bd9415fs e

LED Driver for LCD Backlights
White LED Driver for 4Ch Large LCD Panels
(DC/DC converter type)
BD9415FS
1.1 ●General Description
Key Specifications
BD9415FS is a high efficiency driver for white LEDs and
designed for large LCDs. This IC has a built-in boost
DC/DC converter that employs an array of LEDs as the
light source. BD9415FS has various protection functions
against fault conditions, such as over-voltage protection
(OVP), over current limit protection of DC/DC (OCP),
short circuit protection (SCP), over duty protection
(ODP) and open detection of LED string. Therefore,
BD9415FS is available for the fail-safe design over a
wide range of output voltages.




Operating power supply voltage: 11.5V to 35.0V
Oscillator frequency:
500kHz(RT=30kΩ)
Operating current:
6.2mA (Typ)
Operating temperature range:
-40°C to +105°C
1.2 Package
W(Typ) x D(Typ) x H(Max)
13.60mm x 7.80mm x 2.01mm
Pin pitch 0.80mm
SSOP-A32
Features











4Ch LED constant current driver (external FET)
Built-in boost DC/DC converter (external FET)
PWM dimming (individual input terminal of 4ch)
Analog dimming (Linear) function
Low heat generation technology
LED protection function (Open/Short protection)
Output Short Protection (OCP)
Over Duty Protection (ODP)
Over Voltage Protection (OVP)
Under Voltage Lockout Protection (UVLO)
Auto restart function
Figure 1. SSOP-A32
Applications
 TV, Computer Display, Notebook, LCD Backlighting.
Typical Application Circuit
VIN
+
VCC
CVCC
AGND
32
FAILB
SSFB
31
3
UVLO
RT
30
4
REG90
5
STB
6
N
7
PGND
8
CS
9
DUTYON
10
OVP
11
S1
DUTYP
29
PWM4
28
27
PWM3
26
PWM2
PWM1
25
PWM1
LSP
24
VREF
23
G4
22
12
LED1
LED4
21
13
G1
S4
20
14
S2
G3
19
LED3
18
S3
17
15
LED2
16
G2
PWM4
PWM3
PWM2
REG90
CLSP
REG90
BD9415FS
STB
VCC
2
CV R EF
CREG90
1
Figure 2. Typical Application Circuit
○Product structure : Silicon monolithic integrated circuit
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BD9415FS
1.3 Pin Configuration
1
VCC
AGND
32
2
FAILB
SSFB
31
3
UVLO
RT
30
4
REG90
DUTYP
29
PWM4
28
PWM3
27
PWM2
26
PWM1
25
LSP
24
VREF
23
G4
22
LED4
21
STB
6
N
7
PGND
8
CS
9
DUTYON
10
OVP
11
S1
12
LED1
13
G1
S4
20
14
S2
G3
19
15
LED2
LED3
18
16
G2
S3
17
BD9415FS
5
Figure 3. Pin Configuration
1.4 Pin Descriptions
Pin
No.
Pin Name
Pin
No.
Pin
Name
1
VCC
Power supply terminal
32
AGND
Analog GND
2
FAILB
Error detection output pin (open drain)
31
SSFB
Soft start pin & Error amplifier pin
3
UVLO
Under voltage lockout detection pin
30
RT
4
REG90
9.0V output voltage pin
29
DUTYP
Over voltage protection setting pin
5
STB
IC ON/OFF pin
28
PWM4
LED4 External PWM dimming signal input pin
DC/DC switching output pin
27
PWM3
LED3 External PWM dimming signal input pin
Power GND
26
PWM2
LED2 External PWM dimming signal input pin
25
PWM1
LED1 External PWM dimming signal input pin
6
N
7
PGND
Function
Function
DC/DC switching frequency setting pin
8
CS
DC/DC output current detect pin,
OCP input pin
Over duty protection ON/OFF pin
24
LSP
Over voltage protection detection pin
23
VREF
Analog dimming signal input pin
CH1 current detection input pin
22
G4
CH4 dimming signal output pin
9
DUTYON
10
OVP
11
S1
12
LED1
CH1 LED output pin
21
LED4
13
G1
CH1 dimming signal output pin
20
S4
CH4 current detection input pin
14
S2
CH2 current detection input pin
19
G3
CH3 dimming signal output pin
15
LED2
CH2 LED output pin
18
LED3
16
G2
CH2 dimming signal output pin
17
S3
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LED short voltage setting pin
CH4 LED output pin
CH3 LED output pin
CH3 current detection input pin
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BD9415FS
1.5 Block Diagram
VIN
COUT
Di
L
CIN
+
VCC
LED OPEN / SHORT
PROTECT
REG 90
STB
VREG
SCP
OVP
OVP
FILTER
UVLO
UVLO
Auto - Restart
Control
CONTROL
LOGIC
REG 90
FAILB
N
DRIVER
CURRENT
SENSE
RT
+
OSC
SSOK
SSFB
LED SHORT
PROTECT
PWM
COMP
ERROR
AMP -+COMP1 +
COMP4
4V
LSP
2800kΩ
1200kΩ
LED OPEN
PROTECT
DUTYON
DUTY P
300kΩ
Over Duty
Protection
LEB
+
-
× 6. 7
COMP1
+
COMP4
CS
PGND
+
-
LED 1
G1
S1
+
-
LED 2
G2
S2
+
-
LED 3
G3
S3
+
-
LED 4
G4
S4
1/ 5
VREF
+
PWM 1
300kΩ
PWM 4
300kΩ
AGND
Figure 4. Block Diagram
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1.6 Absolute Maximum Ratings (Ta=25°C)
Rating
Unit
-0.3 to +36
V
LED1, LED2, LED3, LED4
FAILB, STB, OVP,
PWM1, PWM2, PWM3, PWM4,
UVLO, VREF, DUTYON
N, REG90, G1, G2, G3, G4
S1, S2, S3, S4, DUTYP, RT,
SSFB, CS, LSP
60
V
20
V
13
V
7
V
Power Dissipation
Pd
0.95 *1
W
Operating Temperature Range
Topr
-40 to +105
°C
Junction Temperature
Tjmax
150
°C
Parameter
Power Supply Voltage
Symbol
VCC
LED1-4
FAILB, STB, OVP,
PWM1-4, UVLO, VREF, DUTYON
N, REG90, G1-4
S1-4, DUTYP, RT, SSFB, CS, LSP
Storage Temperature
Tstg
-55 to +150
°C
(*1) Derate by 7.6mW/°C when operating above Ta=25°C.. (Mounted on 1-layer 70mm x 70mm x 1.6mm board)
1.7 Recommended Operating Conditions (Ta=25°C)
Parameter
Rating
Symbol
Power Supply Voltage
VCC
DC/DC Oscillating Frequency
Fsw
Unit
11.5 to 35.0
100 to 1000
V
(*1)
kHz
VREF Input Voltage
VREF
0.2 to 2.5
V
LSP Input Voltage
VLSP
0.8 to 3.0
V
PWM Input Frequency
FPWM
90 to 2000
Hz
The operating ranges above are acquired by evaluating the IC separately. Please take care when using the IC in
applications.
(*1) When driving external FET as DC/DC, be careful about the input capacity of the FET being used.
1.8 Electrical Characteristics 1/2 (Unless otherwise specified, VCC=24V, Ta=25°C)
Parameter
【Total Current Consumption】
Symbol
Min
Typ
Max
Unit
Condition
Circuit Current
ICC
-
6.2
12.4
mA
Standby Current
IST
-
14
25
μA
VSTB=3.0V, LED1-4=2V,
RT=30kΩ
VSTB=0V
N Pin Source ON Resistance
RONH
-
2.5
3.75
Ω
ION=-10mA
N Pin Sink ON Resistance
RONL
-
3.0
4.5
Ω
ION=10mA
REG90 Output Voltage
REG90
8.91
9.0
9.09
V
IO=0mA
REG90 Available Current
IREG90
20
-
-
mA
REG90_UVLO Detect Voltage
REG90_TH
4.7
5.4
6.1
V
VREG=SWEEP DOWN,
VSTB=0V
VOCP
0.405
0.450
0.495
V
VCS=SWEEP UP
Error Amplifier Base Voltage
SSFB Source Current
(Soft Start)
SSFB Sink Current
VERR
0.7
0.8
