Datasheet
12V～76V input voltage range 3A output current
1ch Buck Converter Integrated FET
BD9G341EFJ
General Description
Key specifications
■ Input voltage
■ Ref voltage(Ta=25℃)
(Ta=-40~85℃)
■ Max output current
■ Operating Temperature
■ Max junction temperature
The BD9G341EFJ is a buck switching regulator with
integrated 150m Ω power MOSFET. Current mode
architecture provides fast transient response and a
simple phase compensation setup. The operating
frequency is programmable from 50kHz to 750kHz.
Additional protection features are included such as
Over Current Protection, Thermal shutdown and Under
voltage lockout. The
under voltage lockout and
hysteresis can be set by external resistor .
Package(s)
Features
12～76[V]
±1.5[%]
±2.0[%]
3 [A] (Max.)
-40℃~85℃
150℃
HTSOP-J8
4.90mm x 6.00mm x 1.00mm
Wide input voltage range from 12V to 76V.
Integrated 80V/3.5A/150mΩ NchFET.
Current mode.
Variable frequency from 50kHz to 750kHz.
Accurate reference voltage.( 1.0 V±1.5 %).
Precision EN threshold ( ±3%).
Soft-start function
0uA Standby current
Over Current Protection (OCP), Under Voltage
Lockout(UVLO), Thermal-Shutdown(TSD),Over
Voltage Protection (OVP)
Thermally enhanced HTSOP-J8 package
Applications
Industrial distributed power applications.
Automotive Application
Battery powered equipment.
Typical Application Circuit
0.1uF
Vin=12～76V
VCC
C1:
10uF/100V
L : 33uH
BST
VOUT=5.0V /3A
LX
R1 Ω
D1
3.0kΩ
EN
C2:
100uF/6.3V
FB
VC
R2 Ω
GND
RT
6800pF
47kΩ
Pin Configuration
0.75kΩ
10kΩ
Figure 1. Typical Application Schematic
〇Product structure : Silicon monolithic integrated circuit
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LX 1
8 VCC
GND 2
7 BST
Thermal Pad
VC 3
6 EN
FB 4
5 RT
Figure 2.Pin Configuration (TOP VIEW)
Pin Description
Pin No.
Pin Name
1
LX
Switching node. It should be connected as near as possible to the schottky
barrier diode, and inductor.
2
GND
Ground pin. GND pattern is kept from the current line of input capacitor to
output capacitor.
3
VC
The output of the internal error amplifier. The phase compensation
implementation is connected between this pin to GND.
4
FB
Voltage feedback pin. This pin is the error-amp input with the DC voltage is
set at 0.75V with feed-back operation.
5
RT
6
EN
7
BST
8
VCC
-
Thermal Pad
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Description
The internal oscillator frequency set pin. The internal oscillator is set with a
single resistor connected between this pin and the GND pin.
Recommended frequency range is 50kHz to 750kHz
Shutdown pin. If the voltage of this pin is below 0.8V,the regulator will be in a
low power state. If the voltage of this pin is between 0.8V and 2.4V. The IC
will be in standby mode. If the voltage of this pin is above 2.6V, the regulator
is operational. An external voltage divider can be used to set under voltage
threshold. If this pin is left open circuit. when converter is operating. This pin
output 10uA source current. If this pin is left open circuit, a 10uA pull up
current source configures the regulator fully operational.
Boost input for bootstrap capacitor
The external capacitor is required between the BST and the Lx pin.
A 0.1uF ceramic capacitor is recommended.
Input supply voltage pin.
Connect to GND.
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BD9G341EFJ
Block Diagram
ON/OFF
EN
10uA
VCC
STANBY
↓
TSD
UVLO
Reference
+
REG
VREF
2.6V
shutdown
VC
OCP
Current Sense
AMP
OVP
FB
1.0V
BST
+
+
Error
AMP
Σ
Current
Comparator
R Q
+
S
0.15Ω
LX
Soft
Start
VOUT
20Ω
Soft Start
Oscillator
Oscillator
20Ω
GND
RT
Figure 3.Block Diagram
Description of Block(s)
1.
Reference
This block generates inner reference voltage.
2.
REG
This block generates 8V reference voltage for bootstrap.
3.
OSC
This block generates inner CLK.
The internal oscillator is set with a single resistor connected between this pin and the GND pin.
Recommended frequency range is 50 kHz to 750 kHz. If RT pin connect to 47kohm, frequency is set 200 kHz.
4.
Soft Start
Soft Start of the output voltage of regulator prevents in-rush current during Start-up.
Soft Start time is 20msec (typ)
5.
ERROR AMP
This is an error amplifier what detects output signal, and outputs PWM control signal.
Internal reference voltage is set to 1.0V.
6.
ICOMP
This is a comparator that outputs PWM signal from current feed-back signal and error-amp output for current-mode.
7.
Nch FET SW
This is a 80V/150mΩ-Power Nch MOSFET SW that converts inductor current of DC/DC converter
Since the current rating of this FET is 3.5A, it should be used within 3.5A including the DC current and ripple current of the
coil.
8.
UVLO
This is a Low Voltage Error Prevention Circuit.
This prevents internal circuit error during increase of Power supply Voltage and during decline of Power supply Voltage.
It monitors VCC Pin Voltage and internal REG Voltage, When VCC Voltage becomes 11V and below, UVLO turns OFF
all Output FET and turns OFF the DC/DC Comparator Output, and the Soft Start Circuit resets.
