BD9411F [ROHM]
BD9411F是白色LED用高效率驱动器,适用于大屏幕液晶驱动器。BD9411F内置了可向光源(LED串联连接的阵列)提供适当电压的DC/DC转换器。BD9411F中内置了应对异常状态的几种保护功能。过电压保护(OVP: over voltage protection), 过电流检测(OCP: over current limit protection of DCDC), LED 过电流保护(LEDOCP: LED over current protection), 过升压保护(FBMAX: over boost protection)等。因此,可在更宽的输出电压条件及负载条件下使用。;型号: | BD9411F |
厂家: | ROHM |
描述: | BD9411F是白色LED用高效率驱动器,适用于大屏幕液晶驱动器。BD9411F内置了可向光源(LED串联连接的阵列)提供适当电压的DC/DC转换器。BD9411F中内置了应对异常状态的几种保护功能。过电压保护(OVP: over voltage protection), 过电流检测(OCP: over current limit protection of DCDC), LED 过电流保护(LEDOCP: LED over current protection), 过升压保护(FBMAX: over boost protection)等。因此,可在更宽的输出电压条件及负载条件下使用。 驱动 CD 过电流保护 驱动器 转换器 |
文件: | 总37页 (文件大小:1931K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LED Drivers for LCD Backlights
1ch Boost up Type
White LED Driver for large LCD
BD9411F
General Description
Key Specifications
BD9411F is a high efficiency driver for white LEDs and is
designed for large LCDs. BD9411F has a boost DCDC
converter that employs an array of LEDs as the light
source.
Operating power supply voltage range: 9.0V to 35.0V
Oscillator frequency of DCDC: 150kHz (RT=100kΩ)
Operating Current:
3.3 mA(Typ)
-40°C to +105°C
Operating temperature range:
BD9411F has some protect functions against fault
conditions, such as over-voltage protection (OVP), over
current limit protection of DCDC (OCP), LED OCP
protection, and over-boost protection (FBMAX).
Therefore it is available for the fail-safe design over a
wide range output voltage.
Package(s)
W(Typ) x D(Typ) x H(Max)
11.20mm x 7.80mm x 2.01mm
Pin pitch 1.27mm
SOP18
Features
DCDC converter with current mode
LED protection circuit (Over boost protection, LED
OCP protection)
Over-voltage protection (OVP) for the output voltage
VOUT
Adjustable soft start
Adjustable oscillation frequency of DCDC
Wide range of analog dimming 0.2V to 3.0V
UVLO detection for the input voltage of the power
stage
LED Dimming PWM Over Duty Protection(ODP)
Figure 1. SOP18
Applications
TV, Computer Display, LCD Backlighting
Typical Application Circuit
VOUT
VCC
VIN
VCC
UVLO
OVP
REG90
STB
GATE
CS
RT
SS
FAIL
DIMOUT
PWM
ADIM
ISENSE
FB
DUTYP
Rs
DUTYON
GND
Figure 2. Typical Application Circuit
○Product structure:Silicon monolithic integrated circuit ○This product has not designed protection against radioactive rays
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BD9411F
Pin Configuration(s)
18
17
16
15
14
13
12
11
10
1
2
3
4
5
6
7
8
9
VCC
REG90
CS
STB
OVP
GATE
DIMOUT
GND
UVLO
SS
DUTYON
PWM
FAIL
ISENSE
FB
DUTYP
RT
ADIM
Figure 3. Pin Configuration
Pin Description(s)
Terminal
Name
No.
Function
1
2
VCC
Power supply pin
IC ON/OFF pin
STB
OVP
3
Over voltage protection detection pin
Under voltage lock out detection pin
Soft start setting pin
4
UVLO
SS
5
6
DUTYON
PWM
FAIL
Over Duty Protection ON/OFF pin
External PWM dimming signal input pin
Error detection output pin
7
8
9
ADIM
RT
ADIM signal input pin
10
11
12
13
14
15
16
DC/DC switching frequency setting pin
Over Duty Protection setting pin
Error amplifier output pin
DUTYP
FB
ISENSE
GND
LED current detection input pin
-
DIMOUT
GATE
Dimming signal output for NMOS
DC/DC switching output pin
DC/DC output current detect pin,
OCP input pin
17
18
CS
REG90
9.0V output voltage pin
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BD9411F
Block Diagram(s)
VCC
VIN
VCC
UVLO
OVP
REG90
STB
VCC
VREG
UVLO
TSD
OVP
UVLO
REG 90
UVLO
1MΩ
REG90
PWM
COMP
GATE
CS
RT
OSC
+
-
-
CONTROL
LOGIC
LEB
Current
sense
SS
SS
REG90
SS-FB
clamper
DIMOUT
FAIL
Fail
detect
LEDOCP
Auto -
Restart
Control
ISENSE
FB
-
+
+
1.015V
PWM
ERROR
amp
Rs
1MΩ
OverBoost
DUTYP
Over Duty
Protection
OSC
DUTYON
1MΩ
ADIM
1/3
GND
Package:SOP18
Figure 4. Block Diagram
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BD9411F
Absolute Maximum Ratings (Tj=25°C)
Rating
Unit
V
Parameter
Power Supply Voltage
SS, RT, ISENSE, FB, CS,
DUTYP Pin Voltage
REG90, DIMOUT, GATE
Pin Voltage
Symbol
VCC
-0.3 to +36
SS, RT, ISENSE, FB, CS,
DUTYP
-0.3 to +7
V
V
REG90, DIMOUT, GATE
-0.3 to +13
OVP, UVLO, PWM, ADIM, STB,
FAIL, DUTYON
Pin Voltage
OVP, UVLO, PWM,
ADIM, STB, FAIL,
DUTYON
-0.3 to +20
V
Operating Temperature Range
Junction Temperature
Topr
Tjmax
Tstg
-40 to +105
150
°C
°C
°C
Storage Temperature Range
-55 to +150
Thermal Resistance(Note 1)
Thermal Resistance (Typ)
Parameter
Symbol
Unit
1s(Note 3)
2s2p(Note 4)
SOP18
Junction to Ambient
Junction to Top Characterization Parameter(Note 2)
θJA
179.3
20.0
119.9
17.0
°C/W
°C/W
ΨJT
(Note 1)Based on JESD51-2A(Still-Air)
(Note 2)The thermal characterization parameter to report the difference between junction temperature and the temperature at the top center of the outside
surface of the component package.
(Note 3)Using a PCB board based on JESD51-3.
(Note 4)Using a PCB board based on JESD51-7.
