Description
The 3842A(AM)/43A(AM)/44A(AM)/45A(AM) are fixed frequency current mode PWM controller. They are specially designed for
OFF−Line 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 3842A(AM) and 3844A(AM) have UVLO thresholds of 16 V (on) and 10 V (off). The corresponding
thresholds for the 3843A(AM)/45A(AM) are 8.4V (on) and 7.6V (off). The MIK3842A(AM) and MIK3843A(AM) can operate within 100% duty
cycle. The 3844A(AM) and UC3845A(AM) can operate within 50% duty cycle.
The 384XA(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
)
Pin Connection
Top view
Block diagram
(toggle flip flop used only in MIK3844, MIK3845)
7
V
8
5V
V
REF
SET/
RESET
UVLO
V
RE
GOOD
F
LOGIC
INTERNAL
BIAS
POWER V
CC
7
1/2 V
REF
+
2 V
FB
ERR
1V
36V
GND
5
2R
C.S.
COMP
R
PWM
LATCH
OUT
6
COMP
1
CURRENT
SENSE
3
R
S
T
R
/C
T
5
OSCILLATOR
POWER GND
Absolute Maximum Ratings
Symbol
V
CC
I
O
V
I
I
SINK (E.A)
Po
Tstg
T
L
Parameter
Supply Voltage (low impedance source)
Output Current
Input Voltage (Analog Inputs pins 2,3)
Error Amp Output Sink Current
Power Dissipation (T
A
=25
0
C)
Storage Temperature Range
Lead Temperature (soldering 5 sec.)
Maximum
30
±1
−0.3
to 5.5
10
1
-65 to150
260
Units
V
A
V
mA
W
o
C
o
C
BEIJING ESTEK ELECTRONICS CO.,LTD
1
ESTEK [ Estek Electronics Co. Ltd ]
