Rohm BD60A00NUX-TR White backlight led drivers for small to medium lcd panels (switching regulator type) Datasheet

BD60A60NUX
LED Drivers for LCD Backlights
White Backlight LED Drivers
for Small to Medium LCD Panels
(Switching Regulator Type)
BD60A00NUX, BD60A60NUX
No.11040EAT42
●Description
This IC is boost DC/DC converter that can drive white LED with constant current. More stabled white LED lighting can be
achieved by direct current connection without electric tolerance and High-speed response by current mode. Moreover,
separating IC power supply (2.7V~5.5V) and coil power supply (2.3V~20V) makes it possible to widen input range, which
will be helpful to be applied to various kinds of applications. Over voltage setting can be selected corresponding to the
number of LED lightings. BD60A00NUX is for max 11 lightings, BD60A60NUX is for max 6 lightings.
●Features
1) Boost DC/DC converter
2) Drive LED 11 lightings (VOUT=3.6V×11+0.7V=40.3V <Vf MAX=3.7V>) BD60A00NUX
3) Brightness control by outside PWM signal (PWM frequency =100Hz~30kHz, 25kHz 1% dimming application)
4) Brightness control by DC input
5) Soft start function (1ms typ.)
6) Over voltage protection 42V typ. ( BD60A00NUX), 28Vtyp.( BD60A60NUX)
7) SBD open protection and output short protection
8) Over current protection
9) LED terminal over voltage protection
10) UVLO
11) VSON008x2030 package (2.0mm × 3.0mm × 0.6mm MAX)
●Applications
Digital video cameras, digital single-lens reflexes, digital still cameras, digital photo frames, personal navigations (PND),
mobile phones, smart phones, MID, PDA, hand-held computers, MP3 players, GPS, digital media players, etc.
●Absolute maximum ratings
Parameter
Symbol
Ratings
Unit
Maximum applied voltage 1
VMAX1
7
V
Maximum applied voltage 2
VMAX2
45
V
Maximum applied voltage 2
VMAX3
31
V
Operating temperature range
Topr
-40 ~ +85
℃
Storage temperature range
Tstg
-55 ~ +150
℃
Power dissipation 1
Pd1
2000
mW
*1
Condition
Vin, EN, PWM, ISET terminals
FB, SW, Vout terminals
BD60A00NUX
FB, SW, Vout terminals
BD60A60NUX
*1
4 layer (ROHM Standard board) has been mounted. When it’s used by more than Ta=25℃, it’s reduced by 20mW/˚C.
●Recommended operating range (Ta=-40℃ ~ +85℃)
Parameter
Symbol
Ratings
Unit
Conditions
Operating power supply voltage
VIN
2.7 ~ 5.5 *
V
Vin terminal
Operating coil voltage
Vcoil
2.3 ~ 20
V
Coil voltage
*When the operating supply voltage is over 4.61V for BD60A00NUX, please refer the application P.17
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© 2011 ROHM Co., Ltd. All rights reserved.
1/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
●Electrical characteristics (Unless otherwise specified, Ta=25℃, Vin=3.6V)
Limits
Parameter
Symbol
Min.
Typ.
Max.
Quiescent Current
Unit
Conditions
Iq
-
0.1
1.0
μA
EN=0V
IddNB
-
1.5
3.0
mA
EN=2.8 V, PWM=0V
IddB
-
2.5
5.0.
mA
EN=2.8 V, PWM=2.8 V
Low Input Voltage range
VthL
-
-
0.5
V
High Input Voltage range
VthH
1.4
-
-
V
Pull down register
Rcnt
65
100
135
kΩ
FB Terminal Control Voltage
FB
0.56
0.70
0.84
V
Switching Frequency
fSW
-
600
-
kHz
Max Duty
Duty
90
95
-
%
FB=0V
SW Transistor ON Resistor
Ronn
-
0.5
-
Ω
Isw=80mA
SW Transistor Leak Current
IqSW
-
0.1
2.0
μA
EN=0V
Icoil
-
750
-
mA
*1
OVP1
40
42
44
V
Detect voltage of VOUT terminal
OVP2
26
28
30
V
Detect Voltage of VOUT terminal
Over Voltage Limit Hysteresis
OVPhy
-
1
-
V
VOUT Terminal Leak Current
IqVOUT
-
0.1
1.0
μA
EN=0V
Sop
-
0.2
-
V
Detect Voltage of VOUT terminal
LEDOVP
4.4
5.9
6.4
V
PWM=2.8V
UVLO
-
2.2
-
V
Vin falling edge
LED Maximum Current
ILMAX
-
-
30
mA
LED Current Accuracy
ILACCU
-
-
±3.0
%
LED Current Limit
ILOCP
-
0
0.1
mA
Current Limit Value at
ISET Resistor 1kΩ Setting
LED Leak Current
IqLED
-
0.1
2.0
μA
EN=0V
Iset
-
0.6
-
V
Current Consumption
(No Boost)
Current Consumption (Boost)
[EN, PWM Terminal]
[Switching Regulator]
[Protection]
Over Current Limit
Over Voltage Limit
BD60A00NUX
Over Voltage Limit
BD60A60NUX
Shot key Diode Open Protection
LED Terminal
Over Voltage Protection
Detect Voltage of Low Voltage
[Current Driver]
ISET Terminal Voltage
*1
VIN=4V, Cout=1µF
ILED=20mA
This parameter is tested with DC measurement.
