Datasheet
LED driver IC series for Automotive lamps
LED Driver with Built-in PWM Signal
Generation Circuit
BD18351EFV-M
Key Specifications
General Description
Input Voltage Range:
4.5 V to 65 V
Output Voltage Range:
6.0 V to 65 V
Absolute Maximum Input / Output Voltage:
70 V
Minimum PWM Dimming Pulse Width:
50 µs
BD18351EFV-M is an LED driver with built-in 1ch boost
controller. It is an optimal IC for LED drive for head lamp /
DRL, tail lamp and turn lamp capable of realizing boost
and buck boost with high-side detection of LED current
setting against output voltage.
Further, cost saving and downsizing of the set can be
realized, since it contains CRTIMER which enables PWM
dimming without microcomputer for applications requiring
PWM dimming of DRL, etc.
Features
AEC-Q100 Qualified (Note 1)
Built-in Switching DC / DC Controller.
LED Current Setting High Side Detection Method
LED Current Precision: ±3.0% (–40 °C to 125 °C)
PWM Signal Generation Circuit with Built-in
CRTIMER (External PWM Dimming Control is
possible.)
Built-in Spread Spectrum Function
Built-in LED Open Detection Function
Built-in LED Anode to Ground Short Function
Package
W(Typ) × D(Typ) × H(Max)
HTSSOP-B24
7.80 mm × 7.60 mm × 1.00 mm
(Note 1) Grade1
Applications
Head lamp, DRL, front position lamp, tail lamp, turn lamp
HTSSOP-B24
Typical Application Circuit
External
power
VOUT
VB
VCC
FAIL
VREG50
ODT
EN
RT
VREG25
DCD
VOUT
DRL
SWDRV
BD18351EFV-M
RS
VREG50
VREG
CS
COMP
SS
IMP
IMN
DISC
CR
PWMOUT
TDISC
GND
DGND
Figure 1. Typical Application Circuit
〇Product structure: Silicon integrated circuit
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 14 • 001
〇This product has no designed protection against radioactive rays
1/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Pin Configuration
HTSSOP-B24
(TOP VIEW)
COMP
1
24
VCC
SS
2
23
EN
GND
3
22
DRL
DCD
4
21
N.C
VREG25
5
20
VREG50
RT
6
19
ODT
RS
7
18
SWDRV
CR
8
17
CS
DISC
9
16
DGND
FAIL
10
15
N.C
TDISC
11
14
IMP
12
13
IMN
PWMOUT
Thermal PAD
Figure 2. Pin Configuration
Pin Description
Terminal
No.
Symbol
Terminal
No.
Symbol
1
COMP
Error amplifier output phase
compensation terminal
13
IMN
LED current detection terminal (-)
2
SS
Soft start setting terminal
14
IMP
LED current detection terminal (+)
3
GND
Small signal GND
15
N.C.
-
4
DCD
DC dimming terminal
16
DGND
5
VREG25
2.5V standard voltage
(DCD Exclusive terminal)
17
CS
6
RT
DC / DC oscillation frequency
setting terminal
18
SWDRV
7
RS
19
ODT
8
CR
20
VREG50
9
DISC
21
N.C.
-
10
FAIL
Error flag output terminal
22
DRL
Terminal for DRL control switching
(High: 100 % mode)
11
TDISC
Discharge time setting terminal
23
EN
EN control terminal (High: Active)
12
PWMOUT
External for PWM dimming
FET gate drive terminal
24
VCC
Function
Spread spectrum frequency
setting terminal
Built-in CRTIMER
PWM dimming frequency /
Duty setting terminal
Built-in CRTIMER
Discharge setting terminal
Function
Power GND
Over current detection setting terminal
External FET gate drive terminal
LED open detection setting terminal
Internal constant voltage 5.0 V
output terminal
Power voltage terminal
(Pay attention that it does not correspond to reverse insertion.)
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
2/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Block Diagram
VREG50
VREG
VREG50
UVLO
VREG25
EN
RT
VREG25
EN
CTL
SLOPE
-
PWM
RAMP
+
DC
DIMMING
ERRAMP
COMP
SWDRV
OCP
CS
IMP
CURRENT
SENSE
+
SS
ODT
DRV
CTL
IMN
+
SS
OPEN
DET
LOGIC CONTROL
OSC
RS
DCD
TSD
-
VCC
FAIL
VOUT
DISC
TDISC
DRL
DISC
PWM
DIMMING
DRV
CTL
PWMOUT
CR
GND
DGND
Figure 3. Block Diagram
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
3/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Description of Blocks
1. Standard voltage (VREG50)
5 V (Typ) is generated from VCC input voltage. This voltage (VREG) is used as power supply for internal circuit, and is also
used to fix terminal at high voltage outside the IC. Please connect CVREG50 = 2.2 μF (Typ) as phase compensation capacity
for VREG50 terminal. If CVREG50 is not connected, circuit operation will become markedly unstable. In addition, please do not
use VREG50 as a power supply except this IC.
2. Concerning LED current setting and luminance adjustment(CURRENTSENSE)
(1) Concerning LED current setting method
VCC
LED current can be calculated by the following formula.
𝐼𝐿𝐸𝐷 =
SWDRV
𝑉𝑅𝐸𝐹1
𝑉𝐷𝐶𝐷
×
𝑅𝑆𝐸𝑇
1.21𝑉
However, assign VDCD = 1.21 V in the case of VDCD > 1.21 V.
RSET
CS
(Example)
In the case of connection of RSET = 0.4 Ω, VDCD = 0.6 V,
IMP
IMN
𝐼𝐿𝐸𝐷 =
0.2𝑉
0.6𝑉
×
≒ 0.25𝐴
0.4𝛺 1.21𝑉
VREF1
ILED: LED current
VREF1: Standard voltage for LED current setting (200 mV (Typ)
RSET: Resistance for LED current setting
VDCD: DCD terminal voltage
Figure 4. LED Current Setting Method
(2) Concerning luminance adjustment by PWM dimming control(PWM DIMMING)
PWM dimming control with built-in CR timer
PWM dimming is operated in 100 % by connecting Di to DRL terminal and turning DRL terminal to High as shown in Figure 1
On the other hand, when DRL terminal is turned low and configuration is made as shown in Figure 5, internal CR timer will
operate, triangle wave is generated by CR terminal, PWMOUT terminal will be controlled to turn LED current off in CR
voltage rise zone and turn LED current on in CR voltage fall zone. CR voltage rise / fall time can be set by the values of
external parts (CCR, RDISC1, RDISC2). Refer to the next page for setting method. In addition, the recommended operation
frequency is 100 Hz to 2 kHz, On Duty 2 % to 45 %, and the recommended range of the external component values are 0.01
µF to 1.0 µF for CCR and 10 kΩ to 33 kΩ for RDISC2.(PWM min pulse width=50 µs)
VREG50
RDISC1
RDISC2
DISC
PWMOUT
+
CCR
CR
1.0V/2.0V
DRV
-
VREG50
DRL
PROTECT
SIGNAL
Figure 5. Example of Application Using Built-in CR Timer
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
4/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Trise
Tfall
2.0V x 0.4
VREG50
CR fall
CR terminal
CR rise
VREG50
1.0V x 0.2
PWMOUT terminal
LED current
LED OFF
LED ON
Trise=0.287×CCR×(RDISC1+RDISC2)
Tfall=0.693×CCR×RDISC2
Figure 6. PWM Dimming Operation
CR terminal rise / fall time can be calculated as shown below.
