BD81A44MUV-M [ROHM]
4ch White LED Driver with Buck-Boost;
| 型号： | BD81A44MUV-M |
| 厂家： | 
ROHM |
| 描述： | 4ch White LED Driver with Buck-Boost |
| 文件： | 总39页 (文件大小：1689K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Datasheet
4ch White LED Driver with Buck-Boost
(40 LED Maximum)
BD81A44MUV-M / BD81A44EFV-M
General Description
Key Specifications
BD81A44MUV-M/EFV-M is a white LED driver with the capability of
withstanding high input voltage (35V Max). This driver has 4ch
constant-current drivers integrated in 1-chip, where each channel
can draw up to 120mA (Max), which is also suitable for high
illumination LED drive. Furthermore, a buck-boost current mode
DC/DC controller is also integrated to achieve stable operation
during power voltage fluctuation. Light modulation (5000:1 dimming
function) is possible by PWM input.
■
■
■
■
■
■
Operating Input Voltage Range
Output LED Current Accuracy
DC/DC Oscillation Frequency 200 to 2200kHz
Operating Temperature Range
LED Maximum Output Current
PWM min pulse width
4.5 to 35 V
±3.0%@50mA
-40 to +125℃
120mA/ch
1.0us
Package(s) W(Typ) x D(Typ) x H(Max)
Features
■
■
■
■
■
■
■
Integrated Buck-Boost current mode DC/DC controller
Integrated 4ch current driver for LED drive
5000:1 PWM dimming @200Hz
VQFN28SV5050
(BD81A44MUV-M)
HTSSOP-B28
(BD81A44EFV-M)
External switching frequency synchronization
Built-In protection function (UVLO, OVP, OCP, SCP)
LED abnormality detection function (Open/Short)
Integrated VOUT discharge function (Buck-Boost or Buck
structure limitation)
W(Typ) × D(Typ) × H(Max) W(Typ) × D(Typ) × H(Max)
5.0mm × 5.0mm ×1.0mm
9.7mm × 6.4mm × 1.0mm
■
AEC-Q100 Qualified (Note 1)
(Note 1) Grade1
Application
For Display audio, CID, Cluster, HUD
Small and Medium type LCD Panels for Automotive use.
Typical Application Circuit
VCC CIN
CREG
COUT
VREG
VDISC
OVP
VCC
EN
CS
BOOT
OUTH
SW
SYNC
RT
OUTL
RRT
DGND
COMP
SS
RPC
CPC
BD81A44MUV-M /
BD81A44EFV-M
LED1
LED2
LED3
LED4
CSS
PWM
ISET
PGND
RISET
VREG
FAIL1
GND
FAIL2
SHDETEN
LEDEN1
LEDEN2
Figure 1. Buck-Boost Application Circuit
○Product structure：Silicon monolithic integrated circuit
○This product has no designed protection against radioactive rays
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Pin Description
VQFN28SV5050 (Top view)
Pin Configuration
VQFN28
SV5050
HTSSOP
Terminal
Name
LEDEN1
LEDEN2
LED1
LED2
LED3
LED4
OVP
Function
-B28
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
1
1
2
3
4
5
6
7
8
LED output pin enable terminal 1
LED output pin enable terminal 2
LED output terminal 1
LED output terminal 2
LED output terminal 3
LED output terminal 4
Over-voltage detection terminal
LED output current setting terminal
LED output GND terminal
Low side FET gate terminal
DC/DC output GND terminal
Output voltage discharge terminal
High side FET source terminal
High side FET gate terminal
High side FET driver power supply terminal
Internal constant voltage
ISET
9
PGND
OUTL
DGND
VDISC
SW
OUTH
BOOT
VREG
EN
CS
VCC
SS
COMP
RT
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
HTSSOP-B28 (Top view)
Enable terminal
DC/DC current sense terminal
Input power supply terminal
“Soft Start” Capacitor connection
ERR AMP output
Oscillation Frequency-setting resistor input
External synchronization input terminal
2
3
4
5
6
7
8
9
SYNC
SHDETEN Short detection enable signal
GND
PWM
FAIL1
FAIL2
Small signal GND terminal
PWM light modulation input terminal
“Failure” signal output terminal
LED open/short detection output signal
Figure 2. Pin Configuration
10
Thermal
PAD
Back side thermal PAD
(Please connect to GND)
-
-
Block Diagram
Figure 3. Internal Block Diagram
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Description of Blocks
1. Voltage Reference (VREG
)
5V (Typ) is generated from the VCC Input Voltage (when at EN=High). This voltage (VREG) is used as power supply of internal
circuit and when fixing the pins outside of the IC at a high voltage, as well. The UVLO protection is integrated in VREG. The
circuit starts to operate at VCC≧4.0V (Typ) and VREG=3.5V (Typ) and stops when at VCC≤3.5V (Typ) or VREG≤2.0V (Typ). For
release/cancellation condition and detection condition, please refer to Table 2 on page 11. Connect a ceramic capacitor
(CREG) to VREG terminal for phase compensation. Creg range is 1.0uF to 4.7uF and recommend value is 2.2uF. If the CREG
is not connected, the operation of circuit will be notably unstable.
2. Constant Current Driver
Table1. LED Control Logic
LEDEN1
LEDEN2
LED1
ON
LED2
ON
LED3
ON
LED4
ON
L
H
L
L
L
ON
ON
ON
OFF
OFF
OFF
H
H
ON
ON
OFF
OFF
H
ON
OFF
If less than four constant-current drivers are used, please make the LED1~4 terminal ‘open’ while the output ‘OFF’ by
LEDEN1 and LEDEN2 terminal. The truth table for these pins is shown above. If the unused constant-current driver output
will be set open without the process of LEDEN1,2 terminals, the ‘open detection’ will be activated. The LEDEN1, 2 terminals
is pulled down internally in the IC and it is low at ‘open’ condition. They should be connected to VREG terminal or fixed to
logic HIGH when in use.
(1) Output Current Setting (RISET)
Figure 4. ILED vs RISET
The Output Current ILED can be obtained by the following equation:
[
]
⁄
[
]
ꢀꢁꢂꢃ ꢄꢅ = (1.0ꢆ ꢇꢀꢈꢂꢉ ꢊΩ ) × 5000
RISET operating range is 41kohm to 250kohm. It can not change the RISET value in the operation.
This IC has ISET-GND short protection that protect LED element from over current when ISET and GND is short. If the RISET
value is under 4.7kohm, the IC detects ISET-GND short and LED current becomes off.
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<Caution of LED current setting>
If the output current ILED is set to >100mA/ch, the stability of LED current within specified operating temperature range will
decrease. LED current supply value will depends on the amount of ripple in output voltage (VOUT). The figure below shows the
temperature and the possible LED current maximum value settings, please adjust the ripple voltage in such a way that the LED
current value setting will fall within the range as shown on the graph below. (∆VOUT：Output Ripple Voltage) Please refer P.22,
there is the detail information of VOUT ripple voltage.
Figure 5. Temperature (Ta) vs Output LED Current (ILED)
(2) PWM Intensity Control
1ms/div
500ns/div
PWM
(2V/div)
PWM
(2V/div)
ILED
(50mA/div)
ILED
(50mA/div)
Figure 6. PWM=150Hz, Duty=0.02%, ILED Waveform
Figure 7. PWM=150Hz, Duty=50.0%, ILED Waveform
The current driver ON/OFF is controlled by PWM terminal. The duty ratio of PWM terminal becomes duty ratio of ILED. If don’t
use PWM dimming, please set the PWM terminal to HIGH. Output light intensity is greatest at 100% input
3. Buck-Boost DC/DC Controller
(1) Number of LED in Series Connection
In this IC, the output voltage of the DC/DC converter (VOUT) is controlled by LED cathode voltage (LED1–4 terminal
voltage) becomes 1.0V (Typ). When two or more LED are operating at the same time, the LED terminal voltage that
connects the highest LED Vf row is held at 1.0V (Typ). Then the voltages of other LED terminal will increased only LED VF
tolerance. Please decide LED VF tolerance by using the description as shown below:
LED series number x LED VF tolerance voltage < Short Detection Voltage 4.2V (Min) － LED Control Voltage 1.1V (Max)
(2) Over Voltage Protection (OVP)
The output of the DC/DC converter (VOUT) should be connected to the OVP pin via voltage divider. If OVP terminal voltage
is over 2.0V (Typ), Over Voltage Protection (OVP) is active and stop the DCDC switching. In determining an appropriate
trigger voltage for OVP function, consider the total number of LEDs in series and the Maximum variation in VF. When OVP
terminal voltage drops to 1.94V (Typ) after OVP operation, the OVP will be released. If ROVP1 is GND side resistance,
ROVP2 is output voltage side resistance and output voltage is VOUT, OVP will occur at below equation.