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© 2011 ROHM Co., Ltd. All rights reserved.
2/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
●Block Diagram and Application
L1
10μH
Coil Power
2.3V to 20V
11 LEDs
Cout
2.2.μF
D1
Cbat
4.7μF
IC Power
2.7V to 5.5V
VOUT
SW
Thermal
Shutdown
Vin
+
-
TSD
Cin
1μF
Over & under Voltage Protect
UVLO
PWMcomp
S
Q
Q1
ERRAMP
+
Control
R
Current
Sense
+
FB
+
Current
OSC
ISET
Driver
Over Current
protect
EN
PWM
GND
Enable control
PWM control
Fig.1 Block Diagram and Application
・Pin assignment table
PIN No.
PIN Name
In/Out
Function
Terminal Diagram
1
EN
In
Enable Control
B
2
VIN
In
Battery Input
C
3
PWM
In
PWM Input
B
4
ISET
In
LED Current Setting Terminal
A
5
FB
In
Feedback Voltage Input
B
6
VOUT
In
Over Voltage Protection Input
B
7
GND
-
GND
C
8
SW
Out
Switching Terminal
B
●Terminal Diagram
Vin
Vin
P IN
P IN
GND
G ND
A
GND
B
C
Fig.2 Terminal Diagram
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© 2011 ROHM Co., Ltd. All rights reserved.
3/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
●Main characteristics examples
1) Efficiency
●BD60A60NUX <efficiency – ILED>
LED 6series, coil : VLF302512MT-100M
●BD60A00NUX <efficiency – ILED>
LED 10series, coil : VLF302512MT-100M coil : VLF302512MT-100M
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4/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
IC Power=5.0V, Coil Power=4V to 16V
・BD60A00NUX
IC Power=5.0V, Coil Power=2.7V to 20V, LED 8serial, LED current =25mA,
coil 1094AS-10M(TOKO), SBD RB060M-60TR(ROHM)
95
eff1
eff2
90
efficiency (%)
BD60A00NUX Vcoil vs efficiency
VIN=5V Ta=25℃
LED 8灯(26V)
coil 1094AS-10M(TOKO)
SBD RB060M-60TR(ROHM)
LED電流設定 25mA
PWM=100%
85
eff1=(Vout*ILED)/(Vcoil*Icoil)*100
eff2=(Vout*ILED)/(Vcoil*Icoil+VIN+IVIN)*100
80
75
70
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Vcoil (V)
・BD60A60NUX
IC Power=5.0V, Coil Power=2.7V to 20V, LED 6serial, LED current =25mA,
coil 1094AS-10M(TOKO), SBD RB521A-40TR(ROHM)
95
BD60A60 Vcoil vs efficiency
VIN=5V Ta=25℃
LED 6灯(20V)
coil 1094AS-10M(TOKO)
SBD RB521S-40(Rohm) for BD60A60
LED電流設定 25mA
PWM=100%
90
efficiency (%)
eff=(Vout*ILED)/(Vcoil*Icoil+VINI*VIN)*100
85
80
75
70
2
3
4
5
6
7
8
9
10
11
12
13
14
Vcoil (V)
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© 2011 ROHM Co., Ltd. All rights reserved.
5/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
100mV/div
VOUT
LED current
PWM
PWM 20kHz Duty 50%
40µs/div
100mV/div
VOUT
LED current
PWM
200ns/div
PWM 20kHz Duty 1%
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© 2011 ROHM Co., Ltd. All rights reserved.
6/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
・BD60A00NUX PWM duty – LED current
IC Power=5.0V, LED 8serial, LED current =25mA, PWM frequency = 20kHz, Ta=25deg
coil 1094AS-10M(TOKO), SBD RB060M-60TR(ROHM)
100.00
BD60A00NUX Vcoil vs efficiency
VIN=5V Ta=25℃
LED 8 灯(26V)
coil 1094AS-10M(TOKO)
SBD RB060M-60TR(ROHM)
LED current 25mA
PWM frequency 20kHz
LED current (mA)
10.00
1.00
0.10
0.01
0.1
1.0
0.4%
10.0
100.0
PWM duty (%)
Possible to Duty 0.4% at PWM=20kHz
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7/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
●Functional Descriptions
1) PWM current mode DC/DC converter
This IC keeps output voltage invariably by setting PWM duty to make FB terminal 0.7V when the power is on. As for the
inputs of the PWM comparator as the feature of the PWM current mode, one is overlapped with error components from
the error amplifier, and the other is overlapped with a current sense signal that controls the inductor current into Slope
waveform to prevent sub harmonic oscillation. This output controls internal Nch Tr via the RS latch. In the period where
internal Nch Tr gate is ON, energy is accumulated in the external inductor, and in the period where internal Nch Tr gate
is OFF, energy is transferred to the output capacitor via external SBD.
