www.fairchildsemi.com
UC3842A/UC3843A
SMPS Controller
Features
Description
•
•
•
•
•
•
•
The UC3842A/UC3843A are fixed PWM controller for OffLine 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 UC3842A/
UC3843A provide low start up current below 0.3mA and
short shutdown delay time typ. 100ns. The UC3842A has
UVLO threshold of 16V(on) and 10V(off). The UC3843A is
8.4V(on) and 7.6V(off). The UC3842A and UC3843A can
operate within 100% duty cycle.
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
8-DIP
1
8-SOP
1
Internal Block Diagram
7 VCC
29V
5V
VREF
VREF 8
SET/
RESET
5 GND
UVLO
Internal
Bias
Good LOGIC
7 PWR
VC
1/2VREF
VFB 2
Error Amp
+
-
C.S
PWM
Comp. LATCH
1/3
R
22V
1V
6 OUTPUT
S
COMP 1
5 PWR
T
C.S 3
RT/CT 4
GND
OSCILLATOR
Rev. 5.0
©2000 Fairchild Semiconductor International
UC3842A/UC3843A
Absolute Maximum Ratings
Parameter
Supply Voltage
Output Current
Analog Inputs (pin 2, 3)
Error Amp. Output Sink Current
Power Dissipation
Symbol
Value
Unit
VCC
30
V
IO
±1
A
VI(ANA)
- 0.3 to 6.3
V
ISINK(EA)
10
mA
PD
1
W
Electrical Characteristics
(VCC = 15V, RT = 10KΩ, CT = 3.3nF, TA = 0°C to + 70°C ,Unless otherwise specified)
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Unit
REFERENCE SECTION
Output Voltage
VREF
4.9
5.0
5.1
V
Line Regulation
∆VREF
VCC = 12V to 25V
-
6
20
mV
Load Regulation
Output Short Circuit
∆VREF
ISC
IO = 1mA to 20mA
Ta = 25°C
-
Initial Accuracy
FOSC
TJ = 25°C
47
52
57
KHz
Voltage Stability
Amplitude
STV
VOSC
VCC = 12V to 25V
VPIN4, Peak to Peak
-
0.2
1.7
1
-
%
V
IDISCHG
TJ = 25°C, Pin4 = 2V
7.8
8.3
8.8
mA
GV
VI(MAX)
(NOTE 2, 3)
VPIN1 = 5V(NOTE 2)
2.85
0.9
3
1.0
3.15
1.1
V/V
V
TJ = 25°C, IO = 1mA
6
25
- 100 - 180
mV
mA
OSILLATOR SECTION
Discharge Current
CURRENT SENSE SECTION
Gain
Maximum Input Signal
PSRR
PSRR
Input Bias Current
IBIAS
Delay to Output
2
TD
VCC = 12V to 25V (NOTE 1, 2)
VPIN3 = 0 V to 2V (NOTE1)
-
70
-
dB
-
-2
-10
uA
-
100
200
ns
UC3842A/UC3843A
Electrical Characteristics (Continued)
(VCC = 15V, RT = 10KΩ, CT = 3.3nF, TA = 0°C to + 70°C, Unless otherwise specified)
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Unit
2.42
2.50
2.58
V
-
-0.3
-2
uA
ERROR AMPLIFIER SECTION
Input Voltage
Input Bias Current
VI
TPIN1 = 2.5V
-
IBIAS
Open Loop Gain
GVO
VO = 2V to 4V (NOTE 1)
65
90
-
dB