[ ]
(
[
]
[
])
[
]
ꢆꢋꢌꢉ ꢆ ꢍ { ꢇꢋꢆꢎ1 ꢊꢏ + ꢇꢋꢆꢎ2 ꢊꢏ /ꢇꢋꢆꢎ1 ꢊꢏ } × 2.0[ꢆ]
OVP will engage when VOUT >32V if ROVP1=22kΩ and ROVP2=330kΩ.
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(3) Buck-Boost DC/DC Converter Oscillation Frequency (FOSC)
Figure 8. RRT vs FOSC
DCDC oscillation frequency can be set via a resistor connected to the RT pin. This resistor determines the charge/discharge
current to the internal capacitor, thereby changing the oscillation frequency. Please set the resistance of RRTusing the above
data and below equation.
ꢖ
[
]
⁄
[
]
ꢐꢑꢒꢓ ꢊꢔꢕ = (81 × 10 ꢇꢇꢉ ꢊΩ ) × ꢗ
Where:
2
81×10 is the constant value in IC (+/-10%)
α is the adjustment factor
(RRT : α = 41kΩ: 1.01, 27kΩ: 1.00, 18kΩ: 0.99, 10 kΩ: 0.98, 4.7kΩ: 0.97, 3.9kΩ: 0.96)
A resistor in the range of 3.6 kΩ to 41 kΩ is recommended. Settings that deviate from the frequency range shown above may
cause switching to stop, and proper operation cannot be guaranteed.
(4) External Synchronization Oscillation Frequency (FSYNC)
If the clock signal input to SYNC terminal, the internal oscillation frequency can be synchronized externally.
Do not switch from external to internal oscillation if the DC/DC converter is active.
The clock input to SYNC terminal is valid only in rising edge.
As for the external input frequency, the input of the internal oscillation frequency ± 20% decided in RT terminal resistance
is recommended.
(5) Soft Start Function (SS)
The soft-start (SS) function can limits the start up current and output rise-time slowly if the capacitor connected to SS
Terminal. It is available for prevention of output voltage overshoot and inrush current. If you don’t use soft-start function,
please set SS terminal open. For the calculation of SS time, please refer to the formula on page 19.
(6) Max Duty
If this IC operates by DCDC switching Max Duty, it would not output expect voltage and LED current decrease or LED
current OFF by SCP. Please set load condition and external parts for DCDC switching Duty does not reach Max Duty.
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4. Protect Function
Table 2. The detect condition of each protect function and the operation during detection
Detect Condition
Protect Function
Operation During Detection
[Detection]
[Release/ Cancellation]
All Blocks Shuts down
(Except for VREG)
All Blocks Shuts down
(Except for VREG)
UVLO
TSD
VCC<3.5V or VREG<2.0V
Tj>175°C
VCC >4.0V and VREG>3.5V
Tj<150°C
OVP
OCP
VOVPP>2.0V
VOVP<1.94V
DCDC switching OFF
DCDC switching OFF
VCS≦VCC-0.2V
VCS>VCC-0.2V
One of the LED1-4
is under 0.3V
EN Reset
or
After SCP delay time,
all block Latch Off
(Except for VREG)
SCP
or
VOVP<0.57V
UVLO Reset
(100ms delay @300kHz)
EN Reset
or
VLED<0.3V
Only the detected channel latches
OFF
LED Open Protection
LED Short Protection
and VOVP>2.0V
UVLO Reset
EN Reset
or
VLED>4.5V
After LED Short delay time,
(100ms delay @300kHz)
only the detected channel latch OFF
UVLO Reset
Figure 9. Protection Flag Output Block Diagram
The operating status of the protection is propagated to FAIL1 and FAIL2 terminals (open-drain outputs). FAIL1 becomes low
when OVP or OCP protection is detected, whereas FAIL2 becomes low when SCP, LED open or LED short is detected. If
the FAIL terminal will not be used as flag output, please make the FAIL terminal open or connect it to GND. But if the FAIL
terminal will be used as a flag output, it is recommended to pull-up the FAIL1, 2 terminals to VREG terminal. The
recommended value of pull-up resistance is 100kΩ.
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(1) Under-Voltage Lock Out (UVLO)
The UVLO shuts down all the circuits except VREG when VCC<3.5V (Typ) or VREG <2.0V (Typ). And UVLO is
released by Vcc>4.0V(Typ) and VREG>3.5V(Typ).
(2) Thermal Shut Down (TSD)
The TSD shuts down all the circuits except VREG when the Tj reaches 175°C (Typ), and releases when the Tj
becomes below 150°C (Typ).
(3) Over-Voltage Protection (OVP)
The output voltage of DC/DC is detected from the OVP terminal voltage, and the over-voltage protection will activate if
the OVP terminal voltage becomes greater than 2.0V (Typ). When OVP is activated, the switching operation of the
DC/DC turns off. And OVP terminal becomes less than 1.94V (Typ), OVP is released and the switching operation of the
DC/DC turns on.
(4) Over-Current Protection (OCP)
The OCP detects the coil current by monitoring the voltage of the high-side resistor, and activates when the CS voltage
becomes less than VCC-0.2V (Typ).
When the OCP is activated, the switching operation of the DC/DC turns off. And CS voltage becomes over than
Vcc-0.2V (typ), OCP is released and the switching operation of the DC/DC turns on.
(5) Short Circuit Protection (SCP)
When the LED terminal voltage becomes less than 0.3V (Typ) or OVP terminal becomes less than 0.57V (typ), the
built-in counter operation will start and the latch will activate at oscillation frequency in 32770 count. In case of
fosc=300kHz, the count time is approximately 100ms. If the LED terminal voltage becomes over 0.3V or OVP terminal
becomes over 1.0V (typ) before 32770 count, the counter resets and SCP is not detected.
(6) LED Open Detection
When the LED terminal voltage is below 0.3V (Typ) and OVP terminal voltage more than 2.0V (Typ) simultaneously,
LED open is detected and latches off the open channel.
(7) LED Short Detection Circuit
If the LED terminal voltage becomes more than 4.5V (Typ), the built-in counter operation will start and the latch will
activate at oscillation frequency in 32770 count. In case of fosc=300kHz, the count time is approximately 100ms. During
PWM dimming, the LED Short Detect operation is carried out only when PWM=High. If the LED terminal voltage
becomes less than 4.5V (Typ) before 32770 count, the counter resets and LED Short is not detected.
When LED Short Detect function will not be used, SHDETEN terminal should be connected to VREG before starting.
When LED Short Detect function is used, the SHDETEN terminal should be connected to GND. In addition, It cannot
change SHDETEN voltage (High or Low) during normal operation.
(8) PWM Low Latch Off Circuit
After the EN is ON, the low interval of PWM input is counted by built-in counter. The clock frequency of counter is the
fosc Frequency, which is determined by RRT, and stops the operation of circuits except VREG at 32768 counts.
In case of fosc=300kHz, the count time is approximately 100ms.