1. CR terminal rise time Trise
𝑇𝑟𝑖𝑠𝑒 = 0.287 × 𝐶𝐶𝑅 × (𝑅𝐷𝐼𝑆𝐶1 + 𝑅𝐷𝐼𝑆𝐶2 ) [𝑠]
2. CR terminal fall time Tfall
𝑇𝑓𝑎𝑙𝑙 = 0.693 × 𝐶𝐶𝑅 × 𝑅𝐷𝐼𝑆𝐶2 [𝑠]
3. PWM dimming frequency FPWM
PWM frequency is determined by Trise and Tfall.
𝐹𝑃𝑊𝑀 =
1
[𝐻𝑧]
(𝑇𝑟𝑖𝑠𝑒 + 𝑇𝑓𝑎𝑙𝑙 )
4. PWM dimming ON Duty (DPWM)
ON Duty of PWM is determined by Trise and Tfall as shown in the description above.
𝐷𝑃𝑊𝑀 =
𝑇𝑓𝑎𝑙𝑙
(𝑇𝑟𝑖𝑠𝑒 + 𝑇𝑓𝑎𝑙𝑙 )
× 100 [%]
(Example) when CCR = 0.1 μF, RDISC1
= 100 kΩ, RDISC2
= 20 kΩ (Typ)
𝑇𝑟𝑖𝑠𝑒 = 0.287 × 𝐶𝐶𝑅 × (𝑅𝐷𝐼𝑆𝐶1 + 𝑅𝐷𝐼𝑆𝐶2 ) = 3.444 [𝑚𝑠]
𝑇𝑓𝑎𝑙𝑙 = 0.693 × 𝐶𝐶𝑅 × 𝑅𝐷𝐼𝑆𝐶2 = 1.386 [𝑚𝑠]
𝐹𝑃𝑊𝑀 =
𝐷𝑃𝑊𝑀 =
1
= 207 [𝐻𝑧]
(𝑇𝑟𝑖𝑠𝑒 + 𝑇𝑓𝑎𝑙𝑙 )
𝑇𝑓𝑎𝑙𝑙
(𝑇𝑟𝑖𝑠𝑒 + 𝑇𝑓𝑎𝑙𝑙 )
× 100 = 28.7 [%]
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
5/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
PWM dimming control with external signal (microcomputer, etc.)
Dimming is possible by direct input of PWM signal from external microcomputer, etc. Input PWM signal in CR terminal. Set
‘High’ level voltage of input signal from microcomputer at no less than 2.5 V for CR threshold voltage, and set ‘Low’ level
voltage at no more than 0.5 V of CR threshold voltage. Recommended input frequency range is 100 Hz to 2 kHz. Minimum
pulse width is 50 µs. It’s necessary that 51kΩ resister need between μ-con and CR terminal like Figure 7. When filter is
required, configure filter in high side of Figure 7 51kΩ.
However verification with actual application is required as filter may cause difference between Input signal to CR terminal
and PWMOUT terminal.
DISC
+
μ-con
51kΩ
CR
DRV
-
PWMOUT
VREG50 x 0.2,
VREG50 x 0.4
Figure 7. External Input of PWM Signal
(3) PWM Dimming with PchMOS
PWM dimming can be performed by PchMOS (Figure 8 (a) Q3) with Figure 8 configuration. In this configuration, RPWM1 /
RPWM2 / RPWM3 controls gate voltage of PchMOS. If RPWM2, RPWM3 are bigger and gate capacitance of Q3 is high, this
result in discrepancy in PWM ON width generated by PWMOUT pin output and LED current ON width controlled by Q3 .
Please thereby perform the evaluation with the actual equipment by the constitution using PchMOS enough because it may
cause instable operation such as high brightness lighting or the acoustic noise of capacitor and inductor.
VCC
IMP
RPWM3
SWDRV
IMN
CS
Q3
IMP
IMN
RPWM1
PWMOUT
Q2
RPWM2
Figure 8 (a). PWM Dimming with PchMOS
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
Figure 8 (b). PWM Dimming with PchMOS
6/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
(4) Brightness control by DC dimming control(DC DIMMING / VREG25)
LED current is linearly controllable corresponding to DCD terminal voltage. DCD terminal is mainly used for derating, and is
used to control deterioration of LED at high temperature or to limit over current to external parts under conditions which
power supply voltage fluctuates by idling stop functions, etc. (Refer to Figure 9). Recommended input range is 0.4 ≤ VDCD ≤
VREG25 and LED current control starts in VDCD ≤ 1.21 V. In addition, the power supply voltage to control DCD can be
controlled with high precision by using VREG25. When DC dimming is not used, short to VREG25 terminal directly.
VREG25
R3
DCD
R2
Calculated Value
LED Current [A]
R1
Measured Value
Surrounding
SurroundingTemperature
Temperature[°C]
[°C]
R1: 12kΩ
R2: 100 kΩ
R3: NTCG104EF104F
Figure 9. Example of Derating Setting Using Thermistor Resistance
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
7/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
3. Boost DC / DC controller
(1) Concerning open detection voltage setting(OPEN DET)
Open of LED is detectable by inputting resistance division connected to
anode side of LED (DC / DC output VOUT) in ODT terminal. LED open
detection voltage is detectable by connecting external resistors (RODT1,
RODT2) as shown in Figure 10, and output voltage VOUT_ODT at the time of
LED open detection voltage is calculable as shown below.
𝑉𝑂𝑈𝑇_𝑂𝐷𝑇
(𝑅𝑂𝐷𝑇1 + 𝑅𝑂𝐷𝑇2 )
=
× 1.5𝑉(𝑇𝑦𝑝)
𝑅𝑂𝐷𝑇2
VOUT
RODT1
ODT
+
RODT2
(Example)
LED open detection will operate with VOUT_ODT = 34.5 V
when RODT1 = 660 kΩ and RODT2 = 30 kΩ.
-
1.5V/1.4V
LED open detection voltage needs higher voltage setting than
overshoot of output voltage at start up to avoid start up failure.
