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FA7700V, FA7701V
s Description
FA7700V/FA7701V are the PWM type DC to DC converter control ICs with 1ch output that can directly drive power MOSFETs. CMOS devices with high breakdown voltage are used in these ICs and low power consumption is achieved. These ICs have not only the functions equivalent to those of FA76XX series but also the functions of directly driving Nch/Pch MOSFETs, lower power consumption, higher frequency operation, and less external components.
CMOS IC For Switching Power Supply Control FA7700V, FA7701V
s Dimensions, mm TSSOP-8
4.4 0.2
6.4 0.3
s Features
* Wide range of supply voltage: VCC=2.5 to 20V * FA7700V: For boost, flyback converter (Maximum output duty cycle is 80%) * FA7701V: For buck converter (Maximum output duty cycle is 100%) * Output stage consist of CMOS push-pull circuit, and achieves a high speed switching of external MOSFETs. (FA7700V: For Nch-MOSFET driving, FA7701V: For Pch-MOSFET driving) * High accuracy reference voltage (Error amplifier): 0.88V2% * Soft start function * Adjustable built-in timer latch for short-circuit protection * Output ON/OFF control function * Less external discrete components needed (2 components less than conventional version of the equivalent products) * Low power consumption Stand-by current: 40A typ. Operating current: 1.2mA typ. (Including error amplifier output current and oscillator current) * High frequency operation: 50kHz to 1MHz * Package: TSSOP-8, thin and small
0.575 typ
1.30 max
3.1
0.3
0.1 0.05
10 to 0
0.65 0.22
0.1
0.5
0.2
s Block diagram FA7700V FA7701V
RT
1
VREF
UVLO
8
0.3V ON/OFF
0.15 0.1
CS
RT
1
VREF
UVLO
8
0.3V ON/OFF
CS
REF
2 3 4
VREF 2.2V
- +
OSC
5.5V 1.5V
S.C.P
BIAS 1.5V Power Good Signal
S.C.DET
+ -
2.2V
7 6 5
VCC
REF
2 3 4
VREF 2.2V
- +
OSC
S.C.P 1.5V S.C.DET 1.5V
BIAS Power Good Signal
+ -
2.2V 5.5V
7 6 5
VCC
IN-
+ -
ON/OFF
OFF
0.88V
+ -
ER.AMP
+ - + +
OUT
IN-
+ -
ON/OFF
OFF
0.88V
+ -
+ - +
OUT
PWM
PWM
ER.AMP
FB
GND
FB
GND
Pin No. Pin symbol Description 1 2 3 4 5 6 7 8 RT REF IN (-) FB GND OUT VCC CS Oscillator timing resistor Internal bias voltage Error amplifier inverting input Error amplifier output Ground Output for driving switching device Power supply ON/OFF, soft start, timer latched short circuit protection
1
FA7700V, FA7701V
s Absolute maximum ratings
Item
Power supply voltage REF terminal output current OUT terminal source current OUT terminal sink current RT, REF, IN-, FB terminal voltage CS terminal voltage CS terminal sink current Power dissipation Operating ambient temperature Operating junction temperature Storage temperature Symbol Vcc IREF ISO peak ISO cont ISI peak ISI cont VRT, VREF VIN-, VFB VCS ICS Pd Ta Tj Tstg Rating 20 2 -400 (peak) -50 (continuos) +150 (peak) +50 (continuos) +2.5 (max.) -0.3 (min.) Self limiting 5.5 (max.) -0.3 (min.) 200 250 (Ta 25C) -30 to +85 +125 -40 to +150 Unit V mA mA mA V V A mW C C C
Maximum power dissipation curve
300
Max. power dissipation [mW]
250 200 150 100 50 0 -30
0
30
60
90
125
150
Ambient temperature [C]
s Recommended operating condition
Item Supply voltage DC feedback resistor of error amplifier VCC terminal capacitance REF terminal capacitance CS terminal capacitance CS terminal sink current Oscillation frequency Symbol VCC RNF CVCC CREF CS Icsin fosc Min. 2.5 100 0.1 0.047 0.01 1* 50
VCC - 1.5 50A + IL RCS [M] VCC - 1.5 1A + IL
Typ. 6
Max. 18
Unit V k F
0.1
1 10 50 1000
F F A kHz
* Lower limit of ICSIN does not include leak current "IL" for capacitor Cs. Set a resistor "RCS [M]" connected between VCC terminal and CS terminal to satisfy the equation.