This IC has many safety functions, and their detection signals stop switching operation at once.
2)
Soft Start
This IC has soft start function, which prevents rush current at turning on.
After EN and PWM are changed L H, soft start becomes effective within 1ms. Soft start doesn't become effective
even if Enable is changed L H, after that. By changing EN and PWM L H, soft start can become effective.
Since a soft start function stops working at the time of following PWM=H when EN=H is held with PWM=L
After EN=H should input a PWM signal within 10ms.
EN
EN
Soft start time Finish
PWM
PWM
Soft Start OFF
Soft Start
Reset
Within 10ms
ON
OFF
ON
OFF
OFF
OFF
Reset
ON
OFF
Reset
Fig.3 Soft start
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8/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
●Protection
・Over voltage protection
At such an error of output open as the output DC/DC and the LED is not connected to IC, the DC/DC boosts too much
and the VOUT terminal exceeds the absolute maximum ratings, and may destruct the IC. Therefore, when the VOUT
becomes sensing voltage or higher, the over voltage limit protection works, turns off the switching Tr, DC/DC will be
stopped, and the output voltage goes down slowly. When output voltage becomes below the hysteresis voltage of Over
voltage protection, A boost function works and output voltage reaches detection voltage again.
This operation is repeated unless the abnormalities in application are recovered.
・Schottky Diode open protection
In the case of external SBD is not connected to IC, or VOUT is shorted to GND, the coil or internal Tr may be destructed.
Therefore, at such an error as VOUT becoming 0.2V or below, turns off the output Tr, and prevents the coil and the IC
from being destructed.
And the IC changes from activation into non-activation, and current does not flow to the coil (0mA).
・Thermal shut down
This IC has thermal shut down function.
The thermal shut down works at 175C or higher, and the IC changes from activation into non-activation.
・Over Current Protection
Over current flows the current detection resistor that is connected to between internal switching transistor source and
GND. Current sense voltage turns more than detection voltage, over current protection is operating and it is prevented
from flowing more than detection current by reducing ON duty of switching Tr without stopping boost.
As over current detector of This IC is detected peak current, current more than over current setting value does not flow.
SW
+
-
< The estimate of the current value which need for the normal operation>
As over current detector of This IC is detected the peak current, it has to estimate peak current to flow to the coil by
operating condition.
In case of,
○ Switching frequency = fsw
Typ=0.6MHz
○ Supply voltage of coil = VIN
○ Inductance value of coil = L
○ Output voltage = VOUT
○ Total LED current = IOUT
○ Average current of coil = Iave
○ Peak current of coil = Ipeak
○ Efficiency = eff
○ ON time of switching transistor = Ton
Ipeak = (VIN / L) × (1 / fsw) × (1-(VIN / VOUT))
Iave=(VOUT × IOUT / VIN) / eff
1/2
Ton=(Iave × (1-VIN/VOUT) × (1/fsw) × (L/VIN) × 2)
As peak current varies according to whether there is the direct current superposed, the next is decided.
(1-VIN/VOUT) × (1/fsw) < Ton
peak current = Ipeak /2 + Iave (continuous mode CCM)
(1-VIN/VOUT) × (1/fsw) > Ton
peak current = (VIN / L)×Ton (discontinuous mode DCM)
(Example 1)
In case of, VIN=6.0V, L=10µH, fsw=0.6MHz, VOUT=32.5V, IOUT=25mA, current =85%
Ipeak = (6.0V / 10µH) × (1 / 0.6MHz) × (1-(6.0V / 32.5V)) =0.82 A
Iave = (32.5V × 25mA / 6.0V) / 85% = 0.16A
Ton = (0.16A × (1-6.0V / 32.5V) × (1 / 0.75MHz) × (10µH /6.0V) × 2)1/2 = 0.85µs
(1- VIN/VOUT) × (1/fsw)=1.36µs > Ton
peak current = (6.0V / 10µH)×0.85µs =0.51A
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9/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
・LED terminal over voltage protection
When FB terminal becomes higher than 5.9V(typ), IC senses the situation trouble after 100us and then stops constant
current driver and DC/DC. Therefore IC becomes never heated, even if output and FB are both shorted. Moreover, if FB
terminal becomes lower than 5.9V(typ), IC senses normal condition and activates constant current driver.
FB
5.9 V
0V
Current Driver
DC/DC
Active
reset
Active
Active
Active
Active
・Prevention of LED terminal over voltage protection malfunction
As the below diagrams show, voltage drop of FB terminal becomes slow when PWM operates by connecting capacitor on
a parallel with LED and decreasing LED current. At that time, LED terminal voltage protection works after condition of FB
terminal > 5.9V keeps more than 100us. LED terminal voltage protection might stop current driver and DC/DC and also
turns off LEDs, so that please set up coil selection and LED current setting less than 100us until FB terminal < 5.9V.
FB
100us
VOUT
Current Driver
DC/DC
5.9 V
reset
Active
reset
reset
Active
reset
FB
PWM
H
L
EN
H
L
・Low voltage detect protection (UVLO)
Supply voltage(VIN) becomes lower than low voltage detect voltage 2.2V(typ), IC stops DC/DC and constant current
driver. Moreover, this function can be off by boosting supply voltage up to more than hysteresis voltage.