ODT resistor will be the current discharge path for the output
Figure 10. ODT terminal Equivalent Circuit
capacitor when PWM = Low. Recommended value for RODT1 is 600
kΩ to 1000 kΩ as Vout ripple may be large and cause LED flickering when PWM = Low with inadequate ohmic value range.
Moreover, the behavior differs by characteristic of output capacitor or LED, therefore sufficient verification with actual
application is required.(Vout drop can be prevented by inserting bigger output capacitor or ODT resistance.)
(2) Concerning number of LED series stages
As shown in Figure 11, although IMP terminal is connected to
boost DC / DC output at highest voltage among applications.
The number of the steps of the LED which can be driven is decided
by the LED opening detection voltage instead of 65V that is
withstand voltage. For example, when the ODT terminal voltage
VODT = 1.35 V at driving a normal LED, the maximum output
voltage VOUT_MAX is as follows.
VCC
SWDRV
1.35𝑉
65𝑉 ×
≒ 55.7𝑉
1.575𝑉
RSET
CS
In other words, drivable LED series stage N is calculable by the
formula below.
𝑉𝐹_𝑀𝐴𝑋 × 𝑁 + 𝑉𝑅𝐸𝐹_𝑀𝐴𝑋 < 55.7𝑉
IMP
IMN
VF_MAX: maximum value of VF of LED
N: number of LED series stages
VREF_MAX: maximum value of standard voltage
for LED current setting
(Example)
When VF_MAX = 3.5 V and VREF_MAX = 0.206 V, number of drivable LED
series stages N is as shown below.
VREF
Figure 11. Example of Application Circuit
𝑁 < (55.7𝑉 − 0.206𝑉 ) ∕ 3.5𝑉 = 15.86
LED drivable number of LED stages is 15.
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
8/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
(3) Concerning oscillation frequency FOSC(OSC)
Connection of resistance with RT terminal enables setting of
oscillation frequency as shown in Figure 12. Connection of RRT
decides charge and discharge current for internal capacitor
and changes DC / DC oscillation frequency. Set RRT by
reference to the theoretical formula below. Recommended
range is 14 kΩ to 51 kΩ. Pay attention that switching may stop
if recommended frequency setting range is exceeded, and
operation assurance is not possible.
99 × 102
𝐹𝑂𝑆𝐶 [𝑘𝐻𝑧] =
𝑅𝑅𝑇 [𝑘𝛺]
Figure 12. RRT vs DC / DC Oscillation Frequency FOSC
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
9/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
(4) Concerning spread spectrum setting(RAMP)
Connection of capacitor to RS terminal enables operation in Spread spectrum mode (SSCG mode). Comparator of
0.6 V (Typ) / 0.75 V (Typ) standard voltage is built in RS terminal, and DC / DC oscillation frequency is diffused by changing
RT terminal voltage to triangle waveform with the capacitor connected to RS terminal in SSCG mode. Theoretical attenuation
ΔD [dB] is calculable by the formula below.
𝛥𝐷[𝑑𝐵] = 10 × log (
FOSC_RAMP: oscillation frequency when SSCG mode is
ON (Center)
FOSC: oscillation frequency when SSCG mode is OFF
CRS: RS terminal connection capacitor
RRT: RT terminal connection resistance
𝐹𝑅𝑆 [𝑘𝐻𝑧]
)
𝐹𝑂𝑆𝐶_𝑅𝐴𝑀𝑃 [𝑘𝐻𝑧] × 0.222
However, setting value of DC / DC oscillation frequency differs depending on ON / OFF of SSCG mode. In order to operate
when SSCG mode is ON in the same frequency zone as when SSCG mode is OFF, select from Figure 12 RT resistance for
1.18 times as high DC / DC oscillation frequency as the DC / DC oscillation frequency. When SSCG mode is not used,
short-circuit RS terminal and VREG50 terminal.
Further, FRS can be calculated by the formula below. Setting should satisfy the formula of 0.3 kHz ≤ FRS ≤ 10 kHz.
𝐹𝑅𝑆 [𝑘𝐻𝑧] =
9
8 × 𝑅𝑅𝑇 [𝑘𝛺] × 𝐶𝑅𝑆 [𝜇𝐹 ]
(Example) When using at DC / DC oscillation frequency (FOSC_RAMP) of 300 kHz with SSCG mode is ON, select RRT ≈ 28 kΩ
from Figure 12 to make DC / DC oscillation frequency (FOSC) to be 354 kHz. When operating under this condition with
connection of CRS = 0.047µF and with SSCG mode ON, effect of ΔD = -18.9 dB can be predicted.
VREG50
CURRNET
MIRROR
ON/
OFF
RS
+
+
OFF/
ON
CRS
-
VRT
VRT
15/16×VRT
3/4×VRT
+
CURRENT
CONTROL
-
RT
RRT
Figure 13. Equivalent Circuit Diagram of RS and RT terminals
Noise Level
FOSC
±11.1%
⊿D[dBµV]
FOSC_RAMP
FOSC
(FOSC=FOSC_RAMP × 1.18)
Frequency Band
Figure 14. Noise Level Comparison with SSCG Mode ON / OFF
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
10/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
SSCG:OFF(RS
terminal
connectwith
to VREG50)
SSCG=OFF
(VREG50
short-circuits
RS terminal)
SSCG:ON(RS
terminalisconnect
to Capacitance)
SSCG ON (A capacitor
connected
to RS terminal)
0.8V(=VRT)
RS
0.75V(=15/16VRT)
VRT
VRT
0.6V(=3/4VRT)
As for the period of IRS, it is setable in C RS.
VRT/2RRT
IRS
IRS
15/32×VRT/RRT
IRS
IRS
3/8×VRT/RRT
Switching output
Switching output
SWDRV
SWDRV
It is output in same switching frequency(FOSC)
Switching frequency changes by
the change of FOSC±11.1%.
Figure 15. Timing Chart when SSCG Mode is ON / OFF
Because switching frequency changes in High
section of the PWM like Figure 16 when spectrum
spreading is controlled in a PWM dimming, an
output voltage ripple changes in A and B. In addition,
the LED current is also affected by the ripple as it
may seem that LED flickers when this occurs
periodically, please thoroughly verify with the actual
equipment. As countermeasures, make the
frequency of the RS pin fast to reduce a ripple in
High section of the PWM.
PWM
Vertical Scale)
Swit ching F requ ency
FO SC3
FO SC2
FO SC4
RS
FO SC1
330 kHz
A
Th e fre quen cy depe nds on
the attach in g exte rnally
(PWM doe s not d epend )
B
ILED
Even if On width of the PWM is the same as A in B, the voltage states o f the RS pin ar e differ ent. Th eref ore, in th e spectr um
spr eading, the swit ching fr eque ncy is differ ent f rom a timing of A in B.