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(9) Output Voltage Discharge Circuit (VDISC function)
When EN restart with Vout charge remaining, there is the possibility of LED flicker. Therefore restarting DC/DC must be
operated after discharging Vout. If using only pull-down resistance as setting OVP for discharge, it takes a lot time for
discharging Vout. Therefore this product has functionality of circuit for Vout discharge. Vout discharge function is
available for BuckBoost or Buck application. It is need to connect Vout and VDISC terminal and use VDISC function.
When VDISC terminal is connected to Vout, the output can be discharged when DCDC circuit becomes OFF (with EN
changing high to low or detection of protect).
The discharge time Tdisc is expressed in the following equations.
[ ]
[ ]
ꢚ×ꢛꢜꢝꢞ ꢛ ×ꢟꢜꢝꢞ ꢠ
[ ]
ꢉꢘꢙꢒꢓ ꢒ =
[ ]
ꢡ×ꢢꢣꢢꢤꢟ ꢥ
Where:
Tdisc : DC/DC Output Discharge Time
COUT : DC/DC Output Capacity
Vout : DC/DC Output Voltage
IDISC : Discharge current
Please confirm IDISC value that 25% of Vout voltage from following graph and input above equation. For example,
when using Vout=20V, please use IDISC value of Vout=5V (approximately 76mA). It will take Tdisc time for Vout
discharge. Please set EN=Low time over than Tdisc for prevent LED flicker.
This Tdisc value is reference data. Please verifying by actual measurements.
Vout vs IDISC
0.12
0.10
0.08
0.06
0.04
0.02
0.00
0
5
10
15
20
25
30
35
40
Vout [V]
Figure.10 Vout vs IDISC
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Absolute Maximum Ratings (Ta=25°C)
Parameter
Symbol
VCC
Rating
40
Unit
V
Power Supply Voltage
BOOT, OUTH Pin Voltage
SW, CS Pin Voltage
VBOOT, VOUTH
45
40
V
V
VSW, VCS
BOOT-SW Pin Voltage
VBOOT-SW
7
V
LED1 to 4, VDISC Pin Voltage
PWM, SYNC, EN pin Voltage
VLED1,2,3,4, VVDISC
VPWM, VSYNC, VEN
40
V
-0.3 to +7
-0.3 to +7 < VCC
-0.3 to +7 < VREG
-40 to +150
-55～+150
120 (Note 1)
V
VREG, OVP, FAIL1, FAIL2,
SS, RT pin Voltage
VVREG, VOVP, VFAIL1, VFAIL2,
VSS, VRT
V
LEDEN1, LEDEN2, ISET,
VLEDEN1, VLEDEN2, VISET
VOUTL, VCOMP, VSHDETEN
V
OUTL, COMP, SHDETEN pin Voltage
Junction Temperature Range
Storage Temperature Range
LED Maximum Output Current
Tj
℃
℃
mA
Tstg
ILED
(Note 1) Current level per channel. Please set LED current that does not over Junction Temperature Range (Tj) maximum.
Recommended Operating Ratings
Rating
Parameter
Symbol
Unit
Min
4.5
-40
200
200
40
Max
35
(Note 2)
Power Supply Voltage
Operating Temp Range
VCC
Topr
V
℃
+125
2200
2200
60
DC/DC Oscillation Frequency Range
FOSC
FSYNC
FSDUTY
kHz
kHz
%
(Note 3) (Note 4)
External Synchronization Frequency Range
External Synchronization Pulse Duty Range
(Note2) It is near Vcc terminal voltage. Please be careful the voltage drop by Vcc line impedance.
(Note3) If don’t use an external synchronization frequency, please make the SYNC open or connect to GND.
(Note4) If using an external synchronization frequency, don’t change to internal oscillation in the middle of process.
Recommended Parts Ratings
Rating
Parameter
Symbol
Unit
Min
1.0
Max
4.7
VREG Capacitor
CREG
RISET
RRT
μF
kΩ
kΩ
μF
LED Current setting Resistance
41
250
41
DC/DC Oscillation Frequency setting Resistance
Soft Start setting Capacitor
3.6
CSS
0.047
0.47
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Thermal Resistance(Note 1)
Thermal Resistance (Typ)
Parameter
Symbol
Unit
1s(Note 3)
2s2p(Note 4)
VQFN28SV5050
Junction to Ambient
Junction to Top Characterization Parameter(Note 2)
θJA
128.5
12
31.5
9
°C/W
°C/W
ΨJT
HTSSOP-B28
Junction to Ambient
Junction to Top Characterization Parameter(Note 2)
θJA
107.0
6
25.1
3
°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.
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
(Note 4)Using a PCB board based on JESD51-5, 7.
Thermal Via(NOTE 5)
Layer Number of
Material
Board Size
114.3mm x 76.2mm x 1.6mmt
2 Internal Layers
Measurement Board
Pitch
Diameter
4 Layers
FR-4
1.20mm
Φ0.30mm
Top
Bottom
Copper Pattern
Thickness
Copper Pattern
Thickness
Copper Pattern
Thickness
70μm
Footprints and Traces
70μm
74.2mm x 74.2mm
35μm
74.2mm x 74.2mm
(Note 5) This thermal via connects with the copper pattern of all layers..
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Electrical Characteristics (VCC=12V, Ta = -40°C to +125°C *Unless otherwise specified)
Limit
Normal
Parameter
Symbol
Unit
mA
μA
Conditions
Min
-
Max
10
EN=High, SYNC=High, RT=OPEN
PWM=Low, ISET=OPEN,CIN=10μF
Circuit Current
ICC
-
Standby Current
[VREG]
IST
-
-
10
EN=Low, VDISC=OPEN
Reference Voltage
[OUTH]
VREG
4.5
5.0
5.5
V
IREG=-5mA, CREG=2.2μF
OUTH High Side ON-Resistor
RONHH
RONHL
VOLIMIT
1.5
0.8
3.5
2.5
7.0
5.5
Ω
Ω
V
IOUTH=-10mA
IOUTH=10mA
OUTH Low Side ON-Resistor
OCP Detection Voltage
[OUTL]
VCC-0.22 VCC-0.2 VCC-0.18
OUTL High Side ON-Resistor
RONLH
RONLL
1.5
0.8
3.5
2.5
10.0
5.5
Ω
Ω
IOUTL=-10mA
IOUTL=10mA
OUTL Low Side ON-Resistor
[SW]
SW Low Side
ON-Resistor
RON_SW
4.0
10.0
25.0
Ω
ISW=10mA
[Error AMP]
LED Control Voltage
COMP Sink Current
VLED
0.9
35
1.0
80
1.1
145
-35
V
ICOMPSINK
ICOMPSOURCE
μA
μA
VLED=2V, VCOMP=1V
VLED=0.5V, VCOMP=1V
COMP Source Current
-145
-80
[Oscillator]
Oscillation Frequency 1
fosc1
fosc2
285
300
315
kHz RT=27kΩ
kHz RT=3.9kΩ
Oscillation Frequency 2
[OVP]
1800
2000
2200
OVP Detection Voltage
VOVP1
1.9
2.0
2.1
V
V
VOVP=Sweep up
OVP Hysteresis Width
VOVPHYS1
0.02
0.06
0.10
VOVP=Sweep down
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Electrical Characteristics (VCC=12V, Ta = -40°C to +125°C *Unless otherwise specified)
Limit
Parameter
Symbol
Unit
Conditions
Min
Normal
Max
[UVLO]
UVLO Detection Voltage
UVLO Hysteresis Width
[LED Output]
VUVLO
VUHYS
3.2
3.5
0.5
3.8
V
V
VCC : Sweep down
0.25
0.75
VCC : Sweep up,VREG>3.5V
ILED=50mA, Ta=25℃
∆ILED1=(ILED/ILED_AVG-1)×100
-3
-5
-
-
+3
+5
+3
+5
1.1
%
%
%
%
V
LED Current Relative
Dispersion
ILED1
ILED=50mA, Ta=-40℃～125℃
∆ILED1=(ILED/ILED_AVG-1)×100
ILED=50mA, Ta=25℃
∆ILED2=(ILED/50mA-1)×100
-3
-
LED Current Absolute
Dispersion
ILED2
ILED=50mA, Ta=-40℃～125℃
∆ILED2=(ILED/50mA-1)×100
-5
-
ISET Voltage
VISET
TMIN
fPWM
0.9
1.0
RISET=100kΩ
FPWM=150Hz～15kHz,
ILED=20mA～100mA
PWM Minimum Pulse Width
1
-
-
-
μs
PWM Frequency
0.15
20
kHz
[Protection Circuit]
LED Open Detection Voltage
LED Short Detection Voltage
VOPEN
0.2
4.2
0.3
4.5
0.4
4.8
V
V
VLED1,2,3,4= Sweep down
VLED1,2,3,4= Sweep up
VSHORT
LED Short Detection Latch
OFF Delay Time
tSHORT
70
100
130
ms
RRT=27kΩ
SCP Latch OFF Delay Time
PWM Latch OFF Delay Time
tSCP
70
70
100
100
130
130
ms
ms
RRT=27kΩ
RRT=27kΩ
tPWM
ISET-GND Short Protection
impedance
RISETPROT
-
-
4.7
kΩ
[Logic Input]
EN, SYNC, SHDETEN,
PWM, LEDEN1, LEDEN2
EN, SYNC, SHDETEN,
PWM, LEDEN1, LEDEN2
Input High Voltage
Input Low Voltage
Input Current
VINH
VINL
IIN
2.1
GND
15
-
-
VREG
0.8
V
V
VIN=5V(EN,SYNC, SHDETEN
PWM, LEDEN1, LEDEN2,)
50
100
μA
[FAIL Output (Open Drain)]
FAIL Low Voltage
VOL
-
0.1
0.2
V
IOL=0.1ｍA
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Typical Performance Curves
10
5.5
5.0
4.5
4.0
3.5
VCC=4.5~35V
EN=3.3V
PWM=0V
VCC=12V~35V
EN=3.3V
PWM=5V
8
Ta=25°C
6
4
2
0
5
15
25
35
-40
0
40
80
120
Supply Voltage：VCC[V]
Temperature：Ta [℃]
Figure 11. Circuit Current vs Supply Voltage
Figure 12. VREG vs Temperature
3000
2500
2000
1500
1000
400
350
300
250
200
VCC=12V
EN=3.3V
RT=3.9kΩ
VCC=12V
EN=3.3V
RT=27kΩ
-40
0
40
80
120
-40
0
40
80
120
Temperature：Ta [℃]
Temperature：Ta [℃]
Figure 13. Switching Frequency vs
Temperature (@ 300 kHz)
Figure 14. Switching Frequency vs Temperature
(@ 2000 kHz)
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Typical Performance Curves – continued
60
50
40
30
20
60
50
40
30
20
10
0
VCC=12V
EN=3.3V
VLED=2V
PWM=VREG
VCC=12V
EN=3.3V
VLED=SWEEP
10
Ta=25°C
0
0
1
2
3
4
5
-40
0
40
80
120
LED Voltage：VLED [V]
Temperature：Ta [℃]
Figure 16. LED Current vs Temperature
Figure 15. LED Current vs LED Voltage
100
95
90
85
80
100
95
90
VCC=12V
EN=3.3V
PWM=VREG
Ta=25°C
LED8series 4ch
VCC=12V
EN=3.3V
PWM=VREG
Ta=25°C
LED4series 4ch
85
80
20
40
60
80
100
120
20
40
60
80
100
120
Output current：ILED1-4 [mA]
Output current：ILED1-4 [mA]
Figure 17. Efficiency vs Output Current
(Buck-Boost Application)
Figure 18. Efficiency vs Output Current
(Boost Application)
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Timing Chart (Start up and Protection)
4.5V
VCC
EN *1
3.5V
VREG
UVLO
SYNC *1
PWM *1
SS
Vf
SW/OUTL/
OUTH
①
VOUT
OVP
1.94V
2.0V
2.0V
1.94V
VOVP
1.0V
②LED2=OPEN
③LED3=SHORT ④LED4=GND
ILED1
ILED2
ILED3
ILED4
VLED1
VLED2
VLED3
VLED4
1.0V
Hi-z
Hi-z
Hi-z
Hi-z
100ms *2
100ms *2
Under 0.3V
Over 4.5V
Under 0.3V
FAIL1 *3
FAIL2 *3
Figure 19. Startup and Protect function timing chart
*1 Vcc, EN, PWM, SYNC are input sequence free.
*2 The count time of 32770clk × 1/FOSC. In case of fosc=300kHz, the count time is approximately 100ms.
*3 Above timing chart is the case of pulling up FAIL1 and FAIL2 terminal to VREG.
1. When VOVP less than 1.0V, regardless of PWM input, the DC/DC switching operation will be active (Pre-Boost function).
And if VOVP reaches 1.0V, the Pre-Boost is finished.
2. When VLED2 less than 0.3V and VOVP more than 2.0V, LED Open Protect is active and LED2 is turned OFF. Then
FAIL2 becomes Low.
3. If The condition of VLED3 more than 4.5V passes 100ms (@fosc=300kHz), LED3 is turned OFF. Then FAIL2 becomes
Low.
4. When VLED4 short to GND, increase the Vout voltage. Then VOVP rises over 2.0V, FAIL1 becomes Low. If OVP occur,
DCDC switching is OFF and decrease Vout voltage, then OVP repeats ON/OFF. And DCDC switching and LED current
of each CH is OFF after approximately 100ms. (In case of fosc=300kHz).
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Timing Chart (Start up and Restart)
4.5V
VCC
2.0ms *1
EN
3.5V
3.5V
2.0V
VREG
UVLO
SYNC
PWM
SS
SW/OUTL/
OUTH
①
VOUT
VOVP
1.0V
1.0V
ILED1
ILED2
ILED3
ILED4
1.0V
Hi-z
1.0V
VLED1
Hi-z
VLED2
Hi-z
Hi-z
Hi-z
Hi-z
VLED3
Hi-z
VLED4
Hi-z
FAIL1 *3
FAIL2 *3
Figure 20. Start up and EN restart timing chart
*1 EN Low term when EN restart needs more 2.0ms
*2 Please restart after Vout voltage discharged. Vout discharge function (P.8) or external discharge switch is available. If EN
restart with Vout voltage remaining, there is possibility of LED flash.
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Application Examples
When using as Boost DC/DC converter
VCC CIN
CREG
COUT
VREG
VDISC
OVP
CS
VCC
EN
BOOT
OUTH
SW
SYNC
RT
OUTL
RRT
DGND
COMP
SS
RPC
CPC
BD81A44MUV-M /
BD81A44EFV-M
LED1
LED2
LED3
LED4
CSS
PWM
ISET
PGND
RISET
FAIL1
FAIL2
GND
SHDETEN
LEDEN1
LEDEN2
Figure 21. Boost application circuit
Note: When using as boost DC/DC converter, if the VOUT and LED terminal are shorted, the over-current from VIN cannot be
prevented. To prevent overcurrent, carry out measure such as inserting fuse in between VCC and RCS.
When using as Buck DC/DC Converter
VCC CIN
CREG
COUT
VREG
VDISC
OVP
CS
VCC
EN
BOOT
OUTH
SW
SYNC
RT
OUTL
RRT
DGND
COMP
SS
RPC
CPC
BD81A44MUV-M /
BD81A44EFV-M
LED1
LED2
LED3
LED4
CSS
PWM
ISET
PGND
RISET
FAIL1
FAIL2
GND
SHDETEN
LEDEN1
LEDEN2
Figure 22. Buck application circuit
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PCB Application Circuit
Figure 23. PCB Application Circuit
・Please arrange RRT resistor closest to RT pin and do not attach capacitor.
・Please arrange RISET resistor closest to ISET pin and do not attach capacitor.
・Please attach the decoupling capacitor of CIN and CREG to IC pin as close as possible.
・Because there is possibility that big current may flow into DGND and PGND, please make the impedance low.