Now this Threshold has Hysteresis of 200mV.
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9.
EN
Shutdown function. If the voltage of this pin is below 0.8V, the regulator will be in a low power state. If the voltage of
this pin is between 0.8V and 2.4V will be standby mode. If the voltage of this pin is above 2.6V, the regulator is
operational. An external voltage divider can be used to set under voltage threshold. If this pin is left open circuit. when
converter is operating. This pin output 10uA source current. If this pin is left open circuit, a 10uA pull up current source
configures the regulator fully operational. When IC turn off, EN pin is pulled down by pull down resistor that sink above
10uA.
10. OCP
Over current protection
If the current of power MOSFET is over 6.0A (typ), this function reduces duty pulse –by- pulse and restricts the
over current. If IC detects OCP 2 times sequentially, the device will stop and after 20 msec restart.
11. TSD
This is Thermal Shutdown Detection
When it detects an abnormal temperature exceeding Maximum Junction Temperature (Tj=150℃), it turns OFF all
Output FETs, and turns OFF the DC/DC Comparator Output. When Temperature falls, and the IC automatically returns
12. OVP
Over voltage protection.
Output voltage is monitored with FB terminal, and output FET is turned off when it becomes 120% of set-point voltage.
Absolute Maximum Ratings
Item
Symbol
Ratings
Unit
Maximum input voltage
VCC
80
V
BST
VBST
85
V
Maximum input current
Imax
3.5
A
BST to LX
⊿VBST
15
V
EN
VEN
80
V
LX
VLX
80
V
FB
VFB
7
V
3.76
(NOTE1)
Power Dissipation
Pd
Operating Temperature
Topr
-40～+85
℃
W
Storage Temperature
Tstg
-55～+150
℃
Junction Temperature
Tjmax
150
℃
(NOTE1)During mounting of 70×70×1.6t mm 4layer board.Reduce by 5.4mW for every 1℃ increase..(Above 25℃)
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Electrical Characteristics (Unless otherwise specified Ta=25℃, VCC=48V, Vo=5V,EN=3V,RT=47kΩ )
Parameter
Symbol
Limit
Min
Typ
Max
Unit
Condition
【Circuit Current】
Stand-by current of VCC
Ist
―
0
10
µA
VEN=0V
Circuit current of VCC
Icc
―
1.5
2.0
mA
FB=1.5V
Detect Voltage
Vccuv
10.4
11
11.6
V
Hysteresis width
Vuvhy
―
200
300
mV
VFBN
0.985
1.000
1.015
V
VFBA
IFB
Isource
Isink
Tsoft
AVEA
1.000
0
40
-40
20
10000
300
1.020
1
65
-15
25
―
―
V
uA
uA
uA
msec
V/V
GEA
0.980
-1
15
-65
15
―
―
GCS
―
10
―
A/V
Iocp
3.5
6.0
―
A
【Under Voltage Lock Out (UVLO)】
【Error Amp】
FB threshold voltage
FB Input bias current
VC source current
VC sink current
Soft start time
Error amplifier DC gain
Trans conductance
Ta=25℃
Ta=-40~85℃
VFB=2.0V
µA/V
【Current Sense Amp 】
VC to switch current trans conductance
【OCP】
Detect current
OCP latch count
NOCP
―
2
―
count
OCP latch hold time
TOCP
15
20
25
msec
RonH
―
150
―
mΩ
VENON
1.3
―
2.4
V
Venuv
IEN
2.52
9.0
2.6
10.0
2.68
11.0
V
µA
Fosc
Toff
180
―
200
―
220
500
kHz
nsec
【出力部】
Lx NMOS ON resistance
【CTL】
EN Pin inner REG on voltage
EN Pin IC output on threshold
EN pin
【Oscillator】
Oscillator frequency
Forced off time
ON
IC on or off threshold
VEN=3V
RT:R=47kΩ
Recommended Operating Ratings(Ta=25℃)
Item
Power Supply Voltage
Symbol
VCC
Rating
Min
Typ
Max
12
―
76
1.0
(Note2)
―
(Note3)
VCC
Unit
V
Output voltage
VOUT
Output current
IOUT
-
―
3.0
V
A
Oscillator frequency
Fosc
50
―
750
kHz
(Note2) Restricted by minduty=f×MinOn Time ( f :frequency)
If the voltage of Vcc×minduty [V] lower than 1V, this value is minimum output.