A ripple of the outp ut voltag e chan ges, and LED curr ent m ay be t here by differ ent f rom A in B.
Figure 16. Spectrum Spread Action in the PWM Dimming
(5) Soft start function(SS)
Soft start function is built-in so that incoming current can be prevented by insertion of external capacitor. The charge current
of the soft start is 5 μA (Typ) and will be as Figure 17 independent to PWM. The inrush current can be suppressed by
increasing soft start capacity, but boot-time becomes longer. On the other hand, as for the boot-time, it becomes faster by
lowering soft start capacity, attention is necessary because an inrush current becomes bigger, and may cause acoustic noise
of the coil during the startup. The soft start capacity is recommended to be 0.01 μF to 1 μF to suspend the overshoot of the
LED current during start up.
The RS terminal is pulled up by VREG50 until SS terminal
arrives at 70%of VREG50 as soon as EN terminal is
inputted High voltage . After that, RS terminal starts to be
controlled.
(See the timing chart of SS terminal and RS terminal in the
P.28 Figure.44)
Therefore, Spread spectrum don’t operate as soon as
EN terminal is inputted High voltage, even if connect a
capacitor to RS terminal
EN
CR
PWMOUT
SS
Figure 17. SS Operation Timing Chart
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
11/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
(6) Concerning start up time(ERRAMP)
Startup time difference between PWM = 100 % (DRL = High) and PWM dimming control is described in this paragraph
EN
EN
PWMOUT
SS
PWMOUT
0.7V
SS
0.7V
COMP
COMP
COMP terminal is charged when PWM=High
VOUT
VOUT
ILED
ILED
Figure 18 (b). PWM Dimming start up
Figure 18 (a). PWM = 100% start up
SS terminal and COMP terminal is charged, When EN is
inputted. Until SS terminal reaches 0.7 V, COMP terminal is
fixed at 0.7 V. When SS terminal exceeds 0.7V, COMP
terminal starts to rise up to voltage which can output required
switching duty determined by input/output voltage difference.
During PWM control, SS terminal is charged synchronized
with EN while COMP terminal is charged synchronized with
PWM. Startup time is basically same with previous
description but as charge of COMP terminal is synchronized
with PWM, COMP voltage rise to the voltage which can
output required switching duty will be slower resulting In
longer start up time compared with PWM = 100 % operation.
Especially by reducing PWM dimming rate, start up time will
be longer.
Startup time [ms]
Figure 19 describes actual measurement result of startup time.
Measurement Condition: VCC = 12 V, FPWM = 200 Hz, VOUT = 25 V (LED 7series), Ta = 27deg, other condition as described in
P.38.
(Startup time will be from UVLO release to VOUT reaching 90 %.)
Larger the CPC constant is, and smaller DPWM is, start
up time will be longer. Startup time shall be
sufficiently evaluated in actual application.
Figure 19. Startup time measurement data
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
12/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
4. Self-assessment function
Table 1. Concerning detection condition and operation after detection of each protection function (when VCC = 13 V)
Protection
function
Detection condition
[Detection]
[Release]
Error flag output (Note 1)
Operation after detection
At time of detection:
FAIL High→Low
At time of recovery:
FAIL Low→High
UVLO
VCC < 3.9 V
VCC > 4.25 V
Shut down of all blocks
(Other than VREG50 / VREG25)
TSD
Tj > 175 C
Tj < 150 C
Shut down of all blocks
(VREG50 / VREG25 are included)
-
OCP
VCS ≥ 300 mV
VCS < 300 mV
Switching output is Off
-
VIMP-VIMN ≥ 0.3 V
VIMP - VIMN < 0.3 V
(Timer time
depends on
TDISC setting)
Shut down of all blocks
(Other than VREG50 / VREG25)
At time of detection:
FAIL High→Low
At time of recovery:
FAIL Low→High
VODT < 1.4 V
Shut down of all blocks
(Other than VREG50 / VREG25)
At time of detection:
FAIL High→Low
At time of recovery:
FAIL Low→High
SCP
LED open
detection
VODT > 1.5 V
(Note1) FAIL output shown above is FAIL terminal voltage in the case of pull-up resistance such ad external power.
FAIL
TSD
UVLO
UVLO
OPEN
OPEN
SCP
TIMER
(TDISC)
Figure 20. Protection Flag Output Part Block Diagram
(1)Low voltage malfunction protection function (UVLO)
The UVLO shuts down all the circuits except VREG50, VREG25 when VCC < 3.9V (Typ) And UVLO is released by Vcc > 4.25 V
(Typ).
(2) Temperature protection function (TSD)
TSD shuts circuits other than VREG at 175 C (Typ) and recovers them at 150 C (Typ).
(3) Over current protection function (OCP)
Over current is detected by the detection resistance with which current flowing in power FET is connected to source side. Over
current protection function operates when CS terminal voltage is no less than 300 mV (Typ).The over current protection function
controls DC / DC switching outputs.
(4) Output ground detection function (SCP)
When, in an application circuit such as Figure 45, LED Anode- GND short-circuits, the potential difference of IMP terminal and the
IMN terminal is more than 0.3 V (Typ), and a ground detection function works, and the output is off. When ground protection is
activated, charge (11 μA (Typ)) is started to a capacitor connected to TDISC terminal (recommend range: 0.01μF to 0.47μF).
After TDISC terminal voltage arrived at 1.0V (Typ), the TDISC terminal discharges and Low → High outputs SWDRV / PWMOUT
again. A ground detection function works again afterwards when the potential difference of IMP terminal and the IMN terminal
becomes than 0.3 V (Typ). In addition, it works normally when TDISC terminal voltage becomes less than 0.3V (Typ), and the
potential differences of IMP terminal and the IMN terminal become less than 0.3 V (Typ). As for the details, please refer to Figure
21. (Note that GND short-circuit of the IMP terminal cannot be detected.)
(5) LED open detection function
When ODT terminal voltage is above 1.5 V (Typ), LED open detection operates to reset SWDRV / PWMOUT = Low, and
discharges SS again, outputs Fail High → Low, and the output voltage decreases by ODT resistance. When ODT terminal
voltage is less than 1.4 V (Typ), begins to recharge SS, re-starts DC / DC operation and outputs FAIL Low→High.
Timing chart at the time of protection circuit operation (DRL = High)
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
13/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Output ground short protection function
①
VCC
VCC
4.25V
④
VOUT
GND short
GND short
open
⑤
VOUT
IMP
⑥
SWDRV
②
IMN
0.3V
0.2V
0.2V
IMP-IMN
CS
VOUT GND
short
TDISC
⑧
⑦
TDISC
1.0V
0.3V
⑨
③
PWMOUT
⑨
⑥
SWDRV
TDISC
⑥
CTDISC
PWMOUT
⑥
FAIL
Figure 21. Output Ground short protection operation timing chart
When GND short circuit occurs in such conformation as shown
in Figure 1, large current continues to flow from VCC.