Unity Gain Bandwidth
GBW
TJ= 25°C (NOTE 1)
0.7
1
-
MHz
PSRR
PSRR
VCC = 12V to 25V (NOTE 1)
60
70
-
dB
Output Sink Current
ISINK
VPIN2 = 2.7V
VPIN1 = 1.1V
2
6
-
mA
ISOURCE
VPIN2 = 2.3V
VPIN1 = 5.0V
-0.5
-0.8
-
mA
Output Source Current
Output High Voltage
VOH
VPIN2 = 2.3V
R1 = 15KΩ to GND
5
6
-
V
Output Low Voltage
VOL
VPIN2 = 2.7V
R1 = 15KΩ to Pin8
-
0.8
1.1
V
VOL
ISINK = 20mA
-
0.1
0.4
V
ISINK = 200mA
-
1.5
2.2
V
ISOURCE = 20mA
13
13.5
-
V
ISOURCE = 200mA
12
13.5
-
V
OUTPUT SECTION
Output Low Level
Output High Level
VOH
Rise Time
tR
TJ = 25°C, C1 = 1nF (NOTE 1)
-
40
100
ns
Fall Time
tF
TJ = 25°C, C1 = 1nF (NOTE 1)
-
40
100
ns
VCC = 27V, C1 = 1nF
-
22
-
V
UC3842A
15
16
17
V
Output Voltage Swing Limit
VOLIM
UNDER VOLTAGE LOCKOUT SECTION
Start Threshold
Min. Operating Voltage
( After turn on )
VTH
VTL
UC3843A
7.8
8.4
9.0
V
UC3842A
9
10
11
V
UC3843A
7.0
7.6
8.2
V
UC3842A/UC3843A
94
96
100
%
PWM SECTION
Maximum Duty Cycle
DMAX
Minimum Duty Cycle
DMIN
-
-
-
0
%
Start-Up Current
IST
-
-
0.2
0.4
mA
Operating Supply Current
ICC
VPIN2 = VPIN3 = 0V
-
11
17
mA
VCC Zener Voltage
VZ
ICC = 25mA
-
29
-
V
TOTAL STANDBY CURRENT
* 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 V2 = 0V.
3. Gain defined as: GV = ∆VPIN1∆VPIN3(VPIN3 = 0 to 0.8V)
3
UC3842A/UC3843A
Mechanical Dimensions
Package
1.524 ±0.10
#5
2.54
0.100
5.08
MAX
0.200
7.62
0.300
3.40 ±0.20
0.134 ±0.008
+0.10
0.25 –0.05
+0.004
0~15°
4
0.010 –0.002
3.30 ±0.30
0.130 ±0.012
0.33
0.013 MIN
0.060 ±0.004
#4
0.018 ±0.004
#8
9.60
MAX
0.378
#1
9.20 ±0.20
0.362 ±0.008
(
6.40 ±0.20
0.252 ±0.008
0.46 ±0.10
0.79
)
0.031
8-DIP
UC3842A/UC3843A
Mechanical Dimensions (Continued)
Package
8-SOP
MIN
#5
6.00 ±0.30
0.236 ±0.012
8°
0~
+0.10
0.15 -0.05
+0.004
0.006 -0.002
MAX0.10
MAX0.004
1.80
MAX
0.071
3.95 ±0.20
0.156 ±0.008
5.72
0.225
0.41 ±0.10
0.016 ±0.004
#4
1.27
0.050
#8
5.13
MAX
0.202
#1
4.92 ±0.20
0.194 ±0.008
(
0.56
)
0.022
1.55 ±0.20
0.061 ±0.008
0.1~0.25
0.004~0.001
0.50 ±0.20
0.020 ±0.008
5
UC3842A/UC3843A
Ordering Information
6
Product Number
Package
UC3842AN
8 DIP
UC3842AD
8 SOP
UC3843AN
8 DIP
UC3843AD
8 SOP
Operating Temperature
0 ~ + 70°C
UC3842A/UC3843A
7
UC3842A/UC3843A
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
INTERNATIONAL. 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.