0.9
V
VREF=1.5V
ISSFBSO_S
-13
-10
-7
μA
VSSFB=2V
ISSFBSINK
80
100
120
μA
LED=2.0V、VSSFB=1.0V
SSFB source Current
ISSFBSOUR
-115
-100
-85
µA
LED=0V、VSSFB=1.0V
Oscillation Frequency
FCT
440
500
560
kHz
RRT=30kΩ
MAX DUTY
DUTY_MAX
91
95
99
%
0.05
0.20
0.35
V
【Switching Block】
【REG90 Block】
【Over Current Limit Protection (OCP) Block】
OCP Detect Voltage
【Error Amplifier Block】
【CT Oscillator Block】
【Short Circuit protection (SCP) detect Block】
SCP Detect Voltage
VSCP
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VOVP=SWEEP DOWN
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BD9415FS
1.8 Electrical Characteristics 2/2 (Unless otherwise specified, VCC=24V, Ta=25°C)
Parameter
Symbol
【Over Voltage Protection (OVP) Block】
Min
Typ
Max
Unit
Condition
OVP Detect Voltage
VOVP
2.91
3.00
3.09
V
OVP Detect Hysteresis
VOVP_HYS
50
100
200
mV
VOVP=SWEEP DOWN
OVP Pin Leak Current
IOVP
-2
0
2
µA
VOVP=4.0V
VCC=SWEEP UP
VOVP=SWEEP UP
【UVLO Block】
UVLO Unlock Voltage(VCC)
VUVLO_VCC
6.5
7.5
8.5
V
UVLO Hysteresis(VCC)
VUHYS_VCC
150
300
600
mV
VCC=SWEEP DOWN
UVLO Unlock Voltage
VUVLO
2.375
2.5
2.625
V
VUVLO=SWEEP UP
UVLO Hysteresis
VUHYS
50
100
150
mV
VUVLO=SWEEP DOWN
UVLO Input Resistance
RUVLO
360
600
840
kΩ
VUVLO=4.0V
DTYON_H
1.5
-
18
V
DUTYON Pin LOW Voltage
DTYON_L
DUTYON Pin Pull Down
RDTYON
Resistance
【Over Duty Protection (ODP) Block】
PWM ODP Protection Detect
DODP
Duty
【Filter Block】
AUTO Timer
TAUTO
-0.3
-
0.8
V
180
300
420
kΩ
VDUTYON=3.0V
-
35
-
%
FPWM=120Hz, DUTYP=341kΩ
-
163
-
ms
FCT=800kHz
-
20
-
ms
FCT=800kHz
196
200
204
294.6
300
305.4
392.8
400
407.2
【DUTYON Block】
DUTYON Pin HIGH Voltage
Abnormal Detection Timer
TCP
【LED Driver Block】
VREF=1.0V
VS
491
500
509
OPEN Detection Voltage
VOPEN
0.12
0.2
0.28
V
SHORT Detection Voltage
VSHORT
5.6
6.0
6.4
V
2.8
3.0
3.2
V
VLED=SWEEP UP
-2
0
2
µA
VREF=3.0V
SHORT Mask Voltage
VREF Leak Current
VSHORT
_MASK
IVREF
mV
VREF=1.5V
S Pin Voltage
VREF=2.0V
VREF=2.5V
VLED=SWEEP DOWN
VLED=SWEEP UP,
VLSP=0.895V
【STB Block】
STB Pin HIGH Voltage
STBH
2.0
-
18
V
STB Pin LOW Voltage
STBL
-0.3
-
0.8
V
STB Pull Down Resistance
RSTB
0.5
1.0
1.5
MΩ
PWM Pin HIGH Voltage
VPWM_H
1.5
-
18
V
PWM Pin LOW Voltage
VPWM_L
-0.3
-
0.8
V
PWM Pin Pull Down Resistance
RPWM
180
300
420
kΩ
VPWM=3V
VFAILB_L
0.25
0.5
1.0
V
IFAILB=1mA
VSTB=3V
【PWM Block】
【FAILB Block(OPEN DRAIN)】
FAILB LOW Output Voltage
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1.9 Typical Performance Curves (Reference data)
8.0
14
7.0
12
10
5.0
VREG90[V]
ICC[mA]
6.0
4.0
3.0
8
6
4
2.0
STB=3.0V
LED1-4=2.0V
Ta=25°C
1.0
STB=3.0V
PWM=3.0V
STB=3.0V
Ta=25°C
REG90=-10mA
Ta=25°C
2
0.0
0
10
15
20
25
VCC[V]
30
5
35
Figure 5. Operating Circuit Current
15
20
VCC[V]
25
30
35
Figure 6. REG90 Line Regulation
0.6
100
0.5
Sx Feecback Voltage[V]
80
Duty Cycle[%]
10
60
40
20
0.4
0.3
0.2
0.1
VCC=24V
Ta=25°C
0
VCC=24V
Ta=25°C
0.0
0
1
2
SSFB[V]
3
4
0.0
Figure 7. Duty Cycle vs SSFB Character
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0.5
1.0
1.5
2.0
VREF[V]
2.5
3.0
Figure 8. S Pin Feedback Voltage vs VREF Character
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2.1
Pin Descriptions
○PIN1:VCC
This is the power supply pin of the IC. Input range is from 11.5V to 35V.
The operation starts at more than 7.5V(Typ) and shuts down at less than 7.2V(Typ).
○PIN2:FAILB
This is FAILB signal output (OPEN DRAIN) pin. At normal operation, NMOS will be in OPEN state, during abnormality
detection NMOS will be in ON (500 ohm(Typ))state.
○PIN3:UVLO
Under Voltage Lockout pin is the input voltage of the power stage. IC starts boost operation if UVLO is more than
2.5V(Typ) and stops if lower than 2.4V(Typ). It can also be used for reset when latched off by protection.
The power of step-up DC/DC converter needs to be set detection level by dividing the resistance.
○PIN4:REG90
The REG pin is used in the DC/DC converter driver block to output 9V. Available current is 20mA(Min). Using the REG pin
at current higher than 20mA can affect the IC base voltage, causing the IC to malfunction and leading to heat generation
of the IC itself. To avoid this problem, it is recommended to make load setting to the minimum level.
The characteristic of VCC line regulation at REG90 is shown as [Figure 6]. VCC must be used in more than 11.5V for
stable 9V output. Place the ceramic capacitor connected to REG90 pin (2.2uF to 10uF) closest to REG90-AGND pin.
○PIN5:STB
This is the ON/OFF setting terminal of the IC. It is allowed for use to reset the IC from shutdown.
※The IC state is switched according to voltages input in the STB pin.
※Avoid using the STB pin between two states (0.8 to 2.0V).
○PIN6:N
The N pin is used to output power to the external NMOS gate driver for the DC/DC converter in the amplitude range of
approximately 0V to 9V. Output ON resistance H - side is 2.5Ω (Typ) and L-side is 3.0Ω (Typ).
Frequency can be set by the resistor connected to RT. Refer to <RT> pin description for the frequency setting.
○PIN7:PGND
The PGND pin is a power ground pin for the driver block of the N output pin.
○PIN8:CS
CS pin is current detector for DC/DC current mode inductor current control pin.
Current flowing through the inductor is converted into voltage by the current sensing resistor RCS connected to the CS
pin and this voltage is compared with voltage set with the error amplifier to control the DC/DC output voltage. The CS pin
also incorporates the over current protection (OCP) function. If the CS voltage reaches 0.45V(Typ) or more, switching
operation will be forced to stopped.
○PIN9: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
ODP=ON
DUTYON= -0.3V to +0.8V
ODP=OFF
DUTYON= +1.5V to +18.0V
○PIN10:OVP
The OVP pin is an input pin for over voltage protection and short circuit protection of DC/DC output voltage. When voltage
of it exceeds 3.0V(Typ), N pin will stop. This case is not CP count. When OVP pin voltage <0.2V(Typ) or lower, short
circuit protection (SCP) function is activated, and output of gate driver will become low immediately. And system is
