Document
UNISONIC TECHNOLOGIES CO., LTD
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 8.4V(on) and 7.6V(off).
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
ORDERING INFORMATION
Ordering Number
Lead Free
Halogen Free
UC3842BL-D08-T
UC3842BP-D08-T
UC3842BL-S08-R
UC3842BP-S08-R
UC3843BL-D08-T
UC3843BP-D08-T
UC3843BL-S08-R
UC3843BP-S08-R
Package
DIP-8 SOP-8 DIP-8 SOP-8
Packing
Tube Tape Reel
Tube Tape Reel
www.unisonic.com.tw Copyright © 2019 Unisonic Technologies Co., Ltd
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QW-R103-012.G
UC3842B/3843B
MARKING
Package
DIP-8
UC3842B
SOP-8
PIN CONFIGURATION
COMP 1 VFB 2 CS 3
RTCT 4
LINEAR INTEGRATED CIRCUIT
UC3843B
876 5
UTC UC3843B
1 23 4
Date Code
L: Lead Free P: Halogen Free Lot Code
8 VREF 7 VCC 6 OUTPUT 5 GND
PIN DESCRIPTIONS
PIN NO. 1
PIN NAME COMP
I/O O
2 VFB I
3 CS I
4
RTCT
I
5 GND
6
OUTPUT
O
7 VCC
8
VREF
O
DESCRIPTION Error amp output to provide loop compensation maintaing VFB at 2.5V Error amp inverting input, The non-inverting input of error amp is 2.5V band gap reference Current sense input to PWM control gate drive of output To set oscillator frequency and maximum output duty cycle Power ground To direct drive power MOSFET Power supply 5V regulated output provides charging current for CT through RT
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
2 of 11
QW-R103-012.G
UC3842B/3843B
BLOCK DIAGRAM
LINEAR INTEGRATED CIRCUIT
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
3 of 11
QW-R103-012.G
UC3842B/3843B
LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATINGS(TA=25°C, unless otherwise specified)
PARAMETER
SYMBOL
RATINGS
UNIT
Total Power Supply and Zener Current
(ICC + IZ)
30
mA
Output Current, Source or Sink (Note 2) Output Energy (capacitive load per cycle)
IO W
1.0 A 5.0 μJ
Current Sense and Voltage Feedback Inputs Error Amp. Output Sink Current
VIN IO(SINK)
-0.3 ~ +5.5 10
V mA
Power Dissipation
DIP-8 SOP-8
PD
1250 800
mW mW
Operating Junction Temperature Operating Temperature
TJ TOPR
+150 0 ~ +70
°C °C
Storage Temperature
TSTG
-65 ~ +150
°C
Notes: 1. Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional device operation is not implied.
2. Maximum Package power dissipation limits must be observed.
THERMAL DATA
PARAMETER Junction to Ambient
DIP-8 SOP-8
SYMBOL θJA
RATINGS 100 156
UNIT C/W C/W
ELECTRICAL CHARACTERISTICS
(0°C ≤TA≤70°C, VCC=15V (Note 1), RT=10k, CT=3.3nF, unless otherwise specified)
PARAMETER
SYMBOL
TEST CONDITIONS
REFERENCE SECTION Output Voltage Line Regulation Load Regulation Temperature Stability Total Output Variation Output Noise Voltage Long Term Stability Output Short Circuit Current
VREF ∆VLINE ∆VLOAD
TS VREF eN
S ISC
IO=1.0mA, TJ =25°C VCC=12V ~ 25V IO=1.0mA ~ 20mA
Line, Load, Temperature F=10kHz ~ 10Hz, TJ =25°C TA=125°C,1000Hrs
OSCILLATOR SECTION
Frequency
Frequency Change with Voltage Frequency Change with Temperature Oscillator Voltage Swing (Peak to Peak)
F fOSC/V
TJ =25°C TA=0°C ~ 70°C TJ =25°C (RT=6.2k,CT=1.0nF) 12 ≤ VCC ≤25V
fOSC/T 0°C ≤TA ≤70°C
VOSC
Discharge Current
IDISCHG
TJ =25°C 0°C ≤TA ≤70°C
MIN 4.9
4.82
-100 49 48 225
7.8 7.6
TYP
5.0 2.0 15 0.2
50 5 -155
52
250 0.2 0.5
1.6 8.3 8.3
MAX UNIT
5.1 20 35
5.18
-245
V mV mV mV/°C V μV mV mA
55 56 kHz 275 1.0 %
%
V
8.8 8.8
mA
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
4 of 11
QW-R103-012.G
UC3842B/3843B
LINEAR INTEGRATED CIRCUIT
ELECTRICAL CHARACTERISTICS (Cont.)
PARAMETER
SYMBOL
TEST CONDITIONS
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
CURRENT SENSE SECTION Current Sense Input Voltage Gain Maximum Current Sense Input Threshold
VFB II(BIAS) GVO GBW PSRR ISINK ISOURCE VOH VOL
GV
VI(THR)
Vo=2.5V VFB=5.0V 2 ≤VO≤4V TJ =25°C 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 2, 3)
(Note 2)
P.