Layer Number of
Measurement Board
Material
FR-4
Board Size
Single
114.3mm x 76.2mm x 1.57mmt
Top
Copper Pattern
Thickness
Footprints and Traces
70μm
Layer Number of
Measurement Board
Material
FR-4
Board Size
114.3mm x 76.2mm x 1.6mmt
2 Internal Layers
4 Layers
Top
Copper Pattern
Bottom
Copper Pattern
74.2mm x 74.2mm
Thickness
Copper Pattern
Thickness
Thickness
Footprints and Traces
70μm
74.2mm x 74.2mm
35μm
70μm
Recommended Operating Ranges
Parameter
Symbol
VCC
Range
Unit
V
Power Supply Voltage
9.0 to 35.0
50 to 1000
0.2 to 3.0
90 to 2000
DC/DC Oscillation Frequency
Effective Range of ADIM Signal
PWM Input Frequency
fsw
kHz
V
VADIM
FPWM
Hz
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BD9411F
Electrical Characteristics (Unless otherwise specified VCC=24V Tj=25°C)
Parameter
【Total Current Consumption】
Circuit Current
Symbol
Min
Typ
Max
Unit
Conditions
ICC
IST
-
-
3.3
40
6.6
80
mA
VSTB=3.0V, PWM=3.0V
VSTB=0V
Circuit Current (standby)
【UVLO Block】
μA
Operation Voltage(VCC
)
VUVLO_VCC
VUHYS_VCC
VUVLO
6.5
150
2.88
250
-2
7.5
300
3.00
300
0
8.5
600
3.12
350
2
V
mV
V
VCC=SWEEP UP
VCC=SWEEP DOWN
VUVLO=SWEEP UP
VUVLO=SWEEP DOWN
VUVLO=4.0V
Hysteresis Voltage(VCC
)
UVLO Release Voltage
UVLO Hysteresis Voltage
UVLO Pin Leak Current
【DC/DC Block】
VUHYS
mV
μA
IVUVLO_LK
ISENSE Threshold Voltage 1
ISENSE Threshold Voltage 2
ISENSE Threshold Voltage 3
VLED1
VLED2
VLED3
0.225
0.656
0.988
0.233
0.667
1.000
0.242
0.677
1.012
V
V
V
VADIM=0.7V
VADIM=2.0V
VADIM=3.0V
VADIM=3.3V
(as masking analog dimming)
RT=100kΩ
ISENSE Clamp Voltage
Oscillation Frequency
VLED4
FCT
0.990
142.5
-0.3
1.015
150
-
1.040
157.5
VRT
×90%
V
kHz
V
RT Short Protection Range
VRT_DET
RT=SWEEP DOWN
RT Terminal Voltage
VRT
1.6
90
2.0
95
2.4
99
V
RT=100kΩ
RT=100kΩ
GATE Pin MAX DUTY Output
DMAX_DUTY
%
GATE Pin ON Resistance
(as source)
GATE Pin ON Resistance
(as sink)
SS Pin Source Current
SS Pin ON Resistance at OFF
Soft Start Ended Voltage
【DC/DC Block】
RON_GSO
2.5
2.0
5.0
4.0
10.0
8.0
Ω
Ω
RON_GSI
ISSSO
RSS_L
-3.75
-
-3.0
3.0
-2.25
5.0
μA
kΩ
V
VSS=2.0V
VSS_END
3.52
3.70
3.88
SS=SWEEP UP
VISENSE=0.2V, VADIM=3.0V,
VFB=1.0V
VISENSE=2.0V, VADIM=3.0V,
VFB=1.0V
FB Source Current
FB Sink Current
IFBSO
IFBSI
-115
85
-100
100
-85
μA
μA
115
【DC/DC Protection Block】
OCP Detect Voltage1
OCP Detect Voltage2
OVP Detect Voltage
VCS1
VCS2
360
0.85
2.88
150
-2
400
1.00
3.00
200
0
440
1.15
3.12
250
2
mV
V
CS=SWEEP UP, Pulse by pulse
CS=SWEEP UP
VOVP
V
VOVP SWEEP UP
OVP Detect Hysteresis
OVP Pin Leak Current
VOVP_HYS
IOVP_LK
mV
μA
VOVP SWEEP DOWN
VOVP=4.0V, VSTB=3.0V
【LED Protection Block】
LED OCP Detect Voltage
Over Boost Detection Voltage
【Dimming Block】
VLEDOCP
VFBH
2.88
3.84
3.00
4.00
3.12
4.16
V
V
VISENSE=SWEEP UP
VFB=SWEEP UP
ADIM Pin Leak Current
ISENSE Pin Leak Current
ILADIM
-2
-2
0
0
2
2
μA
μA
VADIM=2.0V
IL_ISENSE
VISENSE=4.0V
DIMOUT Source ON
Resistance
DIMOUT Sink ON Resistance
【REG90 Block】
RON_DIMSO
RON_DIMSI
5.0
4.0
10.0
8.0
20.0
16.0
Ω
Ω
REG90 Output Voltage 1
REG90 Output Voltage 2
REG90 Available Current
VREG90_1
VREG90_2
| IREG90
VREG90_TH
8.91
8.865
15
9.00
9.00
-
9.09
9.135
-
V
V
IO=0mA
IO=-15mA
|
mA
VREG90=SWEEP DOWN,
VSTB=0V
STB=ON->OFF, VREG90=8.0V,
PWM=L
REG90_UVLO Detect Voltage
REG90 Discharge Resistance
5.22
13.2
6.00
22.0
6.78
30.8
V
VREG90_DIS
kΩ
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BD9411F
Electrical Characteristics (Unless otherwise specified VCC=24V Tj=25°C)
Parameter
【STB Block】
Symbol
Min
Typ
Max
Unit
Conditions
STB Pin HIGH Voltage
STB Pin LOW Voltage
STB Pull Down Resistance
【PWM Block】
VSTBH
VSTBL
RSTB
2.0
-0.3
600
-
-
18
0.8
V
V
1000
1400
kΩ
VSTB=3.0V
VPWM=3.0V
PWM Pin HIGH Voltage
PWM Pin LOW Voltage
PWM Pin Pull Down Resistance
【DUTYON Block】
VPWM_H
VPWM_L
RPWM
1.5
-0.3
600
-
-
18
0.8
V
V
1000
1400
kΩ
DUTYON Pin HIGH Voltage
DUTYON Pin LOW Voltage
DUTYON Pin Pull Down
Resistance
VDTYON_H
VDTYON_L
RDTYON
1.5
-
-
18
V
V
-0.3
0.8
600
1000
1400
kΩ
VDUTYON=3.0V
【Over Duty Protection Block】
PWM ODP Protection Detect
Duty
DODP
-
35
-
%
FPWM=120Hz, DUTYP=341kΩ
VDUTYP
×90%
DUTYP Short Protection Range
VDTYP_DET
VDTYP
-0.3
1.6
-
V
V
DUTYP=SWEEP DOWN
DUTYP Terminal Voltage
【Filter Block】
2.0
2.4
DUTYP=100kΩ
Abnormal Detection Timer
AUTO Timer
tCP
-
-
20
-
-
ms
ms
FCT=800kHz
FCT=800kHz
tAUTO
163
【FAIL Block 】
FAIL Pin LOW Voltage
VFAILL
0.25
0.5
1.0
V
IFAIL=1mA
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BD9411F
Typical Performance Curves (Reference data)
80
70
60
50
40
30
20
10
0
4.0
3.5
3.0
2.5
2.0
1.5
STB=0V
PWM=0V
Ta=25°C
1.0
STB=3.0V
PWM=3.0V
Ta=25°C
0.5
0.0
10
15
20
25
VCC[V]
30
35
10
15
20
25
VCC[V]
30
35
Figure 5. Operating circuit current
Figure 6. Standby circuit current
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
100
80
60
40
20
0
VCC=24V
VCC=24V
Ta=25°C
Ta=25°C
0
1
2
3
4
0
1
2
3
4
VADIM[V]
VFB[V]
Figure 7. Duty cycle vs FB character
Figure 8. ISENSE feedback voltage vs ADIM character
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Pin Descriptions
○Pin 1: VCC
This is the power supply pin of the IC. Input range is from 9V to 35V.
The operation starts at more than 7.5V(Typ) and shuts down at less than 7.2V(Typ).
○Pin 2: STB
This is the ON/OFF setting terminal of the IC.
At startup, internal bias starts at high level, and then PWM DCDC boost starts after PWM rise edge inputs.
Note: IC status (IC ON/OFF) transits depending on the voltage inputted to STB terminal. Avoid the use of intermediate
level (from 0.8V to 2.0V).
○Pin 3: OVP
The OVP terminal is the input for over-voltage protection. If OVP is more than 3.0V(Typ), the over-voltage protection
(OVP) will work. At the moment of these detections, it sets GATE=L, DIMOUT=L and starts to count up the abnormal
interval. If OVP detection continued to count four GATE clocks, IC's operation will be stop. (Please refer to "OVP
Detection" Timing Chart on Page26)
The OVP pin is high impedance, because the internal resistance is not connected to a certain bias.