stopped after a CP count. The setting example is separately described in the section ”3.2.6 OVP Setting”.
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○PIN11, 14, 17, 20 :S1-S4, PIN23 : VREF
LED constant current driver is connected to the source of bill FET outside. Output current ILED is inversely proportional to
the resistance value. This is the input pin for analog dimming signal. Output current ILED is directly proportional to the
input voltage value. VREF pin is high impedance because the internal resistance is not connected to a certain bias.
Even if VREF function is not used, pin bias is still required because the open connection of this pin is not a fixed potential.
VREF pin voltage is set as 「VVREF」, LED current 「ILED」can be calculated as below.
ILED[ A] 
VREF [V]
 0.2 RS[Ω ]
LED
ILED
VREF  1.2V , RS  2[]
G
+
ILED  120[mA] -
S 240mV
RS
Figure 9. ILED setting example
For the adjustment of LED current with analog dimming by VREF, note that the output voltage of the DC/DC converter
largely changes accompanied by LED VF changes if the VREF voltage is changed rapidly. In particularly, when the VREF
voltages changed from high to low, it makes the LED terminal voltage seem higher transiently, which may influence
application such as activation of the LED short circuit protection. It needs to be adequately verified with an actual device
when analog dimming is used.
○PIN12, 15, 18, 21:LED1-LED4
LED constant current driver output pins. Drain of external NMOS is connected. Setting of LED current value is adjustable
by setting the VREF voltage and connecting a resistor to S pin. For details, see the explanation of <PIN:11, 14, 17, 20 S1
- S4, Pin23 : VREF >.
The abnormal voltage of this pin activates the protection function of LED OPEN detection, LED SHORT detection.
Please refer to < 2.2 List of The Protection Function Detection Condition> for details.
○PIN13, 16, 19, 22:G1-G4
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.
○PIN24:LSP
LED Short detection voltage setting pin. Resistance voltage divider is internally on IC. It is set as 1.2V.
When need to establish the other voltage, use an external resistance voltage divider.
LSP pin voltage is set as LED SHORT PROTECTION detection voltage and can be calculated as below.
LEDSHORT  6.7 VLSP[V ] LEDSHORT:LSP detection voltage, VLSP:LSP pin voltage
Set LSP voltage in the range of 0.8V to 3.0V.
In addition to considering the voltage of the internal resistance voltage divider, it's necessary to establish the voltage of
the LSP terminal.
○PIN25, 26, 27, 28:PWM1-PWM4
These are the PWM dimming signal input terminals. The high / low level of PWM pins are the following.
State
PWM pin voltage
PWM=H
PWM= +1.5V to +18.0V
PWM=L
PWM= -0.3V to +0.8V
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○PIN29: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)
RDUTYP 
1172  ODPduty[%]
f PWM [ Hz]
[k] The RDUTYP setting ranges from 15kΩ to 600kΩ.
The setting example is separately described in section ”3.2.6 ODP Setting”.
○PIN30: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)
RRT 
15000
f SW [kHz]
[k] ○PIN31:SSFB
The SSFB pin is used to make setting of soft start time and duty for soft start, and DC/DC current mode control error
amplifier. It performs constant current charge of 10uA to the external capacitor connected to SSFB terminal, which
enables soft-start of DC/DC converter.
The SSFB pin detects the voltages of LED pins (1 to 4) and controls inductor current so that the pin voltage of the LED
located in the row with the highest Vf will come to 0.8V(Typ) (VREF=1.5V). As a result, the pin voltages of other LEDs
become higher by Vf variation. After completion of soft start, the SSFB pin is put into high-impedance state with the PWM
signal being in the low state, thus maintaining the SSFB voltage.
Since the LED protection function (OPEN/SHORT detection) works when it turns to the LED feedback mode.
○PIN32:AGND
This is the GND pin of the IC.
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2.2 List of the Protection Function Detection Condition (Typical Condition)
Detection Condition
Protection
Release
Detection
Pin
Function
Condition
Detection Condition
SS
PWM
Protection Type
(*2)
LED Open
LEDx
LEDx < 0.2V
H(4clk)
After
Soft start
LED Short
LEDx
LEDx > 6.7×VLSP
H(4clk)
After
Soft start
LEDx > 0.2V
(3clk)
LEDx < 6.7xVLSP
(3clk)
LED Driver
FET D-S Short
Sx
Sx > 0.6V
―
―
Sx < 0.6V
LED GND
Short
LEDx
LEDx < 0.2V
And
SSFB > 4.0V
H
―
LEDx > 0.2V
Or
SSFB < 3.6V
OVP
OVP
OVP > 3.0V
―
―
OVP < 2.9V
SCP
OVP
OVP < 0.2V
―
―
OVP > 0.25V
VCCUVLO
VCC
VCC < 7.2V
―
―
VCC > 7.5V
UVLO
UVLO
UVLO < 2.4V
―
―
UVLO > 2.5V
OCP
CS
CS > 0.45V
―
―
―
Over PWM
(*1)
duty
PWM
DUTYON = H
And
PWM interval > setting
by DUTYP resistor
H
―
―
Auto Restart in
relevant CH
Auto Restart in
relevant CH
Whole Auto
Restart
Whole Auto
Restart
Return
immediately.
Whole Auto
Restart
Return
immediately.
Return
immediately.
Return
immediately.
(Pulse by Pulse)
Return
immediately.
The clock number of timer operation corresponds to the boost pulse clock.
(*1)When PWM Duty count starts, PWM=H → L is input, when PWM=L → H is input, the ODP is reset.
The G (1 to 4) output, the N pin output maintain L until PWM=H → L is input in PWM = 100% again when ODP works once.
(*2) The release condition of OPEN protection depends on its release timing.
No.
The Release Condition
The timing of release of LEDx voltage (LEDx > 0.2V)
1
LED pin voltage is released during PWM=H.
2
LED pin voltage is released during PWM=L.
LED pin voltage is normal range during 3clk (3 positive edge)
As PWM=L, LED pin voltage do not exceed Short protection
voltage (VLSP) during more than 3clk or PWM positive edge is
input when LED pin voltage do not exceed VLSP for more than
3clk.
2.3 List of Protection function
Operation of the Protection Function
Protection function
STB
LED Open
DC/DC Gate
Output
Stop N output
