FA5304AP(S)/FA5305AP(S)
s
Description
The FA5304AP(S) and FA5305AP(S) are bipolar ICs for
switching power supply control and can directly drive a power
MOSFET. These ICs contain many functions in a small 8-pin
package. With these ICs, a high-performance power supply
can be created compactly because not many external
components are needed.
Bipolar IC
For Switching Power Supply Control
FA5304AP(S)/FA5305AP(S)
s
Dimensions, mm
SOP-8
8
5
s
Features
• Drive circuit for connecting a power MOS-FET (I
O
=
±1.5A)
• Wide operating frequency range (5 to 600kHz)
• Pulse-by-pulse overcurrent limiting function
Positive voltage detection: FA5304AP(S)
Negative voltage detection: FA5305AP(S)
• Overload cutoff function (Latch or non-protection mode
selectable)
• Output ON/OFF control function by external signals
• Overvoltage cutoff function in latch mode
• Undervoltage malfunction prevention function (ON at 16V
and OFF at 8.7V)
• Error amplifier for control by tertiary winding detection
• Low standby current (90
µ
A typ.)
• 8-pin package (DIP/SOP)
1
6.05
4
+0.1
–0.05
8.2
±0.3
5.3
°
0~10
0.4
±0.1
1.27
±0.2
0.6
DIP-8
8
5
s
Applications
• Switching power supply for general equipment
1
9.3
1.5
4
6.5
3.0min 4.5max
3.4
0.3
7.6
2.54
±0.25
0.5
±0.1
0~15
˚
0~1
5˚
2.0max
+0.1 5
–0.0
0.20
1
FA5304AP(S)/FA5305AP(S)
s
Block diagram
FA5304AP(S)
Pin
No.
1
2
3
4
5
6
7
8
Pin
symbol
Description
Inverting input to error amplifier
Error amplifier output
Overcurrent (+) detection
Ground
Output
Power supply
Oscillator timing capacitor
Soft-start and ON/OFF control
IN (–)
FB
IS (+)
GND
OUT
VCC
CT
CS
FA5305AP(S)
Pin
No.
1
2
3
4
5
6
7
8
Pin
symbol
Description
Inverting input to error amplifier
Error amplifier output
Overcurrent (–) detection
Ground
Output
Power supply
Oscillator timing capacitor
Soft-start and ON/OFF control
IN (–)
FB
IS (–)
GND
OUT
VCC
CT
CS
2
FA5304AP(S)/FA5305AP(S)
s
Absolute maximum ratings
Common to FA5304AP(S) and FA5305AP(S)
Item
Supply voltage
Output current
Error amplifier input
voltage
Feedback terminal input voltage
Overcurrent detection
terminal input voltage
CS terminal input current
Total power dissipation
(Ta = 25°C)
Operating temperature
Storage temperature
Symbol
Rating
30
±1.5
4
4
–0.3 to +4
2
800 (DIP-8) *
1
550 (SOP-8) *
2
–30 to +85
–40 to +150
Unit
V
A
V
V
V
mA
mW
°C
°C
Notes:
* 1 Derating factor Ta > 25°C : 8.0mW/°C ( on PC board )
* 2 Derating factor Ta > 25°C : 5.5mW/°C ( on PC board )
s
Recommended operating conditions
Common to FA5304AP(S) and FA5305AP(S)
Item
Supply voltage
Symbol
Min.
10
100
0.1
5
1
600
Max.
30
Unit
V
kΩ
V
CC
I
O
V
IN
V
FB
V
IS
I
CS
P
d
T
opr
T
stg
V
CC
Error amplifier feedback resistor
R
NF
Soft-start capacitor
C
S
Oscillation frequency
f
OSC
µ
F
kHz
s
Electrical characteristics
(Ta=25°C, V
CC
=18V,fosc=135kHz)
Oscillator section
Item
Oscillation frequency
Frequency variation 1 (due to supply voltage change)
Frequency variation 2 (due to temperature change)
Common to FA5304AP(S) and FA5305AP(S)
Symbol
Test condition
Min.
112
Typ.
135
±1
±4
Max.
148
Unit
kHz
%
%
f
OSC
f
dv
f
dT
C
T
= 360pF
V
CC
= 10 to 30V
T
a
= –30 to +85°C
Error amplifier section
Item
Reference voltage
Input bias current
Open-loop voltage gain
Unity-gain bandwidth
Maximum output voltage (Pin 2)
Output source current (Pin 2)
Common to FA5304AP(S) and FA5305AP(S))
Symbol
Test condition
Min.
1.90
–500
80
1.0
Typ.
2.00
–50
Max.
2.10
Unit
V
nA
dB
MHz
V
200
–100
–50
mV
V
B
I
B
A
V
f
T
V
OM+
V
OM–
I
MO+
V
1
= 2V
R
NF
= 100kΩ
R
NF
= 100kΩ
V
OM
= 1V
2.70
µ
A
Pulse width modulation circuit section
Item
Input threshold voltage (Pin 2)
Maximum duty cycle
Common to FA5304AP(S) and FA5305AP(S)
Symbol
Test condition
Duty cycle = 0%
Duty cycle =
D
MAX
Min.
0.80
1.70
42
Typ.
1.00
1.90
45
Max.
1.20
2.10
50
Unit
V
V
%
V
TH FBO
V
TH FBM
D
MAX
Soft-start circuit section
Item
Charge current (Pin 8)
Input threshold voltage (Pin 8)
Common to FA5304AP(S) and FA5305AP(S)
Symbol
Test condition
Pin 8 = 0V
Duty cycle = 0%
Duty cycle =
D
MAX
Min.
–15
0.80
1.70
Typ.
–10
1.00
1.90
Max.