(Note3) Restricted by maxduty =f×forced off time
The maximum output is Vcc×maxduty – Iout*Ron Ron:。
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Typical Performance Characteristics
220
1.02
215
1.015
210
1.01
FB THRESHOLD [V]
FREQUENCY [kHz]
(Unless otherwise specified, Ta=25℃，VCC=24V, VOUT=5V)
205
200
195
190
185
1.005
1
0.995
0.99
0.985
180
0.98
-50
0
50
100
12
TEMPERATURE [℃ ]
72
Fig.5 FB Threshold Voltage- Input Voltage
1.02
500
1.015
480
FORCED OFF TIME [n sec]
FB THRESHOLD [V]
52
INPUT VOLTAGE[V]
Fig.4 Oscillator Frequency - Temperature
1.01
1.005
1
0.995
0.99
0.985
460
440
420
400
380
360
340
320
0.98
300
-50
0
50
100
-50
TEMPERATURE [℃ ]
0
50
100
TEMPERATURE [℃ ]
Fig.7 Forced off time - Temperature
Fig.6 FB Threshold Voltage - Temperature
12
8
11.8
7.5
11.6
7
OCP THRESHOLD [A]
UVLO THRESHOLD [V]
32
11.4
11.2
11
10.8
10.6
10.4
10.2
6.5
6
5.5
5
4.5
4
10
3.5
-50
0
50
100
-50
TEMPERATURE [℃ ]
50
100
TEMPERATURE [℃ ]
Fig.8 UVLO Threshold Voltage - Temperature
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0
Fig.9 OCP Detect Current - Temperature
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EN PIN INNER REG THRESHOLD [V]
25
SOFT START TIME [msec]
24
23
22
21
20
19
18
17
16
15
-50
0
50
2.3
2.1
1.9
1.7
1.5
1.3
-50
100
50
100
TEMPERATURE [℃ ]
TEMPERATURE [℃ ]
Fig.11 EN Pin Inner REG ON
Threshold - Temperature
Fig.10 Soft Start Time - Temperature
11
EN UVLO SOURCE CURRENT[uA]
2.7
EN UVLO THRESHOLD [V]
0
2.65
2.6
2.55
10.8
10.6
10.4
10.2
10
9.8
9.6
9.4
9.2
9
2.5
-50
0
50
-50
100
0
50
100
TEMPERATURE [℃ ]
TEMPERATURE [℃ ]
Fig.13 EN Source Current - Temperature
Fig.12 ENUVLO Threshold - Temperature
Fig.14 NMOS ON Resistance -Temperature
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Reference Characteristics of Typical Application Circuits
Vout=5V , f=200kHz
0.1uF
Vin=12～76V
VCC
C1:
10uF/100V
L : 33uH
BST
VOUT=5.0V /3A
LX
R1 Ω
D1
3.0kΩ
EN
C2:
100uF/6.3V
FB
VC
R2 Ω
GND
0.75kΩ
RT
6800pF
10kΩ
47kΩ
Parts ：
：SUMIDA
CDRH129LD
C1
：TDK
C5750X7S2A106K
10μF/100V
C2
：TDK
C4532X5R0J107M
100μF/6.3V
D1
：Rohm
RB095B-90
L
33μH
100
90
VCC=24V
80
48V
EFFICIENCY [%]
70
60
50
60V
40
76V
30
20
10
0
1
10
100
1000
OUTPUT CURRENT[mA]
Fig.15 Efficiency – Output Current
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BD9G341EFJ
VEN [5V/div]
Io [500mA/div]
Vout [2V/div]
Overshoot Voltage: 170mV
VLx [10V/div]
Vout [100mV/div]
ILx [0.5A/div]
Undershoot Voltage: 260mV
5msec/div
2msec/div
Fig.16 Start-up Characteristics
Fig.17 Load Response
Iout:100mA ⇔1A
Vout:offset 5V
40mV/div
Vout:offset 5V
40mV/div
Vout Ripple :26mV
Vout Ripple :40mV
5usec/div
10usec/div
Fig.18 Lx Switching/Vout Ripple
Io = 100mA
Fig.19 Lx Switching/Vout Ripple
Io=1A
Phase
Phase
Gain
Gain
Fig.20 Frequency Response
Io=100mA
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Fig.21 Frequency Response
Io=3.0A
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Reference Characteristics of Typical Application Circuits
Vout=3.3V , f=200kHz
0.1uF
Vin=12～76V
VCC
C1:
10uF/100V
L : 33uH
BST
VOUT=3.3V /3A
LX
R1 Ω
D1
1.3kΩ
EN
C2:
100uF/6.3V
FB
0.56kΩ
VC
R2 Ω
GND
0.01uF
RT
47kΩ
Parts ：
6.2kΩ
：SUMIDA
CDRH129LD
C1
：TDK
C5750X7S2A106K
10μF/100V
C2
：TDK
C4532X5R0J107M
100μF/6.3V
D1
：Rohm
RB095B-90
L
33μH
100
90
VCC=24V
80
EFFICIENCY [%]
70
48V
60
50
60V
40
30
76V
20
10
0
1
10
100
1000
OUTPUT CURRENT[mA]
Fig.22 Efficiency – Output Current
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BD9G341EFJ
VEN [5V/div]
Io [500mA/div]
Vout [2V/div]
Overshoot Voltage: 160mV
VLx [10V/div]
Vout [100mV/div]
ILx [0.5A/div]
Undershoot Voltage: 230mV
5msec/div
2msec/div
Fig.23 Start-up Characteristics
Fig.24 Load Response
Iout:100mA ⇔1A
Vout:offset 3.3V
40mV/div
Vout:offset 3.3V
40mV/div
Vout Ripple :30mV
Vout Ripple :35mV
10usec/div
5usec/div
Fig.25 Lx Switching/Vout Ripple
Io = 100mA
Fig.26 Lx Switching/Vout Ripple
Io=1A
Phase
Phase
Gain
Gain
Fig.27 Frequency Response
Io=100mA
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Fig.28 Frequency Response
Io=3A
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Detailed Description
◇Frequency setting
Arbitrary internal oscillator frequency setup is possible by connecting RT resistance. Recommended frequency range is
50 kHz to 750 kHz.
For setting frequency f [Hz] 、RT resistance is looked for using the following formula.
1
400 10 9
f
[Ω ]
RT
96 .48 10 12
If setting frequency is 200kHz, RT is 47kΩ.