・In pins of ISET, RT and COMP, please pay attention so that noise will not get in.
・Since PWM, OUTH, OUTL, SW, SYNC and LED 1-4 are switching, please pay attention so that it will not affect
the surrounding pattern.
・There is a heat dissipation PAD at the back of package. Please solder the board for the heat dissipation PAD.
・Please set the gate resistor of step-down FET (M1) to 0Ω. If resistor is connected, M1 OFF timing is delayed in M1 parasitic
capacity and gate resistor, and the penetrating current flows to the internal transistor of M1 and SW. OCP may be detected
by penetrating current.
・To reduce noise, please consider the board layout in the shortest MIN impedance for Boost loop
(D2→COUT→DGND→M2→D2) and Buck loop (VCC→RCS→M1→D1→DGND→GND→CIN→VCC).
・The ringing of Low side FET is decreased by RG1, but if RG1 value is increased, there is concern about a decrease of
efficiency. Please evaluate to determine the proper value of RG1 to be used.
.
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PCB Board External Components List（Buck Boost application）
serial No.
1
component name
CIN1
component value
10μF
－
product name
GCM32EC71H106KA01
－
Manufacturer
murata
－
2
CIN2
3
CIN3
－
－
－
4
RCS1
RCS2
RCS3
CCS
100mΩ
100mΩ
Short
－
MCR100 Sieries
MCR100 Sieries
－
Rohm
Rohm
－
5
6
7
－
－
8
CSS
0.1μF
0.01μF
5.1kΩ
27kΩ
100kΩ
100kΩ
2.2μF
0.1μF
Short
22μH
－
GCM15R71H104KE37
GCM15R71H104KE37
MCR03 Series
MCR03 Series
MCR03 Series
MCR03 Series
GCM188C71A225KE01
GCM155R71H104KE37
－
murata
murata
Rohm
Rohm
Rohm
Rohm
murata
murata
－
9
CPC1
RPC1
RRT1
RFL1
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
RFL2
CREG
CBOOT
RBOOT
L1
SLF12565T-220M3R5-PF
RSS070N05
TDK
M1
Rohm
Rohm
Rohm
Rohm
murata
murata
murata
murata
Rohm
Rohm
Rohm
－
M2
－
RSS070N05
D1
－
RB050L-40
D2
－
RB050L-40
COUT1
COUT2
COUT3
COUT4
ROVP1
ROVP2
RISET1
RG1
10μF
10μF
10μF
10μF
30kΩ
360kΩ
100kΩ
0Ω
GCM32EC71H106KA01
GCM32EC71H106KA01
GCM32EC71H106KA01
GCM32EC71H106KA01
MCR03 Series
MCR03 Series
MCR03 Series
－
* Above components should be changed by load or conditions.
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Selection of Components Externally Connected
Follow the steps as shown below for selecting the external components.
1. Computation of Input Peak Current IL_MAX from application condition
L value is
feed back
2. Set the RCS value so that it becomes IOCP>IL_MAX
VOUT
3. Select the value of L so that it becomes 0.05V/μs<
･RCS<0.63xFosc [MHz]
L
Please judge the L value. If it’s OK, go to 4. And if it’s NG, go back to 1.
4. Select the coil, schottky diode, MOSFET and RCS which meets the current
and voltage ratings.
5. Select the output capacitor which meets with the ripple voltage requirements.
6. Select the input capacitor.
7. Select the BOOT – SW capacitor.
8. Phase Characteristics adjustment (CPC, RPC)
9. Over-Voltage Protection setting (ROVP1, ROVP2).
10. Soft Start Time Selection (CSS).
11. Check the Startup Time
Cpc, CSS adjustment
(When use Boost
application)
12. EN restart check
13. Actual Operation Confirmation
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1. Input Peak Current IL_Max Computation
Internal IC
VIN
Rcs
IL
CS
M1
OUTH
L
D2
Vout
SW
D1
Cout
M2
OUTL
Figure 24. Output Application Circuit Diagram (In case of Buck-Boost application)
(1) Max Output Voltage (Vout_Max) Computation
Consider the VF variation and number of LED connection in series for Vout_Max derivation
ꢆꢑꢦꢧ_ꢨꢗꢩ = (ꢆ + ∆ꢆ ) × ꢪ + 1.1ꢆ
Vout_Max [V] : Max Output Voltage
VF[V] : LED VF Voltage
ꢠ
ꢠ
∆VF[V] : LED VF Voltage Variation
N : LED series number
(P) Max Output Current IOUT_MAX Computation
ꢀꢑꢦꢧ_ꢨꢗꢩ = ꢀꢁꢂꢃ × 1.05 × ꢨ
Iout_Max[A] : Max Input Peak Current
ILED[A] : Output Current per Channel
M : LED parallel number
(P) Max Input Peak Current IL_MAX Computation
ꢀꢁ_ꢨꢗꢩ = ꢀꢁ_ꢅꢆꢫ + 1 ∕ 2∆ꢀꢁ
IL_Max[A] : Max Input Peak Current
IL_AVG[A] : Max Input Average Current
ΔIL[A] : Input Current Amplification
(In case of Boost application)
ꢀꢁ_ꢅꢆꢫ = ꢆꢑꢦꢧ_ꢨꢗꢩ × ꢀꢑꢦꢧ_ꢨꢗꢩ ∕ (ꢬ × ꢆꢭꢭ)
ꢯ
ꢛꢜꢝꢞ_ꢲꢳꢴꢵꢛꢟꢟ
ꢛꢜꢝꢞ_ꢲꢳꢴ
∆ꢀꢮ = ꢛꢟꢟ
×
×
ꢮ
ꢠꢜꢰꢱ
(In case of Buck-Boost application)
ꢀꢁ_ꢅꢆꢫ = (ꢆꢭꢭ + ꢆꢑꢦꢧ_ꢨꢗꢩ) × ꢀꢑꢦꢧ_ꢨꢗꢩ ∕ (ꢬ × ꢆꢭꢭ)
ꢯ
ꢛꢜꢝꢞ_ꢲꢳꢴ
∆ꢀꢮ = ꢛꢟꢟ
×
×
ꢮ
ꢠꢜꢰꢱ
ꢛꢟꢟꢶꢛꢜꢝꢞ_ꢲꢳꢴ
(In case of Buck application)
ꢀꢁ_ꢅꢆꢫ = ꢀꢑꢦꢧ_ꢨꢗꢩ ∕ ꢬ
ꢯ
ꢛꢟꢟꢵꢷꢛꢜꢝꢞ_ꢲꢳꢴ
∆ꢀꢮ = ꢛꢜꢝꢞ
×
×
ꢮ
ꢠꢜꢰꢱ
ꢛꢟꢟ
VCC[V]：Input Voltage
Fosc[Hz]：Switching Frequency
η：Efficiency
L[H]：Coil Value
The worst case for VIN is Minimum, so the Minimum value should be applied in the equation.
The current-mode Type of DC/DC convertor is adopted for BD81A34MUV-M/EFV-M, which is optimized with the use of the
recommended L value in the design stage. This recommendation is based upon the efficiency as well as the stability. The L
values outside this recommended range may cause irregular switching waveform and hence deteriorate stable operation.
N (efficiency) becomes almost 80%.
2. Setting of Over-Current Protection (IOCP) Value
[ ]
ꢀꢋꢭꢎ ꢅ = ꢆꢑꢓꢸ_ꢨꢙꢹ[ꢆ](= 0.18ꢆ) ÷ ꢇꢓꢒ[ꢏ] > ꢀꢁ_ꢨꢗꢩ[ꢅ]
RCS should be selected by above equation.
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3. Selection of the inductor
In order to achieve stable operation of the current mode DC/DC converter, we recommend selecting the L value in the range
indicated below.
[ ]
[ ]
ꢆꢑꢦꢧ ꢆ × ꢇꢓꢒ ꢏ
⁄
0.05[ꢆ ꢺꢒ] <
< 0.63 × ꢐꢑꢒꢓ[ꢨꢔꢕ]
[
]
ꢁ ꢺꢔ
Since there is almost ±30% variation in the value of coil L, keep enough margin and set.
