|
|
PDF FA5305AP Data sheet ( Hoja de datos )
| Número de pieza | FA5305AP | |
| Descripción | Bipolar IC For Switching Power Supply Control | |
| Fabricantes | Fuji Electric | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de FA5305AP (archivo pdf) en la parte inferior de esta página. Total 17 Páginas | ||
|
No Preview Available !
FA5304AP(S)/FA5305AP(S) Bipolar IC
For SwitcFhAin5g30P4oAwPe(rSS)/uFpAp5l3y0C5oAnPt(rSo)l
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.
s Features
• Drive circuit for connecting a power MOS-FET (IO = ±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 (90µA typ.)
• 8-pin package (DIP/SOP)
s Applications
• Switching power supply for general equipment
s Dimensions, mm
SOP-8
8
5
14
6.05
0.4±0.1 1.27±0.2
DIP-8
8
5
1 9.3 4
1.5
0.6
2.54±0.25 0.5±0.1
0~15˚
7.6
0.3 +–00.1.05
0~15˚
1
1 page  
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 CT connected to CT pin, and
approximately given by the following equation:
f (kHZ) =
4.8 • 104
CT (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 n2
be the number of turns of secondary winding L2 and n3 be the
number of turns of tertiary winding L3. VCC and Vout are given by
Vcc= 2(V)•(R1+R2)/R2....................................(2)
VOUTȃ(n2/n3)•(Vcc+VD3)–VD2........................(3)
(where VD2 and VD3 are the forward voltage drops across diodes D2
and D3 respectively).
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 R4 and C4 as shown in
figure 2. R4 should be between several tens of ohms to
several kiloohms and C4 should be between several thousand
picofarads to one microfarads.
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.
FA5304AP(S)/FA5305AP(S)
Fig. 1 Configuration with error amplifier
Fig. 2 Configuration with optocoupler (FB pin input)
Fig. 3 PWM comparator
Fig. 4 PWM comparator timing chart
5
5 Page 
FA5304AP(S)/FA5305AP(S)
(2) Startup circuit connected to rectified line
This method is not suitable for FA5304A and FA5305A,
especially concerned with re-startup operation just after power-
off or startup which AC input voltage goes up slowly. Fig. 21
shows a startup circuit that a startup resistor RA is connected
to rectified line directly.
The period from power-on to startup is determined by RA, RB
and CA. RA, RB and CA must be designed to satisfy the
following equations.
dVcc/dt(V/s)=
(1/CA )•{( VIN –Vccon )/RA– Vccon/RB –Iccst } >
1.8/(Cs(µF))................................................(8)
RA(kΩ)< (VIN– 9.2(V))/{0.4(mA) + (9.2(V)/RB(kΩ))}..............(9)
VIN: ǰ2 •(AC input effective voltage)
After power-off, once VCC falls down below OFF threshold
voltage, VCC rises up again and re-startup occurs while the
capacitor C1 is discharged until approximately zero because
VCC voltage rises up by the current flowing RA.
This operation is repeated several times.
After the repeated operation, IC stops in the condition that VCC
voltage is equal to Vccon (=ON threshold) because capacitor
C1 is discharged gradually and the decreased VCC inclination
is out of the condition required by equation (4).
After that, re-startup by power-on can not be guaranteed even
when equation (8) is satisfied. The image of that the startup is
impossible is shown in Fig. 22. It is necessary to startup IC
that supply current Icc (startup) to VCC is over 4mA in the
condition of Tj < 100 °C during Vcc is kept at Vccon(Լ16V,
balance state at Vccon after the repeated operation.
Icc (start-up) > 4mA..............................(10)
at Vcc=Vccon, Tj<100°C, after power-off
This balance state that startup is impossible tends to occur at
higher temperature.
If power-on is done when Vcc is not kept at Vccon (for
example: power-off is done and after enough time that C1 is
discharged until Vcc can not be pulled up to Vccon), the IC can
startup in the condition given by equation(8).
In some cases, such as when the load current of power supply
is changed rapidly, you may want to prolong the hold time of
the power supply output by means of maintaining Vcc over the
off threshold.
For this purpose, connect diode D4 and electrolytic capacitor
C4 as shown in Fig. 23. This prolongs the hold time of the
power supply voltage Vcc regardless of the period from power-
on to startup.
Fig. 21 Startup circuit example(2)
Startup is impossible (dVcc/dt <1.8/Cs
just before Vcc reaches Vccon).
Icc>4mA is necessary for startup at
Tj <100°C and dVcc/dt=0.
Power OFF
Vccon
Vccoff
Power ON
Startup is impossible
Fig. 22 Image of Vcc waveform when re-startup is impossible
Fig. 23 Startup circuit example(3)
11
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet FA5305AP.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| FA5305AP | Bipolar IC For Switching Power Supply Control | Fuji Electric |
| FA5305APS | Bipolar IC For Switching Power Supply Control | Fuji Electric |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |