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BD8313HFN_11 [ROHM]

Output 1.5A or Less High-efficiency Step-down Switching Regulator with Built-in Power MOSFET; 输出1.5A或更少的高效率降压开关稳压器具有内置功率MOSFET
BD8313HFN_11
型号： BD8313HFN_11
厂家： ROHM    ROHM
描述：

Output 1.5A or Less High-efficiency Step-down Switching Regulator with Built-in Power MOSFET
输出1.5A或更少的高效率降压开关稳压器具有内置功率MOSFET

稳压器 开关
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Single-chip Type with Built-in FET Switching Regulators  
Output 1.5A or Less  
High-efficiency Step-down Switching Regulator  
with Built-in Power MOSFET  
No.11027EDT05  
BD8313HFN  
●Description  
BD8313HFN produces step-down output including 1.2, 1.8, 3.3, or 5 V from 4 batteries, batteries such as Li2cell or Li3cell,  
etc. or a 5V/12V fixed power supply line.  
BD8313HFN allows easy production of small power supply by a wide range of external constants, and is equipped with an  
external coil/capacitor downsized by high frequency operation of 1.0 MHz, built-in synchronous rectification SW capable of  
withstanding 15 V, and flexible phase compensation system on board.  
●Features  
1) Incorporates Pch/Nch synchronous rectification SW capable of withstanding 1.2 A/15V.  
2) Incorporates phase compensation device between input and output of Error AMP.  
3) Small coils and capacitors to be used by high frequency operation of 1.0MHz  
4) Input voltage 3.5 V – 14 V  
Output current 1.2A(7.4V input, 3.3V output)  
0.8A(4.5V input, 3.3V output)  
5) Incorporates soft-start function.  
6) Incorporates timer latch system short protecting function.  
7) As small as 2.9mm×3 mm, SON 8-pin package  
HSON8  
●Application  
For portable equipment like DSC/DVC powered by 4 dry batteries or Li2cell and Li3cell, or general consumer-equipment  
with 5 V/12 V lines  
●Operating Conditions (Ta = 25°C)  
Parameter  
Power supply voltage  
Symbol  
VCC  
Voltage circuit  
3.5 - 14  
Unit  
V
Output voltage  
VOUT  
1.2 - 12  
V
●Absolute Maximum Ratings  
Parameter  
Symbol  
VCC, PVCC  
Iinmax  
Pd  
Rating  
15  
Unit  
V
Maximum applied power voltage  
Maximum input current  
Power dissipation  
1.2  
A
630  
mW  
°C  
°C  
°C  
Operating temperature range  
Storage temperature range  
Junction temperature  
Topr  
-25～+85  
-55～+150  
+150  
Tstg  
Tjmax  
*1 When used at Ta = 25℃ or more installed on a 70×70×1.6tmm board, the rating is reduced by 5.04mW/℃.  
* These specifications are subject to change without advance notice for modifications and other reasons.  
www.rohm.com  
2011.04 - Rev.D  
1/17  
© 2011 ROHM Co., Ltd. All rights reserved.  
Technical Note  
BD8313HFN  
●Electrical Characteristics  
(Unless otherwise specified, Ta = 25 °C, VCC = 7.4 V)  
Target Value  
Typ  
Parameter  
Symbol  
Unit  
Conditions  
Min  
Max  
[Low voltage input malfunction preventing circuit]  
Detection threshold voltage  
Hysteresis range  
[Oscillator]  
VUV  
-
2.9  
3.2  
V
VREG monitor  
ΔVUVhy  
100  
200  
300  
mV  
Oscillation frequency  
[Regulator]  
Fosc  
0.9  
1.0  
5.0  
1.1  
MHz  
V
Output voltage  
[Error AMP]  
VREG  
4.65  
5.35  
INV threshold voltage  
Input bias current  
Soft-start time  
VINV  
IINV  
Tss  
0.99  
-50  
1.00  
0
1.01  
50  
V
nA  
VCC = 12.0 V , VINV = 6.0 V  
4.8  
8.0  
11.1  
msec  
[PWM comparator]  
LX Max Duty  
Dmax  
-
-
(※)100  
%
[Output]  
PMOS ON resistance  
NMOS ON resistance  
Leak current  
RONP  
RONN  
Ileak  
-
-
450  
300  
0
600  
420  
1
mΩ  
mΩ  
uA  
-1  
[STB]  
Operation  
VSTBH  
VSTBL  
RSTB  
2.5  
-0.3  
250  
-
-
14  
0.3  
700  
V
V
STB pin  
control voltage  
No-operation  
STB pin pull-down resistance  
[Circuit current]  
400  
kΩ  
VCC pin  
Standby current  
PVCC pin  
ISTB1  
ISTB2  
ICC1  
-
-
-
-
-
-
1
1
uA  
uA  
uA  
uA  
Circuit current at operation VCC  
Circuit current at operation PVCC  
600  
30  
900  
50  
VINV = 1.2 V  
VINV = 1.2 V  
ICC2  
(※1)100% is MAX Duty as behavior of a PWM conparetor.  