①
②
③
④
⑤
⑥
UVLO is cancelled when VCC > 4.25 V (Typ).
IMP-IMN terminal voltage rises to become 200 mV.
Switching Duty gradually expands and is stabilized at IMP-IMN of 200 mV.
Output voltage is stabilized.
LED Anode-GND short-circuits.
It becomes IMP-IMN ≥ 0.3 V (Typ) and performs output Short circuit detection (SCP) and outputs SWDRV / PWMOUT =
Low. Discharges an SS terminal and the FAIL terminal changes into High → Low.
⑦ When SCP is detected, capacitor connected to TDISC will be charged (11 µA (Typ)) until VTDISC becomes 1.0 V (Typ).
⑧ Once SCP detection is released at VTDISC ≥ 1.0 V (Typ), capacitor connected to TDISC starts to discharge, and SS
charging, SWDRV / PWMOUT operate normally.
⑨ If SCP condition VTDISC ≥ 0.3 V (Typ) is fulfilled restarts from condition “6” operates normally if SCP condition is not
fulfilled.
Operation described above is performed in the LED anode ground
short fault. However, even if SCP is detected by the potential
difference of IMP pin and the IMN pin, there is delay time of internal
circuit after detection and require time before PchMOS is off.
Therefore allowable current of PchMOS may be exceeded
transiently.(It may be exceeded in “8” of the timing mentioned above.)
Therefore, like Figure 22, PMOS can be turned off on an expressway
by adding PNP Tr externally.
When Output shorts to ground while supply voltage dropping, Gate
voltage may not be turned off. If sufficient Gate voltage cannot be
secured SCP may not be detected.
Figure 22. LED Anode Ground Fault Protection
Attaching Externally Circuitry
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
14/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
LED open protection function (DRL = High)
VCC
Connector comes off
(LED open)
③
VOUT
VCC
COUT
4.25V
②
RSET
Open
0.2V
IMP-IMN
0.2V
④
Discharge by ODT resistance
1.5V
1.4V
IMP
IMN
⑦
①
SWDRV
CS
Connector return
ODT
⑤
⑥
⑧
VREF
ILED
SWDRV
PWMOUT
VOUT
PWMOUT
ODT
Figure 23. Output Ground Short Protection Operation Timing Chart
①
②
③
④
⑤
UVLO is released when VCC > 4.25 V (Typ).
IMP-IMN terminal voltage rises to become 200 mV.
Connector of LED opens.
Output voltage over boost due to IMP-IMN ≈ 0 V. (ODT which is resistor divided voltage of output voltage will steeply rise.)
When ODT ≥ 1.5 V, LED open is detected and SWDRV / PWMOUT becomes Low. Also, SS pin will be discharged and Fail
pin becomes High → Low.
⑥ The LED open detection is released at ODT ≤ 1.4 V, and the FAIL terminal becomes Low → High.
Then DC / DC restarts the operation, however due to LED open condition voltage will be over boosted again.
⑦ LED is connected again.
⑧ When ODT ≤ 1.4 V, will be re-started and resumes to normal operation.
(During “8” condition if PWMOUT = High is applied while capacitors are still charged above nominal Vout, it could detect SCP
detection due to IMP-IMN ≥ 0.3 V. After TTDISC resumes to normal operation.)
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
15/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
VCC
5. Output electric charge electric discharge circuit (VOUTDISC)
When supply voltage of LSI is turned off in such configuration as shown in Figure 24,
output capacitor may not be fully discharged and may remain charged in some
cases. When power is supplied again while output capacitor is charged,transient
current flows through the route of output capacitor→RSET→LED→PWM dimming
FET→GND which cause LED flashing. Later, when switching duty is output, LED is
lit. In order to suppress such a flash phenomenon, this LSI incorporates output
charge discharge circuit.
In order for output discharge circuit to operate, discharge of output capacitor starts
when either one of the conditions of UVLO is detected (VCC ≤ 3.9 V) or VEN ≤ 1.35 V
are satisfied. (Output discharge circuit is also operated at LED open detection.)
Turn off PWM after EN turned off power supply OFF sequence when PWM input is
controlled with an external signal.
VOUT
SWDRV
COUT
CS
RSET
IDISC
IMP
VREF1
IMN
ILED
PWMOUT
VOUT
TDISC
Figure 24. Application Example
There is no output
discharge circuit
There is an output
discharge circuit
VCC
VCC
TOFF
Output discharge
circuit
OFF
PWMOUT
output
PWMOUT
output
Output voltage
VOUT
Output voltage
VOUT
LED current
ILED
LED current
ILED
A
B
C
ON
D
OFF
E
F
A. Because VCC is off, and the PWMOUT terminal is off,
the LED current does not flow. Because PWMOUT
terminal is OFF, output capacitor COUT is discharged by
resistance connected to ODT terminal, and output
voltage VOUT gradually decreases.
D. Because V CC is off, and the PWMOUT terminal is off,
the LED current does not flow. Because PWMOUT
terminal is OFF, output capacitor COUT is discharged by
resistance connected to ODT terminal. However, the
output electric charge electric discharge circuit in the IMP
terminal works, and output voltage VOUT greatly decreases.
B. When VCC is turned on again, getting started of output
voltage VOUT is late by a soft start function. On the other
hand, the PWMOUT terminal is turned on in sync with a
reintroduction of VCC. Therefore LED current flows from
an output capacitor transiently, and LED shines for an
instant, and LED darkens when the electric charge of the
output capacitor is discharged besides.
E. When VCC is turned on again, getting started of output
voltage VOUT is late by a soft start function. On the other
hand, the PWMOUT terminla is turned on in sync with a
reintroduction of VCC, but the LED does not shine because
VF cannot open.
C. Output voltage stands up, and LED turns on again.
F. Output voltage stands up, and LED turns on.
Figure 25. Output Discharge Circuit Operation Explanation at the time of the VCC Drop
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
16/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Concerning output discharge circuit operation at the time of UVLO detection
①3.95V
VCC
UVLO
signal
Output voltage
VOUT
1A
Discharge current
IDISC
②
③
10mA
Normal
operation
① UVLO is detected when VCC < 3.95 V.
② When UVLO is detected, discharge circuit is turned
on to discharge charge accumulated in output
capacitor, and output voltage falls by IDISC.
③ IDISC falls accompanying fall of output voltage.
(Refer to electric properties of output voltage VOUT
and discharge current IDISC.)