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.
www.fairchildsemi.com
7/12/00 0.0m 001
Stock#DSxxxxxxxx
” 2000 Fairchild Semiconductor International
Product Folder - Fairchild P/N UC3842A - SMPS Controller
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spaceOptoelectronics
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The UC3842A/UC3843A are fixed
applications
PWM controller for Off-Line and DC to This pagePrint version
New products
DC converter applications. The internal
Product selection and
circuits include UVLO, low start up
current circuit, temperature
parametric search
compensated reference, high gain error
Cross-reference
amplifier, current sensing comparator,
search
and high current totem-pole out-put for
driving a POWER MOSFET. Also
technical information
UC3842A/ UC3843A provide low start
up current below 0.3mA and short
buy products
shutdown delay time typ. 100ns. The
technical support
UC3842A has UVLO threshold of
16V(on) and 10V(off). The UC3843A
my Fairchild
is 8.4V(on) and 7.6V(off). The
space
UC3842A and UC3843A can operate
company
within 100% duty cycle.
back to top
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
back to top
file:///D|/PDF/UC3842A.html (1 of 2) [26-Jul-2002 2:32:43 PM]
Application
notes
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(PCNs)
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Product Folder - Fairchild P/N UC3842A - SMPS Controller
Product status/pricing/packaging
Product
Product status
Package type
Leads
Packing method
UC3842AN
Full Production
DIP
8
RAIL
UC3842AD
Full Production
SOIC
8
RAIL
UC3842ADX
Full Production
SOIC
8
TAPE REEL
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© Copyright 2002 Fairchild Semiconductor
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file:///D|/PDF/UC3842A.html (2 of 2) [26-Jul-2002 2:32:43 PM]
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Product Folder - Fairchild P/N UC3843A - SMPS Controller
SEARCH | Parametric | Cross Reference
space
Fairchild Semiconductor
space
GO
space
space
Product Folders and
Datasheets
space
space
space >> Find products >>
Home
find products
space
space
space
UC3843A
Products groups
SMPS Controller
Analog and Mixed
Signal
Datasheet
Contents
Discrete
Download this
General description | Features | Product
Interface
datasheet
status/pricing/packaging
Logic
PDF
space
Microcontrollers
Non-Volatile
General description
Memory
e-mail this datasheet
spaceOptoelectronics
[EMarkets and
mail]
The UC3842A/UC3843A are fixed
applications
PWM controller for Off-Line and DC to This pagePrint version
New products
DC converter applications. The internal
Product selection and
circuits include UVLO, low start up
current circuit, temperature
parametric search
compensated reference, high gain error
Cross-reference
amplifier, current sensing comparator,
search
and high current totem-pole out-put for
driving a POWER MOSFET. Also
technical information
UC3842A/ UC3843A provide low start
up current below 0.3mA and short
buy products
shutdown delay time typ. 100ns. The
technical support
UC3842A has UVLO threshold of
16V(on) and 10V(off). The UC3843A
my Fairchild
is 8.4V(on) and 7.6V(off). The
space
UC3842A and UC3843A can operate
company
within 100% duty cycle.
back to top
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
back to top
file:///D|/PDF/UC3843A.html (1 of 2) [26-Jul-2002 2:32:58 PM]
Application
notes
Related Links
Request samples
Dotted line
How to order products
Dotted line
Product Change Notices
(PCNs)
Dotted line
Support
Dotted line
Distributor and field sales
representatives
Dotted line
Quality and reliability
Dotted line
Design tools
Product Folder - Fairchild P/N UC3843A - SMPS Controller
Product status/pricing/packaging
Product
Product status
Package type
Leads
Packing method
UC3843AD
Full Production
SOIC
8
RAIL
UC3843ADX
Full Production
SOIC
8
TAPE REEL
UC3843AN
Full Production
DIP
8
RAIL
back to top
space
Home | Find products | Technical information | Buy products |
Support | Company | Contact us | Site index | Privacy policy
space
© Copyright 2002 Fairchild Semiconductor
space
file:///D|/PDF/UC3843A.html (2 of 2) [26-Jul-2002 2:32:58 PM]
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