Using in region where High side PMOS is 100% on state when the same or less input voltage than output voltage is supplied as an  
application circuit causes detection of SCP then DC/DC converter stops.  
Not designed to be resistant to radiation  
www.rohm.com  
2011.04 - Rev.D  
2/17  
© 2011 ROHM Co., Ltd. All rights reserved.  
Technical Note  
BD8313HFN  
●Description of Pins  
Pin No. Pin Name  
Function  
1
2
3
4
5
6
7
8
GND  
VCC  
VREG  
PGND  
Lx  
Ground terminal  
Control part power input terminal  
5 V output terminal of regulator for internal circuit  
Power transistor ground terminal  
Coil connecting terminal  
GND  
VCC  
INV  
STB  
PVCC  
Lx  
VREG  
PGND  
PVCC  
STB  
DC/DC converter input terminal  
ON/OFF terminal  
INV  
Error AMP input terminal  
Fig.1 Terminal layout  
●Block Diagram  
ON/OFF  
STB  
PVCC  
VCC  
VREG  
UVLO  
Reference  
5V REG  
STBY_IO  
VREF  
DC/DC  
converter  
100% High  
Duty  
PRE  
DRIVER  
SCP  
OSC  
1.0MHz  
450mΩ  
OSC×4000 ｃount  
STOP  
LX  
TIMMING  
CONTROL  
PWM  
CONTROL  
Step down  
VREG  
PRE  
DRIVER  
300mΩ  
ERROR_AMP  
VREF  
GND  
Soft  
PGND  
Start  
OSC×8000 ｃount  
INV  
Fig.2 Block diagram  
www.rohm.com  
2011.04 - Rev.D  
3/17  
© 2011 ROHM Co., Ltd. All rights reserved.  
Technical Note  
BD8313HFN  
●Description of Blocks  
1. Reference  
This block produces ERROR AMP standard voltage.  
The standard voltage is 1.0 V.  
2. 5 V Reg  
5 V low saturation regulator for internal analog circuit  
BD8313HFN is equipped with this regulator for the purpose of protecting the internal circuit from high voltage. Therefore,  
this output is reduced when VCC is less than 5 V, then PMOS ON resistance increases and Power efficiency and  
Maximum output current of DC/DC converter decreases in this region. Please see attached data (fig14,15,16,17) about  
increasing of PMOS ON resistance in this region.  
3
4
UVLO  
Circuit for preventing low voltage malfunction  
Prevents malfunction of the internal circuit at activation of the power supply voltage or at low power supply voltage.  
Monitors VCC pin voltage to turn off all output FET and DC/DC converter output when VCC voltage is lower than 2.9 V,  
and reset the timer latch of the internal SCP circuit and soft-start circuit. This threshold contains 200 mV hysteresis.  
SCP  
Timer latch system short-circuit protection circuit  
When DC/DC converter is 100% High Duty , the internal SCP circuit starts counting.  
The internal counter is in synch with OSC, the latch circuit is activated about 4 msec after the counter counts about 4000  
oscillations to turn off DC/DC converter output.  
To reset the latch circuit, turn off the STB pin once. Then, turn it on again or turn on the power supply voltage again.  
5
6
OSC  
Circuit for oscillating sawtooth waves with an operation frequency fixed at 1.0 MHz  
ERROR AMP  
Error amplifier for detecting output signals and output PWM control signals  
The internal standard voltage is set at 1.0 V.  
A primary phase compensation device of 200 pF, 62 kΩ is built in-between the inverting input terminal and the output  
terminal of this ERROR AMP.  
7
8
9
PWM COMP  
Voltage-pulse width converter for controlling output voltage corresponding to input voltage  
Comparing the internal SLOPE waveform with the ERROR AMP output voltage, PWM COMP  
controls the pulse width to the output to the driver.  
SOFT START  
Circuit for preventing in-rush current at startup by bringing the output voltage of the DC/DC converter into a soft-start  
Soft-start time is in synch with the internal OSC, and the output voltage of the DC/DC converter reaches the set voltage  
after about 8000 oscillations.  
PRE DRIVER/TIMING CONTROL  
CMOS inverter circuit for driving the built-in synchronous rectification SW  
The synchronous rectification OFF time for preventing feedthrough is about 25 nsec.  
10 STBY_IO  
Voltage applied on STB pin (7 pin) to control ON/OFF of IC  
Turned ON when a voltage of 2.5 V or higher is applied and turned OFF when the terminal is open or 0 V is applied.  
