximum input Signal VI(MAX) (Note Power Supply Rejection PSRR 12VVCC25V Ratio Input Bias Current IBIAS UNDER-VOLTAGE LOCKOUT SECTION B3842/B3844 Start Threshold VTH(ST) B3843/B3845 Min-Operating Voltage B3842/B3844 VOPR(MIN) (after Turn B3843/B3845 SECTION B3842/B3844 Duty Cycle D(MAX) B3843/B3845 Duty Cycle (MIN) TOTAL STANDBY CURRENT B3842A/43A/44A/45A Start-Up Current B3842A1/43A1/44A1/45A1 Operating Supply Current ICC(OPR) V3=V2=ON Zener Voltage 2.85
3.15 17.5 11.5
UNIT
14.5
0.17 0.45
Block Diagram
Linear,
2478 Armstrong Street, Livermore, 94550 Tel: (925) 989-7144, Fax: (925) 940-9556
www.baylinear.com
B384X
Figure Error Configuration
Figure Under-Voltage Lockout
3842
3843
Figure Current Sense Circuit
Linear,
2478 Armstrong Street, Livermore, 94550 Tel: (925) 989-7144, Fax: (925) 940-9556
www.baylinear.com
B384X
Linear,
2478 Armstrong Street, Livermore, 94550 Tel: (925) 989-7144, Fax: (925) 940-9556
www.baylinear.com
B384X
Figure Slope Conpensation Techigues
B3842A
B3842A
Figure 5:Latched Shutdown
Linear,
2478 Armstrong Street, Livermore, 94550 Tel: (925) 989-7144, Fax: (925) 940-9556
www.baylinear.com
B384X
Linear,
2478 Armstrong Street, Livermore, 94550 Tel: (925) 989-7144, Fax: (925) 940-9556
www.baylinear.com
B384X
Linear,
2478 Armstrong Street, Livermore, 94550 Tel: (925) 989-7144, Fax: (925) 940-9556
www.baylinear.com
B384X
Linear,
2478 Armstrong Street, Livermore, 94550 Tel: (925) 989-7144, Fax: (925) 940-9556
www.baylinear.com
Advance Information- These data sheets contain descriptions products that development. specifications based engineering calculations, computer simulations and/ initial prototype evaluation. Preliminary Information- These data sheets contain minimum maximum specifications that based initial device characterizations. These limits subject change upon completion full characterization over specified temperature supply voltage ranges.
application circuit examples only explain representative applications devices intended guarantee circuit design permit industrial property right other rights execute. Linear takes responsibility problems related industrial property right resulting from contents shown data book. Typical parameters vary different applications. Customer's technical experts must validate operating parameters including Typical" each customer application.
LIFE SUPPORT NUCLEAR POLICY Linear products authorized should used within life support systems which intended surgical implants into body support sustain life, aircraft, space equipment, submarine, nuclear facility applications without specific written consent Linear President.
Linear,
2478 Armstrong Street, Livermore, 94550 Tel: (925) 989-7144, Fax: (925) 940-9556
www.baylinear.com

Current Mode Controller B3842/43/44/45A&A1 Description

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