RT resistance is related to frequency as shown in Figure 26.
1000
900
FREQUENCY [kHz]
800
700
600
500
400
300
200
100
0
5
50
RT resistance [k ohm]
Fig.29 Oscillator Frequency - RT resistance
◇External UVLO threshold
The high precision reset function is built in EN terminal of BD9G341EFJ, and arbitrary low-voltage malfunction prevention
setup is possible by connecting EN pin to resistance division of input voltage.
When you use, please set R1 and R2 to arbitrary UVLO threshold level (Vuv) and hysteresis (Vuvhys) like below.
0.1uF
Vin=Vuv～76V
VCC
C1:
10uF/100V
L : 33uH
BST
VOUT=5.0V /3A
LX
R1 Ω
D1
C2:
100uF/6.3V
3.0kΩ
EN
FB
VC
R2 Ω
GND
RT
0.75kΩ
6800pF
47kΩ
10kΩ
Fig.30 External UVLO setup
R1=
Vuvhys
IEN
[ohm]
R2=
VEN×R1
Vuv-VEN
[ohm]
IEN:EN pin source current 10uA(typ) VEN: EN pin output on threshold 2.6V(typ)
As an example in typical sample, When Vcc voltage which IC turned on 15V, Hysteresis width 1V, The resistance
divider set to R1=100kΩ,R2=20kΩ.
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◇OCP operation
The device has over current protection for protecting the FET from over current.
To detect OCP 2 times sequentially, the device will stop and after 20msec restart.
OCP threshold
VC
VC voltage discharged
by OCP latch
VC voltage rising by
output connect to GND
force the High side FET OFF
by detecting OCP current
(pulse by pulse protection)
Lx
output connect to GND
VOUT
OCP
set the OCP latch by detecting
the OCP current 2 times sequencially
OCP latch reset after 1320msec
msec
(300ｋHz 4000 counts)
OCP_LATCH
Fig.31 Timing chart at OCP operation
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●Application Components Selection Method
(1) Inductors
Something of the shield type that fulfills the current rating (Current value
Ipeak below), with low DCR is recommended. Value of Inductance influences
Inductor Ripple Current and becomes the cause of Output Ripple.
In the same way as the formula below, this Ripple Current can be made small
for as big as the L value of Coil or as high as the Switching Frequency.
IL
・・・ (1)
2
VCC VOUT VOUT 1
IL
L
VCC
f
Δ IL
Ipeak IOUT
Fig.32 inductor Current
・・・ (2)
(⊿IL: Output Ripple Current, VCC: Input Voltage, VOUT: Output Voltage, f: Switching Frequency)
For design value of Inductor Ripple Current, please carry out design tentatively with about 20%～50% of Maximum Input
Current.
In the BD9G341EFJ, it is recommended the below series of 4.7μH～33μH inductance value.
Recommended Inductor：SUMIDA CDRH127H Series
(2) Output Capacitor
In order for capacitor to be used in output to reduce output ripple, Low ceramic capacitor of ESR is recommended.
Also, for capacitor rating, on top of putting into consideration DC Bias characteristics, please use something whose maximum
rating has sufficient margin with respect to the Output Voltage.
Output ripple voltage is looked for using the following formula.
VPP IL
1
IL RESR
2 f COUT
・・・ (3)
Please design in a way that it is held within Capacity Ripple Voltage.
In the BD9G341EFJ, it is recommended a ceramic capacitor over 10μF.
VOUT
(3) Output voltage setting
ERROR AMP
R1
FB
The internal reference voltage of ERROR AMP is 1.0V.
Output voltage is determined like (4) types.
VOUT
R1 R2
R2
R2
VREF
1.0 V
・・・ (4)
Fig.33 Output voltage setting
(4) Bootstrap Capacitor
Please connect from 0.1uF (Laminate Ceramic Capacitor) between BST Pin and Lx Pins.
(5) Catch Diode
BD9G341EFJ should be taken to connect external catch diode between Lx Pin and GND Pin. The diode require adherence to
absolute maximum Ratings of application. Opposite direction voltage should be higher than maximum voltage of Lx Pin
(VCCMAX + 0.5V). The peak current is required to be higher than IOUTMAX +⊿IL.
(6) Input Capacitor
BD9G341EFJ needs an input decoupling capacitor. It is recommended a low ceramic capacitor ESR over 4.7μF. Additionally, it
should be located as close as possible.
Capacitor should be selected by maximum input voltage with input ripple voltage.
Input ripple voltage is calculated by using the following formula.
VCC
IOUT
VOUT VOUT
・・・
1f CVCC VCC VCC
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CVCC: Input capacitor
RMS ripple current is calculated by using the following formula.
VOUT
VOUT
(1
)
VCC
VCC
ICVCC IOUT
・・・ (6)
If VCC=2VOUT, RMS ripple current is maximum. That is determined by (9) .
ICVCC_max
IOUT
2
・・・ (7)
(7) About Adjustment of DC/DC Comparator Frequency Characteristics
Role of Phase compensation element C1, C2, R3
0.1uF
VCC
L : 33uH
BST
VOUT=5.0V /3A
LX
10uF/100V
R1 Ω
D1
3.0kΩ
100uF/6.3V
EN
FB
VC
R2 Ω
GND
RT
0.75kΩ
C1
47kΩ
C2
R3
Fig.34 Feedback voltage resistance setting method
Stability and Responsiveness of Loop are controlled through VC Pin which is the output of Error Amp.