[ ]
[
]
ꢛꢜꢝꢞ ꢛ ×ꢻꢱꢰ ꢼ
The smaller
allows stability improvement but slows down the response time.
[
]
ꢮ ꢽꢾ
If the condition of VCC is under 5V, please satisfy below equation when selecting the coil.
[ ]
[ ]
12 × ꢆꢭꢭ ꢆ × ꢆꢭꢭ ꢆ × ꢬ
ꢁ[ꢺꢔ] <
[ ]
ꢆꢑꢦꢧ ꢆ × ꢀꢁꢂꢃ[ꢅ] × ꢐꢑꢒꢓ[ꢨꢔꢕ]
The coil outside of above equations may cause Low LED brightness.
4. Selection of Coil L, Diode D1, D2, MOSFET M1, RCS and COUT
Current Rating
Voltage Rating
―
Heat Loss
Coil L
Diode D1
Diode D2
MOSFET M1
MOSFET M2
RCS
> IL_Max
> IOCP
> IOCP
> IOCP
> IOCP
―
―
> VCC_Max
> Vovp_Max
> VCC_Max
> Vovp_Max
―
―
―
―
―
> Iocp2 × Rcs
―
COUT
―
>Vovp_Max
Please consider external parts deviation and make the setting with enough margin.
In order to achieve fast switching, choose the MOSFET’s with the smaller gate-capacitance.
5. Selection of Output Capacitor
Select the output capacitor COUT based on the requirement of the ripple voltage Voutpp.
[ ]
20 × ꢀꢁꢂꢃ ꢅ
ꢆꢑꢦꢧꢸꢸ[ꢆ] =
+ ∆ꢀꢮ[ꢅ] × ꢇꢿꢤꢻ[ꢏ]
[
]
[ ]
ꢐꢑꢒꢓ ꢔꢕ × ꢭꢑꢦꢧ ꢐ × ꢬ
Actually, VOUT ripple voltage is sensitive to PCB layout and external components characteristics. Therefore, when designing
for mass-production, stability should be thoroughly investigated and confirmed in the actual physical design. Available Cout
max value is 500uF.
6. Selection of Input Capacitor
We recommend an input capacitor greater than 10μF with the small ESR ceramic capacitor. The input capacitor outside of
our recommendation may cause large ripple voltage at the input and hence lead to malfunction.
7. Selection of BOOT – SW capacitor
When using the BuckBoost application or Buck application, please input BOOT – SW capacitor 0.1uF.
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8. Phase Characteristics adjustment
Vout
LED1~4
Internal IC
COMP
A
RPC
CPC
Figure 25. COMP terminal Application Circuit Diagram
About Application Stability Condition
The stability in LED voltage feedback system is achieved when the following conditions are met.
(1) The phase delay when gain is 1(0dB) is below 150°C (or simply, phase margin >30°C).
(2) The frequency (Unity Gain Frequency) when gain is 1(0dB) is <1/10 of switching frequency.
One way to assure stability based on phase margin adjustment is setting the Phase-lead fz close to switching frequency. In
addition, the Phase-lag fp1 shall be decided based on COUT and Output impedance RL.
Respective formula shall be as follows.
ꢯ
Phase-lead ꣀꢕ[ꢔꢕ] = ꢖꣁꢻꣂꢱ[ꣃ]ꢟꣂꢱ ꢠ
[ ]
ꢯ
Phase-lag ꣀꢸ1[ꢔꢕ] = ꢖꣁꢻ
(Note) The output impedance calculated from ꢇꢮ = ꢛꣅ
ꢢꣅ
[
]
ꣃ ꢟꢜꢝꢞ[ꢠ]
꣄
Good stability would be obtained when the fz is set between 1kHz～10kHz.
It is important to keep in Mind that these are very loose guidelines, and adjustments may have to be made to ensure stability
in the actual circuitry. It is also important to note that stability characteristics can change greatly depending on factors such
as substrate layout and load conditions. Therefore, when designing for mass-production, stability should be thoroughly
investigated and confirmed in the actual physical design.
9. Setting of Over Voltage Protection(OVP)
Over voltage protection (OVP) is set from the external resistance ROVP1 and ROVP2.
The setting described below will be important in the either boost, buck, buck-boost applications.
Internal IC
Vout
ROVP2
2.0V/1.94V
OVP
ROVP1
1.0V/0.57V
Figure 26. OVP Application Circuit
The OVP terminal detects the over voltage when at >2.0V (Typ) and stops the DC/DC switching. In addition, it detects the
open condition when OVP terminal is at >2.0V (Typ) and LED1 to 4 pin voltage is at <0.3V (Typ), and the circuit is latched to
OFF (Please refer to page 11, Protect Function). In preventing error in detection of OPEN, it is necessary that the resistor
divide voltage of the maximum value of output voltage shall be less than the MIN value of OPEN detection voltage. Please
set the ROVP1 and ROVP2 is such a way the formula shown below can be met.
(
)
[ ]⁄(
[ ]
[ ])
ꢆꢑꢦꢧ ꢨꢗꢩ [ꢆ] × {ꢇꢋꢆꢎ1 ꢏ ꢇꢋꢆꢎ1 ꢏ + ꢇꢋꢆꢎ2 ꢏ } < ꢆꢋꢆꢎꢑꢸꢹ(ꢨꢙꢹ)[ꢆ] …(1)
Vout : DC/DC Output Voltage
VOVPopen : OVP Pin Open Detection Voltage
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Sample 1: When VF=3.2V±0.3V LED is used in 8series
(
)
(
)
(
)
ꢆꢑꢦꢧ ꢨꢗꢩ [ꢆ] = 1.1ꢆ ꢁꢂꢃꢷꢓꢑꢹꢧꢑꢷꢑꢧꢗꢷꢨꢗꢩ + 3.2ꢆ + 0.3ꢆ × 8 = 29.1ꢆ
(
)
Open Detection OVP Pin Voltage ꢆꢋꢆꢎꢑꢸꢹꢷ ꢨꢙꢹ = 1.9ꢆ
If ROVP1=20kΩ, please set by ROVP2 > 286.3kΩ from (1)
Sample 2: VF=3.2V±0.3V LED is used in 3series
(
)
(
)
(
)
ꢆꢑꢦꢧ ꢨꢗꢩ [ꢆ] = 1.1ꢆ ꢁꢂꢃꢷꢓꢑꢹꢧꢑꢷꢑꢧꢗꢷꢨꢗꢩ + 3.2ꢆ + 0.3ꢆ × 3 = 11.6ꢆ
(
)
Open Detection OVP Pin Voltage ꢆꢋꢆꢎꢑꢸꢹꢷ ꢨꢙꢹ = 1.9ꢆ
If ROVP1=20kΩ, please set by ROVP2 > 102.21kΩ from (1).
10. Setting of Soft Start time
The soft start circuit minimizes the coil current at the input and overshoot at the output voltage during the start-up condition.
A capacitance in the range of 0.047 to 0.47µF is recommended. A capacitance of less than 0.047µF may cause overshoot at
the output voltage. However, a capacitance greater than 0.47µF may cause massive reverse current through the parasitic
elements when power supply is OFF and may damage the IC.
Soft start time TSS (Typ) is below.
[ ]
ꢉꢈꢈ ꢒ = ꢭꢈꢈ[ꢺꢐ] × 3.3[ꢆ] ∕ 5[ꢺꢅ]
CSS: The capacitance at SS terminal
11. Check the Start up time
If the PWM duty at start up is small, the start up time is longer. If you want to setup the Startup Time shorter, small CPC value
is available, but it needs phase margin check. Below data is PWM duty vs Startup Time of representative two conditions.