VIN
5%
2.20 V
2.32 V
0V
DC/DC
Current Driver
Active
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© 2011 ROHM Co., Ltd. All rights reserved.
reset
10/22
Active
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
●Operating of the application deficiency
1) When 1 LED or 1string OPEN during the operating
Since FB terminal is set to 0V when set to OPEN, Output boosts up to the over voltage protection voltage. When over
voltage is detected, the boosting operation stops and then output voltage goes down slowly. Later, if output voltage
becomes less than hysteresis of over current protection, output voltage keeps boosting up to over voltage protection
voltage again.
Vout
Hysteresis voltage
FB voltage
FB
LED
connection
normal
Open
LED current
20mA
0mA
Fig. 8 LED open detect
2)
When LED short-circuited in the plural
Even if one LED short-circuits during boost operation, it usually passes along LED and it is turned on. By making LED
shorted, FB terminal voltage increases by LED VF. Therefore output voltage becomes lower by LED VF, and the
condition turns to be normal.
VOUT
output
VF of LED
LED short
0.7V+VF of LED
FB
FB 0.7V
LED current
VF of LED
20mA
Fig. 9 One LED shorted
VOUT
VOUT
VIN
LED short
5.9V
FB 0.7V
FB
0.1mA
LED current 20mA
100uS
Fig.10 FB terminal – VOUT terminal shorted
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11/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
3)
When Schottky diode(SBD) remove
In the situation that connection is opened and also DC/DC is activated, SW terminal voltage becomes more than rated
voltage due to a lack of parts that can accept the current accumulated inside the coil. Consequently IC might be
destroyed. To prevent the IC destruction, SBD open protection is functioned. SW terminal is never destroyed as
boosting operation is stopped after VOUT terminal detects less than 0.2V.
4)
When resistance linked to an ISET terminal short-circuits
Since Resistor connected to ISET terminal becomes 0Ω, LED current setting value becomes more than rating. In order
to avoid this trouble, this IC has LED current limit protection. By using this function, setting current of rating current
driver becomes 0mA, and the current flow of LED is almost same as leak current.
●Control signal input timing
2.2V
①
VIN
VIN
②
Min. 100µs
③
EN
EN
PWM
PWM
DC/DC VOUT
DC/DC VOUT
Min. 10ms
Fig.11 Control signal input timing
When input control signals such as Enable and PWM without completing the standup of supply voltage (VIN), be
careful of the following points.
① Input each control signal after VIN exceeds 2.2V and UVLO is off.
② When input Enable and PWM, the standup time should be placed as Min.100µs from 2.2V to stable voltage for
VIN.
③ Since a soft start function stops working at the time of following PWM=H when EN=H is held with PWM=L.
After EN=H should input a PWM signal within 10ms.
●Start control (EN) and select LED current driver (PWM)
This IC can control the IC system by EN terminal and also turns off compulsorily by setting “L” level input voltage 0.4V or
below. It also powers on when EN becomes more than “H” level input voltage 1.4V. In the case of EN=H, LED current fixed
by ISET resistor with PWM=H flows. When it is selected at PWM=L, LED current stop to flow.
EN
L
H
L
H
PWM
L
L
H
H
IC
Off
On
Off
On
LED current
Off
Off
Off
Current fixed by ISET
●LED current setting range
LED current sets up normal current by resister (RISET) connected to ISET voltage.
Each setting current is shown as below.
Normal current = 600/RISET [A]
Normal current setting range is 10mA~30mA, and also LED current at off setting is MAX 2µA of leak current.
ISET Normal current setting example
RISET
20.0kΩ (E96)
24.0kΩ (E24)
30.0kΩ (E24)
56.0kΩ (E24)
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© 2011 ROHM Co., Ltd. All rights reserved.
LED current
30.0mA
25.0mA
20.0mA
10.7mA
12/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
●Brightness control
There are two dimming method available; the first method is analog dimming that applies analog voltage to ISET terminal,
and the second method is digital dimming that inputs PWM to PWM terminal. Since each method has the different merits,
please choose a suitable method for the application of use.
Current driver PWM control is controlled by providing PWM signal to PWM, as it is shown Fig.12.
The current set up with ISET is chosen as the H section of PWM and the current is off as the L section. Therefore, the
average LED current increases in proportion to duty cycle of PWM signal. This method that internal circuit and DC/DC
work, because it becomes to switch the driver, the current tolerance is a few when the PWM brightness is adjusted, so
it makes it possible to brightness control until 0.4µs (MIN1% at 25kHz). And, don't use for the brightness control,
because effect of ISET changeover is big under 0.4µs ON time and under 3µs OFF time. Typical PWM frequency is
100Hz~25kHz.