2
FA7700V, FA7701V
s Electrical characteristics (Ta=25C, VCC=6V, RT=22k) Internal bias section (REF terminal voltage)
Item Output voltage Line regulation Load regulation Variation with temperature Symbol VREF VLINE VLOAD VTC1 VTC2 Test condition REF terminal source current IREF=0mA Vcc=2.5 to 20V, IREF=0mA IREF=0 to 2mA Ta=-30 to 25C Ta=25 to 85C 2 2 0.3 0.3 14 12 mV mV % % Min. 2.16 Typ. 2.23 Max. 2.30 Unit V
Oscillator section (Frequency set by RT terminal)
Item Oscillation frequency Line regulation Variation with temperature Symbol fosc fLINE fTC1 fTC2 Test condition RT=22k Vcc=2.5 to 20V Ta=-30 to 25C, 50k to 1MHz Ta=25 to 85C, 50k to 1MHz Min. 155 Typ. 185 0.1 2 3 Max. 215 Unit kHz % % %
Error amplifier section (IN- terminal, FB terminal)
Item Reference voltage Input current VB line regulation VB variation with temperature Open loop gain Unity gain bandwidth Output current Source Sink Symbol VB IIN- VBLINE VBTC1 VBTC2 AVO fT IOHE IOLE FB terminal=VREF- 0.5V FB terminal=0.5V -220 3 Vcc=2.5 to 20V Ta=-30 to 25C Ta=25 to 85C 70 1.5 -160 6 -100 12 Test condition IN- terminal, FB terminal: Shorted (voltage follower) -500 1 0.3 0.3 +500 5 nA mV % % dB MHz A mA Min. 0.863 Typ. 0.880 Max. 0.897 Unit V
Pulse width modulation (PWM) section (FB terminal voltage and duty cycle)
Item FB 0% threshold FB 50% threshold Maximum duty cycle FA7700 Symbol VFB0 VFB50 DMAX1 DMAX2 DMAX3 FA7701 DMAX Test condition Duty cycle = 0% Duty cycle = 50% RT=100k, f=50kHz RT=22k, f 185kHz RT=3k, f 1MHz 85 83 80 100 Min. 0.560 Typ. 0.660 0.880 90 88 86 95 93 92 Max. 0.760 Unit V V % % % %
Undervoltage lock-out section (VCC terminal voltage)
Item ON threshold OFF threshold Hysteresis voltage Variation with temperature Symbol VCCON VCCOF VCCHY VCCHY Ta= -30 to 25C Ta= 25 to 85C 1.60 0.04 Test condition Min. Typ. 2.07 1.93 0.14 +0.2 -0.2 0.24 Max. 2.30 Unit V V V mV/C mV/C
3
FA7700V, FA7701V
ON/OFF section (CS terminal voltage)
Item ON/OFF threshold Threshold variation with temperature Symbol VONOF VONTC Ta = -30 to 85C Test condition Min. 0.150 Typ. 0.300 +0.5 Max. 0.450 Unit V mV/C
Soft start section (CS terminal voltage)
Item Threshold voltage 1 Threshold voltage 2 Symbol VCS0 VCS50 Test condition Duty cycle=0% Duty cycle=50% Min. 0.560 Typ. 0.660 0.880 Max. 0.760 Unit V V
Timer latched short circuit protection section (FB terminal, CS terminal)
Item Short detection threshold voltage Latched mode threshold voltage Latched mode reset voltage Latched mode hysteresis CS terminal clamped voltage Symbol VFBTH VCSTH VCSRE VCSHY VCSCL1 VCSCL2 Test condition FB terminal voltage CS terminal voltage CS terminal voltage CS terminal voltage FB terminal<1.35V, CS sink current= +1A FB terminal>1.65V, CS sink current= +150A Min. 1.350 2.050 1.700 50 1.400 4.500 Typ. 1.500 2.200 2.030 170 1.500 5.500 Max. 1.650 2.350 2.300 350 1.600 6.500 Unit V V V mV V V
Output stage section (OUT terminal)
Item High side on resistance Low side on resistance Rise time Fall time FA7700 FA7701 FA7700 FA7701 tf Symbol RONH RONH RONL RONL tr Test condition VCC=6V, source current= -50mA VCC=2.5V, source current= -50mA VCC=6V, sink current= +50mA VCC=2.5V, sink current= +50mA 330pF load to GND terminal 330pF load to VCC terminal 330pF load to GND terminal 330pF load to VCC terminal Min. Typ. 10 18 5 5 20 25 45 40 Max. 20 36 10 10 Unit ns ns ns ns
Overall section (Supply current to VCC terminal)
Item OFF mode supply current Operating mode supply current Latched mode supply current Symbol ICCST1 ICC0 ICC1 ICCLAT Test condition CS terminal=0V Duty cycle=0%, OUT:Open, IN-=0V, FB:Open Duty cycle=50%, OUT:Open, IN-, FB:Shorted CS terminal >2.35V, IN-=0V, FB:Open Min. Typ. 40 0.9 1.2 0.9 Max. 100 1.5 2.0 1.5 Unit A mA mA mA