Even if OVP function is not used, pin bias is still required because the open connection of this pin is not a fixed potential.
The setting example is separately described in the ”OVP Setting" section on Page16.
○Pin 4: UVLO
Under Voltage Lock Out pin is the input voltage of the power stage. , IC starts the boost operation if UVLO is more than
3.0V(Typ) and stops if lower than 2.7V(Typ).
The UVLO pin is high impedance, because the internal resistance is not connected to a certain bias.
Even if UVLO function is not used, pin bias is still required because the open connection of this pin is not a fixed
potential.
The setting example is separately described in the ”UVLO Setting" section on Page15
○Pin 5: SS
This is the pin which sets the soft start interval of DC/DC converter. It performs the constant current charge of 3.0 μA(Typ)
to external capacitance Css. The switching duty of GATE output will be limited during 0V to 3.7V(Typ) of the SS voltage.
So the soft start interval Tss can be expressed as follows
TSS 1.23106 CSS[sec]ꢀ CSS: the external capacitance of the SS pin.
The logic of SS pin asserts low is defined as the DC/DC operation stop state after protection function or PWM is not input
high level after STB reset release. When SS capacitance is under 1nF, take note if the in-rush current during startup is
too large, or if over boost detection (FBMAX) mask timing is too short.
Please refer to soft start behavior in the “Timing Chart" section on Page13.
○Pin 6: DUTYON
This is the ON/OFF setting terminal of the LED PWM Over Duty Protection (ODP). By adjusting DUTYON input voltage, it
is ON/OFF of the ODP adjusted.
State
DUTYON input voltage
DUTYON= -0.3V to +0.8V
ODP=ON
ODP=OFF
DUTYON= 1.5V to 18.0V
○Pin 7: PWM
This is the PWM dimming signal input terminal. The high / low level of PWM pins are the following.
State
PWM input voltage
PWM= 1.5V to 18.0V
PWM= ‐0.3V to +0.8V
PWM=H
PWM=L
○Pin 8: FAIL
This is FAIL signal output (OPEN DRAIN) pin. At normal operation, NMOS will be in ON (500 ohm Typ) state, during
abnormality detection NMOS will be in OPEN state (OFF).
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BD9411F
○Pin 9: ADIM
This is the input pin for analog dimming signal. The ISENSE feedback point is set as 1/3 of this pin bias. If more than
3.0V(Typ) is input, ISENSE feedback voltage is clamped to limit to flow LED large current. In this condition, the input
current is caused. Please refer to <ISENSE> terminal explanation.
○Pin 10: RT
This is the DC/DC switching frequency setting pin. DCDC frequency is decided by connected resistor.
○The relationship between the frequency and RT resistance value (ideal)
15000
RRT
[k]ꢀ
fSW [kHz]
The oscillation setting ranges from 50kHz to 1000kHz.
The setting example is separately described in the ”DCDC Oscillation Frequency Setting” section on Page15
○Pin 11: DUTYP
This is the ODP setting pin. The ODP (Over Duty Protection) is the function to limit DUTY of LED PWM frequency fPWM by
ODP detection Duty (ODPduty) set by resistance (RDUTY) connected to DUTYP pin.
○Relationship between LED PWM frequency fPWM, ODP Detection Duty and DUTYP resistance (ideal)
1172ODP [%]
duty
RDUTYP
[k]ꢀ
fPWM [Hz]
The RDUTYP setting ranges from 15kΩ to 1MΩ.
The setting example is separately described in the ”ODP Setting” section on Page16.
○Pin 12: FB
This is the output terminal of error amplifier.
FB pin rises with the same slope as the SS pin during the soft-start period.
After soft -start completion (SS>3.7V(Typ)), it operates as follows.
When PWM=H, it detects ISENSE terminal voltage and outputs error signal compared to analog dimming signal (ADIM).
When PWM=L, IC holds the OVP voltage at the edge of PWM=H to L, and operates to hold the adjacent voltage. Please
refer to “Timing Chart” section
It detects over boost (FBMAX) over FB=4.0V(Typ). After the SS completion, if FB>4.0V and PWM=H continues 4clk GATE,
the CP counter starts. After that, only the FB>4.0V is monitored, When CP counter reaches 16384clk (214clk), IC's
operation will be stop. (Please refer to “Timing Chart” section on Page27.)
The loop compensation setting is described in section "Loop Compensation" on Page21.
○Pin 13: ISENSE
VOUT
This is the input terminal for the current detection. Error amplifier compares
ISENSE voltage and the lower voltage between 1/3 of the ADIM (analog
dimming terminal) voltage and 1.015V(Typ) for FB voltage control.
And this terminal detects abnormal LED's over-current when ISENSE voltage
continues over 3.0V(Typ) during 4CLKs (equivalent to 40us at fosc = 100kHz),
DC/DC operation becomes stop. (Please refer to “Timing Chart” section on Page
BD9411
DIMOUT
28.)
Error AMP
ISENSE
ADIM
-
+
+
1.015V
1/3
Rs
1.015V
1.0V
Gain=1/3
67mV
FB
3.0
0
0.2
ADIM[V]
Figure 9. Relationship of the feedback voltage and ADIM
Figure 10. ISENSE terminal circuit example
○Pin 14: GND
This is the GND pin of the IC.
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BD9411F
VOUT
○Pin 15: DIMOUT
This is the output pin for external dimming NMOS. The table below shows the rough output
logic of each operation state, and the output H level is REG90. Please refer to “Timing
Chart” section for detailed explanations, because DIMOUT logic has an exceptional
behavior. Please insert the resistor RDIM between the dimming MOS gate to improve the
over shoot of LED current, as PWM turns from low to high.
REG90
DIM
R
DIMOUT
Status
Normal
DIMOUT output
Same logic to PWM
GND Level
ISENSE
Abnormal
BD9411
Figure 11. DIMOUT terminal circuit
example
○Pin 16: GATE
This is the output terminal for driving the gate of the boost MOSFET. The high level is REG90. Frequency can be set by
the resistor connected to RT. Refer to <RT> pin description for the frequency setting.
○Pin 17: CS
The CS pin has two functions.
VIN
1. DC / DC current mode Feedback terminal
The inductor current is converted to the CS pin voltage by the sense resistor RCS.
This voltage compared to the voltage set by error amplifier controls the output
pulse.
BD9411
2. Inductor current limit (OCP) terminal
Id
GATE
CS
The CS terminal also has an over current protection (OCP). If the voltage is more
than 0.4V(Typ), the switching operation will be stopped compulsorily. And the
next boost pulse will be restarted to normal frequency.
In addition, the CS voltage is more than 1.0V(Typ) during 4CLKs GATE operation,
IC operation will be stop. As above OCP operation, if the current continues to flow
nevertheless GATE=L because of the destruction of the boost MOS, IC will stops
the operation completely.
CCS
RCS
GND
Figure 12. CS terminal circuit example
Both of the above functions are enabled after 300ns (Typ) when GATE pin
asserts high, because the Leading Edge Blanking function (LEB) is included into this IC to prevent the effect of noise.
Please refer to “OCP Setting / Calculation Method for the Current Rating of DCDC Parts” section on Page18, for detailed
explanation.
If the capacitance CCS in the right figure is increased to a micro order, please be careful that the limited value of NMOS
drain current Id is more than the simple calculation. Because the current Id flows not only through RCS but also through
CCS, as the CS pin voltage moves according to Id.
○Pin 18: REG90
10
This is the 9.0V(Typ) output pin. Available current is 15mA
(min).
The characteristic of VCC line regulation at REG90 is shown as
figure. VCC must be used in more than 10.5V for stable 9V
output.
8
Please place the ceramic capacitor connected to REG90 pin
(1.0μF to 10μF) closest to REG90-GND pin.