Incorporates approximately 400 kΩ pull-down resistance.  
11 Pch/Nch FET SW  
Built-in synchronous rectification SW for switching the coil current of the DC/DC converter  
Incorporates a 450 mΩ PchFET SW capable of withstanding 15 V.and 300 mΩ SW capable of withstanding 15 V.  
Since the current rating of this FET is 1.2 A, it should be used within 1.2 A including the DC current and ripple current of  
the coil.  
www.rohm.com  
2011.04 - Rev.D  
4/17  
© 2011 ROHM Co., Ltd. All rights reserved.  
Technical Note  
BD8313HFN  
●Reference data  
(Unless otherwise specified, Ta = 25°C, VCC = 7.4 V)  
1.02  
1.01  
1.00  
0.99  
0.98  
1.02  
1.01  
1.00  
0.99  
0.98  
5.3  
5.2  
5.1  
5.0  
4.9  
4.8  
4.7  
-40  
0
40  
80  
120  
-40  
-20  
0
20  
40  
60  
80  
100  
120  
0
2
4
6
8
10  
12  
14  
TEMPERATURE [℃]  
VCC [V]  
TEMPERATURE [℃]  
Fig.3. INV  
threshold temperature property  
Fig.5. VREG  
output temperature property  
Fig.4. INV  
threshold power supply property  
1.2  
1.2  
8
7
6
5
4
3
2
1
0
1.1  
1.0  
0.9  
0.8  
1.1  
1.0  
0.9  
0.8  
3
6
9
12  
15  
0
2
4
6
8
10  
12  
14  
-40  
0
40  
80  
120  
VCC [V]  
TEMPERATURE [℃]  
VCC [V]  
Fig.8. fosc  
voltage property  
Fig.6. VREG  
output power supply property  
Fig.7. fosc  
temperature property  
3.50  
0.25  
0.20  
0.15  
0.10  
0.05  
0.00  
500  
400  
300  
200  
100  
600  
500  
400  
300  
200  
100  
0
Hysteresis width  
ID=500mA  
ID=500mA  
3.30  
3.10  
2.90  
2.70  
2.50  
UVLO release voltage  
UVLO detection voltage  
-40  
0
40  
80  
120  
-40  
0
40  
80  
120  
3
6
9
12  
15  
TEMPARATURE [℃]  
VCC [V]  
Environmental temperature Ta [°C]  
Fig.9. UVLO  
threshold temperature property  
Fig.11. Nch FET ON resistance  
power supply property  
Fig.10. Nch FET ON resistance  
temperature property  
www.rohm.com  
2011.04 - Rev.D  
5/17  
© 2011 ROHM Co., Ltd. All rights reserved.  
Technical Note  
BD8313HFN  
800  
1000  
800  
600  
400  
200  
0
3.0  
2.5  
2.0  
1.5  
1.0  
0.5  
0.0  
Ta=85℃  
ID=500mA  
ID=500mA  
600  
Ta=25℃  
400  
200  
0
Ta=-25℃  
0.0  
1.0  
2.0  
-40  
0
40  
TEMPARATURE [℃]  
80  
120  
3
6
9
12  
15  
VCC [V]  
Io [A]  
Fig.13. Pch FET ON resistance  
power supply property  
Fig.14.PchFET ON resistance  
Io property [VCC=3.5V]  
Fig.12. Pch FET ON resistance  
temperature property  
3.0  
2.5  
2.0  
1.5  
1.0  
0.5  
0.0  
3.0  
3.0  
2.5  
2.0  
1.5  
1.0  
0.5  
0.0  
2.5  
2.0  
1.5  
1.0  
0.5  
0.0  
Ta=25℃  
Ta=85℃  
Ta=85℃  
Ta=25℃  
Ta=85℃  
Ta=25℃  
Ta=-25℃  
Ta=-25℃  
Ta=-25℃  
0.0  
1.0  
2.0  
0.0  
1.0  
2.0  
0.0  
1.0  
2.0  
Io [A]  
Io [A]  
Io [A]  
Fig.17.PchFET ON resistance  
Io property [VCC=5.0V]  
Fig.16.PchFET ON resistance  
Io property [VCC=4.5V]  
Fig.15.PchFET ON resistance  
Io property [VCC=4.0V]  
1000  
800  
600  
400  
200  
0
1000  
800  
600  
400  
200  
0
2.5  
ON  
2.0  
1.5  
1.0  
OFF  
0
2
4
6
8
10  
12  
14  
-50  
0
50  
100  
150  
-40  
0
40  
80  
120  
Ta [℃]  
TEMPARATURE [℃]  
VCC [V]  
Fig.20. Circuit current  
voltage property  
Fig.18. STB  
threshold temperature property  
Fig.19. Circuit current  
temperature property  
www.rohm.com  
2011.04 - Rev.D  
6/17  
© 2011 ROHM Co., Ltd. All rights reserved.  