The combination of zero and pole that determines Stability and Responsiveness is adjusted by the combination of resistor and
capacitor that are connected in series to the VC Pin.
DC Gain of Voltage Return Loop can be calculated for using the following formula.
Adc Rl G CS A VEA
VFB
VOUT
・・・ (8)
Here, VFB is Feedback Voltage (1.0V).AEA is Voltage Gain of Error amplifier (typ: 55.6dB),
Gcs is the Trans-conductance of Current Detect (typ: 10A/V), and Rl is the Output Load Resistance value.
There are 2 important poles in the Control Loop of this DC/DC.
The first occurs with/ through the output resistance of Phase compensation Capacitor (C1) and Error amplifier.
The other one occurs with/through the Output Capacitor and Load Resistor.
These poles appear in the frequency written below.
fp1
G EA
2 C1 A VEA
fp 2
1
2 COUT Rl
・・・ (9)
・・・ (10)
Here, GEA is the trans-conductance of Error amplifier (typ: 300 µA/V).
Here, in this Control Loop, one zero becomes important. With the zero which occurs because of Phase compensation Capacitor
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C1 and Phase compensation Resistor R3, the Frequency below appears.
fz1
1
2 C1 R3
・・・ (11)
Also, if Output Capacitor is big, and that ESR (RESR) is big, in this Control Loop, there are cases when it has an important,
separate zero (ESR zero).
This ESR zero occurs due to ESR of Output Capacitor and Capacitance, and exists in the Frequency below.
1
2 COUT RESR
fz ESR
・・・ (12)
(ESR zero)
rd
nd
In this case, the 3 pole determined with the 2 Phase compensation Capacitor (C2) and Phase Correction Resistor (R3) is
used in order to correct the ESR zero results in Loop Gain.
This pole exists in the frequency shown below.
fp3
1
2 C2 R3
・・・ (13)
(Pole that corrects ESR zero)
The target of Phase compensation design is to create a communication function in order to acquire necessary band and Phase
margin.
Cross-over Frequency (band) at which Loop gain of Return Loop becomes “0” is important.
When Cross-over Frequency becomes low, Power supply Fluctuation Response, Load Response, etc worsens.
On the other hand, when Cross-over Frequency is too high, instability of the Loop can occur.
Tentatively, Cross-over Frequency is targeted to be made 1/20 or below of Switching Frequency.
Selection method of Phase Compensation constant is shown below.
1.
Phase Compensation Resistor (R3) is selected in order to set to the desired Cross-over Frequency.
Calculation of RC is done using the formula below.
R3
2 COUT fc VOUT
GEA G CS
VFB
・・・ (14)
Here, fc is the desired Cross-over Frequency. It is made about 1/20 and below of the Normal Switching Frequency (fs).
2.
Phase compensation Capacitor (C1) is selected in order to achieve the desired phase margin.
In an application that has a representative Inductance value (about several 3.3µH～10µH), by matching zero of
compensation to 1/4 and below of the Cross-over Frequency, sufficient Phase margin can be acquired. C1 can be
calculated using the following formula.
C1
3.
4
2 R3 fc
・・・ (15)
Examination whether the second Phase compensation Capacitor C2 is necessary or not is done.
If the ESR zero of Output Capacitor exists in a place that is smaller than half of the Switching Frequency, a second Phase
compensation Capacitor is necessary. In other words, it is the case wherein the formula below happens.
1
fs
2 COUT RESR 2
・・・ (16)
In this case, add the second Phase compensation Capacitor C2, and match the frequency of the third pole to the Frequency
fp3 of ESR zero.
C2
COUT RESR
R3
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PCB Layout
Layout is a critical portion of good power supply design. There are several signals paths that conduct fast changing currents
or voltages that can interact with stray inductance or parasitic capacitance to generate noise or degrade the power supplies
performance. To help eliminate these problems, the VCC pin should be bypassed to ground with a low ESR ceramic bypass
capacitor with B dielectric. Care should be taken to minimize the loop area formed by the bypass capacitor connections, the
VCC pin, and the anode of the catch diode. See Fig.28 for a PCB layout example. The GND pin should be tied directly to
the thermal pad under the IC and the thermal pad. In order to reduce the influence of the impedance and L of the parasitic,
the high current line is thick and short.
Input decoupling capacitor should be located as close to the VCC pins
In order to minimize the parasitic capacitor and impedance of pattern, catch diode and inductance should be located as
close to the Lx pin.
The thermal pad should be connected to any internal PCB ground planes using multiple VIAs directly under the IC.
GND feedback resistor, phase compensation element and RT resistor don’t give the common impedance resistor against
high current line.
VOUT
Output
Capacitor
Inductor
Topside
Ground
Area
Catch
Diode
Compensation
Network
LX
VCC
GND
BST
VC
EN
FB
RT
Input Bypass
Capacitor
VCC
Route BST Capacitor
Trace on another layer to
provide with wide path for
topside ground
Resistor
Divider
Signal VIA
Thermal VIA
Figure 35. Evaluation Board Pattern
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Power Dissipation
t
It is shown below reducing characteristics of power dissipation to mount 70mm×70mm×1.6mm PCB
Junction temperature must be designed not to exceed 150℃.