6
4
2
0
0
5
10
15
20
25
30
35
VCC[V]
Figure 13. REG90 line regulation
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List of The Protection Function Detection Condition (Typ Condition)
Detect condition
Detection condition
Protect
function
Detection
pin
Release
condition
Timer
operation
Protection Type
PWM
SS
Immediately auto-restart
after detection
(Judge periodically
whether normal or not)
Immediately auto-restart
after detection
FBMAX
FB
FB > 4.0V
H(4clk) SS>3.7V
FB < 4.0V
214clk
4clk
LED OCP
ISENSE
ISENSE > 3.0V
-
-
ISENSE < 3.0V
(Judge periodically
whether normal or not)
RT GND
SHORT
Release
RT=GND
RT
RT
RT<VRT×90%
RT>5V
-
-
-
-
NO
NO
Restart by release
Restart by release
RT HIGH
SHORT
Release
RT=HIGH
UVLO
UVLO
REG90
VCC
UVLO<2.7V
REG90<6.0V
VCC<7.2V
-
-
-
-
-
-
UVLO>3.0V
REG90>6.5V
VCC>7.5V
NO
NO
NO
Restart by release
Restart by release
Restart by release
REG90UVLO
VCCUVLO
Immediately auto-restart
after detection
(Judge periodically
whether normal or not)
OVP
OCP
OVP
CS
OVP>3.0V
CS>0.4V
CS>1.0V
-
-
-
-
-
-
OVP<2.8V
-
4clk
NO
Pulse by pulse
Immediately auto-restart
after detection
(Judge periodically
whether normal or not)
OCP
detection2
CS
CS<1.0V
4clk
DUTYP GND
SHORT
DUTYP HIGH
SHORT
Release
DUTYP=GND
Release
DUTYP
DUTYP
DUTYP <VDUTYP×90%
DUTYP >5V
-
-
-
-
NO
NO
Restart by release
Restart by release
DUTYP=HIGH
DUTYON=H
and
PWM on duty > setting
duty by DUTYP resistor
ODP(*1)
PWM
H
-
-
NO
Cycle by cycle
To reset the FBMAX, LED OCP, OVP and OCP detection2 protection, please set STB logic to ‘L’ once. Otherwise the detection of
VCCUVLO, REG90UVLO is required.
The clock number of timer operation corresponds to the boost pulse clock.
(*1) When PWM Duty count start, PWM=H → L is input, when PWM=L → H is input, the ODP is reset.
The GATE output, the DIMOUT output maintain L until PWM=H → L is input in PWM = 100% again when ODP works once.
List of The Protection Function Operation
Operation of the protect function
Protect function
DC/DC gate
output
Dimming transistor
(DIMOUT) logic
SS pin
FAIL pin
Stop after timer
operation
Discharge after timer
operation
High after timer
operation
FBMAX
Low after timer operation
Immediately high,
Low after timer operation
Discharge after timer
operation
High after timer
operation
LED OCP
Stop immediately
RT GND SHORT
RT HIGH SHORT
Stop immediately
Stop immediately
Immediately low
Immediately low
Not discharge
Not discharge
Low
Low
Low after REG90UVLO
detects
STB
Stop immediately
Discharge immediately
Low
UVLO
Stop immediately
Stop immediately
Stop immediately
Immediately low
Immediately low
Immediately low
Discharge immediately
Discharge immediately
Discharge immediately
Low
Low
Low
REG90UVLO
VCC UVLO
Discharge after timer
operation
OVP
OCP
Stop immediately
Immediately low
Normal operation
Low
Stop immediately
Not discharge
Low
Stop after timer
operation
Discharge after timer
operation
High after timer
operation
OCP detection2
Low after timer operation
DUTYP GND SHORT
DUTYP HIGH SHORT
ODP
Stop immediately
Stop immediately
Immediately low
Immediately low
Immediately low
Immediately low
Not discharge
Not discharge
Not discharge
Low
Low
Low
Please refer to “Timing Chart” section for details.
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BD9411F
Application Circuit Example
Introduce an example application using the BD9411F.
Basic Application Example
VOUT
VCC
VIN
VCC
UVLO
OVP
REG90
STB
RT
GATE
CS
SS
FAIL
PWM
ADIM
DIMOUT
ISENSE
FB
DUTYP
Rs
DUTYON
GND
Figure 14. Basic application example
Analog Dimming or PWM Dimming Examples
VOUT
VOUT
VCC
VIN
VCC
VIN
VCC
UVLO
VCC
UVLO
OVP
OVP
REG90
STB
RT
REG90
STB
RT
GATE
CS
GATE
CS
SS
SS
FAIL
PWM
ADIM
FAIL
REG90
REG90
OPEN
DIMOUT
DIMOUT
PWM
ADIM
ISENSE
FB
ISENSE
FB
DUTYP
DUTYP
Rs
Rs
DUTYON
DUTYON
GND
GND
Figure 15. Example circuit for analog dimming
Figure 16. Example circuit for PWM dimming
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BD9411F
External Components Selection
1. Start Up Operation and Soft Start External Capacitance Setting
The below explanation is the start up sequence of this IC
1
SS
SLOPE
5V
VOUT
STB
FB
COMP
OSC
SS
GATE
CS
Css
DRIVER
OSC
SS=FB
Circuit
PWM
LED_OK
GATE
VOUT
2
DIMOUT
ISENSE
FB
3
ILED
PWM
4
LED_OK
6
5
Figure 17. Startup waveform
Figure 18. Circuit behavior at startup
○Explanation of start up sequence
1. Reference voltage REG90 starts by STB=H.
2. SS starts to charge at the time of first PWM=H. At this moment, the SS voltage of slow-start starts to equal FB
voltage,and the circuit becomes FB=SS regardless of PWM logic.
3. When FB=SS reaches the lower point of internal sawtooth waveform, GATE terminal outputs pulse and starts to boost
VOUT.
4. It boosts VOUT and VOUT reaches the voltage to be able to flow LED current.
5. If LED current flows over decided level, FB=SS circuit disconnects and startup behavior completes.
6. Then it works normal operation by feedback of ISENSE terminal. If LED current doesn't flow when SS becomes over
3.7V(Typ), SS=FF circuit completes forcibly and FBMAX protection starts.
○Method of setting SS external capacitance
According to the sequence described above, start time Tss that startup completes with FB=SS condition is the time that
FB voltage reaches the feedback point.
The capacitance of SS terminal is defined as Css and the feedback voltage of FB terminal is defined as VFB. The
equality on TFB is as follows.
C [μF] VFBꢀ[V]
ss
T
[sec]
ss
3ꢀ[μA]
If Css is set to a very small value, rush current flows into the inductor at startup.
On the contrary, if Css is enlarged too much, LED will light up gradually.
Since Css differs in the constant set up with the characteristic searched for and differs also by factors, such as a voltage
rise ratio, an output capacitance, DCDC frequency, and LED current, please confirm with the system.
【Setting example】
When Css=0.1uF,Iss=3μA,and startup completes at VFB=3.7V, SS setting time is as follows.
6
0.1ꢀ10 [F] 3.7[V]
T
ꢀ ꢀ0.123 [sec]
ss
6
3 1ꢀ0 [A]
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2. VCC Series Resistance Setting
VIN
Here are the following effects of inserting series resistor Rvcc into VCC line.
(i) In order to drop the voltage VCC, it is possible to suppress the heat
generation of the IC.
RVCC
Δ V
(ii) It can limit the inflow current to VCC line.
VCC
However, if resistance RVCC is set bigger, VCC voltage becomes under minimum
operation voltage (VCC<9V). RVCC must be set to an appropriate series
resistance.
I_IN
ICC
IC’s inflow current line I_IN has the following inflow lines.