4
FA7700V, FA7701V
s Characteristic curves Oscillation frequency (fOSC) vs. timing resistor resistance (RT)
10000
Oscillation frequency (fOSC) vs. ambient temperature
5 4
Oscillation frequency variation [%]
Oscillation frequency [kHz]
3 2 1 0
1000
fosc=1MHz
fosc=185kHz
-1 -2 -3 -4
fosc=50kHz
100
10
1
10
100
-5 -40
-20
0
20
40
60
80
100
Timing resisitor RT [k]
Ambient temperature Ta [C]
Duty cycle vs. FB terminal voltage FA7700
100 90 80 70
Duty cycle vs. CS terminal voltage FA7700
100 90 80 70
Duty cycle [%]
Duty cycle [%]
fosc=1MHz
60 50 40 30
60 50 40 30 20 10 0 0.5 0.7 0.9
fosc=1MHz
fosc=185kHz
20 10 1.1 1.3 0 0.5 0.7
fosc=185kHz
0.9
1.1
1.3
FB terminal voltage [V]
CS terminal voltage [V]
Duty cycle vs. FB terminal voltage FA7701
100 90 80 70
Duty cycle vs. CS terminal voltage FA7701
100 90 80 70
Duty cycle [%]
60 50 40 30 20 10 0 0.5 0.7
fosc=1MHz
Duty cycle [%]
fosc=1MHz
60 50 40 30 20
fosc=185kHz
fosc=185kHz
10 1.1 1.3 0 0.5 0.7 0.9 1.1 1.3
0.9
FB terminal voltage [V]
CS terminal voltage [V]
5
FA7700V, FA7701V
Maximum duty cycle vs. ambient temperature FA7700
94 92
Error amp. reference voltage vs. ambient temperature
0.90
fosc=50kHz
0.89
88 86
fosc=185kHz
Reference voltage [V]
90
Max. duty cycle [%]
0.88
fosc=1MHz
84
0.87
82 80 -40
-20
0
20
40
60
80
100
0.86 -40
-20
0
20
40
60
80
100
Ambient temperature Ta [C]
Ambient temperature Ta [C]
Internal bias voltage vs. ambient temperature
2.28
Undervoltage lock-out vs. ambient temperarure
2.20 2.15
Vcc terminal ON/OFF threshold
2.26
Internal bias voltage [V]
2.10 2.05 2.00
Vcc ON
2.24
2.22
Vcc OFF
1.95 1.90 1.85
2.20
2.18 -40
-20
0
20
40
60
80
100
1.80 -40
-20
0
20
40
60
80
100
Ambient temperature Ta [C]
Ambient temperature Ta [C]
CS terminal ON/OFF threshold vs. ambient temperature
0.40
CS terminal voltage vs. CS terminal sink current
200 180 -30C Ta=25C 85C Ta=-30C Ta=25C
CS terminal ON/OFF threshold
CS terminal sink current [ A]
0.35
160 140 120 100 80 60 40 20
0.30
Ta=85C
0.25
FB>1.65V
0.20
FB<1.35V
0.15 -40
-20
0
20
40
60
80
100
0 0 1 2 3 4 5 6
7
Ambient temperature Ta [C]
CS terminal voltage [V]
6
FA7700V, FA7701V
Operating mode supply current vs. VCC
2
Operating mode supply current vs. VCC
3
Operating mode supply current [mA]
Operating mode supply current [mA]
Duty=50% IN(-)-FB:shorted 1.5 fosc=1MHz
Duty=50% IN(-)-FB:shorted 2.5
2
fosc=1MHz
1 fosc=185kHz 0.5
1.5
1
fosc=185kHz
0.5
0
0
0.5
1
1.5
2
2.5
3
0
4
6
8
10
12
14
16
18
20
Vcc [V]
Vcc [V]
OFF mode supply current vs. temperature
60 CS=0V 55
Operating mode supply current vs. temperature
1.5 RT=22k
Operating mode supply current [mA]
1.4 1.3 Vcc=20V (Duty=50%) 1.2 1.1 1 0.9 0.8 0.7 0.6 -40 Vcc=6V (Duty=0%) Vcc=6V (Duty=50%)
OFF mode supply current [ A]
50
Vcc=20V
45
40 Vcc=6V 35
30 -40
-20
0
20
40
60
80
100
-20
0
20
40
60
80
100
Temperature Ta [C]
Temperature Ta [C]
Latched mode supply current vs. temperature
1
Oscillation frequency vs. operating mode supply current
3
Operating mode supply current [mA]
Operating mode supply current [mA]
0.95
Vcc=6V RT=22k CS > 2.35V
Vcc=6V Duty=50% 2.5
0.9
2
0.85
1.5
0.8
1
0.75
0.5
0.7 -40
-20
0
20
40
60
80
100
0 10
100
1000
Temperature Ta [C]
Oscillation frequency [kHz]
7
FA7700V, FA7701V
OUT terminal source current vs. OUT terminal voltage
450 400
OUT terminal sink current vs. OUT terminal voltage
200
OUT terminal source current [mA]
350 300 250 200 Vcc=6V 150 100 Vcc=2.5V 50 0 Vcc=12V Vcc=20V
OUT terminal source current [mA]
150
100
50
0
0 5 10 15 20 25
0
0.5
1
1.5