Condition 1 (Boost, below figure left side)
Vcc = 12V, Vout = 30V (assumed LED 8 series), RRT = 27kΩ (Fosc = 300kHz), CPC=0.01μF, RPC=5.1kΩ, CSS = 0.1μF,
ROVP1 = 20kΩ, ROVP2 = 360kΩ
PWM duty vs Startup Time
(Boost)
PWM duty vs Startup Time
(Boost, Zoom up)
1000
900
800
700
600
500
400
300
200
100
0
1000
900
800
700
600
500
400
300
200
100
0
0
20
40
60
80
100
0
0.2
0.4
0.6
0.8
1
PWM duty [%]
PWM duty [%]
Figure 27. PWM Duty vs Startup Time (Boost)
Condition 2 (BuckBoost, below figure right side)
Vcc = 12V, Vout = 20V (assumed LED 5 series), RRT = 27kΩ (Fosc = 300kHz), CPC=0.01μF, RPC=5.1kΩ, CSS = 0.1μF,
ROVP1 = 30kΩ, ROVP2 = 360kΩ
PWM duty vs Startup Time
(BuckBoost)
PWM duty vs Startup Time
(BuckBoost, Zoom up)
1000
900
800
700
600
500
400
300
200
100
0
1000
900
800
700
600
500
400
300
200
100
0
0
20
40
60
80
100
0
0.2
0.4
0.6
0.8
1
PWM duty [%]
PWM duty [%]
Figure 28. PWM Duty vs Startup Time (BuckBoost)
Above data is only reference data. Actual Startup Time depends on layout pattern, parts value and part characteristics,
Please verify your design by the actual measurements.
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12. EN restart check
EN restart when Vout voltage is remain, it possible to detect SCP. Please set the condition according to applications.
When use the BuckBoost or Buck application.
Please connect Vout and VDISC terminal and set EN=Low time refer to the below equation.
[ ]
[ ] < ꢂꢪꢷꢁꢑꢷꢉꢙꢄꢷ[ꢒ]
ꢚ×ꢛꢜꢝꢞ ꢛ ×ꢟꢜꢝꢞ ꢠ
[ ]
ꢉꢘꢙꢒꢓ ꢒ =
[ ]
ꢡ×ꢢꢣꢢꢤꢟ ꢥ
Regarding Tdisc details, please refer P.8.
When use the Boost application.
Please adjust CSS and Cpc value according to below. If Cpc value is changed, phase margin will changed, and if CSS value
is changed, start up time is changed. Please verifying by actual measurements.
[ ]
0.4 + 2.7 × ꢹ − ꢆꢭꢭ ꢆ
1
[ ]
(
)
ꢉ1 ꢒ = (
×
+ 1.56) × ꢭꢸꢓ[ꢺꢐ]/ 0.46 × ꢃꢦꢧ꣎[%]
[ ] [ ]
ꢐꢑꢒꢓ ꢊꢔꢕ × ꢇꢇꢉ ꢊꢔꢕ × 138ꢺ
0.4 + 2.7 × ꢹ
[ ]
[
]
ꢉ2 ꢒ = ꢭꢈꢈ ꢺꢐ × 0.61 + 29.8/ꢐꢑꢒꢓ[ꢊꢔꢕ]
[ ]
Please adjust CSS and Cpc value with ꢉ1 ꢒ < ꢉ2[ꢒ]
n : LEDseries number
RRT[kΩ] : RT resistence
CSS[μF] : SS capacitor
VCC[V] : Power supply
Cpc[μF] : COMP capacitor
Fosc[kHz] : DCDC Frequency
Duty[%] : PWM Duty
Ex.) n=7, Vcc=7V, Fosc=300kHz, RRT=27kΩ, Cpc=0.01μF, CSS=0.1μF, PWM Duty = 1%
0.4 + 2.7 × 7 − 7
1
[ ]
ꢉ1 ꢒ = (
( )
+ 1.56) × 0.01/ 0.46 × 1 = 46.3ꢄꢒ
×
0.4 + 2.7 × 7
29.8
300 × 27 × 138ꢺ
[ ]
ꢉ2 ꢒ = 0.1 × 0.61 +
= 160.3ꢄꢒ
300
[ ]
ꢉ1 ꢒ < ꢉ2[ꢒ] This condition is OK.
13. Verification of the operation by taking measurements
The overall characteristics may change based on load current, input voltage, output voltage, inductance, load capacitance,
switching frequency, and PCB layout. We strongly recommend verifying your design by the actual measurements.
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Additional parts for EMC
1. This part adjusts “Slew Rate” of high side FET.
2. This part decreases noise of current loop of high side FET.
3. This part decreases spectrum of high frequency on power line.
4. This low Pass Filter decreases noise of power line.
5. This common mode filter decreases noise of power line.
6. This snubber circuit decreases spectrum of high frequency of low side FET.
7. This snubber circuit decreases ringing of switching for low side FET.
5
4
3
VCC
CIN
CREG
COUT
VREG
VDISC
OVP
CS
VCC
EN
BOOT
OUTH
SW
1
7
SYNC
RT
6
OUTL
RRT
DGND
COMP
SS
RPC
CPC
BD81A44MUV-M /
BD81A44EFV-M
LED1
LED2
LED3
LED4
CSS
PWM
ISET
PGND
RISET
FAIL1
FAIL2
GND
SHDETEN
LEDEN1
LEDEN2
Figure 29. Application parts for EMC
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Attention Point for PCB Layout
The layout pattern influences characteristic, such as
efficiency and a ripple greatly. So, it is necessary to
examine carefully about it.
VCC
Boost DC/DC has “Loop1” (in the right side figure).
Placement of these parts should be compact. And wiring
should be low-impedance (e.g. Cout’s GND and DGND
should be very near). Also, Back-Boost DC/DC has “Loop2”.
Placement of these parts and wiring should be compact
and low-impedance (e.g. Cin’s GND and D1’s GND should
be very near).
BD81A44MUV/EFV-M
Rcs
M1
Cin
CS
OUTH
D1
SW
<Loop2>
L
Vout
OUTL
D2
M2
Cout
<Loop1>
Figure 30. Circuit of DC/DC block
Cout
D2
Cin
D1
<Loop1>
M1
RCS
<Loop2>
Figure 31. BD81A44EFV-M PCB TOP-layer
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Calculation of Power Consumption
ꢎꢓ = ꢀꢓꢓ × ꢆꢭꢭ
・・・①Circuit Power
+ꢭꢙꢒꢒ1 × ꢆꢇꢂꢫ × ꢐꢒ × ꢆꢇꢂꢫ
+ꢭꢙꢒꢒ2 × ꢆꢇꢂꢫ × ꢐꢒ × ꢆꢇꢂꢫ
・・・②Boost FET Power
・・・③Buck FET Power
・・・④Current Driver Power
(
)
+{ꢆꢁꢂꢃ × ꢨ + ∆ꢆꣀ × ꢨ − 1 } × ꢀꢁꢂꢃ
Pc[W]
Ciss1[F]
Fsw[Hz]
M
:
:
:
:
IC Power Consumption
Boost FET Gate Capacitance
Switching Frequency
Icc[A]
:
Max Circuit Current
Buck FET Gate Capacity
LED Control Voltage
LED Vf torelance
VCC [V]
VREG[V]
ILED [A]
:
:
:
Power Supply Voltage
VREG Voltage
Ciss2[F]
VLED[V]
△Vf[V]
:
:
LED Output Current
Number of LED Parallel
:
<Sample Calculation>
Icc=10mA, VCC=12V, Ciss1=2000pF, Ciss2=2000pF, VREG=5V, Fsw=2200kHz, VLED=1V, ILED=50mA, N=7, M=4
Vf=3.5V, ∆Vf=0.5V, n=80%
(
)
ꢆꢑꢦꢧ = 3.5ꢆ + 0.5ꢆ × 7ꢷꢒꢙꢒ + 1ꢆ = 29ꢆ
ꢀꢑꢦꢧ = 50ꢄꢅ × 1.05 × 4ꢷꢸꢗꢗ = 0.21ꢅ
(
)⁄
⁄
ꢀꢁ_ꢅꢆꢫ = 12 + 29ꢆ 12ꢆ × 0.21ꢅ 0.8 = 0.897ꢅ
( )
ꢎꢓ 4 = 10ꢄꢅ × 12ꢆ + 2000ꢸꢐ × 5ꢆ × 2200ꢊꢔꢕ × 5ꢆ + 2000ꢸꢐ × 5ꢆ ×
{
(
)}
2200ꢊꢔꢕ × 5ꢆ + 1.0ꢆ × 4 + 0.5ꢆ × 4 − 1 × 50ꢄꢅ = 0.615[꣏]
The above mentioned is a simple calculation and sometimes the value may differ from the actual value.