4000
④3760mW
HTSOP-J8 Package On 70mm×70mm×1.6mm t glass epoxy PCB
①1-layer board （Backside copper foil area 0mm×0mm）
②2-layer board ( Backside copper foil area 15mm×15mm)
③2-layer board （Backside copper foil area 70mm×70mm）
④4-layer board （Backside copper foil area 70mm×70mm）
POWER DISSIPATION - mW
3500
3000
2500
③2210mW
2000
1500
②1100mW
1000
①820mW
500
0
0
25
50
75
100
125
150
Ambient Temperature - ℃
Figure 36.Power Dissipation Characteristic
Power Dissipation Estimate
The following formulas show how to estimate the device power dissipation under continuous mode operations. They should
not be used if the device is working in the discontinuous conduction mode.
The device power dissipation includes:
2
1) Conduction loss：Pcon = IOUT × RonH × VOUT/VCC
2) Switching loss： Psw = 16n × VCC × IOUT × fsw
3) Gate charge loss：Pgc = 500p×7×fsw
4) Quiescent current loss：Pq = 1.5m × VCC
Where:
IOUT is the output current (A）, RonH is the on-resistance of the high-side MOSFET（Ω）, VOUT is the output voltage (V).
VCC is the input voltage (V) fsw is the switching frequency (Hz).
Therefore
Power dissipation of IC is the sum of above dissipation.
Pd = Pcon + Psw + Pgc + Pq
For given Tj, Tj =Ta + θja × Pd
Where:
Pd is the total device power dissipation (W), Ta is the ambient temperature (℃)
Tj is the junction temperature (℃), θja is the thermal resistance of the package (℃)
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I/O Equivalent Schematic
Pin.
No
端子名
端子等価回路図
Pin.
No
端子名
5
RT
端子等価回路図
BST
1
Lx
2
GND
7
BST
8
VCC
VCC
RT
LX
GND
GND
VCC
3
VC
VC
6
GND
EN
EN
GND
FB
4
FB
GND
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Operational Notes
1.
Reverse Connection of Power Supply
Connecting the power supply in reverse polarity can damage the IC. Take precautions against reverse polarity when
connecting the power supply, such as mounting an external diode between the power supply and the IC’s power
supply pins.
2.
Power Supply Lines
Design the PCB layout pattern to provide low impedance supply lines. Separate the ground and supply lines of the
digital and analog blocks to prevent noise in the ground and supply lines of the digital block from affecting the analog
block. Furthermore, connect a capacitor to ground at all power supply pins. Consider the effect of temperature and
aging on the capacitance value when using electrolytic capacitors.
3.
Ground Voltage
Ensure that no pins are at a voltage below that of the ground pin at any time, even during transient condition.
OR
4.
Ground Wiring Pattern
When using both small-signal and large-current ground traces, the two ground traces should be routed separately but
connected to a single ground at the reference point of the application board to avoid fluctuations in the small-signal
ground caused by large currents. Also ensure that the ground traces of external components do not cause variations
on the ground voltage. The ground lines must be as short and thick as possible to reduce line impedance.
5.
Thermal Consideration
Should by any chance the power dissipation rating be exceeded the rise in temperature of the chip may result in
deterioration of the properties of the chip. The absolute maximum rating of the Pd stated in this specification is when
the IC is mounted on a 70mm x 70mm x 1.6mm glass epoxy board. In case of exceeding this absolute maximum
rating, increase the board size and copper area to prevent exceeding the Pd rating.
6.
Recommended Operating Conditions
These conditions represent a range within which the expected characteristics of the IC can be approximately
obtained. The electrical characteristics are guaranteed under the conditions of each parameter.
7.
Inrush Current
When power is first supplied to the IC, it is possible that the internal logic may be unstable and inrush
current may flow instantaneously due to the internal powering sequence and delays, especially if the IC
has more than one power supply. Therefore, give special consideration to power coupling capacitance,
power wiring, width of ground wiring, and routing of connections.
8.
Operation Under Strong Electromagnetic Field
Operating the IC in the presence of a strong electromagnetic field may cause the IC to malfunction.
9.
Testing on Application Boards
When testing the IC on an application board, connecting a capacitor directly to a low-impedance output pin may
subject the IC to stress. Always discharge capacitors completely after each process or step. The IC’s power supply
should always be turned off completely before connecting or removing it from the test setup during the inspection
process. To prevent damage from static discharge, ground the IC during assembly and use similar precautions during
transport and storage.
10. Inter-pin Short and Mounting Errors
Ensure that the direction and position are correct when mounting the IC on the PCB. Incorrect mounting may result in
damaging the IC. Avoid nearby pins being shorted to each other especially to ground, power supply and output pin.
Inter-pin shorts could be due to many reasons such as metal particles, water droplets (in very humid environment)
and unintentional solder bridge deposited in between pins during assembly to name a few.
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Operational Notes – continued
11. Unused Input Pins
Input pins of an IC are often connected to the gate of a MOS transistor. The gate has extremely high impedance and
extremely low capacitance. If left unconnected, the electric field from the outside can easily charge it. The small
charge acquired in this way is enough to produce a significant effect on the conduction through the transistor and
cause unexpected operation of the IC. So unless otherwise specified, unused input pins should be connected to the
power supply or ground line.
12. Regarding the Input Pin of the IC
This monolithic IC contains P+ isolation and P substrate layers between adjacent elements in order to keep them
isolated. P-N junctions are formed at the intersection of the P layers with the N layers of other elements, creating a
parasitic diode or transistor. For example (refer to figure below):
When GND > Pin A and GND > Pin B, the P-N junction operates as a parasitic diode.