Normal operation
(Stop when all LED
CH stop)
LED Short
Normal operation
LED Driver
FET D-S Short
Stop after 2 count
14
LED Driver
Soft-start
FAILB Pin
Stop immediately
Discharge immediately
HiZ
Normal operation
Low after timer latch
Normal operation
Low after timer latch
Discharge after stop
Low after timer latch
14
Stop after 2 count
Stop in relevant CH
14
Stop after 2 count
Stop in relevant CH
14
Stop after 2 count
LED GND Short
Stop after
*
6
(CP +2 )count
VCCUVLO
Stop N output
Only detected LED ch
stops after CP count
Other LED ch stop
operation
*
6
after(CP +2 )count
Stop immediately
Discharge immediately
HiZ
UVLO
Stop N output
Stop immediately
Discharge immediately
HiZ
OVP
Stop N output
Normal operation
Normal operation
SCP
*
6
(CP +2 ) Discharge
after count
Low after timer latch
Stop N output
Normal operation
Normal operation
Stop N output
OCP
Normal operation
Normal operation
(Pulse by Pulse)
Over PWM duty
Normal operation
Stop in relevant CH
Normal operation
※CP : Count movement after detection of D-S SHORT, LED_OPEN, SHORT.
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HiZ
Low after timer latch
HiZ
HiZ
TSZ02201-0F2F0C100140-1-2
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BD9415FS
3.1 Application Circuit Example
An example application using the BD9415FS.
3.1.1 Basic Application Example
VIN
+
VCC
CVCC
AGND
32
FAILB
SSFB
31
3
UVLO
RT
30
4
REG90
5
STB
6
N
7
PGND
8
CS
9
DUTYON
10
OVP
11
S1
DUTYP
29
PWM4
28
PWM3
27
PWM3
PWM2
26
PWM2
PWM1
25
PWM1
LSP
24
VREF
23
G4
22
12
LED1
LED4
21
13
G1
S4
20
14
S2
G3
19
15
LED2
LED3
18
16
G2
S3
17
PWM4
REG90
CLSP
REG90
BD9415FS
STB
VCC
2
CV R EF
CREG90
1
Figure 10. Basic Application Example
3.1.2 Application Example of Unused CH
VCC
+
( )
CVCC
AGND
32
FAILB
SSFB
31
3
UVLO
RT
30
4
REG90
5
STB
6
N
LEDunused
7
PGND
8
CS
9
DUTYON
10
OVP
11
S1
DUTYP
29
PWM4
28
PWM3
27
PWM3
PWM2
26
PWM2
PWM1
25
LSP
24
VREF
23
G4
22
12
LED1
LED4
21
13
G1
S4
20
14
S2
G3
19
15
LED2
LED3
18
16
G2
S3
17
PWM4
REG90
PWM1
CLSP
REG90
BD9415FS
STB
VCC
2
CV R EF
CREG90
1
LEDunused
Figure 11. Application Example of Unused CH
When an LED terminal was unused, please dispose the unused CH as follows.
・Please input lower than 3.0V (typical) of voltage to a LEDx pin (ex. 1.0 to 2.0V).
・Gx pin, Sx pin is short
・Unused PWMx = L
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3.2 External Components Selection
3.2.1 Startup operation and soft start (SSFB) capacitance setting
The following section describes the sequence for the startup of this IC.
①
10uA
5V
STB
Soft-Start(ISS=10uA)
VOUT
Q D
PWM
COMP
IFB(Sink, Source)=±100uA)
DRIVER
OSC
OSC
CS
ILED
SSFB
N
PWM
LED_OK
LEDx
SSFB
②
PWM=L:STOP
N
RSSFB
VOUT
CSSFB
Gx
ILED
③
Sx
LED_ DRIVER
LED_OK
PWMx
④
⑤
⑥
Figure 12. Startup Waveform
Figure 13. Circuit Behavior at Startup
 Description of startup sequence
(1) Set the STB and PWM pin to “ON”.
(2) Set all systems to “ON”, SSFB charge will be initiated.
(3) Since the SSFB pin reach the lower limit of the internal sawtooth wave of the IC, the DC/DC converter operates to
start VOUT voltage rising.
(4) The VOUT voltage continuously rising to reach a voltage at which LED current starts flowing.
(5) When the LED current reaches the set amount of current, the startup operation is completed.
(6) After that, conduct normal operation following the feedback operation sequence with the LED pins.
If the SSFB pin sink/source current is ±100uA, the LED protection function will be activated.
 SSFB capacitance setting procedure
As aforementioned, this IC stops DC/DC converter when the PWM pin is set to Low level and conducts step-up operation
only in the section in which the PWM pin is maintained at High level. Consequently, setting the PWM duty cycle to the
minimum will extend the startup time. The startup time also varies with application settings of output capacitance, LED
current, output voltage, and others.
Startup time at minimum duty cycle can be approximated according to the following method:
Make measurement of VOUT startup time with a 100% duty cycle, first. Take this value as “Trise100”.
The startup time “Trise_min” for the relevant application with the minimum duty cycle is given by the following equation.
Trise _ min 
Trise _ 100[sec]
[sec]
Min _ Duty [ratio ]
However, since this calculation method is just for approximation, use it only as a guide.
Assuming that the SSFB pin voltage is VSSFB, the time is given by the following equation:
TSSFB 
CSSFB[ F ]  VSSFB[V ]
10[ A]
[ Sec ]
As a result, it is recommended to make SSFB capacitance setting so that “TSSFB” will be greater than “Trise_min”
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3.2.2 LED Current Setting (VREF pin, Sx pin)
First, VREF pin voltage is determined. When performing Analog dimming, be careful of VREF pin input range(0.2 to 2.5V)
and decide typical voltage.
In BD9415FS, LED constant current is controlled by Sx pin voltage as a reference point. Sx pin is controlled to become
one fifth of the voltage of VREF pin voltage. In the case of VREF=1V, it is set to Sx=0.2V.
Therefore, when the resistance to Sx pin versus GND is set to "RS", the relationship between RS, VREF and ILED is as
follows
R S [ohm] 
VVREF [V ]
I LED [ A]  5
REG90=9V
3.2.3 LED Short Detection Voltage Setting (LSP terminal)
The voltage of LED short detection can be arbitrarily set up with LSP
pin voltage. It is possible to change the LED short detection voltage,
please input (0.8V to 3.0V) to LSP pin.
About LED short detection voltage, if "VLEDshort" and LSP pin
voltage are set to "VLSP", it is as follows
4V
LSP
COMP
+
R3
2800k
R4
1200k
VLEDSHORT [V ]
6.7
CLSP
R2
3700k
VLSP 
R1
LSP
LEDx
800k
Figure 14. LSP setting example
Since the setting range of a LSP pin is set to 0.8V to 3.0V, VLEDshort can be set up in 5.36V to 20.1V.
○ Equation of setting LSP detect Voltage
When the detection voltage VLSP of LSP is set up by resistance division of R1 and R2 using REG90,
it becomes like the following formula.