OUT terminal voltage [V]
OUT terminal voltage [V]
Error amplifier gain and phase vs. frequency
80 180 160 60 140
Gain
Gain [dB]
40
120 100
Phase
80 20
1M 390 + -
60 40 20 0
0
+
-20
3
6
3
6
3
6
3
6
3
6
0
1k
10k
100k
1M
10M
Frequency [Hz]
8
Phase [deg]
FA7700V, FA7701V
s Description of each circuit
OSC
1. Reference voltage circuit This circuit consists of the reference voltage circuit using band gap reference, and also serves as the power supply of the internal circuit. The precision of output is 2.23V3%. It is stabilized under the supply voltage of 2.5V or over. The precision of reference voltage of error amplifier circuit is 0.88V2%, and the reference voltage circuit is connected to the non-inverting input of the error amplifier circuit. 2. Oscillator The oscillator generates a triangular waveform by charging and discharging the built-in capacitor. A desired oscillation frequency can be determined by the value of the resistor "RT" connected to the RT terminal (Fig. 1). The built-in capacitor voltage oscillates between approximately 0.66V and 1.1V with almost the same charging and discharging gradients. You can set the desired oscillation frequency by changing the gradients using the resistor connected to the RT terminal. (Large RT: Low frequency, small RT: High frequency) The oscillator waveform cannot be observed from the outside because a terminal for this purpose is not provided. The oscillator output is connected to the PWM comparator. 3. Error amplifier circuit The IN(-) terminal (Pin 3) is an inverting input terminal. The non-inverting input is internally connected to the reference voltage (0.88V2%; 25C). The FB terminal (Pin 4) is the output of the error amplifier. Gain setting and phase compensation setting is done by connecting a capacitance and a resistor between the FB terminal and the IN(-) terminal. Vout which is the output voltage of DC to DC converter can be calculated by: R1 + R2 Vout = VB R2 Gain AV between the Vout and the FB terminal can be calculated by: RNF AV = - R1 4. PWM comparator The PWM comparator has 4 input terminals. (Fig. 4) The oscillator output is compared with the CS terminal voltage , and the error amplifier voltage , then, the lower voltage between and is preferred. While the preferred voltage is lower than the oscillator output, the PWM comparator output is Low. While the preferred voltage is higher than the oscillator output, the PWM comparator output is High (Fig. 5). When the IC starts, the capacitor connected to the CS terminal is charged through the resistor connected to the power supply, and then the output pulses begin to widen gradually as the operation of soft start. In steady operation, the pulse width is determined based on the voltage of the error amplifier , and then the output voltage is stabilized. The Dead Time control voltage ( DT voltage) of FA7700 and FA7701 has different characteristics to adjust the ICs to various types of power supply circuits being controlled and also to reduce external discrete components as many as possible. FA7700 is developed for fly-back circuits, and boost circuits, and the DT voltage is set in the IC so that the maximum output duty cycle is fixed to 80% min.. (Maximum output duty cycle changes according to operation frequencies. --See page 6 "Maximum output duty vs. temperature".) It prevents magnetic saturation of the transformer or the like when a short-circuit in the output circuit occurs. FA7701 is developed for buck circuits, and it is designed for the maximum output duty cycle of 100%. The timing chart of PWM comparator is described in Fig. 5.