Technical Note  
BD8313HFN  
●Example of Application1  
Input: 4.5 to 10 V, output: 3.3 V / 500mA  
VBAT=4.5～10V  
10μF  
GRM31CBE106KA75L  
（Murata）  
GND  
VCC  
INV  
ON/OFF  
STB  
10pF  
1μF  
GRM188B11A105KA61  
（Murata）  
PVCC  
VREG  
PGND  
68k  
3.3V/500mA  
200k  
Lx  
4.7μH  
1127AS4R7M（TOKO）  
51k  
1μF  
GRM188B11A105KA61  
（Murata）  
22k  
10μF  
GRM31CB11A106KA01  
（Murata）  
Fig.21 Reference application diagram1  
●Reference application data 1 (Example of application1)  
3.50  
3.45  
3.40  
3.35  
3.30  
3.25  
3.20  
3.15  
3.10  
3.05  
3.00  
100  
80  
VCC=4.5V  
VCC=4.5V  
VCC=5.5V  
60  
VCC=7.5V  
VCC=5.5V  
40  
VCC=7.5V  
20  
0
1
10  
100  
1000  
1
10  
100  
1000  
OUTPUT CURRENT [mA]  
OUTPUT CURRENT [mA]  
Fig.23 Load regulation (VOUT = 3.3 V)  
Fig.22 Power conversion efficiency (VOUT = 3.3 V)  
www.rohm.com  
© 2011 ROHM Co., Ltd. All rights reserved.  
2011.04 - Rev.D  
7/17  
Technical Note  
BD8313HFN  
●Reference application data 2 (Input 4.5 V, 6.0 V, 8.4 V, 10 V, output 3.3 V ) (Example of application1)  
60  
40  
180  
120  
60  
60  
40  
180  
60  
40  
180  
120  
60  
Phase  
Phase  
Phase  
120  
60  
20  
20  
20  
0
0
0
0
0
0
Gain  
Gain  
Gain  
-20  
-40  
-60  
-60  
-120  
-180  
-20  
-40  
-60  
-60  
-120  
-180  
-20  
-40  
-60  
-60  
-120  
-180  
100  
1000  
10000 100000 1000000  
Frequency[Hz]  
100  
1000  
10000 100000 1000000  
Frequency[Hz]  
100  
1000  
10000 100000 1000000  
Frequency[Hz]  
Fig.24 Frequency response 1  
(VCC=4.5V, Io=250mA)  
Fig.25 Frequency response 2  
(VCC=6.0V, Io=250mA)  
Fig.26 Frequency response 3  
(VCC=8.4V, Io=250mA)  
60  
180  
120  
60  
60  
180  
120  
60  
60  
180  
120  
60  
Phase  
Phase  
40  
40  
20  
Phase  
40  
20  
20  
0
0
0
0
0
0
Gain  
Gain  
Gain  
-20  
-40  
-60  
-60  
-120  
-180  
-20  
-40  
-60  
-60  
-120  
-180  
-20  
-40  
-60  
-60  
-120  
-180  
100  
1000  
10000 100000 1000000  
Frequency[Hz]  
100  
1000  
10000 100000 1000000  
Frequency[Hz]  
100  
1000  
10000 100000 1000000  
Frequency[Hz]  
Fig.27 Frequency response 4  
(VCC=10V, Io=250mA)  
Fig.28 Frequency response 5  
(VCC=4.5V, Io=500mA)  
Fig.29 Frequency response 6  
(VCC=6.0V, Io=500mA)  
60  
180  
120  
60  
60  
40  
20  
0
180  
120  
60  
Phase  
Phase  
40  
20  
0
0
0
Gain  
Gain  
-20  
-40  
-60  
-60  
-120  
-180  
-20  
-40  
-60  
-60  
-120  
-180  
100  
1000  
10000 100000 1000000  
Frequency[Hz]  
100  
1000  
10000 100000 1000000  
Frequency[Hz]  
Fig.30 Frequency response 7  
(VCC=8.4V, Io=500mA)  
Fig.31 Frequency response 8  
(VCC=10V, Io=500mA)  
www.rohm.com  
2011.04 - Rev.D  
8/17  
© 2011 ROHM Co., Ltd. All rights reserved.  
