CALLM FA5305AS, FA5304AS, FA5304AP, FA5305AP Datasheet
FA5304AP(S)/FA5305AP(S)
1
■ 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.
■ 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 (90
µ
A typ.)
• 8-pin package (DIP/SOP)
■ Applications
• Switching power supply for general equipment
■ Dimensions, mm
Á SOP-8
6.05
5.3
8.2
±0.3
0.4
±0.1
1.27
±0.2
0.6
0.20
+0.1
–0.05
0~10°
1
4
8
5
2.0max
Á DIP-8
Bipolar IC
For Switching Power Supply Control
FA5304AP(S)/FA5305AP(S)
1
8
5
4
9.3
6.5
7.6
3.4
4.5max
1.5
3.0min
0~15˚
0~15˚
0.5
±0.1
2.54
±0.25
0.3
+0.1
–0.05
FA5304AP(S)/FA5305AP(S)
2
■ Block diagram
Á FA5304AP(S)
Pin Pin Description
No. symbol
1 IN (–) Inverting input to error amplifier
2 FB Error amplifier output
3 IS (+) Overcurrent (+) detection
4 GND Ground
5 OUT Output
6 VCC Power supply
7 CT Oscillator timing capacitor
8 CS Soft-start and ON/OFF control
Á FA5305AP(S)
Pin Pin Description
No. symbol
1 IN (–) Inverting input to error amplifier
2 FB Error amplifier output
3 IS (–) Overcurrent (–) detection
4 GND Ground
5 OUT Output
6 VCC Power supply
7 CT Oscillator timing capacitor
8 CS Soft-start and ON/OFF control
FA5304AP(S)/FA5305AP(S)
3
■ Absolute maximum ratings
Common to FA5304AP(S) and FA5305AP(S)
Item Symbol Rating Unit
VCC 30 V
IO ±1.5 A
VIN 4V
VFB 4V
VIS –0.3 to +4 V
ICS 2mA
Pd 800 (DIP-8) *
1
mW
550 (SOP-8) *
2
Topr –30 to +85 °C
Tstg –40 to +150 °C
■ Recommended operating conditions
Common to FA5304AP(S) and FA5305AP(S)
Item Symbol Min. Max. Unit
Supply voltage VCC 10 30 V
Error amplifier feedback resistor RNF 100 kΩ
Soft-start capacitor CS 0.1 1
µ
F
Oscillation frequency fOSC 5 600 kHz
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
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 )
■ Electrical characteristics (Ta=25°C, VCC=18V,fosc=135kHz)
Oscillator section Common to FA5304AP(S) and FA5305AP(S)
Item Symbol Test condition Min. Typ. Max. Unit
Oscillation frequency fOSC CT = 360pF 112 135 148 kHz
Frequency variation 1 (due to supply voltage change) fdv VCC = 10 to 30V ±1%
Frequency variation 2 (due to temperature change) fdT Ta = –30 to +85°C ±4%
Error amplifier section Common to FA5304AP(S) and FA5305AP(S))
Item Symbol Test condition Min. Typ. Max. Unit
Reference voltage VB 1.90 2.00 2.10 V
Input bias current IB V1 = 2V –500 –50 nA
Open-loop voltage gain AV 80 dB
Unity-gain bandwidth fT 1.0 MHz
Maximum output voltage (Pin 2) VOM+ RNF = 100kΩ 2.70 V
VOM– RNF = 100kΩ 200 mV
Output source current (Pin 2) IMO+ VOM = 1V –100 –50
µ
A
Pulse width modulation circuit section Common to FA5304AP(S) and FA5305AP(S)
Item Symbol Test condition Min. Typ. Max. Unit
Input threshold voltage (Pin 2) VTH FBO Duty cycle = 0% 0.80 1.00 1.20 V
VTH FBM Duty cycle = DMAX 1.70 1.90 2.10 V
Maximum duty cycle DMAX 42 45 50 %
Soft-start circuit section Common to FA5304AP(S) and FA5305AP(S)
Item Symbol Test condition Min. Typ. Max. Unit
Charge current (Pin 8) ICHG Pin 8 = 0V –15 –10 –5
µ
A
Input threshold voltage (Pin 8) VTH CSO Duty cycle = 0% 0.80 1.00 1.20 V
VTH CSM Duty cycle = DMAX 1.70 1.90 2.10 V
FA5304AP(S)/FA5305AP(S)
4
Overcurrent limiting circuit section
Item Symbol Test condition FA5304AP(S) FA5305AP(S) Unit
Min. Typ. Max. Min. Typ. Max.
