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 Package Operating temperature
KA3842AM SO-8 0 to +700C
BLOCK DIAGRAM
Absolute Maximum Ratings
Characteristic Symbol Value Unit
Supply Voltage VCC 30 V
Output Current IO±1A
Analog Inputs VI−0.3 to VCC V
Error Amp Output Sink Current ISINK (E.A) 10 mA
Power Dissipation (TA=250C) PO1W
Wing Shing Computer Components Co., (H.K.)Ltd. Tel:(852)2341 9276 Fax:(852)2797 8153
Homepage: http://www.wingshing.com E-mail: wsccltd@hkstar.com
Linear Integrated Circuit
have UVLO thresholds of 16 V(on) and 10 V (off).
operate
within 100%
duty cycle
PIN CONNECTION
SO-8
1
in applications
external components as Motorola's parts,among others .The
SO-8
"
DIP-8
DIP-8
"
"
KA3842A
KA3842AM
KA3842AMM
KA3842AN
KA3842AMN
KA3842AM
KA3842A,KA3842AM
The KA3842A has been proven
KA3842AM
has been optimized for compatibility with Samsung's parts
Many applications can use either
KA3842A or KA3842AM
KA3842AM
Electrical characteristics (*VCC=15V, RT=10kΩΩ, CT=3.3nF, TA=00C to +700C, unless
otherwise specified)
Characteristics Symbol Test Condition Min Typ Max Unit
Reference Section
Reference Output Voltege VREF TJ = 25°C, IREF = 1 mA 4.9 5.0 5.1 V
Line Regulation ∆VREF 12V ≤ VCC ≤ 25 V 6.0 20 mV
Load Regulation ∆VREF 1 mA ≤ IREF ≤ 20mA 6.0 25
Short Circit Output Current ISC TA = 25°C-100 -180 mA
Oscillator Section
Oscillation Freguency fTJ = 25°C47 52 57 KHz
Frequency Change with
Voltage ∆f/∆VCCF 12V ≤ VCC ≤ 25 V 0.05 1.0 %
Oscillator Amplitude V(OSC) 1.6 Vp-p
Error Amplifier Section
Input Bias Current IBIAS -0.1 -2 µA
Input Voltage VI(E.A) V1 = 2.5V 2.42 2.5 2.58 V
Open Loop Voltage Gain GVO 2V ≤ V0 ≤ 4V 65 90 dB
Power Supply Rejection Ratio PSRR 12V ≤ VCC ≤ 25 V 60 70
Output Sink Current ISINK V2 = 2.7V, V1 = 1.1V 27mA
Output Source Current ISOURCE V2 = 2.3V, V1 = 5V -0.5 -1.0 mA
High Output Voltage VOH V2 = 2.3V, RL = 15KΩ to GND 5.0 6.0 V
Low Output Voltage VOL V2 = 2.7V, RL = 15KΩ to PIN 8 0.8 1.1
Current Sense Section
Gain GV(Note 1 & 2) 2.85 3.0 3.15 V/V
Maximum Input Signal VI(MAX) V1 = 5V (Note1) 0.9 1.0 1.1 V
Power Supply Rejection Ratio PSRR 12V ≤ VCC ≤ 25 V (Note 1) 70 dB
Input Bias Current IBIAS -3.0 -10 µA
Output Section
Low Output Voltage VOL ISINK = 20 mA 0.08 0.4
ISINK = 200 mA 1.4 2.2 V
High Output Voltage VOH ISINK = 20 mA 13 13.5
ISINK = 200 mA 12 13.0
Rise Time tRTJ = 25°C, CL = 1nF (Note 3) 45 150 nS
Fall Time tFTJ = 25°C, CL = 1nF (Note 3) 35 150
Under−−Voltage Lockout Section
Start Theshold VTH(ST) 14.5 16.0 17.5 V
Min. Operating Voltage VOPR(min) 8.5 10 11.5 V
(After Turn On)
PWM Section
Max. Duty Cycle D(MAX) 95 97 100 %
Min. Duty Cycle D(MAX) 0
Total Standby Current
Start−Up Current IST 0.17 0.3 mA
Operating Supply Current ICC (OPR) V3 = V2 = 0V 14 17
Zener Voltage VZ30 38 V
* Adjust VCC above the start threshold before setting at 15V
Note 1: Parameter measured at trip point of lath with V2=0
Note 2: Gain defined as A=∆V1/∆V3 ; 0 ≤ V3 ≤ 0.8V
Note 3: These parameters, although guaranteed, are not 100% tested in production.
2
KA3842A/KA3842AM
Pad Location
Chip size: 2.38 x 1.63 mm
Pad Coordinates µµmPad Coordinates µµm
NXYNXY
1 90 110 5 1680 1450
2 1050 110 6 1310 1410
3 1310 110
4 2000 150 7 815 1410
8 460 1390
3
KA3842A/KA3842AM
DIM. mm inch
MIN. TYP. MAX. MIN. TYP. MAX.
A 1.75 0.069
a1 0.1 0.25 0.004 0.010
a2 1.65
0.065
a3 0.65 0.85 0.026 0.033
b 0.35 0.48 0.014 0.019
b1 0.19 0.25 0.007 0.010
C 0.25 0.5 0.010 0.020
c1 45°(typ.)
D (1) 4.8 5.0 0.189 0.197
E 5.8 6.2 0.228 0.244
e 1.27 0.050
e3 3.81 0.150
F (1) 3.8 4.0 0.15 0.157
L 0.4 1.27 0.016 0.050
M 0.6 0.024
S8°(max.)
(1) D andF do not include moldflash orprotrusions. Mold flash or
potrusions shall not exceed0.15mm (.006inch).
SO8
OUTLINE AND
MECHANICAL DATA
4
KA3842A/KA3842AM
KA3842AM
KA3842AMM
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.
14
58
F
NOTE 2 –A–
–B–
–T–
SEATING
PLANE
H
J
GDK
N
C
L
M
M
A
M
0.13 (0.005) B M
T
DIM MIN MAX MIN MAX
INCHESMILLIMETERS
A9.40 10.16 0.370 0.400
B6.10 6.60 0.240 0.260
C3.94 4.45 0.155 0.175
D0.38 0.51 0.015 0.020
F1.02 1.78 0.040 0.070
G2.54 BSC 0.100 BSC
H0.76 1.27 0.030 0.050
J0.20 0.30 0.008 0.012
K2.92 3.43 0.115 0.135
L7.62 BSC 0.300 BSC
M––– 10 ––– 10
N0.76 1.01 0.030 0.040
__
Attention: M=10
o
5
KA3842A/KA3842AM
KA3842AN
KA3842AMN