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I/O Equivalence Circuit
SS
COMP
RT
VREG
VCC
VREG
VREG
VREG
5k
12.5Ω
1k
10k
SS
COMP
RT
1k
1k
SYNC,PWM
SHDETEN,LEDEN1,LEDEN2
FAIL1,FAIL2
VREG
VREG
VREG
SHDETEN
10k
10k
1k
PWM
SYNC
FAIL1
FAIL2
LEDEN1
LEDEN2
100k
100k
LED1~4
OVP
ISET
VREG
VREG
LED1
LED2
LED3
LED4
100k
10k
1k
10k
10k
10k
OVP
ISET
1k
90k
10k
10k
2Ω
OUTL
VDISC
SW
VREG
VREG
VCC
OUTL
VDISC
SW
OUTH
BOOT
VREG
BOOT
BOOT
BOOT
VCC
VREG
1k
OUTH
BOOT
VREG
SW
SW
SW
SW
EN
CS
VCC
VCC
5k
EN
CS
62.5k
125k
166Ω
1.1k
2p
All values are Typ value.
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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. Furthermore, connect a capacitor to ground at
all power supply pins. Consider the effect of temperature and aging on the capacitance value when using electrolytic
capacitors.
3. Ground Voltage
Ensure that no pins are at a voltage below that of the ground pin at any time, even during transient condition.
4. Ground Wiring Pattern
When using both small-signal and large-current ground traces, the two ground traces should be routed separately but
connected to a single ground at the reference point of the application board to avoid fluctuations in the small-signal
ground caused by large currents. Also ensure that the ground traces of external components do not cause variations
on the ground voltage. The ground lines must be as short and thick as possible to reduce line impedance.
5. Thermal Consideration
Should by any chance the power dissipation rating be exceeded the rise in temperature of the chip may result in
deterioration of the properties of the chip. In case of exceeding this absolute maximum rating, increase the board size
and copper area to prevent exceeding the Pd rating.
6. Recommended Operating Conditions
These conditions represent a range within which the expected characteristics of the IC can be approximately obtained.
The electrical characteristics are guaranteed under the conditions of each parameter.
7. Inrush Current
When power is first supplied to the IC, it is possible that the internal logic may be unstable and inrush current may flow
instantaneously due to the internal powering sequence and delays, especially if the IC has more than one power
supply. Therefore, give special consideration to power coupling capacitance, power wiring, width of ground wiring, and
routing of connections.
8. Operation Under Strong Electromagnetic Field
Operating the IC in the presence of a strong electromagnetic field may cause the IC to malfunction.
9. Testing on Application Boards
When testing the IC on an application board, connecting a capacitor directly to a low-impedance output pin may
subject the IC to stress. Always discharge capacitors completely after each process or step. The IC’s power supply
should always be turned off completely before connecting or removing it from the test setup during the inspection
process. To prevent damage from static discharge, ground the IC during assembly and use similar precautions during
transport and storage.
10. Inter-pin Short and Mounting Errors
Ensure that the direction and position are correct when mounting the IC on the PCB. Incorrect mounting may result in
damaging the IC. Avoid nearby pins being shorted to each other especially to ground, power supply and output pin.
Inter-pin shorts could be due to many reasons such as metal particles, water droplets (in very humid environment) and
unintentional solder bridge deposited in between pins during assembly to name a few.
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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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.
Figure 32. Example of hic IC structure
13. Ceramic Capacitor
When using a ceramic capacitor, determine the dielectric constant considering the change of capacitance with
temperature and the decrease in nominal capacitance due to DC bias and others.
14. Area of Safe Operation (ASO)
Operate the IC such that the output voltage, output current, and power dissipation are all within the Area of Safe
Operation (ASO).
15. Thermal Shutdown Circuit(TSD)
This IC has a built-in thermal shutdown circuit that prevents heat damage to the IC. Normal operation should always
be within the IC’s power dissipation rating. If however the rating is exceeded for a continued period, the junction
temperature (Tj) will rise which will activate the TSD circuit that will turn OFF all output pins. When the Tj falls below
the TSD threshold, the circuits are automatically restored to normal operation.
Note that the TSD circuit operates in a situation that exceeds the absolute maximum ratings and therefore, under no
circumstances, should the TSD circuit be used in a set design or for any purpose other than protecting the IC from
heat damage.
16. Over Current Protection Circuit (OCP)
This IC incorporates an integrated overcurrent protection circuit that is activated when the load is shorted. This
protection circuit is effective in preventing damage due to sudden and unexpected incidents. However, the IC should
not be used in applications characterized by continuous operation or transitioning of the protection circuit.
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Ordering Information
B D 8 1 A 4 4 M U V
-
-
ME2
Package
MUV:VQFN28SV5050
Packing & foaming specification
M: High reliability design
E2: reel shape embossed taping
(VQFN28SV5050)
B
D
8
1
A
4
4
E
F
V
ME2
Package
EFV:HTSSOP-B28
Packing & foaming specification
M: High reliability design
E2: reel shape embossed taping
(HTSSOP-B28)
Marking Diagram
VQFN28SV5050 (TOP VIEW)
HTSSOP-B28 (TOP VIEW)
Part Number Marking
Part Number Marking
LOT Number
BD81A
44MUV
BD81A44EFV
LOT Number
1PIN MARK
1PIN MARK
Part Number Marking
BD81A44MUV
Package
VQFN28SV5050
HTSSOP-B28
Orderable Part Number
BD81A44MUV-ME2
BD81A44EFV
BD81A44EFV-ME2
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Physical Dimension Tape and Reel Information (BD81A44MUV-M)
Package Name
VQFN28SV5050
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Physical Dimension, Tape and Reel Information (BD81A44EFV-M)
Package Name
HTSSOP-B28
<Tape and Reel information>
Tape
Embossed carrier tape (with dry pack)
Quantity
2500pcs
E2
Direction
of feed
The direction is the 1pin of product is at the upper left when you hold
reel on the left hand and you pull out the tape on the right hand
(
)
Direction of feed
1pin
Reel
Order quantity needs to be multiple of the minimum quantity.
∗
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Revision History
Date
Revision
001
Changes
2016/1/13
New
P.9 Absolute Maximum Ratings PWM, SYNC and EN terminal.
Before : -0.3 to +7 < VCC
After : -0.3 to +7
P.10 Thermal Resistance
2016/4/26
002
003
2 internal layers / Copper Pattern, Bottom / Copper Pattern
Before : 74.2mm2(Square)
After : 74.2mm x 74.2mm
P.29 I/O Equivalence Circuit
Change RT, OUTL, OUTH and EN terminal.
2016/10/19
P.12 Change the PWM Frequency Limit Max value 15kHz to 20kHz.
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Notice
Precaution on using ROHM Products
(Note 1)
1. If you intend to use our Products in devices requiring extremely high reliability (such as medical equipment
,
aircraft/spacecraft, nuclear power controllers, 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 not designed 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-PAA-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-PAA-E
Rev.003
© 2015 ROHM Co., Ltd. All rights reserved.
Daattaasshheeeett
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.
Datasheet
Buy
BD81A44EFV-M - Web Page
Distribution Inventory
Part Number
Package
Unit Quantity
BD81A44EFV-M
HTSSOP-B28
2500
Minimum Package Quantity
Packing Type
Constitution Materials List
RoHS
2500
Taping
inquiry
Yes
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