R2[k]  R4[k]  REG 90[V ]  R3  4[V ]  R1[k]
LEDSHORT  
( 2 )
  6.7 [V ]  ( R1[k]  R3[k]  R2  R4  R2[k]  R4[k]  R1[k]  R3[k] 
【Setting example】
Assuming that LSP is approximated by Equation (1) in order to set LSP detection voltage to 6V, R1 comes to 68kΩ. and
R2 comes to 7.6kΩ.
When calculating LSP detection voltage taking into account internal IC resistance by Equation (2), it will be given as:


7.6[k]  1200[k]  9[V ]  2800[k]  4[V ]  68[k]
LEDSHORT  
 ( 2)
  6.7  6.078[V ]  (68[k]  2800[k]  7.6[k]  1200[k]  7.6[k]  1200[k]  68[k]  2800[k] 
*Also including the variation in IC, please also take the part variation in a set into consideration for an actual constant
setup, and inquire enough to it.
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3.2.4 DCDC Oscillation Frequency Setting
RRT which connects to RT pin sets the oscillation frequency f SW of DCDC.
○Relationship between frequency fSW and RT resistance (ideal)
RRT 
15000
f SW [kHz]
Frequency (fsw)
[k] 【setting example】
When DCDC frequency fSW is set to 200kHz, RRT is as follows.
GATE
CS
RT
RRT
15000
15000