・IC’s circuit current…ICC
・Current of RREG connected to REG90…IREG
・Current to drive FET’s Gate…I_GATE
+
-
REG90
IREG
Internal
BLOCK
RREG
IDCDC
These decide the voltage ΔV at RVCC
.
VCC terminal voltage at that time can be expressed as follows.
VCC[V]VIN[V]
ICC[A] IDCDC[A] IREG [A]
RVCC 9[V]
I_GATE
GATE
DCDC
DRIVER
Here, judgement is the 9V minimum operation voltage.
Please consider a sufficient margin when setting the series resistor of VCC
.
Figure 19. VCC series resistance
circuit example
【setting example】
Above equation is translated as follows.
VIN[V]9[V]
RVCC []
ICC[A] IDCDC[A] IREG [A]
When VIN=24V, ICC=2.0mA, RREG=10kΩ and IDCDC=2mA, RVCC’s value is calculated as follows.
24[V]9[V]
0.002[A] 0.002[A]5.8[V]/10000[]
RVCC []
3.26[k]
(ICC is 3.3mA(Typ)) . Please set each values with tolerance and margin.
3. LED current setting
LED current can be adjusted by setting the resistance RS [Ω] which connects
VOUT
to ISENSE pin and ADIM[V].
Relationship between RS and ILED current
With DC dimming (ADIM<3.0V)
BD9411
1 ADIM[V]
ILED [A]
DIMOUT
RS
[]
3
Error AMP
ISENSE
ADIM
Without DC dimming (ADIM>3.0V)
-
+
+
1.015V
1.015[V]
ILED [A]
RS
[]
1/3
Rs
【setting example】
FB
If ILED current is 200mA and ADIM is 2.0V, we can calculate RS as below.
1 ADIM[V] 1 2.0[V]
3 0.2[A]
RS
3.33[]
3 ILED[A]
Figure 20. LED current setting example
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4. DCDC Oscillation Frequency Setting
RRT which connects to RT pin sets the oscillation frequency fSW of DCDC.
○Relationship between frequency fSW and RT resistance (ideal)
15000
fSW[kHz]
RRT
[k]ꢀ
Frequency(fsw)
【setting example】
When DCDC frequency fsw is set to 200kHz, RRT is as follows.
GATE
CS
15000
15000
RRT
75 [k]ꢀꢀ
fsw[kHz] 200[kHz]
RT
Rcs
RRT
GND
Figure 21. RT terminal setting example
5. UVLO Setting
Under Voltage Lock Out pin is the input voltage of the power stage. IC starts boost operation if UVLO is more than
3.0V(Typ) and stops if lower than 2.7V(Typ).
The UVLO pin is high impedance, because the internal resistance is not connected to a certain bias.
So, the bias by the external components is required, because the open connection of this pin is not a fixed potential.
Detection voltage is set by dividing resistors R1 and R2. The resistor values can be calculated by the formula below.
○UVLO detection equation
As VIN decreases, R1 and R2 values are set in the following formula by the VINDET that UVLO detects.
(VIN
[V] 2.7[V])
2.7[V]
DET
VIN
R1 R2[kΩ]
[kΩ]ꢀ
○UVLO release equation
R1 and R2 setting is decided by the equation above. The equation of UVLO
release voltage is as follows.
R1
UVLO
(R1[kΩ] R2[kΩ])
+
-
ON OFF
/
VIN
3.0V
[V]ꢀ
CAN
2.7V/3.0V
R2
R2[kΩ]
CUVLO
【setting example】
If the normal input voltage, VIN is 24V, the detect voltage of UVLO is 18V, R2 is
30kΩ, R1 is calculated as follows.
Figure 22. UVLO setting example
(VINDET [V] 2.7[V])
2.7[V]
(18[V] 2.7[V])
2.7[V]
R1 R2[k]
30[k]
170.0 [k]
By using these R1 and R2, the release voltage of UVLO, VINCAN, can be calculated too as follows.
(R1[k] R2[k])
R2[k]
170[k]30[k]
30[k]
VINCAN 3.0[V]
3.0[V]
[V]ꢀ 20.0 [V]
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6. ODP Setting
RDUTYP which connects to ODP pin sets the ODP detection duty.
○Relationship between LED PWM frequency fPWM, ODP Detection Duty and DUTYP resistance (ideal)
1172ODP [%]
duty
RDUTYP
[k]ꢀ
fPWM [Hz]
GATE
CS
【setting example】
DUTYP
When LED PWM frequency fPWM, is set to 120Hz and ODP Detection Duty
(ODPduty) is set to 35%, RDUTYP is as follows.
RCS
RDUTYP
DIMOUT
ISENSE
117235[%]
RDUTYP
341.8[k]ꢀ
RS
PWM
120[Hz]
GND
fPWM
Figure 23. ODP setting example
PWM
GATE
DIMOUT
ODPduty
Figure 24. The GATE and the DIMOUT waveform as PWM dimming (ODP)
7. OVP Setting
The OVP terminal is the input for over-voltage protection of output voltage.
The OVP pin is high impedance, because the internal resistance is not connected to a certain bias.
Detection voltage of VOUT is set by dividing resistors R1 and R2. The resistor values can be calculated by the formula
below.
○OVP detection equation
If VOUT is boosted abnormally, VOVPDET, the detect
VOUT
voltage of OVP, R1, R2 can be expressed by the following formula.
(VOVPDET [V]3.0[V])
R1
OVP
R1 R2[k]
[k]ꢀ
OVP
+
-
3.0[V]
2.8V/3.0V
R2
○OVP release equation
COVP
By using R1 and R2 in the above equation, the release voltage of
OVP, VOVPCAN can be expressed as follows.
(R1[k] R2[k])
VOVP 2.8V
[V]ꢀ
CAN
R2[k]
Figure 25. OVP setting example
【setting example】
If the normal output voltage, VOUT is 40V, the detect voltage of OVP is 48V, R2 is 10kΩ, R1 is calculated as follows.
(VOVPDET [V]3.0[V])
3.0[V]
(48[V]3[V])
3[V]
R1 R2[k]
10[k]
150ꢀ[k]
By using these R1 and R2, the release voltage of OVP, VOVPCAN can be calculated as follows.
(R1[k] R2[k])
R2[k]
10[k] 150[k]
10[k]
VOVP 2.8[V]
2.8[V]
[V]ꢀ 44.8ꢀ[V]
CAN
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BD9411F
8. Protection Timer (CP Counter) Setting, Auto-Restart Timer Setting
About over boost protection (FBMAX), protection timer (CP Counter) is set by counting the clock frequency which is set
at the RT pin. About the behavior from abnormal detection for use timer, please refer to the “Timing Chart” section.
The condition FB>4.0V(Typ) and PWM=H continues more than four GATE clocks, counting starts from the timing. After
that, FBMAX protection monitor only the FB voltage and DCDC operation will be stop after below time has passed.
RRT
RRT [k]
TIMERTIME 214
AUTOTIME 217
16384
131072
[s]ꢀ
[s]ꢀ
1.51010
1.5107
RRT [k]
RRT
1.51010
1.5107
Here, TIMERTIME = time until IC's operation stop, AUTOTIME = auto restart timer’s time
RRT = Resistor value connected to RT pin
【setting example】
Protection Timer time when RT=100kohm
RRT [k]
1.5107
100[k]
1.5107
TIMERTIME 16384
16384
109.2[ms]ꢀ
RRT [k]
1.5107
100[k]
1.5107
AUTOTIME 131072
131072
873.8[ms]ꢀ
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BD9411F
DCDC Parts Selection
1. OCP Setting / Calculation Method for the Current Rating of DCDC Parts
OCP detection stops the switching when the CS pin voltage is more than 0.4V(Typ). The resistor value of CS pin, RCS
needs to be considered by the coil L current. And the current rating of DCDC external parts is required more than the
peak current of the coil.