RT
Fig. 1
1.1V
RT value: small
RT value: large
0.66V
Fig. 2
Vout
RNF
R1 IN(-) R2
Er. AMP 3 4 FB
VB
PWM
(0.88V)
Fig. 3
Oscillation output CS terminal voltage Error amplifier output DT voltage
- + + +
Fig. 4
PMW output
Error amplifier output Oscillation output
CS terminal voltage DT voltage
PWM output pulse
Fig. 5
9
FA7700V, FA7701V
5. Soft start function As described in Fig. 6, RCS is connected between CS terminal and VCC terminal, and Cs is connected between CS terminal and GND. The voltage of CS terminal rises when starting the power supply, because Cs is charged by Vcc through Rcs. The soft start function starts by charging a capacitor Cs connected to PWM comparator. To estimate the soft start period, the time (ts) between the start and the moment when the width of output pulse reaches 50% is calculated by: ts [ms] Cs RCS 1n
RCC Rcs
0.3 V
+
REF OFF
C3 ON/OFF
CS Cs
8
5.5V FB 1.5V
Output off
+
2.2V C1 S.C.P
( VCCVCC ) - 0.88
C2
Cs : Capacity of Cs [F] Rcs : Resistance of Rcs [k] Vcc : Supply voltage [V]
+
S.C.DET 1.5V
The maximum current flowing in Rcs should be within the recommended value (50A max.). Vcc - 1.5 50A + IL Rcs [M] Vcc - 1.5 1A + IL
Fig. 6
Vcc
(IL: leak current of capacitor Cs)
Note: This IC operates ON/OFF function by the CS terminal (CS < 0.3V typ. : OFF), then it turns off the internal bias voltage VREF (off mode). Therefore, you can not connect the resistor "Rcs" between CS terminal and REF terminal, and can connect the resistor only to VCC terminal.
CS ON/OFF Cs
CS terminal voltage [V]
6. ON/OFF circuit The ON/OFF function can be controlled by external signal to the CS terminal, the IC becomes off mode. When the CS terminal voltage is below 0.30V(typ.), the output of ON/OFF comparator C3 is set to LOW, and the internal power source VREF is shut off, then the IC is switched to the off mode. The power consumption in the off mode is 40A(typ.). A sample circuit is given in Fig. 7. 7. Timer latch short-circuit protection circuit The short-circuit protection circuit consists of two comparators C1, C2 (Fig. 6). In steady operation, the output of S.C.DET comparator C2 is set to High, and the CS terminal is clamped by the 1.5V Zener diode, because the output of error amplifier is about 1V. If the converter output voltage drops due to a short-circuit, when the output voltage of error amplifier rises excesses 1.5V, the output of S.C.DET comparator C2 is set to low, and then the clamp of Zener diode is turned off. As a result, the voltage of CS terminal rises up to the lower value of either 5.5 V or the voltage of VCC terminal. If the voltage of CS terminal excesses 2.2V, the output of S.C.P comparator C1 is set to high, and the circuit shuts down the output circuit of the IC. When it occurs, the current consumption of the IC is 0.9mA (typ.) because the IC is set to OFF latch mode. The period (tp) between the occurrence of a short-circuit in the converter output and the triggering of the short-circuit protection function can be calculated by the following expression: tp [ms] Cs RCS 1n
Fig. 7
6 5 4
Lower value of either 5.5V or Vcc terminal voltage
Start-up 3 2.2V 2 1 0 Momentary short circuit Soft start Time Short circuit 1.5V tp Short circuit protection
Fig. 8
( Vcc - 1.5 ) Vcc - 2.2
Cs : Capacitance of Cs [F] Rcs : Resistance of Rcs [k] Vcc : Supply voltage [V] Note: When the IC is used in a product with low VCC voltage, the period (tp) of the triggering of the short-circuit protection described above fluctuates significantly. Therefore, sufficient care should be taken in such cases. Example When Rcs=750k, Cs=0.1F: Vcc=2.5V: tp 90ms Vcc=3.6V: tp 30ms
10
FA7700V, FA7701V
You can reset the off latch mode operation of the short-circuit protection by either of the following ways: lowering the CS voltage below 2.03V (typ.); lowering the Vcc voltage below the Off threshold voltage of undervoltage lock out; 1.93V (typ.); lowering the voltage of FB terminal below 1.5V (typ.) The off latch mode action cannot be triggered by externally applying voltage of over 2.2V forcibly to the CS terminal (1.5V, ZD clamped). Characteristics of the current and the voltage of CS terminal is shown in the characteristic curve (CS terminal voltage vs. CS terminal sink current) on page 6. Be sure to use the IC up to the recommended CS terminal current of 50A. 8. Output circuit The IC contains a push-pull output stage and can directly drive MOSFETs (FA7700: N ch, FA7701: P ch). The maximum peak current of the output stage is a sink current of +150mA, and a source current of -400mA. The IC can also drive NPN, and PNP transistors. The maximum peak current in such cases is 50mA. Be sure to design the output current considering the rating of power dissipation. 