 75[k] f SW [kHz] 200[kHz]
Rcs
RRT
GND
Figure 15. RT terminal setting example
3.2.5 UVLO Setting
Under Voltage Lockout pin is the input voltage of the power stage. IC starts boost
operation if UVLO is more than 2.5V(Typ) and stops if lower than 2.4V(Typ).
Since internal impedance exists in UVLO pin, cautions are needed for selection of
resistance for resistance division.
Vin detection voltage level can be calculated by the following formula using
resistance division of R1 and R2 (unit: kΩ).
Vin
R1
Zin=610kΩ
(typ.)
1400k
530k
125k
480k
UVLO
R2
1000pF
AGND
AGND
Figure 16. UVLO setting example
○ Equation of Setting UVLO Release
 R1  R2 

1
1

Vin DET  2.5  


  R1 [V ]  1400k  125k 530k  480k 
 R2

○ Equation of Setting UVLO Lock
 R1  R2 

1
1

Vinlock  2.4  


  R1 [V ]  1400k  125k 530k  480k  40k 
 R2

*Also including the variation in IC, please also take the part variation in a set into consideration for an actual constant
setup, and inquire enough to it.
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3.2.6 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 Detect Equation
If VOUT is boosted abnormally, VOVPDET, the detect voltage
of OVP, R1, R2 can be expressed by the following formula.
R1  R2[k] 
VOVPDET [V ]  3.0[V ] 
3.0[V ]
[k] ○ OVP Release Equation
By using R1 and R2 in the above equation, the release voltage
of OVP, VOVPCAN can be expressed as follows.
VOVPCAN  2.9[V ] 
VOUT
OVP
R1
+
OVP COMP
-
SCP COMP
-
R1[k]  R2[k]  +
3.0V/2.9V
R2
0.2V
R2[k]
Figure 17 . OVP setting example
【setting example】
If the normal output voltage, VOUT is 58V, the detect voltage of OVP is 63V, R2 is 20kΩ, R1 is calculated as follows.
R1  R2[k] 
VOVPDET [V ]  3.0[V ]   20[k] 63[V ]  3.0[V ]  400[k]

3.0[V ]
3.0[V ]
By using these R1 and R2, the release voltage of OVP, VOVPCAN can be calculated as follows.
VOVPCAN  2.9[V ] 
R1[k]  R2[k]  400[k]  20[k]  60.9[V ]
 2.9[V ] 
R2[k]
20[k]
3.2.7 SCP setting
【3.2.6) The SCP setting「VSCPDET」 voltage is calculated as below when R1,R2 is decided above:
VSCPDET  0.2[V ] 
R1[k]  R2[k]  400[k]  20[k]  40.2[V ]
 0.2[V ] 
R2[k]
20[k]
*Also including the variation in IC, please also take the part variation in a set into consideration for an actual constant
setup, and inquire enough to it.
3.2.8 FAILB Logic
FAILB signal output pin (OPEN DRAIN); when an abnormality is detected, NMOS is brought into GND Level.
The rating of this pin is 20V.
State
FAILB output
In completion of an
abnormality
※
(After CP count )
GND Level
(500ohm (Typ))
In normal state, In STB
OPEN
※CP count : Count movement after detection of D-S SHORT, LED_OPEN, SHORT, SCP.
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3.2.9 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)
RDUTYP 
1172  ODPduty [%]
f PWM [ Hz]
[k] N
【setting example】
When LED PWM frequency fPWM, is set to 120Hz and ODP
Detection Duty (ODPduty) is set to 35%, RDUTYP is as follows.
DUTYP
CS
RDUTYP
RCS
Gx
RDUTYP
1172  35[%]