L1
10μH
Vin
2.7V to 4.6V
30
Cout
2.2μF
Cin
4.7μF
25
Vin
PWM Input
SW
Vout
25mA
PWM
RESET
EN
FB
ISET
R1
24kΩ
GND
LED Current [mA]
1)
20
15
10
5
PWM
ON
OFF
LED current
ON
OFF
Coil current
ON
OFF
0
0
20
40
60
80
PWM Hi duty [%]
100
ON
IC’s active current
Fig.12 PWM sequence
Analog dimming can be operated by applying voltage to ISET terminal via resistor as the below figure shows. ISET
terminal voltage works to become 0.6V regardless of the connected resistor. LED current increases ISET terminal
current 600 times, so that LED current can be minimized by decreasing flow current into ISET terminal using external
DC input
Vin
2.7V to 4.6V
L1
10μH
Cout
2.2μF
Cin
4.7μF
30
Vin
LED ON/OFF
RESET
25
EN
FB
ISET
R1
470kΩ
Vout
PWM
R2 22kΩ
DC
SW
LED Current [mA]
2)
GND
20
15
10
5
1000
1000 x 0.6V
+
0.6V - DAC output
LED current =
22kΩ
470kΩ
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
DC Voltage [V]
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13/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
3)
The brightness control to set large current over IC max setting current is made by giving DC control voltage to VFB pin
of IC via a series resistor as shown in under figure. LED luminance (current) changed by giving DC voltage to VFB
directly. DC voltage is given from filtered one of DAC signal, or PWM signal shown in under figure.
LED current (ILED) is next expression.
ILED = [[(FB-DC) / R1] * R2 + FB ] / RFB
L1
10μH
BD60A60NUX 3LEDx7pararel
Cout
2.2μF
Cin
4.7μF
Vin
3s7p
Vout
SW
PWM
RESET
R2
6.8kΩ
EN
FB
ISET
R1
22kΩ
GND
RFB
6.49Ω
ILED total (mA)
Vin
2.7V to 4.6V
DC
DC (V)
Vin
2.7V to 4.6V
L1
10μH
Cout
2.2μF
Cin
4.7μF
Vin
3s7p
Vout
SW
PWM
RESET
EN
33kΩ
FB
ISET
47kΩ
GND
5Ω
100kΩ
PWM
0 - 3.3V
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© 2011 ROHM Co., Ltd. All rights reserved.
47nF
14/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
●The coil selection
The DC/DC is designed by more than 4.7µH. When L value sets to a lower value, it is possibility that the specific
sub-harmonic oscillation of current mode DC / DC will be happened.
Please do not let L value to 3.3µH or below.
And, L value increases, the phase margin of DC / DC becomes to zero. Please enlarge the output capacitor value when you
increase L value.
●Output capacitor selection
Output Capacitor smoothly keeps output voltage and supplies LED current.
If LED current is set more than 20mA with Vcoil=2.3V~5.5V, please make output capacitor more than 2.2µF. Otherwise
phase margin of DC/DC decreases and might oscillate.
Output Voltage consists of Charge (FET ON) and Discharge (LED current). So Output voltage has Output ripple Voltage
every FET switching.
Output ripple voltage is calculated as following.
Output ripple Voltage
- Switching cycle = T
- Total LED current = ILED
- Switching ON duty = D
- Output ripple Voltage = Vripple
- Output Capacitor (real value) = Creal
- Output Capacitor = COUT
- Decreasing ratio of Capacitor = Cerror
(Capacitor value is decreased by Bias, so)
Creal = COUT × Cerror
Creal = ILED × (1-D) × T / Vripple
COUT = ILED × (1-D) × T / Vripple / Cerror
(Example 1)
In case of, VIN=5.0V, fsw = 0.6MHz, VOUT =32.5V, ILED =20mA, COUT = 2.2µF, Cerror = 50%
T = 1 / 0.6MHz
D = 1 – VIN / VOUT = 1 – 5/32.5
Vripple
= ILED × (1-D) × T / (COUT×Cerror) = 20mA × (5/32.5) ×(1 / 0.6MHz) / (2.2µF×0.5)
= 4.7mV
Cout
Capa [µF]
Creal
0V
35V
50V
Output voltage
●LED selection
Please select LED VF that input voltage is smaller than output voltage (VOUT).
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© 2011 ROHM Co., Ltd. All rights reserved.
15/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
●The separation of the IC power supply and coil power supply
This IC can work in separating the power source in both IC power supply and coil power supply. With this application, it can
obtain that decrease of IC power consumption, and the applied voltage exceeds IC rating 5.5V.
That application is shown in below Fig.14. The coil power supply is connected to high voltage source applied from adapters.
Then the IC power supply is connected to the power supply that should be different from the coil power supply.