9. Power good signal circuit/ Undervoltage lockout circuit The IC contains a protection circuit against undervoltage malfunctions to protect the circuit from the damage caused by malfunctions when the supply voltage drops. When the supply voltage rises from 0V, the circuit starts to operate at VCC of 2.07V (typ.) and outputs generate pulses. If a drop of the supply voltage occurs, it stops output at VCC of 1.93V (typ.). when it occurs, the CS terminal is turned to Low level and then it is reset. The power good signal circuit monitors the voltage of REF terminal, and stops output until the voltage of REF terminal excesses approximately 2V to prevent malfunctions.
s Design advice
1. Setting the oscillation frequency As described in item 2 "Oscillator" of "Description of each circuit", a desired oscillation frequency can be determined by the value of the resistor connected to the RT terminal. When designing an oscillation frequency, you can set any frequency between 50kHz and 1MHz. You can roughly obtain the oscillation frequency from the characteristic curve "Oscillation frequency (fosc) vs. timing resistor resistance(RT)" or the value can be calculated by the following expression. fOSC = 3000 RT = RT -0.9
1.11
( 3000 ) fOSC
fOSC: Oscillation frequency [kHz] RT: Timing resistor [k]
This expression, however, can be used for rough calculation, the value obtained is not guaranteed. The operation frequency varies due to the conditions such as tolerance of the characteristics of the ICs, influence of noises, or external discrete components. When determining the values, be sure to verify the effectiveness of the values of the components in an actual circuit. 2. Operation around the maximum or the minimum output duties As described in characteristic curves on page 5, "output duty cycle vs. FB terminal voltage (VFB)" and "output duty cycle vs. CS terminal voltage (Vcs)", the linearity of the output duty of this IC drops around the minimum output duty and the maximum output duty (FA7701 only). This phenomena are conspicuous when operating in a high frequency (when the pulse width is narrow). Therefore be careful when using high frequency. 3. Restriction of external discrete components To achieve a stable operation of the ICs, the value of external discrete components connected to Vcc, REF, CS, FB terminals should be within the recommended operational conditions. 4. Loss calculation Since it is difficult to measure IC loss directly, the calculation to obtain the approximate loss of the IC connected directly to a MOSFET is described below. When the supply voltage is Vcc, the current consumption of the IC is Icc, the total input gate charge of the driven MOSFET is Qg, the switching frequency is fsw, the total loss Pd of the IC can be calculated by: Pd Vcc (Icc + Qg fsw). The values in this expression is influenced by the effects of the dependency of supply voltage, the characteristics of temperature, or tolerance. Therefore, be sure to verify appropriateness of the value considering the factors above under all applicable conditions. Example: When VCC = 6V, in the case of a typical IC, from the characteristic curve, Icc=1.2mA. When operating in Qg = 6nC, fsw = 500kHz, Pd should be: Pd 6 (1.2mA + 6nC 500kHz) 25.2mW
11
FA7700V, FA7701V
s Application circuit FA7700
Vin 2.5~11V Vout 12V/0.2A
8 CS
7 VCC
6 OUT
5 GND
ON /OFF
FA7700
RT 1 REF 2 IN3 FB 4
Vin
Vout
8 CS
7 VCC
6 OUT
5 GND
ON /OFF
FA7700
RT 1 REF 2 IN3 FB 4
12
FA7700V, FA7701V
s Application circuit FA7701
Vin 7~18V Vout 5V/0.5A
8 CS
7 VCC
6 OUT
5 GND
ON /OFF
FA7701
RT 1 REF 2 IN3 FB 4
Parts tolerances characteristics are not defined in the circuit design sample shown above. When designing an actual circuit for a product, you must determine parts tolerances and characteristics for safe and economical operation.
13

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