 341.8[k] 120[ Hz]
PWM
Sx
RS
GND
Figure 18. ODP setting example
fPWM
PWM
N
GATE
Gx
DIMOUT
ODPduty
Figure 19. The GATE and the DIMOUT waveform as PWM dimming (ODP)
3.2.10 Timer Latch Time (CP Counter) Setting, Auto-Restart Timer Setting
Timer latch time (CP Counter) is set by counting the clock frequency which is set at the RT pin. About the behavior from
abnormal detection to latch-off, please refer to the section “3.5.2 and 3.5.3 Timing Chart”.
When various abnormal conditions happen, counting starts from the timing, latch occurs after below time has passed.
Furthermore, even if PWM=L, if abnormal condition continues, timer count will not reset.
LATCHTIME  214 
AUTOTIME  217 
RRT []
100[k]
 16384 
 [ s] 10
1.5  10
1.5  107
RRT []
100[k]
 131072 
[ s] 10
1.5  10
1.5  107
Here, LATCHTIME = time until latch condition occurs, AUTOTIME = auto restart timer’s time
RRT = Resistor value connected to RT pin
【setting example】
Timer latch time when RT=30kohm (500kHz)
LATCHTIME  16384 
AUTOTIME  131072 
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RRT [k]
30[k]
 16384 
 32.8[ms] 7
1.5  10
1.5  107
RRT [k]
30[k]
 131072 
 262.1[ms] 7
1.5  10
1.5  107
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3.3. DCDC Parts Selection
3.3.1. OCP Setting / Calculation Method for the Current Rating of DCDC Parts
OCP detection stops the switching when the CS pin voltage is more than 0.45V(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]
LED total current = IOUT [A]
DCDC input voltage of the power stage = VIN [V]
Efficiency of DCDC =η [%]
L
VIN
fsw
VOUT [V ]  I OUT [ A]
[ A] VIN [V ] [%]
GATE
And the ripple current of the inductor L (ΔIL[A]) can be calculated by
using DCDC the switching frequency, fSW, as follows.
IL 
CS
Rcs
GND
(VOUT [V ]  VIN [V ])  VIN [V ]
[ A] L[ H ]  VOUT [V ]  f SW [ Hz]
(V)
IL[ A]
[ A] 2
… (1)
N[V]
On the other hand, the peak current of the inductor IPEAK can be expressed
as follows.
I PEAK  I IN [ A] 
Therefore, the bottom of the ripple current IMIN is
(A)
IL[ A]
 I IN [ A] 
or 0
2
(t)
Ipeak
If IMIN>0, the operation mode is CCM (Continuous Current Mode),
otherwise the mode is DCM (Discontinuous Current Mode).
(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)
Peak voltage VCSPEAK is as follows.
Imin
(t)
(V)
0.4V
VCS[V]
VCS PEAK  RCS  I PEAK [V ] ΔIL
IIN
IL[A]
I min
IOUT
IL
And then, the average input current IIN is calculated by the following
equation.
I IN 
VOUT
0.45V
VCSpeak
As this VCSPEAK reaches 0.4V (typical), the DCDC output stops the
switching.
Therefore, RCS value is necessary to meet the condition below.
RCS  I PEAK [V ]  0.45[V ] (t)
Figure 20. 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.
I PEAK _ DET 
0.45[V ]
[ A] RCS []
… (2)
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] = 0.48A
DCDC input voltage of the power stage = VIN [V] = 24V
Efficiency of DCDC=η [%]=90%
Averaged input current IIN is calculated as follows.
I IN 
VOUT [V ]  I OUT [ A] 40[V ]  0.48[ A]

 0.89[ A] VIN [V ]  [%]
24[V ]  90[%]
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.
IL 
(VOUT [V ]  VIN [V ])  VIN [V ]
(40[V ]  24[V ])  24[ A]

 0.48[ A] L[ H ]  VOUT [V ]  f SW [ Hz] 100  10 6 [ H ]  40[V ]  200  103[ Hz]
Therefore the inductor peak current, IPEAK is
I PEAK  I IN [ A] 
IL[ A]
0.48[ A]
[ A]  0.89[ A] 
 1.13[ A] 2
2
…calculation result of the peak current
If RCS is assumed to be 0.3Ω
VCS PEAK  RCS  I PEAK  0.3[]  1.13[ A]  0.339[V ]  0.45[V ]
…RCS value confirmation
The above condition is met.
And IPEAK_DET, the current OCP works, is
I PEAK _ DET 
0.45[V ]
 1.35[ A]
0.3[]
If the current rating of the used parts is 2A,
Ipeak  Ipeak _ det  The current raying  1.33[ A]  1.35[ A]  2.0[ A]
…current rating confirmation 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.
I MIN  I IN [ A] 
IL[ A]
[ A]  1.13[ A]  0.48[ A]  0.65[ A]  0 2
This inequality implies that the operation is continuous current mode.
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3.3.2. Inductor Selection
The inductor value affects the input ripple current, as shown the previous section 3.3.1.
IL 
ΔIL
I IN 
(VOUT [V ]  VIN [V ])  VIN [V ]
[ A] L[ H ]  VOUT [V ]  f SW [ Hz]
VOUT [V ]  I OUT [ A]
[ A] VIN [V ] [%]
VIN
IL
I PEAK  I IN [ A] 
IL[ A]
[ A] 2
L
VOUT
RCS
COUT
Where
L: coil inductance [H]
VOUT: DCDC output voltage [V]
VIN: input voltage [V]
IOUT: output load current (the summation of LED current) [A]
IIN: input current [A]
fSW: oscillation frequency [Hz]
Figure 21. 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.
3.3.3. Output Capacitance COUT Selection
Output capacitor needs to be selected in consideration of equivalent series resistance
VIN
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
IL
component is high.
L
Output ripple voltage _VOUT is determined by Equation (4):
VOUT
RESR
RCS
COUT
VOUT  IL  RESR [V ] 
(4)
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 22. 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.
3.3.4. 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.
3.3.5. 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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3.4 Loop Compensation
A current mode DCDC converter has each one pole (phase lag) f P 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.
VIN
VOUT
ILED
L
VOUT
-
RCS
FB
gm
RESR
+
RFB1
COUT
CFB2
CFB1
Figure 23. Output stage and error amplifier diagram
i.
Calculate the pole frequency fP and the RHP zero frequency fZRHP of DC/DC converter
fP 
I LED
[ Hz]
2  VOUT  COUT
f ZRHP 
Where I LED  the summation of LED current, D 
ii.
VOUT  (1  D)2
[ Hz]
2  L  I LED
VOUT  VIN
VOUT
(Continuous Current Mode)
Calculate the phase compensation of the error amp output(fc = fZRHP/5)
RFB1 
f RHZP  RCS  I LED
[ ]
5  f P  gm  VOUT  (1  D)
CFB1 
1
5