When GND > Pin B, the P-N junction operates as a parasitic transistor.
Parasitic diodes inevitably occur in the structure of the IC. The operation of parasitic diodes can result in mutual
interference among circuits, operational faults, or physical damage. Therefore, conditions that cause these diodes to
operate, such as applying a voltage lower than the GND voltage to an input pin (and thus to the P substrate) should
be avoided.
Resistor
Transistor (NPN)
Pin A
Pin B
C
E
Pin A
N
P+
P
N
N
P+
N
Pin B
B
Parasitic
Elements
N
P+
N P
N
P+
B
N
C
E
Parasitic
Elements
P Substrate
P Substrate
GND
GND
Parasitic
Elements
GND
Parasitic
Elements
GND
N Region
close-by
Figure 37. Example of monolithic IC structure
13. Ceramic Capacitor
When using a ceramic capacitor, determine the dielectric constant considering the change of capacitance with
temperature and the decrease in nominal capacitance due to DC bias and others.
14. Area of Safe Operation (ASO)
Operate the IC such that the output voltage, output current, and power dissipation are all within the Area of Safe
Operation (ASO).
Operational Notes – continued
15. Thermal Shutdown Circuit(TSD)
This IC has a built-in thermal shutdown circuit that prevents heat damage to the IC. Normal operation should always
be within the IC’s power dissipation rating. If however the rating is exceeded for a continued period, the junction
temperature (Tj) will rise which will activate the TSD circuit that will turn OFF all output pins. When the Tj falls below
the TSD threshold, the circuits are automatically restored to normal operation.
Note that the TSD circuit operates in a situation that exceeds the absolute maximum ratings and therefore, under no
circumstances, should the TSD circuit be used in a set design or for any purpose other than protecting the IC from
heat damage.
16. Over Current Protection Circuit (OCP)
This IC incorporates an integrated overcurrent protection circuit that is activated when the load is shorted. This
protection circuit is effective in preventing damage due to sudden and unexpected incidents. However, the IC should
not be used in applications characterized by continuous operation or transitioning of the protection circuit.
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Ordering Information
B D 9 G 3 4
Part Number
1
E
F
Package
EFJ: HTSOP-J8
J
-
E2
Packaging and forming specification :
Embossed tape and reel
Marking Diagrams
HTSOP-J8
4.90mm x 6.00mm x 1.00mm
HTSOP-J8
(TOP VIEW)
HTSOP-J8(TOP VIEW)
Part Number Marking
D 9 G 3 4 1
LOT Number
1PIN MARK
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Physical Dimension, Tape and Reel Information
Package Name
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BD9G341EFJ
Revision History
Date
Revision
15.Jul.2014
001
Changes
New Release
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Datasheet
Notice
Precaution on using ROHM Products
1.
Our Products are designed and manufactured for application in ordinary electronic equipments (such as AV equipment,
OA equipment, telecommunication equipment, home electronic appliances, amusement equipment, etc.). If you
(Note 1)
, transport
intend to use our Products in devices requiring extremely high reliability (such as medical equipment
equipment, traffic equipment, aircraft/spacecraft, nuclear power controllers, fuel controllers, car equipment including car
accessories, safety devices, etc.) and whose malfunction or failure may cause loss of human life, bodily injury or
serious damage to property (“Specific Applications”), please consult with the ROHM sales representative in advance.
Unless otherwise agreed in writing by ROHM in advance, ROHM shall not be in any way responsible or liable for any
damages, expenses or losses incurred by you or third parties arising from the use of any ROHM’s Products for Specific
Applications.
(Note1) Medical Equipment Classification of the Specific Applications
JAPAN
USA
EU
CHINA
CLASSⅢ
CLASSⅡb
CLASSⅢ
CLASSⅢ
CLASSⅣ
CLASSⅢ
2.
ROHM designs and manufactures its Products subject to strict quality control system. However, semiconductor
products can fail or malfunction at a certain rate. Please be sure to implement, at your own responsibilities, adequate
safety measures including but not limited to fail-safe design against the physical injury, damage to any property, which
a failure or malfunction of our Products may cause. The following are examples of safety measures:
[a] Installation of protection circuits or other protective devices to improve system safety
[b] Installation of redundant circuits to reduce the impact of single or multiple circuit failure
3.
Our Products are designed and manufactured for use under standard conditions and not under any special or
extraordinary environments or conditions, as exemplified below. Accordingly, ROHM shall not be in any way
responsible or liable for any damages, expenses or losses arising from the use of any ROHM’s Products under any
special or extraordinary environments or conditions. If you intend to use our Products under any special or
extraordinary environments or conditions (as exemplified below), your independent verification and confirmation of
product performance, reliability, etc, prior to use, must be necessary:
[a] Use of our Products in any types of liquid, including water, oils, chemicals, and organic solvents
[b] Use of our Products outdoors or in places where the Products are exposed to direct sunlight or dust
[c] Use of our Products in places where the Products are exposed to sea wind or corrosive gases, including Cl2,
H2S, NH3, SO2, and NO2
[d] Use of our Products in places where the Products are exposed to static electricity or electromagnetic waves
[e] Use of our Products in proximity to heat-producing components, plastic cords, or other flammable items
[f] Sealing or coating our Products with resin or other coating materials
[g] Use of our Products without cleaning residue of flux (even if you use no-clean type fluxes, cleaning residue of
flux is recommended); or Washing our Products by using water or water-soluble cleaning agents for cleaning
residue after soldering
[h] Use of the Products in places subject to dew condensation
4.