Shown below are the calculation method of the coil peak current, the selection method of RCS (the resistor value of CS
pin) and the current rating of the external DCDC parts at Continuous Current Mode.
(the calculation method of the coil peak current, Ipeak at Continuous Current Mode)
At first, since the ripple voltage at CS pin depends on the application
condition of DCDC, the following variables are used.
Vout voltage=VOUT[V]
VOUT
L
VIN
LED total current=IOUT[A]
DCDC input voltage of the power stage =VIN[V]
Efficiency of DCDC =η[%]
IL
And then, the average input current IIN is calculated by the following
equation.
fsw
VOUT [V] IOUT [A]
VIN [V][%]
IIN
[A]ꢀ
GATE
CS
And the ripple current of the inductor L (ΔIL[A]) can be calculated by using
RCS
DCDC the switching frequency, fSW, as follows.
GND
(VOUT [V]VIN [V])VIN [V]
L[H]VOUT [V] fSW [Hz]
ΔIL
[A]
(V)
On the other hand, the peak current of the inductor Ipeak can be expressed
as follows.
IL[A]
… (1)
I peak IIN [A]
[A]
2
Therefore, the bottom of the ripple current Imin is
(A)
(t)
IL[A]
Ipeak
or 0
ꢀ
Imin IIN [A]
2
ΔIL
IIN
Imin
If Imin>0, the operation mode is CCM (Continuous Current Mode),
otherwise the mode is DCM (Discontinuous Current Mode).
(t)
(the selection method of Rcs at Continuous Current Mode)
Ipeak flows into RCS and that causes the voltage signal to CS pin. (Please
refer to the timing chart at the right)
(V)
0.4V
Peak voltage VCSpeak is as follows.
VCS peak RCS I peak [V]
VCSpeak
As this VCSpeak reaches 0.4V(Typ), the DCDC output stops the switching.
Therefore, RCS value is necessary to meet the condition below.
(t)
RCS Ipeak[V] 0.4[V]
Figure 26. Coil current waveform
(the current rating of the external DCDC parts)
The peak current as the CS voltage reaches OCP level (0.4V (Typ)) is defined as Ipeak_det
.
0.4[V]
I peak_ det
[A]
… (2)
RCS []
The relationship among Ipeak (equation (1)), Ipeak_det (equation (2)) and the current rating of parts is required to meet the
following
Ipeak Ipeak_det The current rating of parts
Please make the selection of the external parts such as FET, Inductor, diode meet the above condition.
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[setting example]
Output voltage = VOUT [V] = 40V
LED total current = IOUT [A] = 0.48V
DCDC input voltage of the power stage = VIN [V] = 24V
Efficiency of DCDC =η[%] = 90%
Averaged input current IIN is calculated as follows.
VOUT [V] IOUT [A]
VIN [V][%]
40[V]0.48[A]
24[V]90[%]
IIN [A]
ꢀ
0.89 [A]
If the switching frequency, fSW = 200kHz, and the inductor, L=100μH, the ripple current of the inductor L (ΔIL[A]) can be
calculated as follows.
(VOUT [V]VIN [V])VIN [V]
(40[V] 24[V])24[V]
ΔIL
ꢀ
0.48[A]
L[H]VOUT [V] fSW [Hz] 100106[H]40[V]200103[Hz]
Therefore the inductor peak current, Ipeak is
IL[A]
0.48[A]
Ipeak IIN [A]
ꢀ[A] 0.89[A]
1.13[A]
…calculation result of the peak current
2
2
If Rcs is assumed to be 0.3Ω
VCSpeak Rcs Ipeak 0.3[]1.13[A] 0.339 [V]0.4V
…RCS value confirmation
The above condition is met.
And Ipeak_det, the current OCP works, is
0.4[V]
I peak_ det
1.33[A]
0.3[]
If the current rating of the used parts is 2A,
…current rating confirmation
Ipeak Ipeak_det The current rating
1.13[A]1.33[A] 2.0[A]
of DCDC parts
This inequality meets the above relationship. The parts selection is proper.
And IMIN, the bottom of the IL ripple current, can be calculated as follows.
IL[A]
IMIN IIN [A]
[A] 1.13[A]0.48[A] 0.65[A] 0ꢀ
2
This inequality implies that the operation is continuous current mode.
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2. Inductor Selection
The inductor value affects the input ripple current, as shown the "OCP setting" on Page18.
(VOUT [V]VIN [V])VIN [V]
ΔIL
[A]
L[H]VOUT [V] fSW [Hz]
Δ IL
VOUT [V] IOUT [A]
VIN [V][%]
IIN
[A]ꢀ
VIN
IL[A]
Ipeak IIN [A]
[A]
IL
2
L
Where
VOUT
L: coil inductance [H]
VIN: input voltage [V]
VOUT: DCDC output voltage [V]
IOUT: output load current (the summation of LED current) [A]
IIN: input current [A] fSW: oscillation frequency [Hz]
RCS
COUT
Figure 27. Inductor current waveform and diagram
In continuous current mode, ⊿IL is set to 30% to 50% of the output load current in many cases.
In using smaller inductor, the boost is operated by the discontinuous current mode in which the coil current returns to
zero at every period.
*The current exceeding the rated current value of inductor flown through the coil causes magnetic saturation, results in
decreasing in efficiency. Inductor needs to be selected to have such adequate margin that peak current does not
exceed the rated current value of the inductor.
*To reduce inductor loss and improve efficiency, inductor with low resistance components (DCR, ACR) needs to be
selected
3. Output Capacitance Cout Selection
Output capacitor needs to be selected in consideration of equivalent series resistance
required to even the stable area of output voltage or ripple voltage. Be aware that set
LED current may not be flown due to decrease in LED terminal voltage if output ripple
VIN
IL
L
component is high.
VOUT
Output ripple voltage ⊿VOUT is determined by Equation (4):
RESR
COUT
ΔVOUT ΔIL RESR[ꢀV]ꢀ・・・・・ꢀꢀ(4)
RCS
When the coil current is charged to the output capacitor as MOS turns off, much output
ripple is caused. Much ripple voltage of the output capacitor may cause the LED current
ripple.
Figure 28. Output capacitor diagram
* Rating of capacitor needs to be selected to have adequate margin against output voltage.
*To use an electrolytic capacitor, adequate margin against allowable current is also necessary. Be aware that the LED
current is larger than the set value transitionally in case that LED is provided with PWM dimming especially.
4. MOSFET Selection
There is no problem if the absolute maximum rating is larger than the rated current of the inductor L, or is larger than
the sum of the tolerance voltage of COUT and the rectifying diode VF. The product with small gate capacitance (injected
charge) needs to be selected to achieve high-speed switching.
* One with over current protection setting or higher is recommended.
* The selection of one with small on resistance results in high efficiency.
5. Rectifying Diode Selection
A schottky barrier diode which has current ability higher than the rated current of L, reverse voltage larger than the
tolerance voltage of COUT, and low forward voltage VF especially needs to be selected.
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Loop Compensation
A current mode DCDC converter has each one pole (phase lag) fp due to CR filter composed of the output capacitor and
the output resistance (= LED current) and zero (phase lead) fZ by the output capacitor and the ESR of the capacitor.
Moreover, a step-up DCDC converter has RHP zero (right-half plane zero point) fZRHP which is unique with the boost
converter. This zero may cause the unstable feedback. To avoid this by RHP zero, the loop compensation that the
cross-over frequency fc, set as follows, is suggested.
fc = fZRHP /5 (fZRHP: RHP zero frequency)
Considering the response speed, the calculated constant below is not always optimized completely. It needs to be
adequately verified with an actual device.
VOUT
VIN
ILED
L
VOUT
-
+
FB
gm
RFB1
CFB1
RESR
COUT
CFB2
RCS
Figure 29. Output stage and error amplifier diagram
i.