2,3cell Battery
Coil Power
2.3V to 20V
L1
10μH
IC Power
2.7V to 4.6V
Step down
DC/DC
Ccoil
4.7μF
Cout
2.2μF
Cin
1μF
Vin
PWM Input
SW
Vout
25mA
PWM
RESET
EN
FB
ISET
R1
24kΩ
GND
Fig.14 Application at the time of power supply separation
1cell Battery
L1
10μH
IC Power
2.3V to 4.6V
Cout
2.2μF
Cin
4.7μF
Vin
PWM Input
SW
Vout
25mA
PWM
RESET
EN
FB
ISET
R1
24kΩ
GND
Fig.15 Application at the time of power supply common
The number of available LEDs by each power supply voltage condition
PWM dimming(LED current setting=25mA)
2セル
1セル
VIN
LEDs
2.7V
3V
3セル
4V
5V
6V
7V
2
C、S C、S C、S C、S
×
×
3
C、S C、S C、S C、S
S
S
4
C、S C、S C、S C、S
S
S
5
C、S C、S C、S C、S
S
S
6
C、S C、S C、S C、S
S
S
7
C、S C、S C、S C、S
S
S
8
C、S C、S C、S C、S
S
S
9
C、S C、S C、S C、S
S
S
10
C、S C、S C、S C、S
S
S
※ C・・・Vcoil-Vin common power supply
S・・・Vcoil-Vin separated power supply
×・・・No use due to LED terminal over voltage protection
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© 2011 ROHM Co., Ltd. All rights reserved.
8V
9V
10V
11V
12V
13V
14V
15V
16V
17V
18V
19V
20V
×
×
S
S
S
S
S
S
S
×
×
S
S
S
S
S
S
S
×
×
S
S
S
S
S
S
S
×
×
×
S
S
S
S
S
S
×
×
×
S
S
S
S
S
S
×
×
×
×
S
S
S
S
S
×
×
×
×
S
S
S
S
S
×
×
×
×
×
S
S
S
S
×
×
×
×
×
S
S
S
S
×
×
×
×
×
×
S
S
S
×
×
×
×
×
×
×
S
S
×
×
×
×
×
×
×
S
S
×
×
×
×
×
×
×
×
S
16/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
●About the order of a power supply injection at the time of power supply separation
Even if the IC power supply is 0V, leak channel is blocked as pull down resistor for power off is placed inside the
IC. The resistor intercepts leak channel from coil power supply. Additionally, there is no order for standing up and down of
coil and IC power supply.
At the time of starting
It doesn’t matter whether coil Power or IC Power becomes activated first.
・ At the time of power supply OFF
Please turn off after make EN terminal “L”. If power supply voltage of coil power becomes low, coil current increases
due to high boosting, which leads to over current limit. In order to avoid this state, before turning off a power supply
it is necessary to surely set EN to L.
・
Coil Power
Free
IC Power
EN
PWM
VOUT
●Input voltage 5V(BD60A00NUX)
The GND noise become big by impedance of PCB boards, so that wake up characteristics might become unstable.
To select input voltage to 5V(input voltage 4.61V over), we recommend under application to insert 4.7Ω
between input voltage line and Vin terminal
L1
10μH
Vin
2.7V to 5.5V
Cin
4.7μF
PWM Input
Cout
2.2μF
4.7Ω
Vin
SW
Vout
25mA
PWM
RESET
EN
FB
RISET
24kΩ
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© 2011 ROHM Co., Ltd. All rights reserved.
ISET
GND
17/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
●PCB Layout
In order to make the most of the performance of this IC, its PCB layout is very important. Characteristics such as efficiency
and ripple and the likes change greatly with PCB layout, which please note carefully
Vin
2.7V to 4.6V
L1
10μH
Cout
2.2μF
Cin
4.7μF
PWM Input
Vin
SW
Vout
25mA
PWM
RESET
EN
FB
RISET
24kΩ
ISET
GND
<Input capacitor Cin (1μF) for coil>
Connect input capacitor Cin (1μF) as close as possible between coil L1 and GND.
<Schottky barrier diode SBD>
Connect schottky barrier diode SBD as close as possible between coils L1and SW pin.
<Output capacitor Cout>
Connect output capacitor Cout between cathode of SBD and GND.
Make both GND sides of Cin and Cout as close as possible.
<LED current setting resistor RISET(24kΩ)>>
Connect LED current setting resistor RISET(24kΩ) as close as possible between ISET pin and GND.
There is possibility to oscillate when capacity is added to ISET terminal, So pay attention that capacity isn’t added.
<Heat radiation of back side PAD>
PAD is used for improving the efficiency of IC heat radiation. Solder PAD to GND pin.
Moreover, connect ground plane of board using via as shown in the patterns of next page.
The efficiency of heat radiation improves according to the area of ground plane.
<Others>
When those pins are not connected directly near the chip, influence is give to the performance of BD60A00NUX, and
may
limit the current drive performance. As for the wire to the inductor, make its resistance component small so as to
reduce electric power consumption and increase the entire efficiency.
The PCB layout in consideration of these is shown in the next page.
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18/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
● Recommended PCB layout
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© 2011 ROHM Co., Ltd. All rights reserved.
19/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
●Selection of external parts
Recommended external parts are as shown below.
When to use other parts than these, select the following equivalent parts.
L1: This coil is for boosting. Recommended capacity value is 10uH. Please use the coil with adequate direct current
capacity and also low direct current resistor.
