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Электронный компонент: IL3842

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TECHNICAL DATA
IL3842
Fixed Frequency Current Mode PWM Controller


DESCRIPTION
Fixed frequency current-mode PWM controller. It is specially designed
for Off Line And DC-to-DC converter applications with minimal external
component. This integrated circuit features a trimmed oscillator for
precise duty cycle control. a temperature compensated reference, high
gain arror amplifier, current sensing comparator, and a high current
totempole output ideally suited for driving a power MOSFET.
Protection circuitry includes built in under-voltage lockout and current
limiting
.

FEATURES
Automatic Feed Forward Compensation
High Gain Totem Pole Output
Internally Trimmed Bandgap Reference
Undervoltage Lockout with Hysteresis
Low Start Up Current
Optimized for offline converter
Double pulse suppression
Current mode operation to 500KHz









ORDERING INFORMATION
Device
Operating
Temperature Range
Package
IL3842 T
A
=0 to +70C
DIP-8










1
IL3842



PIN FUNCTION DESCRIPTION
Pin
No.
Function Description
1 Compensation
This pln is the Error Amplifier output and is made available for loop compensation
2 Voltage
Feedback This is the inverting input of the Error Amplifier. It is normally connected to the switching
power supply outpul through a resistor divider.
3 Current
Sense
A voltage proportional to inductor current is connected to this input. The PWM uses this.
information to terminate the output switch conduction
4 RT/CT
The Oscillator frequency and maximum Output duty cycle are programmed by connecting
resistor R
T
to V
REF
and capacitor C
T
to ground. Operation to 500kHz is possible.
5 GND
This pin is the combined conlrol circuitry and power ground
6 Output
This output directly drives the gate of a power MOSFET. Peak currents up to 1,0A are
sourced and sunk by this pin.
7 Vcc
This pin is the positive supply of the control IC.
8 V
REF
This is the reference output. It provides chsarging current for capacitor C
T
through resistor
R
T





ABSOLUTE MAXIMUM RATINGS
Characteristic Symbol
Value
Unit
Total Power Supply and Zener Current
(I
CC
+ I
Z
) 30
mA
Output Current
I
O
1.0
A
Output Energy (Capacitive Load per Cycle)
W
5.0
J
Error Amp Output Sink Current
I
OE
10 mA
Current Sense and Voltage Feedback Inputs
Vin
-0.3 to 5.5
V
Maximum Power Dissipation @ T
A
= 25
o
C:
P
D
0.862 W
Thermal Resistance,Junction-to-Air
R
JA
145 C/W
Operating Junction Temperature
T
J
+150
o
C
Storage Temperature Range
T
stg
-65 ~ +150
o
C










2
IL3842



ELECTRICAL CHARACTERISTICS
(Vcc=15V unless otherwise noted)
Characteristics Symbol
Min
Max
Unit
REFERENCE SECTION
Reference Output Voltage (I
O
=1.0mA, V
CC
=15V,T
A
=25
10C)
(I
O
=1.0mA, V
CC
=15V,T
A
= Tlow to Thigh)
V
ref
4.9
4.865
5.1
5.135
V
Line Regulation (V
CC
=12V to 25V,T
A
=Tlow to Thigh) Reg
line
20
mV
Load Regulation (I
O
=1.0 to 20mA,T
A
=Tlow to Thigh)
Reg
load
25
mV
Total Output Variation over Line,Load,Temperature
(Note1)
(V
CC
=12V, I
O
=1.0mA,T
A
=Tlow to Thigh)
(V
CC
=25V, I
O
=20mA,T
A
=Tlow to Thigh)
Vfinal 4.82 5.18 V
Output Short Circuit Current (V
CC
=15V) I
SC
-30 -180 mA
OSCILLATOR SECTION
Frequency (V
CC
=15V,Tj=25C,R
T
=10k,C
T
=3.3nF)
(V
CC
=15V, T
A
=Tlow to Thigh,R
T
=10k,C
T
=3.3nF)
f
osc
47
46
57
60
kHz
Frequency Change with Voltage
(V
CC
=12V to 25V, T
A
=Tlow to Thigh,R
T
=10k,C
T
=3.3nF)
f
osc
/V 1.0 %
Discharge Current (Vosc=2.0V, V
CC
=15V)
Tj=25C
T
A
=Tlow to Thigh
Idisch
7.5
7.2
9.3
9.5
mA
ERROR AMPLIFIER SECTION
Voltage Feedback Input (V
O
=2.5V,V
CC
=15V, T
A
=Tlow to Thigh)
V
FB
2.42 2.58 V
Input Bias Current (V
FB
=2.7V,V
CC
=15V, T
A
=Tlow to Thigh)
I
IB
-2.0
A
Open Loop Voltage Gain
(V
O
=2.0V to 4.0V,V
CC
=15V, T
A
=Tlow to Thigh)
A
VOL
65 dB
Unity Gain Bandwidth (V
CC
=15V, T
A
=Tlow to Thigh)
BW
0.7
MHz
Power Supply Rejection Ratio
(V
CC
=12V to 25V, T
A
=Tlow to Thigh)
PSRR
60
dB
Output Current
Sink (V
O
=1.1V,V
FB
=2.7V, V
CC
=15V, T
A
=Tlow to Thigh)
Source (V
O
=5.0V,V
FB
=2.3V, V
CC
=15V, T
A
=Tlow to Thigh)
I
Sink
I
Source
2.0
-0.5
mA
Output Voltage Swing
High State (V
FB
=2.3V, V
CC
=15V,R
L(GND)
=15k, T
A
=Tlow to Thigh)
Low State (V
FB
=2.7V, V
CC
=15V,R
L(5.0)
=15k, T
A
=Tlow to Thigh)
V
OH
V
OL
5.0