Discharge circuit
operation limit
Discharge circuit operation
Figure 26. Explanation of Output Discharge Circuit Operation at UVLO Detection
Concerning output discharge circuit operation by EN control
①1.35V
EN
TTDISC
VREG50
×0.7
②
TDISC
① When EN ≤ 1.35 V, EN is turned off.
② Output is discharged during output discharge time (TTDISC)
set by capacitor connected to TDISC.
𝑇TDISC =
Output voltage
出力電圧VOUT
VOUT
1A
Discharge current
放電電流I
IDISC DISC
Normal
正常動作
Operation
10mA
③
放電回路動作
Discharge
circuit operation
𝑉𝑅𝐸𝐺50 × 0.7 × 𝐶𝑇𝐷𝐼𝑆𝐶
11𝜇𝐴
③ When discharge time TTDISC elapsed, output discharge
circuit stops operation.
放電回路 circuit
Discharge
動作限界 limit
Operation
Figure 27. Explanation of Output Discharge Circuit Operation when EN is off
The recommended capacitance value for this function is 0.01 μF to 0.47 μF, Please do not to connect TDISC to GND.
Caution that even if the values are within recommended range, when output voltage is higher and CTISC is higher heat
dissipation by discharge is to be considered. Sufficient verification by actual application is required.
Flash phenomena is affected by Vf characteristic of LED and time to re-enter power supply. This is also to be sufficiently
verified with actual application.
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
17/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
6. About EN terminal setting (EN CTL)
ON / OFF of the LSI can be controlled by applying resistor devided voltage from power supply to EN terminal. Setting of the
EN terminal voltage to control ON / OFF of the LSI is as follows.
𝑉𝐶𝐶𝑂𝑁 =
𝑉𝐶𝐶𝑂𝐹𝐹 =
(𝑅𝐸𝑁1 + 𝑅𝐸𝑁2 )
× 1.45𝑉(𝑇𝑦𝑝)
𝑅𝐸𝑁2
VCC
REN1
(𝑅𝐸𝑁1 + 𝑅𝐸𝑁2 )
× 1.35𝑉(𝑇𝑦𝑝)
𝑅𝐸𝑁2
EN
REN2
Ex)
The VCC terminal voltage to stop / start operation is as
follows with REN1 = 150 kΩ, REN2 = 51 kΩ condition
-
The operation start voltage
𝑉𝐶𝐶𝑂𝑁 =
1.45V / 1.35V
1.3V/1.5V
(150𝑘𝛺 + 51𝑘𝛺)
× 1.45𝑉(𝑇𝑦𝑝) = 5.71𝑉
51𝑘𝛺
The operation stop voltage
𝑉𝐶𝐶𝑂𝐹𝐹 =
+
Figure 28. About EN terminal setting
(150𝑘𝛺 + 51𝑘𝛺)
× 1.35𝑉(𝑇𝑦𝑝) = 5.32𝑉
51𝑘𝛺
For PWM dimming, do not control PWM with the EN terminal as it may result in unstable operation.
PWM dimming, is to be controlled with CR terminal. (Please refer to P.4 to 6 for the details.)
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
18/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Absolute Maximum Ratings (Ta = 25 °C)
Parameter
Symbol
Rating
Unit
VCC
-0.3 to 70
V
EN, DRL Terminal Voltage
VEN, VDRL
-0.3 to VCC+0.3
V
IMP, IMN Terminal Voltage
VIMP, VIMN
-0.3 to 70
V
The Voltage between IMP and IMN
VIMP - VIMN
3
V
VVREG50, VCS, VRS, VRT, VVREG25
VCR, VDISC, VODT, VPWMOUT, VDCD,
VSS, VCOMP, VSWDRV, VFAIL, VTDISC
-0.3 to 7 < VCC
V
Operation Temperature Range
Topr
-40 to 125
°C
Storage Temperature Range
Tstg
-55 to 150
°C
Tjmax
150
°C
Power Voltage
VREG50, CS, RS, RT, VREG25,
DISC, ODT, PWMOUT, DCD, SS
COMP, SWDRV, FAIL , TDISC terminal voltage
Junction Temperature
Caution: Deterioration or break may occur when absolute maximum ratings of applied voltage, operation temperature range, etc. are exceeded. Also, breaking
situation such as short circuit mode or open mode cannot be assumed. If special mode exceeding absolute maximum rating is assumed, please consider
physical safety measures such as fuse.
Thermal Resistance (Note 1)
Parameter
Symbol
Thermal Resistance (Typ)
Unit
1s(Note 3)
2s2p(Note 4)
θJA
143.8
26.4
°C/W
ΨJT
7
2
°C/W
HTSSOP-B24
Junction to Ambient
Junction to Top Characterization Parameter
(Note 2)
(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
Single
Material
Board Size
FR-4
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.
Layer Number of
Measurement Board
4 Layers
Thermal Via(NOTE 5)
Material
Board Size
FR-4
114.3mm x 76.2mm x 1.6mmt
Top
2 Internal Layers
Pitch
1.20mm
Diameter
Φ0.30mm
Bottom
Copper Pattern
Thickness
Copper Pattern
Thickness
Copper Pattern
Thickness
Footprints and Traces
70μm
74.2mm x 74.2mm
35μm
74.2mm x 74.2mm
70μm
(Note 5)
This thermal via connects with the copper pattern of all layers.
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
19/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Recommended Operating Ratings (Ta = 25 °C)
Parameter
Symbol
Min
Typ
Max
Unit
Power Voltage (Note 1)
VCC
4.5
12
65
V
Output Voltage (Note 2)
VIMP
6.0
40
65
V
FOSC1
200
-
700
kHz
FOSC2
200
-
600
kHz
CRTIMER Frequency
FPWM
100
-
2000
Hz
CRTIMER Output Duty
FDUTY
2
-
45
%
FRS
0.3
-
10
kHz
DC / DC Switching Frequency
(With Spread Spectrum Control OFF)
DC / DC Switching Frequency
(With Spread Spectrum Control ON)
Spectrum Spread Frequency
(Note 1) Apply voltage of no less than 5 V once at the time of stat-up. The value is voltage range after once setting at no less than 5 V.
(Note 2) When become the condition mentioned above except for startup at Boost application, it’s possible that large current flow in LED.
Recommended External Constant Range
Symbol
Min
Max
Unit
CCR
0.01
1.0
μF
RDISC2
10
33
kΩ
Resistance for DC/DC Frequency
RRT
14
51
kΩ
Capacitance for Soft-Start Setting (Note 4)
CSS
0.01
1.0
μF
Capacitance for TDISC Setting (Note 5)
CTDISC
0.01
0.47
μF
Resistance of OVP Setting of VOUT Side (Note 3)
ROVP1
600
1000
kΩ
Parameter
Capacitance for CRTIMER Frequency/Duty
Setting (Note 3)
Resistance for CRTIMER Frequency/Duty
Setting (Note 3)
(Note 3) Since the above values are reference values, when using constants outside the range, please thoroughly check the PWM dimming characteristics.