Calculate the pole frequency fp and the RHP zero frequency fZRHP of DC/DC converter
VOUT (1 D)2
2 L ILED
ILED
fp
[ꢀHz]ꢀꢀ
fZRHP
[ꢀHz]ꢀꢀ
2 VOUT COUT
VOUT VIN
Where ILED = the summation of LED current,
(Continuous Current Mode)
ꢀꢀ
D
VOUT
ii.
Calculate the phase compensation of the error amp output (fc = fZRHP/5)
fZRHP RCS ILED
5 f p gmVOUT (1 D)
RFB1
CFB1
[ꢀ]ꢀꢀ
1
5
[F]
2 RFB1 fC 2 RFB1 fZRHP
gm 4.0104[S]ꢀ
Above equation is described for lighting LED without the oscillation. The value may cause much error if the quick
response for the abrupt change of dimming signal is required.
To improve the transient response, RFB1 needs to be increased, and CFB1 needs to be decreased. It needs to be
adequately verified with an actual device in consideration of variation from parts to parts since phase margin is
decreased.
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Timing Chart
1. PWM Start up 1 (Input PWM Signal After Input STB Signal)
7.5V
VCC
STB
PWM
6.5V
REG90
3.7V
SS
0.4V
0.4V
GATE
FAIL (Note1)
(At pull-up external voltage)
OFF
STANDBY
(*6)
SS
Normal
SS
STANDBY
STATE
(*1) (*2)
(*3)
(*4)
(*5)
Figure 30. PWM Start up 1 (Input PWM Signal After Input STB Signal)
(*1)…REG90 starts up when STB is changed from Low to High. In the state where the PWM signal is not inputted, SS terminal
is not charged and DCDC doesn’t start to boost, either.
(*2)…When REG90 is more than 6.5V(Typ), the reset signal is released.
(*3)…The charge of the pin SS starts at the positive edge of PWM=L to H, and the soft start starts. And while the SS is less than
0.4V, the pulse does not output. The pin SS continues charging in spite of the assertion of PWM or OVP level.
(*4)…The soft start interval will end if the voltage of the pin SS, VSS reaches 3.7V(Typ). By this time, it boosts VOUT to the voltage
where the set LED current flows. The abnormal detection of FBMAX starts to be monitored.
(*5)…As STB=L, the boost operation is stopped instantaneously. (Discharge operation continues in the state of STB=L and
REGUVLO=L. Please refer to the "Turn Off" section on Page24)
(*6)…In this diagram, before the charge period is completed, STB is changed to High again. As STB=H again, the boost
operation restarts the next PWM=H. It is the same operation as the timing of (*2). (For capacitance setting of SS terminal,
please refer to the "Method of setting SS external capacitance" section on Page13.
(Note1) At FAIL terminal pull-up to external voltage, FAIL voltage is "H" until REG90 over 6.5V. (Initial FAIL's NMOS is "OFF"
before IC's circuit will operate).
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2. PWM Start Up 2 (Input STB Signal after Inputted PWM Signal)
7.5V
VCC
STB
PWM
6.5V
REG90
3.7V
0.4V
SS
0.4V
GATE
FAIL (Note1)
(At pull-up external voltage)
STATE
OFF
SS
NORMAL
STANDBY
SS
(*3)
(*4)
(*5)
(*1) (*2)
Figure 31. PWM Start Up 2 (Input STB Signal after Inputted PWM Signal)
(*1)…REG90 starts up when STB=H.
(*2)…When REG90UVLO releases or PWM is inputted to the edge of PWM=L→H, SS charge starts and soft start period is
started. And while the SS is less than 0.4V, the pulse does not output. The pin SS continues charging in spite of the
assertion of PWM or OVP level.
(*3)…The soft start interval will end if the voltage of the pin SS, VSS reaches 3.7V(Typ). By this time, it boosts VOUT to the point
where the set LED current flows. The abnormal detection of FBMAX starts to be monitored.
(*4)…As STB=L, the boost operation is stopped instantaneously (GATE=L, SS=L). (Discharge operation works in the state of
STB=L and REG90UVLO=H. Please refer to the "Turn Off" section on Page24)
(*5)…In this diagram, before the discharge period is completed, STB is changed to High again. As STB=H again, operation will
be the same as the timing of (*1).
(Note1) At FAIL terminal pull-up to external voltage, FAIL voltage is "H" until STB change from "L" to "H". (Initial FAIL's NMOS is
"OFF" before IC's circuit will operate).
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BD9411F
3. Turn Off
STB
PWM
REG90
6.0V
REG90UVLO
DIMOUT
GATE
Vout
SS
FAIL (Note1)
(Pull-up to external voltage)
ON
STATE
Discharge
OFF
(*2)
(*1)
Figure 32. Turn Off
(*1)…As STB=H→L, boost operation stops and REG90 starts to discharge. The discharge curve is decided by REG90
discharge resistance and the capacitor of the REG90 terminal.
(*2)…While STB=L, REG90UVLO=H, DIMOUT becomes same as PWM. When REG90=9.0V is less than 6.0V(Typ), IC
becomes OFF state. VOUT is discharged completely until this time. It should be set to avoid a sudden brightness.
(Note1) At FAIL terminal pull-up to external voltage, FAIL voltage is "H" until STB change from "L" to "H". (Initial FAIL's NMOS is
"OFF" before IC's circuit will operate).
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4. Soft Start Function
STB
PWM
UVLO
2.7V
3.0V
7.2V
VCCUVLO
7.5V
6.0V
6.5V
3.0V
REG90UVLO
OVP
2.8V
4clk
FAIL (Note1)
(At pull-up external voltage)
SS
(*1)
(*2)(*3)
(*4)
(*5)
(*6)
(*7)
Figure 33. Soft Start Function
(*1)…The SS pin charge does not start by just STB=H. PWM=H is required to start the soft start. In the low SS voltage, the
GATE pin duty depends on the SS voltage. And while the SS is less than 0.4V, the pulse does not output.
(*2)…By the time STB=L, the SS pin is discharged immediately.
(*3)…As the STB recovered to STB=H, The SS charge starts immediately by the logic PWM=H in this chart.
(*4)…The SS pin is discharged immediately by the UVLO=L.
(*5)…The SS pin is discharged immediately by the VCCUVLO=L.
(*6)…The SS pin is discharged immediately by the REG90UVLO=L.
(*7)…The SS pin is not discharged by the abnormal detection for use timer Type protection such as OVP until the timer finish.
(Note1) At FAIL terminal pull-up to external voltage, FAIL voltage is "H" until STB change from "L" to "H". (Initial FAIL's NMOS is
"OFF" before IC's circuit will operate).
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BD9411F
5. OVP Detection
STB
PWM
REG90
OVP
3.0V
2.8V
2.8V
3.0V
2.8V
3.0V
Abnormal
COUNTER
Less than
Gate4count
Less than
Gate4count
Gate4count
AUTO COUNTER
131072count
SS
0.4V
GATE
DIMOUT
FAIL
IC's operation stop and
AUTO COUNTER
STATE NORMAL
OVP
NORMAL
OVP
NORMAL
NORMAL
OVP
abnormal
abnormal
abnormal
(*1)
(*3)
(*4) (*5)
(*6)
(*7)
(*2)
Figure 34. OVP Detection
(*1)…As OVP is detected, the output GATE=L, DIMOUT=L, and the abnormal counter starts.
(*2)…If OVP is released within 4 clocks of abnormal counter of the GATE pin frequency, the boost operation restarts.
(*3)…As the OVP is detected again, the boost operation is stopped.
(*4)…As the OVP detection continues up to 4 count by the abnormal counter, IC's operation will be stop. After IC operation stop,
auto counter starts counting.
