FA13842,13843,13844,13845
s
Description
The FA1384X series are CMOS current mode control ICs for
off-line and DC-to-DC converters.
These ICs can reduce start-up circuit loss and are optimum for
high efficiency power supplies because of the low power
dissipation achieved through changes in the CMOS fabrication
process.
These ICs can drive a power MOSFET directly.
The high-performance, compact power supply can be
designed with minimal external components .
CMOS IC
FA13842, 13843, 13844, 13845
For Switching Power Supply Control
s
Dimensions, mm
SOP-8
8
5
1
4
4.9
+0.1
–0.05
s
Features
•
•
•
•
•
•
•
CMOS process
Low-power dissipation
Standby current 2µA (max.), start-up current 30µA (max.)
Pulse-by-pulse current limiting
5V bandgap reference
UVLO (Undervoltage lockout) with hysteresis
Maximum duty cycle
FA13842, 13843: 96%
FA13844, 13845: 48%
• Pin-for-pin compatible with UC384X
Note:
Pins are fully compatible, but characteristics are not.
When our ICs are applied to a power supply circuit
designed for other manufactures' 384X series, the
characteristics and safety features of the power supply
must be checked.
6.0
±0.2
3.9
0.4
±0.1
1.27
±0.2
DIP-8
8
5
s
Types of FA1384X series
Type
UVLO
Maximum duty Package
Start threshold Stop threshold cycle
FA13842P
16.5V±1V
9V±1V
96%
DIP
FA13842N
FA13843P
FA13843N
9.6V±1V
9V±1V
9V±1V
9V±1V
96%
48%
48%
SOP
DIP
SOP
DIP
SOP
DIP
SOP
1
9.3
1.5
4
6.4
3.0min 4.5max
3.3
0~8
°
0.05
0.25
–
+0.1
7.62
FA13844P
16.5V±1V
FA13844N
FA13845P
FA13845N
9.6V±1V
2.54
±0.25
0.46
±0.1
0~15
˚
0~1
5˚
1.7max
0.20
1
FA13842, 13843, 13844, 13845
s
Block diagram
FA13842, 13843
VCC
7
30V
UVLO
OUTPUT
ENB
Pin No. Symbol Function
1
UVLO
VCC 5V REF
ENB
2.5V
8
VREF
Description
Error amplifier output, available
for loop compensation circuit
Inverting input of the error
amplifier
Input voltage proportional to
inductor current
Setting oscillation frequency
and maximum duty-cycle with
resistor R
T
and capacitor C
T
Ground
Output for driving a power
COMP
FB
ISNS
RT/CT
Compensating
Feedback
Current sensing
Oscillator control
2
3
4
6
OUT
RT/CT
4
ER AMP
FB
2
OSC
5
GND
COMP
1
ISNS
3
2R
1R
1V
S Q
FF
R QB
5
6
7
8
GND
OUT
VCC
VREF
Ground
Output
5V Controlled block
MOSFET
Power supply
Power supply
Reference voltage Reference voltage and
current source charging
capacitor C
T
through resistor
R
T
FA13844, 13845
VCC
7
30V
UVLO
OUTPUT
ENB
UVLO
VCC 5V REF
ENB
2.5V
8
VREF
6
OUT
RT/CT
4
ER AMP
FB
2
COMP
1
ISNS
3
2R
1R
OSC
5
GND
1V
S Q
FF
R QB
TFFQ
CLK
QB
5V ControlIed block
s
Absolute maximum ratings
(Ta=25˚C)
I
tem
Supply voltage
Zener current
Output peak current
FB/ISNS terminal input voltage
Error amplifier sink current
Total power dissipation
Thermal resistance
Junction temperature
Ambient temperature
Storage temperature
Symbol
V
CC
I
Z
I
O
V
IN
I
SINK
P
d
Rθ j-a
T
j
T
a
T
stg
Test condition
Low impedance source
Zener clamp (Icc<10mA)
Source current
Sink current
FB, ISNS
at Ta < 50˚C
Junction-air
DIP
SOP
DIP
SOP
Rating
28
Self limiting
10
400
1
–0.3 to 5.3
10
800
400
125
250
150
–25 to 85
–40 to 150
Unit
V
V
mA
mA
A
V
mA
mW
˚C/W
˚C
˚C
˚C
2
FA13842, 13843, 13844, 13845
s
Recommended operating conditions
Item
Supply voltage
Oscillation timing capacitor
Oscillation timing resistor
Oscillation frequency
Symbol
V
CC
C
T
R
T
f
OSC
Min.
10
0.47
2.0
10
Max.
25
10
100
500
Unit
V
nF
kΩ
kHz
s
Electrical characteristics
(Vcc=15V, R
T
=10kΩ, C
T
=3.3nF, Ta=25˚C)
Reference voltage section
Item
Reference voltage
Line regulation
Load current regulation
Temperature regulation
Output current at short-circuit
Symbol
V
REF
L
INE
L
OAD
V
TC
I
OS
Test condition
Tj=25˚C, I
L
=1mA
Vcc=10 to 25V
I
L
=0 to 20mA
Ta=–25 to 85˚C
Tj=25˚C
Min.
