CURRENT−MODE PWM CONTROLLER
−
The KA3842A
are fixe frequency current-mode
PWM controller. They are specially designed for OFF−Line and DC−to−DC converter
applications with minimal external components. These integrated circuits feature a
trimmed oscillator for precise duty cycle control, a temperature compensated reference,
high gain error amplifier, current sensing comparator, and a high current totempole
output ideally suited for driving a power MOSFET.
Protection circuity includes built under−voltage lockout and current limiting.
The
The KA3842A ,KA384AM
can
The KA3842A
have Start-Up Current 0,45 mA
FEATURES
•
•
•
•
Low Start-Up Current
Maximum Duty Cycle
U/V Lockout With Hysteresis
Operating Freguency Up To 500khz
ordering
information
Device
KA3842AM
Package
SO-8
Operating temperature
0 to +70
0
C
BLOCK DIAGRAM
Absolute Maximum Ratings
Characteristic
Supply Voltage
Output Current
Analog Inputs
Error Amp Output Sink Current
Power Dissipation (T
A
=25
0
C)
Symbol
V
CC
I
O
V
I
I
SINK (E.A)
P
O
Value
30
±1
−0.3
to V
CC
10
1
Unit
V
A
V
mA
W
Wing Shing Computer Components Co., (H.K.)Ltd.
Homepage:
http://www.wingshing.com
Tel:(852)2341 9276 Fax:(852)2797 8153
E-mail: wsccltd@hkstar.com
Electrical characteristics (*V
CC
=15V, R
T
=10kΩ, C
T
=3.3nF, T
A
=0
0
C to +70
0
C, unless
Ω
otherwise specified)
Characteristics
Reference Section
Reference Output Voltege
Line Regulation
Load Regulation
Short Circit Output Current
Oscillator Section
Oscillation Freguency
Frequency Change with
Voltage
Oscillator Amplitude
Error Amplifier Section
Input Bias Current
Input Voltage
Open Loop Voltage Gain
Power Supply Rejection Ratio
Output Sink Current
Output Source Current
High Output Voltage
Low Output Voltage
Current Sense Section
Gain
Maximum Input Signal
Power Supply Rejection Ratio
Input Bias Current
Output Section
Low Output Voltage
High Output Voltage
Rise Time
Fall Time
Symbol
V
REF
∆V
REF
∆V
REF
I
SC
f
∆f/∆V
CCF
V
(OSC)
I
BIAS
V
I(E.A)
G
VO
PSRR
I
SINK
I
SOURCE
V
OH
V
OL
G
V
V
I(MAX)
PSRR
I
BIAS
V
OL
V
OH
t
R
t
F
I
SINK
I
SINK
I
SINK
I
SINK
Test Condition
T
J
= 25°C, I
REF
= 1 mA
12V
≤
V
CC
≤
25 V
1 mA
≤
I
REF
≤
20mA
T
A
= 25°C
T
J
= 25°C
12V
≤
V
CC
≤
25 V
Min
4.9
Typ
5.0
6.0
6.0
-100
Max
5.1
20
25
-180
57
1.0
Unit
V
mV
mA
KHz
%
V
p-p
47
52
0.05
1.6
-0.1
-2
2.58
V
1
= 2.5V
2V
≤
V0
≤
4V
12V
≤
V
CC
≤
25 V
V
2
= 2.7V, V
1
= 1.1V
V
2
= 2.3V, V
1
= 5V
V
2
= 2.3V, R
L
= 15KΩ to GND
V
2
= 2.7V, R
L
= 15KΩ to PIN 8
(Note 1 & 2)
V
1
= 5V (Note1)
12V
≤
V
CC
≤
25 V (Note 1)
2.42
65
60
2
-0.5
5.0
2.5
90
70
7
-1.0
6.0
0.8
µA
V
dB
mA
mA
V
1.1
3.15
1.1
-10
0.4
2.2
V/V
V
dB
µA
2.85
0.9
3.0
1.0
70
-3.0
=
=
=
=
20 mA
200 mA
20 mA
200 mA
13
12
T
J
= 25°C, C
L
= 1nF (Note 3)
T
J
= 25°C, C
L
= 1nF (Note 3)
14.5
8.5
0.08
1.4
13.5
13.0
45
35
16.0
10
V
150
150
17.5
11.5
nS
Under−Voltage Lockout Section
−
Start Theshold
V
TH(ST)
Min. Operating Voltage
(After Turn On)
PWM Section
Max. Duty Cycle
Min. Duty Cycle
Total Standby Current
Start−Up Current
Operating Supply Current
Zener Voltage
V
OPR(min)
V
V
D
(MAX)
D
(MAX)
I
ST
I
CC (OPR)
V
Z
V
3
= V
2
= 0V
95
97
100
%
0
0.17
14
38
0.3
17
mA
30
V
* Adjust V
CC
above the start threshold before setting at 15V
Note 1: Parameter measured at trip point of lath with V
2
=0
Note 2: Gain defined as A=∆V
1
/∆V
3
; 0
≤
V
3
≤
0.8V
Note 3: These parameters, although guaranteed, are not 100% tested in production.
DIM.
MIN.
A
a1
a2
a3
b
b1
C
c1
D (1)
E
e
e3
F (1)
L
M
S
3.8
0.4
4.8
5.8
0.65
0.35
0.19
0.25
0.1
mm
TYP.
MAX.
1.75
0.25
1.65
0.85
0.48
0.25
0.5
0.026
0.014
0.007
0.010
0.004
MIN.
inch
TYP.
MAX.
0.069
0.010
0.065
0.033
0.019
0.010
0.020
OUTLINE AND
MECHANICAL DATA
45° (typ.)
5.0
6.2
1.27
3.81
4.0
1.27
0.6
8
°
(max.)
0.15
0.016
0.189
0.228
0.050
0.150
0.157
0.050
0.024
0.197
0.244
SO8
(1) D and F do not include mold flash or protrusions. Mold flash or
potrusions shall not exceed 0.15mm (.006inch).
8
5
–B–
1
4
NOTES:
1. DIMENSION L TO CENTER OF LEAD WHEN
FORMED PARALLEL.
2. PACKAGE CONTOUR OPTIONAL (ROUND OR
SQUARE CORNERS).
3. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
DIM
A
B
C
D
F
G
H
J
K
L
M
N
MILLIMETERS
MIN
MAX
9.40
10.16
6.10
6.60
3.94
4.45
0.38
0.51
1.02
1.78
2.54 BSC
0.76
1.27
0.20
0.30
2.92
3.43
7.62 BSC
–––
10
_
0.76
1.01
INCHES
MIN
MAX
0.370
0.400
0.240
0.260
0.155
0.175
0.015
0.020
0.040
0.070
0.100 BSC
0.030
0.050
0.008
0.012
0.115
0.135
0.300 BSC
–––
10
_
0.030
0.040
F
NOTE 2
–A–
L
C
–T–
SEATING
PLANE
J
N
D
K
M
M
T A
B
H
G
0.13 (0.005)
M
M
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