KA3843 Controller Datasheet

KA3843 Datasheet, PDF, Equivalent


Part Number

KA3843

Description

CurrentMode PWM Controller

Manufacture

ETC

Total Page 9 Pages
Datasheet
Download KA3843 Datasheet


KA3843
KA3842/43/44/45
Inv 59
Current Mode PWM Controller
July 1995 - revised July 2002
DESCRIPTION
KA3842/43/44/45 are fixed frequency current mode PWM
controller. They are specially designed for OFFLine and DC to DC converter applications
with a minimal external components. Internally implemented circuits include 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 circuitry includes built undervoltage lockout
and current limiting.
The UC3842A(AM) and UC3844A(AM) have UVLO thresholds of 16 V (on) and 10 V (off).
The corresponding thresholds for the UC3843A(AM)/45A(AM) are 8.4V (on) and
7.6V
(off). The UC3842A(AM) and UC3843A(AM) can operate within 100% duty cycle. The
UC3844A(AM) and UC3845A(AM) can operate within 50% duty cycle.
The UC384XA(AM) has Start-Up Current 0.17mA (typ).
FEATURES
Low Start-Up and Operating Current
High Current Totem Pole Output
Undervoltage Lockout With Hysteresis
Operating Frequency Up To 300KHz (384XA)
500KHz (384XAM)
BLOCK DIAGRAM
(toggle flip flop used only in UC3844, UC3845)
PIN
CONNECTION
(TOP VIEW)
Absolute Maximum Ratings
Characteristic
Supply Voltage (low impedance
source)
Output Current
Input Voltage (Analog Inputs pins 2,3)
Error Amp Output Sink Current
Power Dissipation (TA=250C)
Storage Temperature Range
Lead Temperature (soldering 5 sec.)
Symbol
VCC
IO
VI
ISINK (E.A)
PO
Tstg
TL
Value
30
±1
0.3 to 5.5
10
1
-65 to150
260
Unit
V
A
V
mA
W
oC
oC
1

KA3843
KA3842/43/44/45
Inv 59
Current Mode PWM Controller
July 1995 - revised July 2002
Electrical characteristics (*VCC=15V, RT=10k, CT=3.3nF, TA=00C to +700C, unless otherwise
specified)
Characteristics
Symbol
Test Condition
Min Typ Max
Reference Section
Reference Output Voltage
Line Regulation
Load Regulation
Short Circuit Output Current
Oscillator Section
VREF
VREF
VREF
ISC
TJ = 25°C, IREF = 1 mA
12V VCC 25 V
1 mA IREF 20mA
TA = 25°C
4.9 5.0 5.1
6.0 20
6.0 25
-100
-180
Oscillation Frequency
f
TJ = 25°C
384XA
384XAM
47 50 57
47 52 57
Frequency Change with
Voltage
f/VCC 12V VCC 25 V
0.05
1.0
Oscillator Amplitude
Error Amplifier Section
V(OSC)
(peak to peak)
1.6
Input Bias Current
IBIAS
VFB=3V
-0.1
-2
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
VI(E.A)
AVOL
PSRR
ISINK
ISOURCE
VOH
VOL
Vpin1 = 2.5V
2V V0 4V
12V VCC 25 V
Vpin2 = 2.7V, Vpin1 = 1.1V
Vpin2 = 2.3V, Vpin1 = 5V
Vpin2 = 2.3V, RL = 15Kto GND
Vpin2 = 2.7V, RL = 15Kto PIN 8
2.42
65
60
2
-0.5
5.0
2.5
90
70
7
-1.0
6.0
0.8
2.58
1.1
Gain
Maximum Input Signal
Supply Voltage Rejection
Input Bias Current
GV
VI(MAX)
SVR
IBIAS
(Note 1 & 2)
V pin1 = 5V (Note1)
12V VCC 25 V (Note 1)
Vpin3 = 3V
2.85
0.9
3.0
1.0
70
-3.0
3.15
1.1
-10
Output Section
Low Output Voltage
VOL
High Output Voltage
VOH
Rise Time
Fall Time
Undervoltage Lockout Section
tR
tF
ISINK = 20 mA
ISINK = 200 mA
ISINK = 20 mA
ISINK = 200 mA
TJ = 25°C, CL = 1nF (Note 3)
TJ = 25°C, CL = 1nF (Note 3)
0.08
0.4
1.4 2.2
13 13.5
12 13.0
45 150
35 150
Start Theshold
VTH(ST)
UC3842A(AM)/44A(AM)
UC3843A(AM)/45A(AM)
14.5
7.8
16.0
8.4
17.5
9.0
Min. Operating Voltage
(After Turn On)
VOPR(min) UC3842A(AM)/44A(AM)
UC3843A(AM)/45A(AM)
8.5 10 11.5
7.0 7.6 8.2
PWM Section
Max. Duty Cycle
D(MAX)
UC3842A(AM)/43A(AM)
UC3844A(AM)/45A(AM)
95 97 100
47 48 50
Min. Duty Cycle
Total Standby Current
D(MAX)
0
StartUp Current
IST UC384XA(AM)
0.17
0.3
Operating Supply Current
ICC (OPR) Vpin3 = Vpin2 = 0V
13 17
Zener Voltage
VZ ICC=25 mA
30 38
* Adjust VCC above the start threshold before setting it to 15V.
Note 1: Parameter measured at trip point of latch with Vpin2=0.
Note 2: Gain defined as A=Vpin1/Vpin3 ; 0 Vpin3 0.8V.
Note 3: These parameters, although guaranteed, are not 100% tested in production.
Unit
V
mV
mA
KHz
%
V
µA
V
dB
mA
mA
V
V/V
V
dB
µA
V
nS
V
V
%
mA
V
2


Features KA3842/43/44/45 Inv № 59 Current Mode PWM Controller July 1995 - revised Jul y 2002 DESCRIPTION KA3842/43/44/45 ar e fixed frequency current mode PWM cont roller. They are specially designed for OFF−Line and DC to DC converter appl ications with a minimal external compon ents. Internally implemented circuits i nclude a trimmed oscillator for precis e duty cycle control, a temperature com pensated reference, high gain error am plifier, current sensing comparator, an d a high current totempole output ideal ly suited for driving a power MOSFET. Protection circuitry includes built und ervoltage lockout and current limiting . The UC3842A(AM) and UC3844A(AM) have UVLO thresholds of 16 V (on) and 10 V (off). The corresponding thresholds fo r the UC3843A(AM)/45A(AM) are 8.4V (on) and 7.6V (off). The UC3842A(AM) and UC3843A(AM) can operate within 100% dut y cycle. The UC3844A(AM) and UC3845A(A M) can operate within 50% duty cycle. The UC384XA(AM) has Start-Up Current 0.17mA (typ). FEATURES • Low.
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