Technical Note  
BD8313HFN  
●Example of application2 input4.5 to 12V, output1.2V / 500mA  
VBAT=4.5~ 12V  
10µF  
GRM31CB31E106KA75L  
(Murata)  
GND  
INV  
100O  
ON/OFF  
STB  
VCC  
10pF  
1µF  
GRM188B11A105KA61  
PVCC  
VREG  
( Murata)  
68kO  
3.3V/500mA  
560kO  
PGND  
Lx  
1µF  
4.7µH  
20kO  
GRM188B11A105KA61  
( Murata)  
NR4012-4R7M  
(Taiyo yuden)  
100kO  
10µF 2para  
GRM31CB11A106KA01  
( Murata)  
Fig.32 Reference application diagram2  
●Reference application data 1 (Example of application2)  
100  
80  
60  
40  
20  
0
1.36  
1.30  
1.24  
1.18  
1.12  
1.06  
1.00  
VCC=7.4V  
VCC=5.0V  
VCC=7.4V  
VCC=5.0V  
VCC=12V  
VCC=12V  
1
10  
100  
1000  
1
10  
100  
1000  
OUTPUT CURRENT [mA]  
OUTPUT CURRENT [mA]  
Fig.33 Power conversion efficiency  
(VOUT = 1.2 V)  
Fig.34 Load regulation  
(VOUT = 1.2 V)  
www.rohm.com  
© 2011 ROHM Co., Ltd. All rights reserved.  
2011.04 - Rev.D  
9/17  
Technical Note  
BD8313HFN  
●Reference application data 2(input5.0V, 7.4V, 10V output1.2V )Example of application(2)  
60  
40  
180  
120  
60  
60  
40  
20  
0
180  
120  
60  
60  
40  
20  
0
180  
120  
60  
Phase  
Phase  
Phase  
20  
Gain  
0
0
0
0
Gain  
Gain  
-20  
-40  
-60  
-60  
-120  
-180  
-20  
-40  
-60  
-60  
-120  
-180  
-20  
-40  
-60  
-60  
-120  
-180  
100  
1000  
10000  
100000 1000000  
100  
1000  
10000  
100000 1000000  
100  
1000  
10000 100000 1000000  
Frequency [Hz]  
Frequency [Hz]  
Frequency [Hz]  
Fig.35 Frequency response 1  
(VCC=5.0V, Io=100mA)  
Fig.36 Frequency response 2  
(VCC=5.0V, Io=300mA)  
Fig.37 Frequency response 3  
(VCC=5.0V, Io=900mA)  
60  
40  
20  
0
180  
60  
40  
20  
0
180  
120  
60  
60  
40  
20  
0
180  
Phase  
Phase  
120  
60  
Phase  
120  
60  
0
0
0
Gain  
Gain  
Gain  
-20  
-40  
-60  
-60  
-120  
-180  
-20  
-40  
-60  
-60  
-120  
-180  
-20  
-40  
-60  
-60  
-120  
-180  
100  
1000  
10000 100000 1000000  
Frequency [Hz]  
100  
1000  
10000  
100000 1000000  
100  
1000  
10000  
100000 1000000  
Frequency [Hz]  
Frequency [Hz]  
Fig.40 Frequency response 6  
(VCC=7.4V, Io=900mA)  
Fig.38 Frequency response 4  
(VCC=7.4V, Io=100mA)  
Fig.39 Frequency response 5  
(VCC=7.4V, Io=300mA)  
60  
40  
20  
0
180  
120  
60  
60  
180  
120  
60  
60  
40  
20  
0
180  
120  
60  
Phase  
Phase  
40  
20  
Phase  
0
0
0
Gain  
0
Gain  
Gain  
-20  
-40  
-60  
-60  
-120  
-180  
-20  
-40  
-60  
-60  
-120  
-180  
-20  
-40  
-60  
-60  
-120  
-180  
100  
1000  
10000  
100000 1000000  
100  
1000  
10000  
100000 1000000  
100  
1000  
10000  
100000 1000000  
Frequency [Hz]  
Frequency [Hz]  
Frequency [Hz]  
Fig.41 Frequency response 7  
(VCC=10V, Io=100mA)  
Fig.42 Frequency response 8  
(VCC=10V, Io=300mA)  
Fig.43 Frequency response 9  
(VCC=10V, Io=900mA)  
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2011.04 - Rev.D  
10/17  
© 2011 ROHM Co., Ltd. All rights reserved.  
Technical Note  
BD8313HFN  
20usec/Div  
20usec/Div  
20usec/Div  
Vout(20m/Div)  
Vout(20m/Div)  
Vout(20m/Div)  
9.2mVpp  
24.4mVpp  
38.4mVpp  
Fig.44 Output ripple 1  
(VCC=12V, Io=40mA)  
Fig.45 Output ripple 2  
(VCC=12V, Io=100mA)  
Fig.46 Output ripple 3  
(VCC=12V, Io=140mA)  
20usec/Div  
20usec/Div  
Vout(20m/Div)  
Vout(20m/Div)  
10.4mVpp  
14.8mVpp  
Fig.47 Output ripple 4  
(VCC=12V, Io=170mA)  
Fig.48 Output ripple 5  
(VCC=12V, Io=900mA)  
●Output ripple voltage  
0.75  
SLOPE  
BD8313HFN is controlled by PWM(Pulse Width  
Modulation)mode.  