(*5)… Once IC operation stop, the boost operation doesn't restart even if OVP is released.
(*6)…When auto counter reaches 131072clk (217clk), IC will be auto-restarted. The auto restart interval can be calculated by the
external resistor of RT pin. (Please refer to the "Timer Latch Time setting, Auto-Restart Timer setting" section on Page17.)
(*7)…The operation of the OVP detection is not related to the logic of PWM.
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BD9411F
6. FBMAX Detection
STB
PWM
REG90
4.0V
4.0V
FB
GATE
・・・・・
・・・・・
①
②
③
④
CP COUNTER
16384count
AUTO COUNTER
131072count
3.7V
SS
FAIL (Note1)
(At pull-up external voltage)
IC's operation stop and
AUTO COUNTER
SS
NORMAL
STANDBY
CP COUNTOR
SS
STATE
(*5)
(*6)
(*1)
(*3)
(*4)
(*2)
Figure 35. FBMAX Detection
(*2)…During the soft start, it is not judged to the abnormal state even if the FB=H(FB>4.0V(Typ)).
(*3)…When the PWM=H and FB=H, the abnormal counter doesn’t start immediately.
(*4)…The CP counter will start if the PWM=H and the FB=H detection continues up to 4 clocks of the GATE frequency. Once the
count starts, only FB level is monitored.
(*5)…When the FBMAX detection continues till the CP counter reaches 16384clk (214clk), IC's operation will be stop. The
operation stop interval can be calculated by the external resistor of RT pin. (Please refer to the "Timer Latch Time setting,
Auto-Restart Timer setting" section on Page17.)
(*6)…When auto counter reaches 131072clk (217clk), IC will be auto-restarted. The auto restart interval can be calculated by the
external resistor of RT pin. (Please refer to the "Timer Latch Time setting, Auto-Restart Timer setting" section on Page17.)
(Note1) At FAIL terminal pull-up to external voltage, FAIL voltage is "H" until STB change from "L" to "H". (Initial FAIL's NMOS is
"OFF" before IC's circuit will operate).
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BD9411F
7. LED OCP Detection
STB
PWM
REG90
ISENSE
3.0V
3.0V
3.0V
3.0V
3.0V
3.0V
Abnormal
COUNTER
4count
Less than
4count
Less than
4count
AUTO COUNTER
131072count
SS
0.4V
GATE
DIMOUT
FAIL
IC's operation stop and
AUTO COUNTER
STATE NORMAL
LEDOCP
abnormal
NORMAL
LEDOCP
abnormal
NORMAL
LEDOCP
abnormal
NORMAL
(*1)
(*3)
(*4) (*5)
(*6)
(*7)
(*2)
Figure 36. LED OCP Detection
(*1)…If ISENSE>3.0V(Typ), LEDOCP is detected, and GATE becomes L. To detect LEDOCP continuously, The DIMOUT is
compulsorily high, regardless of the PWM dimming signal.
(*2)…When the LEDOCP releases within 4 counts of the GATE frequency, the boost operation restarts.
(*3) …As the LEDOCP is detected again, the boost operation is stopped.
(*4)…If the LEDOCP detection continues up to 4 counts of GATE frequency. IC's operation will be stop. After IC operation stop,
auto counter starts counting.
(*5)…Once IC's operation stop, the boost operation doesn't restart even if the LEDOCP releases.
(*6)…When auto counter reaches 131072clk (217clk), IC will be auto-restarted. The auto restart interval can be calculated by the
external resistor of RT pin. (Please refer to the "Timer Latch Time setting, Auto-Restart Timer setting" section on Page17.)
(*7)…The operation of the LEDOCP detection is not related to the logic of the PWM.
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BD9411F
I/O Equivalent Circuits
OVP
UVLO
SS
UVLO
OVP
100k
5V
SS
50k
5V
3k
5V
RT
PWM
DUTYON
DUTYON
PWM
100k
RT
100k
5V
5V
1M
1M
ADIM
FB
DIMOUT / REG90
REG90
ADIM
20k
DIMOUT
GND
FB
5V
100k
VCC
GATE / REG90 / CS
STB
ISENSE
REG90
GATE
STB
ISENSE
100k
20k
5V
5V
100k
1M
GND
CS
VCC
DUTYP
FAIL
DUTYP
FAIL
500
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BD9411F
Operational Notes
1.
2.
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.
Power Supply Lines
Design the PCB layout pattern to provide low impedance supply lines. 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.
4.
Ground Voltage
Ensure that no pins are at a voltage below that of the ground pin at any time, even during transient condition.
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 maximum junction temperature rating be exceeded the rise in temperature of the chip may
result in deterioration of the properties of the chip. In case of exceeding this absolute maximum rating, increase the
board size and copper area to prevent exceeding the maximum junction temperature rating.
6.
7.
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.
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.
9.
Operation Under Strong Electromagnetic Field
Operating the IC in the presence of a strong electromagnetic field may cause the IC to malfunction.
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.
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.
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BD9411F
Operational Notes – continued
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
Pin B
B
E
C
Pin A
B
C
E
P
P+
P+
N
P+
P
P+
N
N
N
N
N
N
N
Parasitic
Elements
Parasitic
Elements
P Substrate
GND GND
P Substrate
GND
GND
Parasitic
Elements
Parasitic
Elements
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 the maximum junction temperature rating are all
within the Area of Safe Operation (ASO).
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 maximum junction temperature 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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BD9411F
Ordering Information
B D 9 4 1 1 F
-
E 2
Part Number
Package
F:SOP18
Packaging and forming specification
E2: Embossed tape and reel
Marking Diagrams
SOP18(TOP VIEW)
Part Number Marking
LOT Number
B D 9 4 1 1 F
1PIN MARK
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BD9411F
Physical Dimension, Tape and Reel Information
Package Name
SOP18
(Max 11.55 (include.BURR))
(UNIT : mm)
PKG : SOP18
Drawing No. : EX115-5001
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BD9411F
Revision History
Date
Revision
001
Changes
20.Feb. 2017
New Release
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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
intend to use our Products in devices requiring extremely high reliability (such as medical equipment (Note 1), transport
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
CLASSⅣ
CLASSⅡb
CLASSⅢ
CLASSⅢ
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 depending on ambient temperature. When used in sealed area, confirm that it is the use in
the range that does not exceed the maximum junction 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 on a surface-mount products, the flow soldering method must
be used on a through hole mount products. If the flow soldering method is preferred on a surface-mount products,
please consult with the ROHM representative in advance.
For details, please refer to ROHM Mounting specification
Notice-PGA-E
Rev.003
© 2015 ROHM Co., Ltd. All rights reserved.
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
A two-dimensional barcode 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 concerned goods might be fallen under listed items of export control prescribed by Foreign exchange and Foreign
trade act, please consult with ROHM 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.
2. ROHM shall not have any obligations where the claims, actions or demands arising from the combination of the
Products with other articles such as components, circuits, systems or external equipment (including software).
3. 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 Products or the information contained in this document. Provided, however, that ROHM
will not assert its intellectual property rights or other rights against you or your customers to the extent necessary to
manufacture or sell products containing the Products, subject to the terms and conditions herein.
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-PGA-E
Rev.003
© 2015 ROHM Co., Ltd. All rights reserved.
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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 not be in an y way responsible or liable for failure, malfunction or accident 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 any damages, expenses or losses incurred by you or third parties resulting from inaccuracy or errors of or
concerning such information.
Notice – WE
Rev.001
© 2015 ROHM Co., Ltd. All rights reserved.
相关型号:
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BD94130MUF-M (新产品)
BD94130MUF-M is embedded 24-channel constant current drivers with 12bit PWM dimming and max 8-line switch controllers. This device can set LED constant current value by setting external ISET resistor. Communication with μ-controller via SPI is feasible.
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