(Note 4) Since the above values are reference values, when using constants outside the range, please thoroughly check the characteristics at startup
(rush current etc.).
(Note 5) Since the above values are reference values, when using a capacitor outside the range, the hiccup time of SCP operation changes, so please fully check
the heat generation of the external FET during SCP operation.
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
20/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Electrical Characteristics (Unless otherwise specified VCC = 13 V, VIMP = 40 V, Ta = -40 °C to 125 °C)
Limit
Parameter
Symbol
Unit
Min
Circuit Current
ICC
-
Typ
3
Condition
Max
6
mA
CVREG = 2.2 μF,
VCS = VODT = 0 V
VEN = VDRL = VCR = GND
VRS = VVREG50
VDCD = VRT = VVREG25
[VREG]
VREG50 Standard Voltage
VVREG50
4.5
5.0
5.5
V
CVREG50 = 2.2 μF
Load current = 0mA to 20
mA
No switching
VREG25 Standard Voltage
VVREG25
2.425
2.50
2.575
V
IVREG25 = 0μA
ΔVVREG25
-
50
100
mV
SWDRV Upper Side ON Resistance
RSWP
-
4
8
Ω
ION = -10 mA
SWDRV Lower Side ON Resistance
RSWN
-
3
6
Ω
ION = 10 mA
Overcurrent Protection Voltage
VOCP
250
300
350
mV
VCS: Sweep up
LED Current Setting Standard Voltage
VREF1
194
200
206
mV
Voltage between VIMP - VIMN
terminals.
LED Ground Short Detection Voltage
VSCPON
0.24
0.3
0.36
V
VSCP ≥ VIMP - VIMN
LED Open Detection Voltage
VOPEN
1.42
1.5
1.575
V
VODT: Sweep up
LED Open Hysteresis Voltage
VHYSOPEN
-
0.1
-
V
VODT: Sweep down
ITDISC
4
11
18
μA
VTDISC = 0V
TDISC Short Timer Detection Voltage
VDTDISC
0.9
1.0
1.1
V
VTDISC: Sweep up
TDISC Short Timer Release Voltage
VRTDISC
0.2
0.3
0.4
V
VTDISC: Sweep down
EN OFF
Voltage
VTDISC
VVREG50
× 0.55
VVREG50
× 0.7
VVREG50
× 0.85
V
TTDISC
20
35
55
ms
CTDISC = 0.1 μF
IDISC
3
10
-
mA
VIMP = 12 V
VVREG50
× 0.18
VVREG50
× 0.36
VVREG50
× 0.20
VVREG50
× 0.40
VVREG50
× 0.22
VVREG50
× 0.44
TPWM
50
-
-
μs
PWMOUT Upper Side
ON Resistance
RPWMOUTP
-
20
40
Ω
ION = -10 mA
PWMOUT Lower Side
ON Resistance
RPWMOUTN
-
5
10
Ω
ION = 10 mA
VREG25
Load Regulation Voltage
IVREG25 = 0μA to 250 μA
[SWDRV]
[LED Current Setting Block]
TDISC Charge Current
TDISC
Discharge
Stop
Vout Discharge Time
Output Charge Discharge Current
[CR TIMER]
CR Threshold Voltage 1
VCRTH1
CR Threshold Voltage 2
VCRTH2
PWM Minimum Pulse Width
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
21/45
V
V
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Electrical Characteristics (Unless otherwise specified VCC = 13 V, VIMP = 40 V, Ta = -40 °C to 125 °C)
Limit
Parameter
Symbol
Unit
Min
Typ
Max
Condition
[ERRAMP]
COMP Source Current
ICOMPSO
-90
-60
-30
μA
VCOMP = 1.2 V,
VDCD = VREG25
VIMP - VIMN = 0 mV
COMP Sink Current
ICOMPSI
30
60
90
μA
VCOMP = 1.2 V,
VDCD = VREG25
VIMP - VIMN = 400 mV
ISS
3
5
7
μA
VSS = 0 V
DC / DC Switching Frequency
FOSC
270
300
330
kHz
RRT = 33 kΩ
Max Duty Output
DMAX
-
95
-
%
RRT = 33 kΩ
RS Frequency
FRS
-
0.75
-
kHz
RS Terminal High Voltage
VRSH
-
0.75
-
V
VRS: Sweep up
RS Terminal Low Voltage
VRSL
-
0.60
-
V
VRS: Sweep down
UVLO Detection Voltage
VUVLO
3.6
3.9
4.2
V
VCC: Sweep down
UVLO Hysteresis Width
VUHYS
250
350
450
mV
VCC: Sweep up
EN Terminal ON Threshold Voltage
VENON
1.35
1.45
1.55
V
VEN: Sweep up
EN Terminal Hysteresis Voltage Width
VHYSEN
-
100
-
mV
VEN: Sweep down
IDRL
4
13
22
μA
VDRL = 13 V
DRL Terminal ON Threshold Voltage
VDRLON
3
-
-
V
VDRL: Sweep up
DRL Terminal OFF Threshold Voltage
VDRLOFF
-
-
0.8
V
VDRL: Sweep down
[Soft start]
Soft Start Charge Current
[Oscillator]
[RAMP]
RRT = 33 kΩ, CRS = 0.047 µF
[UVLO]
[EN/DRL]
DRL Terminal Input Current
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
22/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
3.5
6
3.0
5
Output Voltage: VREG50 [V]
Circuit Current: ICC [mA]
Typical Performance Curves (Reference Data)
2.5
2.0
1.5
1.0
-40℃
25℃
0.5
4
3
2
-40℃
1
25℃
125℃
125℃
0.0
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65
Supply Voltage: VCC [V]
0 5 10 15 20 25 30 35 40 45 50 55 60 65
Supply Voltage: VCC [V]
Figure 30. Output Voltage vs Supply Voltage
(VREG50)
3.0
206
2.5
204
2.0
1.5
1.0
-40℃
0.5
25℃
Reference Voltage: VREF [mV]
Output Voltage: VREG25 [V]
Figure 29. Circuit Current vs Supply Voltage
125℃
200
198
196
194
0.0
-40
0 5 10 15 20 25 30 35 40 45 50 55 60 65
Supply Voltage: VCC [V]
-15
10
35
60
85
110
Temperature: Ta [°C]
Figure 32. Reference voltage vs Temperature
Figure 31. Output Voltage vs Supply Voltage
(VREG25)
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
202
23/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Typical Performance Curves (Reference Data) - Continued
2.55
Output Voltage:VREG25 [V]
Output Voltage: VREG50 [V]
5.2
5.1
5.0
4.9
2.53
2.50
2.48
2.45
4.8
-40
-10
20
50
80
-40
110
-10
20
50
80
110
TEMPERATURE: Ta [°C]
TEMPERATURE: Ta [°C]
Figure 34. Output Voltage vs Temperature
(VREG25)
Figure 33. Output Voltage vs Temperature
(VREG50)
600
325
320
500
310
ILED Current [mA]
Frequency: FOSC [kHz]
315
305
300
295
290
285
400
300
200
100
280
275
-40
