UNISONIC TECHNOLOGIES CO., LTD UC3842G

UNISONIC TECHNOLOGIES CO., LTD UC3842G
UNISONIC TECHNOLOGIES CO., LTD
UC3842G
LINEAR INTEGRATED CIRCUIT
HIGH PERFORMANCE
CURRENT MODE
CONTROLLER
■
FEATURES
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The UTC UC3842G of high performance current mode
controller is specifically designed for off-line and DC-to-DC
converter applications offering the designer a cost effective
solution with minimal external components. This integrated
circuit features approximately 300μA start up current, a
precision reference trimmed the error amplifier input. Also
included are protective features consisting of input and
reference undervoltage lockouts each with hysteresis,
cycle-by-cycle current limiting, and so on.
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DESCRIPTION
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Lead-free:
UC3842GL
Halogen-free: UC3842GP
ORDERING INFORMATION
Ordering Number
Lead Free
UC3842GL-S08-R
UC3842GL-S08-T
UC3842GL-D08-T
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* Low startup and operating current
* User defined switching frequency(Norm is 52kHz)
* Power-saving mode for low power
* Under voltage lockout with hysteresis
* Over voltage protection
* Latching PWM for Cycle-By-Cycle current limiting
* Internally trimmed reference with undervoltage lockout
Halogen Free
UC3842GP-S08-R
UC3842GP-S08-T
UC3842GP-D08-T
Package
Packing
SOP-8
SOP-8
DIP-8
Tape Reel
Tube
Tube
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Normal
UC3842G-S08-R
UC3842G-S08-T
UC3842G-D08-T
www.unisonic.com.tw
Copyright © 2008 Unisonic Technologies Co., Ltd
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UC3842G
LINEAR INTEGRATED CIRCUIT
PIN CONFIGURATION
FB 2
7 VCC
CS 3
6 OUT
CT 4
5 GND
PIN DESCRIPTION
PIN NAME
COMP
FB
CS
CT
GND
OUT
VCC
VREF
I/O
O
I
I
I
O
O
Function
This pin is error amplifier output
The error amplifier inverting input
Current sense input
The capacitor controlling switch frequency
Ground
Output to the gate of external power MOS
Supply voltage
Inter 5V reference voltage output
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PIN NO.
1
2
3
4
5
6
7
8
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8 VREF
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COMP 1
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QW-R103-036.B
UC3842G
BLOCK DIAGRAM
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LINEAR INTEGRATED CIRCUIT
UNISONIC TECHNOLOGIES CO., LTD
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QW-R103-036.B
UC3842G
„
LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATINGS (Ta=25°C)
„
ELECTRICAL CHARACTERISTICS
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(0°C≤Ta≤70°C, VCC=15V, CT=3.3nF , unless otherwise specified)
PARAMETER
SYMBOL
TEST CONDITION
STANDBY SECTION
Reduce Frequency Point of Standby Mode
VCOMP
Right load
REFERENCE SECTION
Reference Output Voltage
VREF
IOUT=1.0mA
Line Regulation
ΔVREF
12V≤VCC≤25V
Load Regulation
ΔVREF
IOUT=1.0mA to 20mA
Output Short Circuit Current
ISC
OSCILLATOR SECTION
Frequency
fOSC
Normal
Frequency Change
ΔfOSC/ΔV 12V≤VCC≤25V
VOSC(P-P)
Oscillator Voltage
VOSCL
VOSCH
ERROR AMPLIFIER SECTION
Input Voltage
VI(EA)
VCOMP=2.5V
Input Bias Current
II(BIAS)
VFB=5V
AVOL
2V≤VOUT≤4V
Unity Gain Bandwidth
TJ=25°C(Note1)
PSRR
12V≤VCC≤25V
Output Sink Current
ISINK
VFB=2.7V, VCOMP=1.1V
Output Source Current
ISOURCE VFB=2.3V, VCOMP=5V
VOUT High
VOH
VFB=2.3V, RL=15K to GND
VOUT Low
VOL
VFB=2.7V, RL=15K to VREF
CURRENT SENSE SECTION
Gain
GV
(Note2,3)
Maximum Input Signal
VI(MAX)
VCOMP=5V(Note2)
PSRR
12V≤VCC≤25V
Input Bias Current
IBIAS
Delay to Output
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PARAMETER
SYMBOL
RATINGS
UNIT
Supply Voltage (Low Impedance Source)
VCC
30
V
Supply Voltage (ICC<30mA)
VCC
Self Limiting
V
Output Current (Peak)
IO(PEAK)
±1
A
Output Energy (Capacity load)
5
μJ
Junction Temperature
TJ
+150
°C
Operating Temperature
TOPR
-40 ~ +125
°C
Storage Temperature
TSTG
-65 ~ +150
°C
Note: 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.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
MIN
4.95
-30
49
2.42
60
0.7
60
2
-0.5
5.0
2.85
0.9
TYP
MAX
2.2
UNIT
V
5.0
3
8
-65
5.05
20
25
-180
V
mV
mV
mA
52
0.2
1.6
1.2
2.8
55
1.0
KHz
%
2.50
-0.3
90
1
70
4
1
5.6
0.8
2.58
-2
3
1
70
-2
150
3.15
1.1
V
V
V
1.1
-10
300
V
μA
dB
MHz
dB
mA
mA
V
V
V/V
V
dB
μA
nS
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UC3842G
ELECTRICAL CHARACTERISTICS (Cont.)
