Data Sheet
CURRENT MODE PWM CONTROLLER
General Description
The AP3842C/3C/4C/5C are high performance fixed
frequency current-mode PWM controller series.
These integrated circuits are optimized for off-line and
DC-DC converter applications with minimum external
components. They feature under-voltage lockout
(UVLO) circuit with low start-up current, trimmed
oscillator for precise duty cycle control, current sense
comparator providing maximum current limiting and a
totem pole output stage for increasing output current.
In addition, these ICs also feature accurate protection
against over-temperature, over-current and maximal
output power.
The AP3842C and AP3844C have UVLO thresholds
of 16V(on) and 10V(off); The corresponding thresh-
olds for AP3843C and AP3845C are 8.4 V(on) and
7.6V(off).
The AP3842C and AP3843C can operate approaching
100% duty cycle; AP3844C and AP3845C can operate
from zero to 50% duty cycle.
These ICs are available in SOIC-8 and DIP-8 pack-
ages.
AP384XC
Features
·
·
·
·
·
·
·
·
Low Start-up Current: 50
µ
A
Robust V
REF
Line/Load Regulation
Low Line Regulation : 4mV
Low Load Regulation : 4mV
High Stability of Reference Voltage over a Full
Temperature Range: 0.2mV/
o
C
Operating Frequency up to 500KHz
High PWM Frequency Stability over a Full Tem-
perature Range: 2.5%
High PWM Frequency Stability under a Full Sup-
ply Voltage Range: 0.2%
Accurate Over-temperature Protection with Hys-
teresis
UVLO with Hysteresis
Applications
·
·
·
·
·
·
Off-line Converter
DC-DC Converter
Voltage Adapter
CRT Monitor Power Supply
Desktop Power Supply
DVD/STB Power Supply
SOIC-8
DIP-8
Figure 1. Package Types of AP3842C/3C/4C/5C
Apr. 2007 Rev. 1. 2
BCD Semiconductor Manufacturing Limited
1
Data Sheet
CURRENT MODE PWM CONTROLLER
Pin Configuration
AP384XC
M/P Package
(SOIC-8/DIP-8)
COMP
V
FB
I
SENSE
R
T
/C
T
1
2
3
4
8
7
6
5
V
REF
V
CC
OUTPUT
GND
Figure 2. Pin Configuration of AP3842C/3C/4C/5C (Top View)
Pin Description
Pin Number
1
2
3
4
Pin Name
COMP
V
FB
I
SENSE
R
T
/C
T
Function
This pin is the Error Amplifier output and is made available for loop compensation.
The inverting input of the Error Amplifier. It is normally connected to the switching
power supply output through a resistor divider.
A voltage proportional to inductor current is connected to this input. The PWM uses
this information to terminate the output switch conduction.
The Oscillator frequency and maximum output duty cycle are programmed by con-
necting resistor R
T
to V
REF
and capacitor C
T
to ground. Operation to 500 kHz is possi-
ble.
The combined control circuitry and power ground.
This output directly drives the gate of a power MOSFET. Peak currents up to 1.0 A are
sourced and sunk by this pin.
The positive supply of the control IC.
This is the reference output. It provides charging current for capacitor C
T
through
resistor R
T
.
5
6
7
8
GND
OUTPUT
V
CC
V
REF
Apr. 2007 Rev. 1. 2
BCD Semiconductor Manufacturing Limited
2
Data Sheet
CURRENT MODE PWM CONTROLLER
Functional Block Diagram
AP384XC
V
CC
GND
7
34V
5
UVLO
S/R
5V
REF
8
V
REF
2.50V
INTERNAL
BIAS
VREF
GOOD
LOGIC
R
T
/C
T
4
OSC
T
6
OUTPUT
OVER TEMP
PROTECT
ERROR
AMP
(Note)
2R
S
R
R
1V
CURRENT
SENSE
COMPARATOR
PWN
LATCH
Note: Toggle flip-flop used
for 3844C/45C only
V
FB
COMP
I
SENSE
2
1
3
Figure 3. Functional Block Diagram of AP3842C/3C/4C/5C
Apr. 2007 Rev. 1. 2
BCD Semiconductor Manufacturing Limited
3
Data Sheet
CURRENT MODE PWM CONTROLLER
Ordering Information
AP384XC
Circuit Type
Package
M: SOIC-8
P: DIP-8
-
E1: Lead Free
Blank: Tin Lead
TR: Tape and Reel
Blank: Tube
AP384XC
Package
Tempera-
ture Range
-40 to 85
o
C
Part Number
Tin Lead
AP3842/3/4/5CM
AP3842/3/4/5CMTR
Lead Free
AP3842/3/4/5CM-E1
AP3842/3/4/5CMTR-E1
AP3842/3/4/5CP-E1
Tin Lead
3842/3/4/5CM
3842/3/4/5CM
Marking ID
Lead Free
3842/3/4/5CM-E1
3842/3/4/5CM-E1
AP3842/3/4/5CP-E1
Packing
Type
Tube
Tape & Reel
Tube
SOIC-8
DIP-8
-40 to 85
o
C AP3842/3/4/5CP
AP3842/3/4/5CP
BCD Semiconductor's Pb-free products, as designated with "E1" suffix in the part number, are RoHS compliant.
Apr. 2007 Rev. 1. 2
BCD Semiconductor Manufacturing Limited
4
Data Sheet
CURRENT MODE PWM CONTROLLER
Absolute Maximum Ratings (Note 1, 2)
Parameter
Supply Voltage
Output Current
Analog Inputs
Error Amp Output Sink Current
Power Dissipation at T
A
< 25
o
C (DIP-8)
Power Dissipation at T
A
<25
o
C (SOIC-8)
Junction Operating Temperature
DIP-8
Thermal Resistance (Junction to Ambient)
SOIC-8
Storage Temperature Range
Lead Temperature (Soldering, 10sec)
ESD (Machine Mode)
T
STG
T
LEAD
R
θJA
160
-65 to 150
+300
250
o
C/W
o
C
o
AP384XC
Symbol
V
CC
I
O
V(ANA)
I
SINK
(E.A)
P
D
(Note 3)
P
D
(Note 3)
T
J
Value
30
Unit
V
A
V
mA
mW
mW
o
o
±
1
-0.3 to 6.3
10
1000
460
-40 to 150
140
C
C/W
C
V
Note 1:
Stresses greater than those listed under "Absolute Maximum Ratings" may cause permanent damage to the
device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indi-
cated under "Recommended Operating Conditions" is not implied. Exposure to "Absolute Maximum Ratings" for extended
periods may affect device reliability.
Note 2: All voltages are with respect to pin 5 and all currents are positive into specified terminal.
Note 3: Board thickness 1.6mm, board dimension 90mm
x
90mm.
Recommended Operating Conditions
Parameter
Oscillation Frequency
Symbol
f
T
A
Min
-40
Max
500
85
Unit
KHz
o
Ambient Temperature
C
Apr. 2007 Rev. 1. 2
BCD Semiconductor Manufacturing Limited
5
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