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
Pin Connection
•
•
•
•
Low Start-Up and Operating Current
High Current Totem Pole Output
Undervoltage Lockout With Hysteresis
Operating Frequency Up To 300KHz (384XA)
500KHz (384XAM
)
Top view
Block diagram
(toggle flip flop used only in MIK3844, MIK3845)
36V
GND
5V
V
SET
/
E
RE
S
T
REF
UVLO
V
GOOD
F
RE
LOGI
C
IN
T
E
RNAL
BIAS
POWER
V
CC
OU
7
1/2 V
REF
2R
+
V
ER
R
C.
CO
S
M
.
FB
2
P
1V
T
R
PW
M
COM
P
LA CH
T
CUR
RENT
SEN
S
E
3
5
R
/C
T
OSCILLATOR
Absolute Maximum Ratings
Symbol
Parameter
Maximum
Units
VCC
IO
Supply Voltage (low impedance source)
30
±1
V
A
Output Current
VI
ISINK (E.A)
Po
Input Voltage (Analog Inputs pins 2,3)
Error Amp Output Sink Current
Power Dissipation (TA=250C)
Storage Temperature Range
−
0.3 to 5.5
V
mA
W
10
1
Tstg
-65 to150
260
oC
TL
Lead Temperature (soldering 5 sec.)
BEIJING ESTEK ELECTRONICS CO.,LTD
1
ESTEK [ Estek Electronics Co. Ltd ]