Value
Manufacturer
Product number
10µH
10µH
10µH
10µH
TDK
TDK
TOKO
TOKO
VLF4012AT-100MR79
VLF302512MT-100M
1094AS-100M
1229AS-H-100M
Vertical
4.0
3.0
3.5
3.5
Size
Horizontal
3.8
2.5
3.7
3.7
Height
1.2
1.2
1.2
1.2
DC current
(mA)
800
690
760
750
DCR
(Ω)
0.30
0.25
0.18
0.24
Cin: This is bypath capacitor for power supply, which removes power supply noise occurred instantly and provides stable
power supply for IC. In order to obtain better quality, please use low ESR products such as ceramic capacitors.
Recommended capacity value is more than 1µF.
C0: This is output smoothing capacitor. Recommended capacity value is 2.2µF.
When choosing capacitors such as Cin and C0, please be careful of pressure. The base line of pressure is about 2 times of
actual applying voltage. If pressure margin decreases, it might be happened that capacity value becomes almost a half of
nominal value.
Pressur Manufactur
Product number
e
e
[ Cin : Power supply voltage capacitor]
1.0µF
10V.
MURATA
GRM185B31A105
[ C0 : Output capacitor ]
1.0µF
50V
MURATA
GRM31MB31H105
2.2µF
50V
MURATA
GRM31CB31H225
Value
Vertical
Size
Horizontal
Height
1.6.
0.8.
0.5.
3.2
3.2
1.6
1.6
1.15
1.6
R1: LED current ILED should be decided when activated.
Value
Tolerance
Manufacturer
Product number
[ R1 : Resistor used for deciding LED current]
20kΩ
±0.5%
ROHM
MCR03PZPZD2002
24kΩ
±0.5%
ROHM
MCR03PZPZD2402
30kΩ
±0.5%
ROHM
MCR03PZPZD3002
56kΩ
±0.5%
ROHM
MCR03PZPZD5602
Vertical
Size
Horizontal
Height
1.6
1.6
1.6
1.6
0.8
0.8
0.8
0.8
0.45
0.45
0.45
0.45
ILED (mA)
30
25
20
10.7
D1: This schottky diode (SBD) is for output rectification. In order to obtain higher switching efficiency, please use low Vf, low
reverse leak, and high current capacity.
Size
Pressure
Manufacturer
Product Number
Vertical
Horizontal
Height
60V
ROHM
RB160M-60
3.5
1.6
0.8
40V
ROHM
RB521S-40
1.6
0.8
0.6
60V
ROHM
RB060M-60
3.5
1.6
0.8
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© 2011 ROHM Co., Ltd. All rights reserved.
20/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
●Cautions on use
(1) Absolute Maximum Ratings
An excess in the absolute maximum ratings, such as supply voltage (Vin), temperature range of operating conditions
(Topr), etc., can break down devices, thus making impossible to identify breaking mode such as a short circuit or an
open circuit. If any special mode exceeding the absolute maximum ratings is assumed, consideration should be given
to take physical safety measures including the use of fuses, etc.
(2) Operating conditions
These conditions represent a range within which characteristics can be provided approximately as expected. The
electrical characteristics are guaranteed under the conditions of each parameter.
(3) Reverse connection of power supply connector
The reverse connection of power supply connector can break down ICs. Take protective measures against the
breakdown due to the reverse connection, such as mounting an external diode between the power supply and the IC’s
power supply terminal.
(4) Power supply line
Design PCB pattern to provide low impedance for the wiring between the power supply and the GND lines.
Furthermore, for all power supply terminals to ICs, mount a capacitor between the power supply and the GND terminal.
At the same time, in order to use an electrolytic capacitor, thoroughly check to be sure the characteristics of the
capacitor to be used present no problem including the occurrence of capacity dropout at a low temperature, thus
determining the constant.
(5) GND voltage
Make setting of the potential of the GND terminal so that it will be maintained at the minimum in any operating state.
Furthermore, check to be sure no terminals are at a potential lower than the GND voltage including an actual electric
transient.
(6) Short circuit between terminals and erroneous mounting
In order to mount ICs on a set PCB, pay thorough attention to the direction and offset of the ICs. Erroneous mounting
can break down the ICs. Furthermore, if a short circuit occurs due to foreign matters entering between terminals or
between the terminal and the power supply or the GND terminal, the ICs can break down.
(7) Operation in strong electromagnetic field
Be noted that using ICs in the strong electromagnetic field can malfunction them.
(8) Inspection with set PCB
On the inspection with the set PCB, if a capacitor is connected to a low-impedance IC terminal, the IC can suffer stress.
Therefore, be sure to discharge from the set PCB by each process. Furthermore, in order to mount or dismount the set
PCB to/from the jig for the inspection process, be sure to turn OFF the power supply and then mount the set PCB to
the jig. After the completion of the inspection, be sure to turn OFF the power supply and then dismount it from the jig. In
addition, for protection against static electricity, establish a ground for the assembly process and pay thorough attention
to the transportation and the storage of the set PCB.
(9) Input terminals
In terms of the construction of IC, parasitic elements are inevitably formed in relation to potential. The operation of the
parasitic element can cause interference with circuit operation, thus resulting in a malfunction and then breakdown of
the input terminal. Therefore, pay thorough attention not to handle the input terminals, such as to apply to the input
terminals a voltage lower than the GND respectively, so that any parasitic element will operate. Furthermore, do not
apply a voltage to the input terminals when no power supply voltage is applied to the IC. In addition, even if the power
supply voltage is applied, apply to the input terminals a voltage lower than the power supply voltage or within the
guaranteed value of electrical characteristics.