PWM output made by comparison SLOPE with FB(error amp  
output) controls switching of IC under the PWM mode.  
When FB level is completely lower than SLOPE level, DC/DC  
converter switches as non- synchronous step-down switching  
mode not to make output voltage level drop quickly caused by  
full ON state of Low side Nch FET.  
FB  
0.25  
PWMoutput  
Ripple voltage of output voltage in non-synchronous mode is  
larger than that in synchronous mode.  
When voltage difference between input and output voltage is large and output current is small, DCDC converter switches as  
this non-synchronous mode then ripple voltage of output voltage could be large.  
In the reference data above ( output ripple 1 to 4 ), ripple voltage at 12V input 1.2V output , output current is smaller than  
100mA is larger than other region.  
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2011.04 - Rev.D  
11/17  
© 2011 ROHM Co., Ltd. All rights reserved.  
Technical Note  
BD8313HFN  
●Reference board pattern  
VOUT  
Lx  
VBAT  
GND  
The radiation plate on the rear should be a GND flat surface of low impedance in common with the PGND flat surface.  
It is recommended to install a GND pin in another system as shown in the drawing without connecting it directly to this PNGD.  
Produce as wide a pattern as possible for the VBAT, Lx and PGND lines in which large current flows.  
●Selection of Part for Applications  
(1) Inductor  
A shielded inductor that satisfies the current rating  
(current value, Ipecac as shown in the drawing below)  
and has a low DCR (direct resistance component) is recommended.  
ΔIL  
Inductor values affect inductor ripple current, which will cause output ripple.  
Ripple current can be reduced as the coil L value becomes larger and the  
switching frequency becomes higher.  
Fig.49 Inductor current  
Ipeak =Iout ＋ ⊿IL/2 [A]  
・・・(1)  
Vin-Vout  
1
f
Vout  
Vin  
⊿IL=  
×
×
[A]  
・・・(2)  
L
(η: Efficiency, ⊿IL: Output ripple current, f: Switching frequency)  
As a guide, inductor ripple current should be set at about 20 to 50% of the maximum input current.  
*Current over the coil rating flowing in the coil brings the coil into magnetic saturation, which may lead to lower efficiency  
or output oscillation. Select an inductor with an adequate margin so that the peak current does not exceed the rated  
current of the coil.  
(2) Output capacitor  
A ceramic capacitor with low ESR is recommended for output in order to reduce output ripple.  
There must be an adequate margin between the maximum rating and output voltage of the capacitor, taking the DC bias  
property into consideration.  
Output ripple voltage is acquired by the following equation.  
1
Vpp=⊿IL×  
＋ ⊿IL×RESR [V]  
・・・(3)  
2π×f×Co  
Setting must be performed so that output ripple is within the allowable ripple voltage.  
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© 2011 ROHM Co., Ltd. All rights reserved.  
2011.04 - Rev.D  
12/17  
Technical Note  
BD8313HFN  
(3) Output voltage setting  
The internal standard voltage of the ERROR AMP is 1.0 V. Output voltage is acquired by Equation (4).  
VOUT  
ERROR AMP  
R1  
R2  
(R1+R2)  
R2  
INV  
Vo=  
×1.0 [V] ・・・ (4)  
VREF  
1.0V  
Fig.50 Setting of voltage feedback resistance  
(4) DC/DC converter frequency response adjustment system  
Condition for stable application  
The condition for feedback system stability under negative feedback is that the phase delay is 135 °or less when gain is 1  
(0dB).  
Since DC/DC converter application is sampled according to the switching frequency, the bandwidth GBW of the whole  
system (frequency at which gain is 0 dB) must be controlled to be equal to or lower than 1/10 of the switching frequency.  
In summary, the conditions necessary for the DC/DC converter are:  
-
-
Phase delay must be 135°or lower when gain is 1 (0 dB).  
Bandwidth GBW (frequency when gain is 0 dB) must be equal to or lower than 1/10 of the switching frequency.  
To satisfy those two points, R1, R2, R3, DS and RS in Fig. 51 should be set as follows.  
VOUT  
[1] R1, R2, R3  
Inside of IC  
R4 C2  
BD8313HFN incorporates phase compensation devices of  
R4=62kΩ and C2=200pF. These C2 and R1, R2, and R3 values  
decide the primary pole that determines the bandwidth of DC/DC  
converter.  