4.75
Typ.
5.00
±3
±3
±0.3
60
Max.
5.25
±20
±25
Unit
V
mV
mV
mV/˚C
mA
Oscillator section
Item
Oscillation frequency
Voltage stability
Temperature stability
Oscillation amplitude
Discharge current
Symbol
f
OSC
fdv
fdt
V
OSC
I
DISCHG
Test condition
Tj=25˚C
Ta=–25 to 85˚C
Vcc=10 to 25V
Ta=–25 to 85˚C
Tj=25˚C
Tj=25˚C
Min.
49
47
±0.25
–0.07
1.6
8.4
Typ.
52
Max.
55
57
±1
Unit
kHz
kHz
%
%/˚C
V
mA
Error amplifier section
Item
Input voltage
Input leak current
Open-loop gain
Unity gain bandwidth
Output source current
Output sink current
Output voltage
Symbol
V
FB
I
FB
A
V
f
T
I
SOURCE
I
SINK
V
H COMP
V
L COMP
Test condition
COMP=2.5V, Tj=25˚C
Min.
2.4
65
FB=2.3V, COMP=0V
FB=2.7V, COMP=1V
FB=2.3V, R
L
=15kΩ to GND
FB=2.7V, R
L
=15kΩ to VREF
0.7
–0.8
2
4.0
Typ.
2.5
72
1
–1.0
15
4.5
80
500
Max.
2.6
±2
Unit
V
µA
dB
MHz
mA
mA
V
mV
Current sensing section
Item
Voltage gain
Maximum input signal
Input bias current
Delay to output
Symbol
A
V IS
V
TH IS
I
IS
T
PD
Test condition
Tj=25˚C
FB=0V
Tj=25˚C, ISNS to OUT
Min.
2.85
0.9
Typ.
3
1.0
–1
150
Max.
3.15
1.1
–5
300
Unit
V/V
V
µA
ns
3
FA13842, 13843, 13844, 13845
Output section
Item
High-level output
Low-level output
Rise time
Fall time
Symbol
V
OH
V
OL
tr
tf
Test condition
I source=–20mA
I source=–100mA
I sink=20mA
I sink=200mA
C
L
=1nF, Tj=25˚C
C
L
=1nF, Tj=25˚C
Min.
14.5
12
Typ.
14.75
13.5
0.15
1.5
40
20
0.3
3
150
150
Max.
Unit
V
V
V
V
ns
ns
Under-voltage lockout section
Item
Start threshold
Min. operating voltage
Hysteresis
Symbol
V
TH ON
V
TH OFF
V
HYS
Test condition
FA13842, 13844
FA13843, 13845
FA13842, 13844
FA13843, 13845
Min.
15.5
8.6
8
Typ.
16.5
9.6
9
7.5
0.6
Max.
17.5
10.6
10
Unit
V
V
V
V
V
PWM section
Item
Maximum duty cycle
Minimum duty cycle
Symbol
Dmax
Dmin
Test condition
FA13842, 13843
FA13844, 13845
FB=5V, COMP=Open
Min.
94
47
Typ.
96
48
Max.
98
50
0
Unit
%
%
%
Overall device
Item
Standby current
Start-up current
Operating current
Zener voltage (Vcc)
Symbol
I
CCL
I
CC ST
I
CC OP
V
Z
Test condition
FA13842, 13844
FA13843, 13845
Min.
Vcc=14V
Vcc=7V
12
3
30
Typ.
Max.
2
2
30
5
34
Unit
µA
µA
µA
mA
V
Vcc=Start threshold
Icc=5mA
28
4
FA13842, 13843, 13844, 13845
s
Characteristic curves
(Ta=25˚C)
Timing resistance vs. oscillation frequency
FA13842, FA13843
100
Output dead time vs. oscillation frequency
FA13842, FA13843
100
V
CC
= 15V
Ta= 25˚C
470pF
2.2nF
C
T
=10nF
10
2.2nF
C
T
=10nF
R
T
resistance (kΩ)
470pF
Output dead time (%)
10
V
CC
= 15V
Ta= 25˚C
1
1
10
100
Oscillation frequency (kHz)
1000
1
10
100
Oscillation frequency (kHz)
1000
Timing resistance vs. oscillation frequency
FA13844, FA13845
100
470pF
2.2nF
Output dead time vs. oscillation frequency
FA13844, FA13845
100
V
CC
= 15V
Ta= 25˚C
90
Output dead time (%)
C
T
=10nF
R
T
resistance (kΩ)
80
10
70
2.2nF
C
T
=10nF
60
470pF
V
CC
= 15V
Ta= 25˚C
1
50
40
1
10
100
Oscillation frequency (kHz)
1000
10
100
Oscillation frequency (kHz)
1000
RT/CT discharge current vs. temperature
10
Output max. duty cycle vs. timing resistance
FA13842, FA13843
100
Output maximum duty cycle (%)
90
80
70
60
RT/CT discharge current (mA)
9.5
9
8.5
8
7.5
50
40
7
–50
0
50
Temperature (˚C)
100
150
1
2
5
R
T
timing resistance (kΩ)
10
5
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