–5
1.20
2.10
Unit
I
CHG
V
TH CSO
V
TH CSM
µ
A
V
V
3
FA5304AP(S)/FA5305AP(S)
Overcurrent limiting circuit section
Item
Input threshold voltage (Pin 3)
Overcurrent detection terminal source current
Delay time
Symbol
Test condition
FA5304AP(S)
Min.
Typ.
0.24
150
0.20
Pin 3 = 0V
0.28
FA5305AP(S)
Max. Min.
Typ.
Max.
Unit
V
TH IS
I
IS
T
PD IS
–0.20 –0.17 –0.14 V
–300 –200 –100 –240 –160 –80
200
µ
A
ns
Latch-mode cutoff circuit section
Item
CS terminal sink current
Cutoff threshold voltage (Pin 8)
Common to FA5304AP(S) and FA5305AP(S)
Symbol
Test condition
Pin 8 = 6V, Pin 2 = 1V
Min.
40
6.5
Typ.
70
7.0
Max.
150
7.5
Unit
I
SINK CS
V
TH CS
µ
A
V
Overload cutoff circuit section
Item
Cutoff threshold voltage (Pin 2)
Common to FA5304AP(S) and FA5305AP(S)
Symbol
Test condition
Min.
2.5
Typ.
2.7
Max.
2.9
Unit
V
V
TH FB
Undervoltage lock-out circuit section
Common to FA5304AP(S) and FA5305AP(S)
Item
OFF-to-ON threshold voltage
ON-to-OFF threshold voltage
Voltage hysteresis
Symbol
Test condition
Min.
15.5
8.20
Typ.
16.0
8.70
7.30
Max.
16.5
9.20
Unit
V
V
V
V
TH ON
V
TH OFF
V
HYS
Output section
Common to FA5304AP(S) and FA5305AP(S)
Item
L-level output voltage
H-level output voltage
Rise time
Fall time
Symbol
Test condition
Min.
Typ.
1.30
16.0
16.5
50
50
Max.
1.80
Unit
V
V
ns
ns
V
OL
V
OH
tr
tf
I
O
= 100mA
I
O
= –100mA,
V
CC
= 18V
No load
No load
Output ON/OFF control circuit section
Common to FA5304AP(S) and FA5305AP(S)
Item
CS terminal source current
OFF-to-ON threshold voltage (Pin 8)
ON-to-OFF threshold voltage (Pin 8)
Symbol
Test condition
Pin 8 = 0V
CS pin voltage
CS pin voltage
0.30
Min.
–15
Typ.
–10
0.56
0.42
Max.
–5
0.76
Unit
I
SOURCE CS
V
TH ON
V
TH OFF
µ
A
V
V
Overall device
Common to FA5304AP(S) and FA5305AP(S)
Item
Standby current
Operating-state supply current
OFF-state supply current
Cutoff-state supply current
Symbol
Test condition
Min.
Typ.
90
9
1.1
1.1
Max.
150
15
1.8
1.8
Unit
I
CC ST
I
CC OP
I
CC OFF
I
CCL
V
CC
= 14V
µ
A
mA
mA
mA
4
FA5304AP(S)/FA5305AP(S)
s
Description of each circuit
1. Oscillator
(See block diagram on page 8.)
The oscillator generates a triangular waveform by charging
and discharging a capacitor. CT pin voltage oscillates
between an upper limit of approx. 3.0V and a lower limit of
approx. 1.0V. The oscillation frequency is determined by a
external capacitance C
T
connected to CT pin, and
approximately given by the following equation:
f (kH
Z
) =
4.8 • 10
4
C
T
(pF)
..................(1)
The recommended oscillation range is between 5k and
600kHz.
The oscillator output is connected to a PWM comparator.
2. Feedback circuit
Figure 1 gives an example of connection in which built-in error
amplifier is used to couple the feedback signal to IN(-) pin. Let n
2
be the number of turns of secondary winding L
2
and n
3
be the
number of turns of tertiary winding L
3
. V
CC
and Vout are given by
Vcc= 2(V)•(R
1
+R
2
)/R
2
....................................(2)
V
OUT
(n
2
/n
3
)•(Vcc+V
D3
)–V
D2
........................(3)
(where V
D2
and V
D3
are the forward voltage drops across diodes D
2
and D
3
respectively).
Fig. 1 Configuration with error amplifier
Here, the following equation must be satisfied to prevent from
the malfunction of OUT pin at shutdown.
(R1•R2)/ (R1+R2)11kΩ...............................(4)
Figure 2 gives an example of connection in which an
optocoupler is used to couple the feedback signal to the FB
pin. If this circuit causes power supply instability, the frequency
gain can be decreased by connecting R
4
and C
4
as shown in
figure 2. R
4
should be between several tens of ohms to
several kiloohms and C
4
should be between several thousand
picofarads to one microfarads.
Fig. 2 Configuration with optocoupler (FB pin input)
3. PWM comparator
The PWM comparator has four inputs as shown in Figure 3.
Oscillator output
x
is compared with CS pin voltage
,
FB pin
,
and DT voltage
{.
The lowest of three inputs
, ,
and
{
is compared with output
x.
If it is lower than the oscillator
output, the PWM comparator output is high, and if it is higher
than the oscillator output, the PWM comparator output is low
(see Fig. 4).
The IC output voltage is high during when the comparator
output is low, and the IC output voltage is low during when the
comparator output is high.
When the IC is powered up, CS pin voltage
controls soft
start operation. The output pulse then begins to widen
gradually. During normal operation, the output pulse width is
determined within the maximum duty cycle (FA5304A,
FA5305A: 45%) set by DT voltage
{
under the condition set
by feedback signal
,
to stabilize the output voltage.
Fig. 3 PWM comparator
Fig. 4 PWM comparator timing chart
5
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