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UTC UC3842B / 3843B LINEAR INTEGRATED CIRCUIT
HIGH PERFORMANCE CURRENT MODE CONTROLLERS
DESCRIPTION
The UTC UC3842B/3843B are specifically designed for Off-Line and dc-to-dc converter applications offering the designer a cost-effective solution with minimal external components. The UC3842B has UVLO thresholds 16V (on) and 10V(off), ideally suited for off-line converters. The UC3843B is tailored for lower voltage applications having UVLO thresholds of 8.5V(on) and 7.6V(off).
SOP-8
FEATURES
*Trimmed Oscillator for Precise Frequency Control *Oscillator Frequency Guaranteed at 250kHz *Current Mode Operation to 500kHz *Automatic Feed Forward Compensation *Latching PWM for Cycle-By-Cycle Current Limiting *Internally Trimmed Reference with Undervoltage Lockout *High Current Totem Pole Output *Undervoltage Lockout with Hysteresis *Low Startup and Operating Current
DIP-8
BLOCK DIAGRAM
UTC
UNISONIC TECHNOLOGIES CO., LTD.
1
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UTC UC3842B / 3843B LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATINGS(Ta=25C)
PARAMETER
Total power supply and Zener current Output current, source or sink (note1) Output energy (capacitive load per cycle) Current sense and voltage feedback inputs Error Amp. Output sink current Power dissipation and thermal characteristics Operating junction temperature Operating ambient temperature Storage temperature range
SYMBOL
(ICC + Iz) Io W Vin Io PD PJA Tj TA Tstg
VALUE
30 1.0 5.0 -0.3 ~ +5.5 10 SOP: 702 SOP: 178 +150 0 ~ +70 -65 ~ +150
UNIT
mA A J V mA mW C/W C C C
DIP:1250 DIP: 100
ELECTRICAL CHARACTERISTICS (0C <=TA<=70C,VCC=15V[note 2],RT=10k,CT=3.3nF,unless
otherwise specified)
PARAMETER Reference Section
Output Voltage Line Regulation Load Regulation Temperature Stability Total Output Variation Output Noise Voltage Long Term Stability Output Short Circuit Current
SYMBOL
VREF Regline Regload Ts Vref Vn S ISC
TEST CONDITIONS
Io=1.0mA,Tj=25C Vcc=12V to 25V Io=1.0mA to 20mA Line, Load, Temperature F=10kHz to 10Hz,Tj=25C TA=125C,1000Hrs
MIN
4.9
TYP
5.0 2.0 3.0 0.2 50 5 -85 52 250 0.2 0.5 1.6
MAX
5.1 20 25 5.18
UNIT
V mV mV mV/C V uV mV mA kHz
4.82
-30 Tj=25C TA=0C to 70C Tj=25C (RT=6.2k,CT=1.0nF) 12<=Vcc<=25V 0C <=TA<=70C 49 48 225
-180 55 56 275 1.0
Oscillator Section
Frequency
Frequency Change with Voltage fOSC/V Frequency Change with fOSC/T Temperature Oscillator Voltage Swing(Peak to VOSC Peak) Discharge Current Idischg
% % V
Tj=25C 0C <=TA<=70C Vo=2.5V VFB=5.0V 2 <=Vo<=4V Tj=25C I2V<=Vcc<=25V Vo=1.1V,VFB =2.7V Vo=5.0V,VFB=2.3V VFB=2.3V, RL=15k to GND VFB=2.7V, RL=15k to Vref (note 3,4)
7.8 7.6 2.42 65 0.7 60 2.0 -0.5 5.0
8.3
8.8 8.8 2.58 -2.0
mA
Error Amplifier Section
Voltage Feedback Input Input Bias Current Open Loop Voltage Gain Unity Gain Bandwidth Power Supply Rejection Ratio Output Sink Current Output Source Current Output Voltage Swing High State Output Voltage Swing Low State VFB IIB AVOL BW PSRR Isink Isource VOH VOL Av 2.50 -0.1 90 1.0 70 12 -1.0 6.2 0.8 3.0 V A dB MHz dB mA mA V V V/V
1.1 3.15
Current Sense section
Current Sense Input Voltage Gain 2.85
UTC
UNISONIC TECHNOLOGIES CO., LTD.
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QW-R103-012,A
UTC UC3842B / 3843B LINEAR INTEGRATED CIRCUIT
PARAMETER
Maximum Current Sense Input Threshold Power Supply Rejection Ratio Input Bias Current Propagation Delay
SYMBOL
Vth PSRR IIB tPLH(In/O ut) VOL VOH VOL
(UVLO)
TEST CONDITIONS
(note 3) 12<=Vcc<=25V (note 3) Current Sense Input to Output
MIN
0.9
TYP
1.0 70 -2 150
MAX
1.1
UNIT
V dB A ns
-10 300
Output Section
Output Low Voltage Output High Level Output Voltage with UVLO Activated Output Voltage Rise Time Output Voltage Fall Time Isink=20mA Isink=200mA Isource=20mA Isource=200mA Vcc=6.0V,Isink=1.0mA Tj=25C,CL=1nF Tj=25C,CL=1nF UTC UC3842B UTC UC3843B UTC3842B UTC3843B 14.5 7.8 8.5 7.0 94 13 12 0.1 1.6 13.5 13.4 0.1 50 50 16 8.4 10 7.6 96 0 0.3 12 36 0.5 17 0.4 2.2 V V V V V ns ns V V V V % % mA mA V
1.1 150 150 17.5 9 11.5 8.2
tr tf Vth VCC(min)
Under-Voltage Lockout Section
Startup Threshold Min. Operating Voltage After Turn-on(Vcc)
PWM Section
Maximum Duty Cycle Minimum Duty Cycle DC(MAX) DC(MIN) Icc+Ic
Total Device
Power Startup Supply Current Vcc=6.5V for UC3843B Vcc=14V for UC3842B Power Operating Supply Current Icc+Ic Note2 Power Supply Zener Voltage Vz Icc=25mA Note 1:Maximum Package power dissipation limits must be observed. Note 2:Adject Vcc above the Startup threshold before setting to 15V. Note 3:This parameter is measured at the latch trip point with VFB=0V. Note 4:Comparator gain is defined as : V Output Compensation AV V Current Sense Input
30
UTC
UNISONIC TECHNOLOGIES CO., LTD.
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QW-R103-012,A
UTC UC3842B / 3843B LINEAR INTEGRATED CIRCUIT
TYPICAL PERFORMANCE CHARACTERISTICS
UTC
UNISONIC TECHNOLOGIES CO., LTD.
4
QW-R103-012,A
UTC UC3842B / 3843B LINEAR INTEGRATED CIRCUIT
UTC
UNISONIC TECHNOLOGIES CO., LTD.
5
QW-R103-012,A
UTC UC3842B / 3843B LINEAR INTEGRATED CIRCUIT
UTC
UNISONIC TECHNOLOGIES CO., LTD.
6
QW-R103-012,A
UTC UC3842B / 3843B LINEAR INTEGRATED CIRCUIT
UTC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all UTC products described or contained herein. UTC products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice.
UTC
UNISONIC TECHNOLOGIES CO., LTD.
7
QW-R103-012,A

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