Cs  
Rs  
R1  
R2  
FB  
Primary pole point frequency  
R3  
1
fp=  
R1×R2  
・・・・(1)  
2π A×(  
+R3)×C2  
R1+R2  
Fig.51 Example of phase  
compensation setting  
DC/DC converter DC Gain  
A: Error AMP Gain  
About 100dB = 105  
VIN  
VO  
1
DC Gain =A×  
×
・・・・(2)  
B: Oscillator amplification = 0.5  
VIN: Input voltage  
OUT: Output voltage  
B
V
By Equations (1) and (2), the frequency fsw of point 0 dB under limitation of the bandwidth of the DC gain at the primary  
pole point is as shown below.  
1
VIN  
VO  
1
fSW = fp×DC Gain =  
×
×
・・・・(3)  
(R1 R2)  
・
B
2πC2×(  
+R3 )  
(R1+R2)  
It is recommended that fsw should be approx.10 kHz. When load response is difficult, it may be set at approx. 20 kHz.  
By Equation (3), R1 and R2, which determine the voltage value, will be in the order of several hundred kΩ. If an  
appropriate resistance value is not available since the resistance is so high and routing may cause noise, the use of R3  
enables easy setting.  
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2011.04 - Rev.D  
13/17  
Technical Note  
BD8313HFN  
[2] Cs and Rs setting  
For DC/DC converter, the 2nd dimension pole point is caused by the coil and capacitor as expressed by the following  
equation.  
1
・・・・(4)  
fLC=  
2π√(LC)  
This secondary pole causes a phase rotation of 180°. To secure the stability of the system, put a zero point in 2 places to  
perform compensation.  
1
・・・・(5)  
Zero point by built-in CR  
Zero point by Cs  
fZ1=  
fZ1=  
= 13kHz  
2πR4C2  
1
・・・・(6)  
2π(R1+R3)CS  
Setting fZ2 to be half to 2 times a frequency as large as fLC provides an appropriate phase margin.  
It is desirable to set Rs at about 1/20 of (R1+R3) to cancel any phase boosting at high frequencies.  
Those pole points are summarized in the figure below. The actual frequency property is different from the ideal  
calculation because of part constants. If possible, check the phase margin with a frequency analyzer or network analyzer.  
Otherwise, check for the presence or absence of ringing by load response waveform and also check for the presence or  
absence of oscillation under a load of an adequate margin.  
(5) (6)  
(3)  
(4)  
Fig.52 Example of DC/DC converter frequency property  
(Measured with FRA5097 by NF Corporation)  
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2011.04 - Rev.D  
14/17  
Technical Note  
BD8313HFN  
●I/O Equivalence Circuit  
STB  
INV  
VCC  
VCC  
VREG  
STB  
INV  
Lx, PGND, PVCC  
VREG  
VCC  
VCC  
PVCC  
VREG  
Lx  
PGND  
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2011.04 - Rev.D  
15/17  
© 2011 ROHM Co., Ltd. All rights reserved.  
Technical Note  
BD8313HFN  
●Ordering part number  
1) Absolute Maximum Rating  
We dedicate much attention to the quality control of these products, however the possibility of deterioration or destruction exists  
if the impressed voltage, operating temperature range, etc., exceed the absolute maximum ratings. In addition, it is impossible to  
predict all destructive situations such as short-circuit modes, open circuit modes, etc. If a special mode exceeding the absolute  
maximum rating is expected, please review matters and provide physical safety means such as fuses, etc.  
2) GND Potential  
Keep the potential of the GND pin below the minimum potential at all times.  
3) Thermal Design  
Work out the thermal design with sufficient margin taking power dissipation (Pd) in the actual operation condition into account.  
4) Short Circuit between Pins and Incorrect Mounting  
Attention to IC direction or displacement is required when installing the IC on a PCB. If the IC is installed in the wrong way,  
it may break. Also, the threat of destruction from short-circuits exists if foreign matter invades between outputs or the  
output and GND of the power supply.  
5) Operation under Strong Electromagnetic Field  
Be careful of possible malfunctions under strong electromagnetic fields.  
6) Common Impedance  
When providing a power supply and GND wirings, show sufficient consideration for lowering common impedance and  
reducing ripple (i.e., using thick short wiring, cutting ripple down by LC, etc.) as much as you can.  
7) Thermal Protection Circuit (TSD Circuit)  
BD8313HFN contains a thermal protection circuit (TSD circuit). The TSD circuit serves to shut off the IC from thermal  
runaway and does not aim to protect or assure operation of the IC itself. Therefore, do not use the TSD circuit for  
continuous use or operation after the circuit has tripped.  
8) Rush Current at the Time of Power Activation  
Be careful of the power supply coupling capacity and the width of the power supply and GND pattern wiring and routing since  
rush current flows instantaneously at the time of power activation in the case of CMOS IC or ICs with multiple power supplies.  
9) IC Terminal Input  
This is a monolithic IC and has P+ isolation and a P substrate for element isolation between each element. P-N junctions  
are formed and various parasitic elements are configured using these P layers and N layers of the individual elements.  