Input threshold voltage (Pin 3) VTH IS 0.20 0.24 0.28 –0.20 –0.17 –0.14 V
Overcurrent detection terminal source current IIS Pin 3 = 0V –300 –200 –100 –240 –160 –80µA
Delay time TPD IS 150 200 ns
Latch-mode cutoff circuit section Common to FA5304AP(S) and FA5305AP(S)
Item Symbol Test condition Min. Typ. Max. Unit
CS terminal sink current ISINK CS Pin 8 = 6V, Pin 2 = 1V 40 70 150
µ
A
Cutoff threshold voltage (Pin 8) VTH CS 6.5 7.0 7.5 V
Overload cutoff circuit section Common to FA5304AP(S) and FA5305AP(S)
Item Symbol Test condition Min. Typ. Max. Unit
Cutoff threshold voltage (Pin 2) VTH FB 2.5 2.7 2.9 V
Undervoltage lock-out circuit section Common to FA5304AP(S) and FA5305AP(S)
Item Symbol Test condition Min. Typ. Max. Unit
OFF-to-ON threshold voltage VTH ON 15.5 16.0 16.5 V
ON-to-OFF threshold voltage VTH OFF 8.20 8.70 9.20 V
Voltage hysteresis VHYS 7.30 V
Output section Common to FA5304AP(S) and FA5305AP(S)
Item Symbol Test condition Min. Typ. Max. Unit
L-level output voltage VOL IO = 100mA 1.30 1.80 V
H-level output voltage VOH IO = –100mA, VCC = 18V 16.0 16.5 V
Rise time tr No load 50 ns
Fall time tf No load 50 ns
Output ON/OFF control circuit section Common to FA5304AP(S) and FA5305AP(S)
Item Symbol Test condition Min. Typ. Max. Unit
CS terminal source current ISOURCE CS Pin 8 = 0V –15 –10 –5
µ
A
OFF-to-ON threshold voltage (Pin 8) VTH ON CS pin voltage 0.56 0.76 V
ON-to-OFF threshold voltage (Pin 8) VTH OFF CS pin voltage 0.30 0.42 V
Overall device Common to FA5304AP(S) and FA5305AP(S)
Item Symbol Test condition Min. Typ. Max. Unit
Standby current ICC ST VCC = 14V 90 150
µ
A
Operating-state supply current ICC OP 915mA
OFF-state supply current ICC OFF 1.1 1.8 mA
Cutoff-state supply current ICCL 1.1 1.8 mA
5
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
■ 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:
..................(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 L2 and n3 be the
number of turns of tertiary winding L
3. VCC and Vout are given by
Vcc= 2(V)•(R
1+R2)/R2....................................(2)
V
OUT앓(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)쏜11kΩ...............................(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 C4 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.
3. PWM comparator
The PWM comparator has four inputs as shown in Figure 3.
Oscillator output ① is compared with CS pin voltage ➁, FB pin
➂, and DT voltage ④. The lowest of three inputs ➁, ➂, and ④
is compared with output ①. 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 ➁ 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 ④ under the condition set
by feedback signal ➂, to stabilize the output voltage.
C
T (pF)
f (kHZ) =
4.8 • 10
4
6
FA5304AP(S)/FA5305AP(S)
4. CS pin circuit
As shown in Figure 5, capacitor C
S is connected to the CS pin.
When power is turned on, the constant current source (10µA)
begins to charge capacitor C
S. Accordingly, the CS pin voltage
rises as shown in Figure 6. The CS pin is connected to an
input of the PWM comparator. The device is in soft-start mode
while the CS pin voltage is between 1.0V and 1.9V common to
FA5304A and FA5305A. During normal operation, the CS pin
is clamped at 3.6V by internal zener diode Zn. If the output
voltage drops due to an overload, etc., the clamp voltage shifts
from 3.6V to 8.0V. As a result, the CS pin voltage rises to 8.0V.
The CS pin is also connected to latch comparator C2. If the pin
voltage rises above 7.0V, the output of comparator C2 goes
high to turn off the bias circuit , thereby shutting the output
down. Comparator C2 can be used not only for shutdown in
response to an overload, but also for shutdown in response to
an overvoltage. Comparator C1 is also connected to the CS
pin, and the bias circuit is turned off and the output is shut
down if the CS pin voltage drops below 0.42V. In this way,
comparator C1 can also be used for output on/off control.
As explained above, the CS pin can be used for soft-start
operation, overload and overvoltage output shutdown and
output on/off control.
Further details on the four functions of the CS pin are given
below.
4.1 Soft start function
Figure 7 shows the soft start circuit. Figure 8 is the soft-start
operation timing chart. The CS pin is connected to capacitor
C
S . When power is turned on, a 10µA constant-current source
begins to charge the capacitor. As shown in the timing chart,
the CS pin voltage rises slowly in response to the charging
current. The CS pin is connected internally to the PWM
comparator. The comparator output pulse slowly widens as
shown in the timing chart.
The soft start period can be approximately evaluated by the
period ts from the time the IC is activated to the time the output
pulse width widens to 30%. Period ts is given by the following
equation:
t
S (mS) = 160CS (µF).................................(2)
Fig. 5 CS pin circuit
Fig. 6 CS pin waveform
Fig. 7 Soft-start circuit
Fig. 8 Soft-start timing chart
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