(10) Ground wiring pattern
If small-signal GND and large-current GND are provided, It will be recommended to separate the large-current GND
pattern from the small-signal GND pattern and establish a single ground at the reference point of the set PCB so that
resistance to the wiring pattern and voltage fluctuations due to a large current will cause no fluctuations in voltages of
the small-signal GND. Pay attention not to cause fluctuations in the GND wiring pattern of external parts as well.
(11) External capacitor
In order to use a ceramic capacitor as the external capacitor, determine the constant with consideration given to a
degradation in the nominal capacitance due to DC bias and changes in the capacitance due to temperature, etc.
(12) Thermal shutdown circuit (TSD)
When junction temperatures become 175℃ (typ) or higher, the thermal shutdown circuit operates and turns a switch
OFF. The thermal shutdown circuit, which is aimed at isolating the LSI from thermal runaway as much as possible, is
not aimed at the protection or guarantee of the LSI. Therefore, do not continuously use the LSI with this circuit
operating or use the LSI assuming its operation.
(13) Thermal design
Perform thermal design in which there are adequate margins by taking into account the permissible dissipation (Pd) in
actual states of use.
(14) Selection of coil
Select the low DCR inductors to decrease power loss for DC/DC converter.
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21/22
2011.12 - Rev.A
Technical Note
BD60A00NUX, BD60A60NUX
●Ordering part number
B
D
6
ROHM
type name
0
A
0
0
N
U
X
-
Package
NUX: VSON008X2030
Part No.
BD60A00:60A00
BD60A60:60A60
T
R
Packaging and forming specification
TR: Embossed tape and reel
VSON008X2030
<Tape and Reel information>
3.0±0.1
2.0±0.1
0.6MAX
1PIN MARK
0.25
TR
The direction is the 1pin of product is at the upper right when you hold
( reel on the left hand and you pull out the tape on the right hand
)
(0.12)
+0.03
0.02 −0.02
1.5±0.1
4000pcs
0.5
1
4
8
5
1.4±0.1
0.3±0.1
C0.25
Embossed carrier tape
Quantity
Direction
of feed
S
0.08 S
Tape
1pin
+0.05
0.25 −0.04
Reel
(Unit : mm)
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22/22
Direction of feed
∗ Order quantity needs to be multiple of the minimum quantity.
2011.12 - Rev.A
Notice
Notes
No copying or reproduction of this document, in part or in whole, is permitted without the
consent of ROHM Co.,Ltd.
The content specified herein is subject to change for improvement without notice.
The content specified herein is for the purpose of introducing ROHM's products (hereinafter
"Products"). If you wish to use any such Product, please be sure to refer to the specifications,
which can be obtained from ROHM upon request.
Examples of application circuits, circuit constants and any other information contained herein
illustrate the standard usage and operations of the Products. The peripheral conditions must
be taken into account when designing circuits for mass production.
Great care was taken in ensuring the accuracy of the information specified in this document.
However, should you incur any damage arising from any inaccuracy or misprint of such
information, ROHM shall bear no responsibility for such damage.
The technical information specified herein is intended only to show the typical functions of and
examples of application circuits for the Products. ROHM does not grant you, explicitly or
implicitly, any license to use or exercise intellectual property or other rights held by ROHM and
other parties. ROHM shall bear no responsibility whatsoever for any dispute arising from the
use of such technical information.
The Products specified in this document are intended to be used with general-use electronic
equipment or devices (such as audio visual equipment, office-automation equipment, communication devices, electronic appliances and amusement devices).
The Products specified in this document are not designed to be radiation tolerant.
While ROHM always makes efforts to enhance the quality and reliability of its Products, a
Product may fail or malfunction for a variety of reasons.
Please be sure to implement in your equipment using the Products safety measures to guard
against the possibility of physical injury, fire or any other damage caused in the event of the
failure of any Product, such as derating, redundancy, fire control and fail-safe designs. ROHM
shall bear no responsibility whatsoever for your use of any Product outside of the prescribed
scope or not in accordance with the instruction manual.
The Products are not designed or manufactured to be used with any equipment, device or
system which requires an extremely high level of reliability the failure or malfunction of which
may result in a direct threat to human life or create a risk of human injury (such as a medical
instrument, transportation equipment, aerospace machinery, nuclear-reactor controller, fuelcontroller or other safety device). ROHM shall bear no responsibility in any way for use of any
of the Products for the above special purposes. If a Product is intended to be used for any
such special purpose, please contact a ROHM sales representative before purchasing.
If you intend to export or ship overseas any Product or technology specified herein that may
be controlled under the Foreign Exchange and the Foreign Trade Law, you will be required to
obtain a license or permit under the Law.
Thank you for your accessing to ROHM product informations.
More detail product informations and catalogs are available, please contact us.
ROHM Customer Support System
http://www.rohm.com/contact/
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R1120A
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