For example, if a resistor and transistor are connected to a terminal as shown on Fig.53:  
○ The P-N junction operates as a parasitic diode when GND > (Terminal A) in the case of a resistor or when GND >  
(Terminal B) in the case of a transistor (NPN)  
○ Also, a parasitic NPN transistor operates using the N layer of another element adjacent to the previous diode in the  
case of a transistor (NPN) when GND > (Terminal B).  
The parasitic element consequently rises under the potential relationship because of the IC’s structure. The parasitic  
element pulls interference that could cause malfunctions or destruction out of the circuit. Therefore, use caution to avoid  
the operation of parasitic elements caused by applying voltage to an input terminal lower than the GND (P board), etc.  
Transistor (NPN)  
Resistor  
B
(Pin B)  
E
C
(Pin A)  
GND  
N
(Pin A)  
P＋  
P＋  
P
P＋  
P＋  
P
N
N
N
N
Ｎ
N
Parasitic Element  
P Substrate  
GND  
P Substrate  
Parasitic Element  
Parasitic Element  
GND  
Fig.53 Example of simple structure of Bipolar IC  
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2011.04 - Rev.D  
16/17  
© 2011 ROHM Co., Ltd. All rights reserved.  
Technical Note  
BD8313HFN  
●Ordering part number  
B D  
8
3
1
3
H F  
N
-
T R  
Part No.  
Part No.  
Package  
Packaging and forming specification  
TR: Embossed tape and reel  
HFN:HSON8  
HSON8  
<Tape and Reel information>  
2.9 0.1  
(0.05)  
(2.2)  
Tape  
Embossed carrier tape  
3000pcs  
(MAX 3.1 include BURR)  
Quantity  
0.475  
8 7 6 5  
TR  
5 6 7 8  
4 3 2 1  
Direction  
of feed  
The direction is the 1pin of product is at the upper right when you hold  
reel on the left hand and you pull out the tape on the right hand  
(
)
+0.1  
–0.05  
0.13  
1 2 3 4  
1pin  
1PIN MARK  
S
0.1  
S
0.65  
0.32 0.1  
M
0.08  
Direction of feed  
Order quantity needs to be multiple of the minimum quantity.  
Reel  
(Unit : mm)  
∗
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2011.04 - Rev.D  
17/17  
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Notice  
N o t e s  
No copying or reproduction of this document, in part or in whole, is permitted without the  
consent of ROHM Co.,Ltd.  
The content specified herein is subject to change for improvement without notice.  
The content specified herein is for the purpose of introducing ROHM's products (hereinafter  
"Products"). If you wish to use any such Product, please be sure to refer to the specifications,  
which can be obtained from ROHM upon request.  
Examples of application circuits, circuit constants and any other information contained herein  
illustrate the standard usage and operations of the Products. The peripheral conditions must  
be taken into account when designing circuits for mass production.  
Great care was taken in ensuring the accuracy of the information specified in this document.  
However, should you incur any damage arising from any inaccuracy or misprint of such  
information, ROHM shall bear no responsibility for such damage.  
The technical information specified herein is intended only to show the typical functions of and  
examples of application circuits for the Products. ROHM does not grant you, explicitly or  
implicitly, any license to use or exercise intellectual property or other rights held by ROHM and  
other parties. ROHM shall bear no responsibility whatsoever for any dispute arising from the  
use of such technical information.  
The Products specified in this document are intended to be used with general-use electronic  
equipment or devices (such as audio visual equipment, office-automation equipment, commu-  
nication devices, electronic appliances and amusement devices).  
The Products specified in this document are not designed to be radiation tolerant.  
While ROHM always makes efforts to enhance the quality and reliability of its Products, a  
Product may fail or malfunction for a variety of reasons.  
Please be sure to implement in your equipment using the Products safety measures to guard  
against the possibility of physical injury, fire or any other damage caused in the event of the  
failure of any Product, such as derating, redundancy, fire control and fail-safe designs. ROHM  
shall bear no responsibility whatsoever for your use of any Product outside of the prescribed  
scope or not in accordance with the instruction manual.  
The Products are not designed or manufactured to be used with any equipment, device or  
system which requires an extremely high level of reliability the failure or malfunction of which  
may result in a direct threat to human life or create a risk of human injury (such as a medical  
instrument, transportation equipment, aerospace machinery, nuclear-reactor controller, fuel-  
controller or other safety device). ROHM shall bear no responsibility in any way for use of any  
of the Products for the above special purposes. If a Product is intended to be used for any  
such special purpose, please contact a ROHM sales representative before purchasing.  
If you intend to export or ship overseas any Product or technology specified herein that may  
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obtain a license or permit under the Law.  
Thank you for your accessing to ROHM product informations.  
More detail product informations and catalogs are available, please contact us.  
ROHM Customer Support System  
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R1120  
A

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