The Products are not subject to radiation-proof design.
5.
Please verify and confirm characteristics of the final or mounted products in using the Products.
6.
In particular, if a transient load (a large amount of load applied in a short period of time, such as pulse. is applied,
confirmation of performance characteristics after on-board mounting is strongly recommended. Avoid applying power
exceeding normal rated power; exceeding the power rating under steady-state loading condition may negatively affect
product performance and reliability.
7.
De-rate Power Dissipation (Pd) depending on Ambient temperature (Ta). When used in sealed area, confirm the actual
ambient temperature.
8.
Confirm that operation temperature is within the specified range described in the product specification.
9.
ROHM shall not be in any way responsible or liable for failure induced under deviant condition from what is defined in
this document.
Precaution for Mounting / Circuit board design
1.
When a highly active halogenous (chlorine, bromine, etc.) flux is used, the residue of flux may negatively affect product
performance and reliability.
2.
In principle, the reflow soldering method must be used; if flow soldering method is preferred, please consult with the
ROHM representative in advance.
For details, please refer to ROHM Mounting specification
Notice – GE
© 2013 ROHM Co., Ltd. All rights reserved.
Rev.002
Datasheet
Precautions Regarding Application Examples and External Circuits
1.
If change is made to the constant of an external circuit, please allow a sufficient margin considering variations of the
characteristics of the Products and external components, including transient characteristics, as well as static
characteristics.
2.
You agree that application notes, reference designs, and associated data and information contained in this document
are presented only as guidance for Products use. Therefore, in case you use such information, you are solely
responsible for it and you must exercise your own independent verification and judgment in the use of such information
contained in this document. ROHM shall not be in any way responsible or liable for any damages, expenses or losses
incurred by you or third parties arising from the use of such information.
Precaution for Electrostatic
This Product is electrostatic sensitive product, which may be damaged due to electrostatic discharge. Please take proper
caution in your manufacturing process and storage so that voltage exceeding the Products maximum rating will not be
applied to Products. Please take special care under dry condition (e.g. Grounding of human body / equipment / solder iron,
isolation from charged objects, setting of Ionizer, friction prevention and temperature / humidity control).
Precaution for Storage / Transportation
1.
Product performance and soldered connections may deteriorate if the Products are stored in the places where:
[a] the Products are exposed to sea winds or corrosive gases, including Cl2, H2S, NH3, SO2, and NO2
[b] the temperature or humidity exceeds those recommended by ROHM
[c] the Products are exposed to direct sunshine or condensation
[d] the Products are exposed to high Electrostatic
2.
Even under ROHM recommended storage condition, solderability of products out of recommended storage time period
may be degraded. It is strongly recommended to confirm solderability before using Products of which storage time is
exceeding the recommended storage time period.
3.
Store / transport cartons in the correct direction, which is indicated on a carton with a symbol. Otherwise bent leads
may occur due to excessive stress applied when dropping of a carton.
4.
Use Products within the specified time after opening a humidity barrier bag. Baking is required before using Products of
which storage time is exceeding the recommended storage time period.
Precaution for Product Label
QR code printed on ROHM Products label is for ROHM’s internal use only.
Precaution for Disposition
When disposing Products please dispose them properly using an authorized industry waste company.
Precaution for Foreign Exchange and Foreign Trade act
Since our Products might fall under controlled goods prescribed by the applicable foreign exchange and foreign trade act,
please consult with ROHM representative in case of export.
Precaution Regarding Intellectual Property Rights
1.
All information and data including but not limited to application example contained in this document is for reference
only. ROHM does not warrant that foregoing information or data will not infringe any intellectual property rights or any
other rights of any third party regarding such information or data. ROHM shall not be in any way responsible or liable
for infringement of any intellectual property rights or other damages arising from use of such information or data.:
2.
No license, expressly or implied, is granted hereby under any intellectual property rights or other rights of ROHM or any
third parties with respect to the information contained in this document.
Other Precaution
1.
This document may not be reprinted or reproduced, in whole or in part, without prior written consent of ROHM.
2.
The Products may not be disassembled, converted, modified, reproduced or otherwise changed without prior written
consent of ROHM.
3.
In no event shall you use in any way whatsoever the Products and the related technical information contained in the
Products or this document for any military purposes, including but not limited to, the development of mass-destruction
weapons.
4.
The proper names of companies or products described in this document are trademarks or registered trademarks of
ROHM, its affiliated companies or third parties.
Notice – GE
© 2013 ROHM Co., Ltd. All rights reserved.
Rev.002
Datasheet
General Precaution
1. Before you use our Pro ducts, you are requested to care fully read this document and fully understand its contents.
ROHM shall n ot be in an y way responsible or liabl e for fa ilure, malfunction or acci dent arising from the use of a ny
ROHM’s Products against warning, caution or note contained in this document.
2. All information contained in this docume nt is current as of the issuing date and subj ect to change without any prior
notice. Before purchasing or using ROHM’s Products, please confirm the la test information with a ROHM sale s
representative.
3.
The information contained in this doc ument is provi ded on an “as is” basis and ROHM does not warrant that all
information contained in this document is accurate an d/or error-free. ROHM shall not be in an y way responsible or
liable for an y damages, expenses or losses incurred b y you or third parties resulting from inaccur acy or errors of or
concerning such information.
Notice – WE
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