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KA3843AC
SMPS Controller
Features
* * * * * * * Low start current 0.2mA (typ) Operating range up to 500kHz Cycle by cycle current limiting Under voltage lock out with hysteresis Short shutdown delay time: typ.100ns High current totem-pole output Output swing limiting: 22V
Description
The KA3843AC are fixed PWM controller for Off-Line and DC to DC converter applications. The internal circuits include UVLO, low start up current circuit, temperature compensated reference, high gain error amplifier, current sensing comparator, and high current totem-pole output for driving a POWER MOSFET. Also KA3843AC provide low start up current below 0.3mA and short shutdown delay time typ. 100ns. The KA3843AC is 8.4V(on) and 7.6V(off). The KA3843AC can operate within 100% duty cycle.
8-DIP
1
8-SOP
1
Internal Block Diagram
7 VCC 29V
VREF 8
Internal Bias 1/2VREF
5V VREF
SET/ RESET UVLO
5 GND
Good LOGIC 7 Error Amp + C.S PWM Comp. LATCH 1/3 1V S R 22V 6 OUTPUT
PWR VC
VFB 2
COMP 1
5 PWR
C.S 3 RT/CT 4
T
GND
OSCILLATOR
Rev. 1.0.1
(c)2005 Fairchild Semiconductor Corporation
KA3843AC
Absolute Maximum Ratings
Parameter Supply voltage Output current Analog inputs (pin2, 3) Error amp. output sink current Power dissipation Symbol VCC IO VI(ANA) ISINK(EA) PD Value 30 +1 -0.3 to 6.3 10 1 Unit V A V mA W
Electrical Characteristics
(VCC = 15V, RT = 10KW, CT = 3.3nF, TA = 0C to +70C ,Unless otherwise specified) Parameter REFERENCE SECTION Output voltage Line regulation Load regulation Output short circuit OSILLATOR SECTION Initial accuracy Voltage stability Amplitude Discharge current CURRENT SENSE SECTION Gain Maximum input signal PSRR Input bias current Delay to output GV VI(MAX) PSRR IBIAS TD (Note2, 3) VPIN1 = 5V(Note2) VCC = 12V to 25V (Note1, 2) VSENSE=0V VPIN3 = 0 V to 2V (Note1) 2.85 0.9 3 1.0 70 -2 100 3.15 1.1 -10 200 V/V V dB uA ns FOSC STV VOSC IDISCHG TJ = 25C VCC = 12V to 25V VPIN4, peak to peak TJ = 25C 47 7.8 52 0.2 1.7 8.3 57 1 8.8 kHz % V mA VREF RLine RLOAD ISC TJ = 25C, IO = 1mA VCC = 12V to 25V IO = 1mA to 20mA Ta = 25C 4.9 5.0 6 6 -100 5.1 20 25 -180 V mV mV mA Symbol Conditions Min. Typ. Max. Unit
Notes: 1. These parameters, although guaranteed, are not 100% tested in production. 2. Parameter measured at trip point of latch with VFB = 0V. V COMP 3. Gain defined as: G V = ------------------------ ;O V SENSE 0.8V V SENSE
2
KA3843AC
Electrical Characteristics (Continued)
(VCC = 15V, RT = 10KW, CT = 3.3nF, TA = 0C to +70C, Unless otherwise specified) Parameter ERROR AMPLIFIER SECTION Input voltage Input bias current Open loop gain Unity gain bandwidth PSRR Output sink current Output source current Output high voltage Output low voltage OUTPUT SECTION Output Low Level Output high level Rise time Fall time Output voltage swing limit VOL VOH tR tF VOLIM ISINK = 20mA ISINK = 200mA ISOURCE = 20mA ISOURCE = 200mA TJ = 25C, C1 = 1nF (Note1) TJ = 25C, C1 = 1nF (Note1) VCC = 27V, C1 = 1nF KA3882E KA3883E KA3882E KA3883E KA3882E/KA3883E VPIN2 = VPIN3 = 0V ICC = 25mA 13 12 15 7.8 9 7.0 94 0.1 1.5 13.5 13.5 40 40 22 16 8.4 10 7.6 96 0.2 11 29 0.4 2.2 100 100 17 9.0 11 8.2 100 0 0.4 17 V V V V ns ns V V V V V % % mA mA V VI IBIAS GVO GBW PSRR ISINK ISOURCE VOH VOL VPIN1 = 2.5V VFB=0V VO = 2V to 4V (Note1) TJ= 25C (Note1) VCC = 12V to 25V (Note1) VPIN2 = 2.7V, VPIN1 = 1.1V VPIN2 = 2.3V, VPIN1 = 5.0V VPIN2 = 2.3V R1 = 15K to GND VPIN2 = 2.7V R1 = 15k to Vref 2.42 65 0.7 60 2 -0.5 5 2.50 -0.3 90 1 70 6 -0.8 6 0.7 2.58 -2 1.1 V uA dB MHz dB mA mA V V Symbol Conditions Min. Typ. Max. Unit
UNDER VOLTAGE LOCKOUT SECTION Start threshold Min. operating voltage ( after turn on ) PWM SECTION Maximum duty cycle Minimum duty cycle TOTAL STANDBY CURRENT Start-up current Operating supply current VCC zener voltage IST ICC VZ DMAX DMIN VTH VTL
* Adjust VCC above the start threshold before setting at 15V Notes : 1. These parameters, although guaranteed, are not 100% tested in production. 2. Parameter measured at trip point of latch with VFB = 0V. V COMP 3. Gain defined as: G V = ------------------------ ;O V SENSE 0.8V V SENSE
3
KA3843AC
Mechanical Dimensions
Package Dimensions in millimeters
8-DIP
1.524 0.10 0.018 0.004 0.060 0.004 0.46 0.10 6.40 0.20 0.252 0.008 0.79 ) 0.031 #8 9.20 0.20 0.362 0.008 9.60 MAX 0.378 #5 2.54 0.100 5.08 MAX 0.200 7.62 0.300 3.40 0.20 0.134 0.008 3.30 0.30 0.130 0.012 0.33 MIN 0.013
#1
#4
0.25 -0.05
0~15
+0.10
0.010 -0.002
+0.004
4
(
KA3843AC
Mechanical Dimensions (Continued)
Package Dimensions in millimeters
8-SOP
5
KA3843AC
Ordering Information
Product Number KA3843AC KA3843ACD Package 8-DIP 8-SOP Operating Temperature 0 ~ +70C
DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. LIFE SUPPORT POLICY FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR 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, and (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 a significant injury of the user.
www.fairchildsemi.com 3/2/05 0.0m 001 Stock#DSxxxxxxxx " 2005 Fairchild Semiconductor Corporation
2. A critical component in 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.

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