1.1
V
CURRENT SENSE SECTION
Current Sense Input Voltage Gain
(V
FB
=0V, V
CC
=15V, T
A
=Tlow to Thigh)
Av
2.85
3.15
V/V
Maximum Current Sense Input Threshold
(V
FB
=0V, V
CC
=15V, T
A
=Tlow to Thigh)
Vth
0.9
1.1
V
Input Bias Current (V
CC
=15V, T
A
=Tlow to Thigh)
I
IB
-10
A
Propagation Delay (Current Sense Input to Output)
(V
CC
=15V, T
A
=Tlow to Thigh)
t
PLH
300
ns








3
IL3842






ELECTRICAL CHARACTERISTICS
(Vcc=15V unless otherwise noted)
Characteristics Symbol
Min
Max
Unit
OUTPUT SECTION
Output Voltage
Low State (Sink=20mA, V
CC
=15V)
(Sink=200mA, V
CC
=15V)
High State (Sink=20mA, V
CC
=15V)
(Sink=200mA, V
CC
=15V)
V
OL
V
OH


13
12
0.4
2.2
V
Output Voltage with UVLO Activated
(V
CC
=6.0V, I
Sink
,=1.0mA, T
A
=Tlow to Thigh)
V
OL(UVL
O)
1.1
V
Output Voltage Rise Time
(C
L
=1.0nF, V
CC
=15V, T
A
=Tlow to Thigh)
tr
150
ns
Output Voltage Fall Time
(C
L
=1.0nF, V
CC
=15V, T
A
=Tlow to Thigh)
tf
150
ns
ONDERVOLTAGE LOCKOUT SECTION
Startup Threshold (V
CC
=0V to 25V,T
A
=Tlow to Thigh)
Vth
14.5
17.5
V
Minimum Operating Voltage After Turn-On
(V
CC
=0V to 25V,T
A
=Tlow to Thigh)
V
CC(min)
8.5
11.5
V
PWM SECTION
Duty Cycle
Maximum (V
CC
=15V, T
A
=Tlow to Thigh,R
T
=10k,C
T
=3.3nF)
Minimum (V
CC
=15V, T
A
=Tlow to Thigh,R
T
=10k,C
T
=3.3nF)
DCmax
DCmin
94

0
%
TOTAL DEVICE
Power Supply Current
Startup: V
CC
=14V
V
CC
=15V Operating
I
CC
1.0
17
mA
Power Supply Zener Voltage (I
CC
=25mA, V
CC
=0 to 40V)
Vz
30
40
V

NOTES:
1
. Vfinal= V
ref25
( Reg
line
+ Reg
load
)/1000
| V
ref70
(V
ref0
)-V
ref25
|
V
ref25
=Vref @ T
A
=25C;
V
ref70
=Vref @ T
A
=70C; V
ref0
=Vref @ T
A
=0C.
2. Tlow= 0C ; Thigh=+70C
4
IL3842
N SUFFIX PLASTIC DIP
(MS - 001BA)
Symbol
MIN
MAX
A
8.51
10.16
B
6.1
7.11
C
5.33
D
0.36
0.56
F
1.14
1.78
G
H
J
0
10
K
2.92
3.81
NOTES:
L
7.62
8.26
1.
Dimensions "A", "B" do not include mold flash or protrusions.
M
0.2
0.36
Maximum mold flash or protrusions 0.25 mm (0.010) per side.
N
0.38
Dimension, mm
2.54
7.62
L
H
M
J
A
B
F
G
D
SEATING
PLANE
N
K
0.25 (0.010) M T
-T-
C
1
8
4
5
5