[F ]
2  RFB1  f C 2  RFB!  f ZRHP
gm  4.0  104 [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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3.5. Timing Chart
3.5.1 PWM Start Up
VCC
STB
REG90
UVLO
7.5V
2.0V
0.8V
5.8V
2.5V
FAILB
(External PullUp)
SSFB
LED_OK
(internal)
VOUT
PWMx
ILEDx
LED Open Detection
LED Short Detection
OFF
(*1) (*2) (*3)
NORMAL
(*4)
OFF
(*5)
Figure 24. Start Up
(*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 5.8V(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. The pin SS continues
charging in spite of the assertion of PWM or OVP level.
(*4)…The soft start interval will end if the LED_OK = H (internal signal), 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.( N=L, SSFB=L)
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3.5.2 LED OPEN Detection
PWM1~4
LED1=OPEN
LED1=Normal
Condition
LED1≒Vout
LED1=OPEN
VLED1
OPEN
THRFESHOLD
0.2V
0.2V
LED1=Normal
Condition
3V
VLED2~4
Internal signal
5V Pull Up
3V
Mask
(4count)
(OPEN DET)
16384
Ab
<
normal count
Internal signal
Mask
(3count)
16384count
(Abnormal Count)
LED1=OFF
ILED1
ILED2~4
FAILB
Internal signal
131072count
AUto Restart Count Start
(131072count)
(Auto Restart)
IC State
Normal
Abnormal
Counting
Normal
Abnormal
Counting
LED1 = OFF
Normal
Judge OK
Figure 25. LED OPEN Detection
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3.5.3 LED SHORT Detection
PWM1~4
LED1=SHORT
LED1=Normal
Condition
6V
6V
VLED1
VLED2~4
LED1=Normal
Condition
LED1=SHORT
6V
Internal signal
(SHORT DET)
Mask
(4counts)
16384
Ab
<
count
normal
Internal signal
16384count
16384count
Mask
(3counts)
(Abnormal Count)
ILED1
LED1 = OFF
LED1 = OFF
ILED2~4
FAILB
Internal signal
IC State
131072count
AUto Restart
Count Start
(131072count)
(Auto Restart)
Normal
Abnormal
Counting
Abnormal
Counting
Normal
LED1 = OFF
Abnormal
Counting
Judge Fail
131072count
LED1 = OFF
Normal
Judge OK
Figure 26. LED SHORT Detection
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3.5.4 Over Duty Protection
PWM1
PWM2
PWM=100%
(35%)
(30%)
dutyH > (35%)
PWM3
PWM4
ILED1
ILED2
(35%)
(35%)
(35%)
(30%)
ILED3
ILED4
(*1)
(*2) (*3)
(*4)
(*5)
(*6)
Figure 27. Over Duty Protection
ODP=35% setup
(*1) …PWM < 35% : Turn on in relevant CH of same time PWM_DutyH.
(*2) …PWM > 35% : An LED of relevant CH is turn off by PWM_DutyH=35%.
(*3) …PWM=H signal beyond 35% is changed, and that doesn't react to IC in particular.
(*4) …PWM > 35% : An LED of relevant CH is turn off by PWM_DutyH=35%.
(*5) …ODP Function= ON : When a PWM signal is equivalent to 100%, LED=OFF continues after 35 %.
(*6) … When the next PWM=H signal is input, an LED is also turn on at the same time.
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3.6 I/O Equivalent Circuits
OVP
UVLO
SSFB
SSFB
100k
OVP
UVLO
5V
RT
PWM1-4
RT
DUTYON
PWM1-4
100k
300k
5V
G1-4
DUTYON
100 k
5V
300k
S1-4
LSP
4V
G1-G4
2800k
S1-S4
LSP
100k
1200k
REG90 / N / PGND / CS
STB
VREF
REG90
N
100k
STB
20 k
VREF
5V
5V
1M
GND
CS
DUTYP
FAILB
LED1-4
LED1-4
DUTYP
FAILB
500
Figure 28. Internal Equivalent Circuits
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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. 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.
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 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.
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.
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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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
Parasitic
Elements
N
P+
N P
N
P+
B
N
C
E
Parasitic
Elements
P Substrate
P Substrate
Parasitic
Elements
Pin B
B
GND
Parasitic
Elements
GND
GND
N Region
close-by
GND
Figure 29. 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.
17. Disturbance light
In a device where a portion of silicon is exposed to light such as in a WL-CSP, IC characteristics may be affected due
to photoelectric effect. For this reason, it is recommended to come up with countermeasures that will prevent the chip
from being exposed to light.
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Ordering Information
B
D
9
4
1
Part Number
5
F
S
-
Package
F: SSOP-A32
E2
Packaging and forming specification
E2: Embossed tape and reel
Marking Diagrams
SSOP-A32(TOP VIEW)
Part Number Marking
BD9415FS
LOT Number
1PIN MARK
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Physical Dimension, Tape and Reel Information
Package Name
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Revision History
Date
Revision
12 May.2016
001
Change
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
(Note 1)
intend to use our Products in devices requiring extremely high reliability (such as medical equipment
, 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
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 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
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Rev.003
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
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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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