PARAMETER
OUTPUT SECTION
SYMBOL
Output Voltage With UVLO Active
VOL(UVLO)
VOL
Output Voltage
VOH
tR
tF
Output Voltage Rise and Fall time
TEST CONDITION
VCC=6V,ISINK=0.1mA;
VCC=7.5V,ISINK=1mA
ISINK=20mA
ISINK=200mA
ISOURCE=20mA
ISOURCE=200mA
CL=1.0nF(Note1)
CL=1.0nF(Note1)
MIN
TYP
0.8
1.1
V
0.1
1.6
14.5
14.6
100
100
0.4
2.2
V
V
V
V
150
150
nS
13.5
8.5
15
10
16.5
11.5
V
V
92
94
0
%
%
10
40
V
mA
μA
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UNDER VOLTAGE LOCKOUT SECTION
Startup Threshold
VTH(STAR-UP)
Min Operating Voltage
VOPR(MIN) After Turn-ON
PWM SECTION
Max Duty Cycle
DMAX
Minimum Duty Cycle
DMIN
TOTAL DEVICE
Power Supply Zener Voltage
VZ
ICC=25mA
Power Operating Supply Current
ICC
Note2
Startup Current
ISTART-UP VCC=14V,UVLO Active
Note: 1. These parameters, although guaranteed, are not 100% tested in production.
2. Parameters measured at trip point of latch with VFB=0.
3. Gain defined as: A=ΔVCOMP/ΔVCS; 0≤VCS≤0.8V
30
39
7
15
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MAX UNIT
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LINEAR INTEGRATED CIRCUIT
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QW-R103-036.B
UC3842G
OPEN-LOOP TEST CIRCUIT
VCOMP
VREF 8
10p
VFB
or
1 COMP
2 FB
VCC 7
VCC
Vpwl
adjust
3 CS
Output 6
4 CT
GND 5
5K
CT
3.3n
CIN
470μ
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Ra
100k
VIN
Rb
100k
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LINEAR INTEGRATED CIRCUIT
High peak current associated with capacity loads necessitate careful grounding techniques. Timing and bypass
capacitors should be connected close to pin5 in single point GND.
UNDER-VOLTAGE LOCKOUT
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ERROR AMPLIFIER CONFIGURATION
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During Under-Voltage Lockout, the output driver is biased to a high impedance state. Pin6 should be shunt to
GND with a bleeder resistor to prevent activing the power switch with output leakage currents.
Error amplifier can source or sink up to 0.5mA
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6 of 8
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UC3842G
„
LINEAR INTEGRATED CIRCUIT
CURRENT SENSE CIRCUIT
Error Amplifier
2R
Is
R
1
R
Rs
C
1V
Current Sense Comparator
3
5
„
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Peak current (IS) determined by the formula: ISMAX=1V/Rs. A small RC filter be required to suppress switch
transients
OSCILLATOR AND STANDBY MODE
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We can judge the state of output load through the voltage of PIN1. In order to reduce the standby power, it will
reduce the OSC frequency at right load. When VCOMP≤2.2V, the OSC frequency begins to reduce. The normal
frequency is 52KHz, the minimum frequency is 14KHz.
Standby mode
Minimum frequency :14KHz
2.2V
Increase
1.2V
Normal
Frequency: 52KHz
OSC triangle wave
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Normal
Frequency: 52KHz
VCOMP
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UC3842G
SHUTDOWN TECHNIQUE
1kΩ
Shutdown
330Ω
3
500Ω
Shutdown
1
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LINEAR INTEGRATED CIRCUIT
To current
Sense resistor
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Shutdown UTC UC3842G can be accomplished by two methods; either raise pin 3 above 1V or pull Pin 1
below a voltage two diode drops above ground.
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.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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QW-R103-036.B
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