-15
10
35
60
85
0
110
0.0
Temperature: Ta [°C]
1.0
1.5
2.0
DCD Terminal Voltage [V]
Figure 36. ILED Current vs DCD Terminal Voltage
Figure 35. Frequency vs Temperature
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
0.5
24/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Typical Performance Curves (Reference Data) - Continued
RRT = 30kΩ
RRT = 30kΩ
CRS = 0.047μF
Figure 38. Spectrum Spread (OFF)
(RS = VREG50 Short)
Figure 37. Spectrum Spread (ON)
Figure 39. PWM Control Operation Start (DRL = Low)
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
25/45
Figure 40. PWM Control Start (DRL = Low)
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Typical Performance Curves (Reference Data) - Continued
Figure 41. PWM Control Operation Start (DRL = High)
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
26/45
Figure 42. PWM Control Operation Stop (DRL = High)
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Timing Chart 1
4.25V
VCC
3.9V
VCC=4.25V
UVLO release
VCC=3.9V
UVLO detect
VREG50
It is ±11.1% for switching frequency
VRT×15/16
RS
VRT×3/4
EN ON
EN ON
EN OFF
EN OFF
EN
1.35V
1.45V
(VCC resistance division)
DRL
DRL=Low
2.0V
1.0V
CR
PWMOUT
0.7V
SS
VREG50×0.7
COMP
SWDRV
VOUT
ILED
Output discharge
circuit
ON
ON
(Output discharge at 10mA)
Figure 43. Start / Stop Sequence Timing chart (At time of PWM Control)
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
27/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Timing Chart 2
VCC
4.25V
VCC=4.25V
UVLO release
3.95V
VCC=3.95V
UVLO detect
VREG50
It is ±11.1% for switching frequency
VRT×15/16
RS
VRT×3/4
EN ON
EN ON
EN OFF
EN OFF
EN
1.35V
1.45V
(VCC resistance division)
DRL ON
DRL OFF
DRL
At the time of the use of DRL, it is
necessary to start faster than EN.
(Note 1)
2.0V
1.0V
CR
PWMOUT
VREG50×0.7
SS
0.7V
COMP
SWDRV
VOUT
ILED
Output discharge
circuit
ON
ON
(Output discharge at 10mA)
Figure 44. Start / Stop Sequence Timing chart (At time of PWM 100 % Control)
(Note 1)
Please apply the logic fix possible voltage to the Hi side before EN by all means when DRL terminal is used on the
High side (PWM 100 % state).
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
28/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Application Examples
External
power
VB
VOUT
VCC
VREG50
FAIL
ODT
EN
VREG25
RT
DCD
VOUT
DRL
RS
COMP
VREG50
BD18351EFV-M
SS
SWDRV
CS
IMP
DISC
IMN
CR
PWMOUT
TDISC
GND
DGND
Figure 45. Boost Application (with PchMOS)
VCC
External
power
VB
VOUT
VCC
VREG50
FAIL
ODT
EN
VREG25
RT
VREG50
DCD
VOUT
DRL
RS
COMP
BD18351EFV-M
SS
SWDRV
CS
IMP
DISC
IMN
CR
PWMOUT
TDISC
GND
VCC
DGND
Figure 46. The application returning LED cathode to the power supply
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
29/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Application Parts Selection Method (Boost mode Application)
Select application parts by the following procedure.
1. Set EN terminal operation voltage.
2. Set PWM dimming rate / frequency.
3. Set switching frequency.
4. Derive input peak current IL_MAX from use condition.
5. Set RCS to make overcurrent protection current value as IOCP > IL_MAX.
Feedback
of L value
6. Set L constant value as (VOUT - VCC) / L × RCS × RRT < 13 × VRT.
7. Set LED open protection voltage
8. Select coil, SBD, MOSFET to satisfy rated current and rated voltage.
9. Set output capacitor to satisfy output ripple voltage condition.
10. Set output discharge time
11. Select input capacitor.
12. Set phase compensation circuit.
13. Set soft start time, start up time.
14. Confirm operation of actual equipment
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
30/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
1. Setting of EN terminal operation voltage
This device can be turned ON / OFF by inputting resistor divided voltage to EN terminal.
EN terminal voltage to controls ON / OFF can be set as shown below.
VCC
(𝑅𝐸𝑁1 + 𝑅𝐸𝑁2 )
=
× 1.45𝑉(𝑇𝑦𝑝)
𝑅𝐸𝑁2
𝑉𝐶𝐶𝑂𝑁
𝑉𝐶𝐶𝑂𝐹𝐹
REN1
EN
(𝑅𝐸𝑁1 + 𝑅𝐸𝑁2 )
=
× 1.35𝑉(𝑇𝑦𝑝)
𝑅𝐸𝑁2
+
REN2
-
Figure 47. Concerning EN terminal Setting Method
2. Setting of PWM dimming rate / frequency
PWM dimming frequency (FPWM) and PWM dimming ON Duty (DPWM) can be set with resistance and capacitor by means of
CR timer function which is built in this device. PWM dimming is 100 % dimming when DRL terminal voltage ≥ 3.0 V and is
controlled by dimming rate set with external C and R in the other range. Also, In addition, the recommended operating
frequency is 100 Hz to 2 kHz. The recommended external components values are; DISC2 to be between 10kΩ to 33 kΩ, CCR
to be between 0.01 µF to 1.0 µF.
Trise
VREG50
RDISC1
Tfall
2.0V
VREG50 x 0.4
CR falling
CR
RDISC2
CCR
CR rising
DISC
CR
1.0V
VREG50
x 0.2
+
DRV
-
PWMOUT
PWMOUT
1.0V/2.0V
LOGIC
ILED
DRL
LED OFF
LED ON
FPWM = 1 / (Trise + Tfall) [Hz]
Trise=0.287×C ×(R
+RDISC2)
Tfall = 0.693 × CCRCR ×DISC1
RDISC2
Tfall=0.693×C
CR×R DISC1
Trise = 0.287 × CCR × (RDISC1 + RDISC2)
DPWM = Tfall / (Trise + Tfall) [%]
Figure 48. Concerning CR Timer Setting Method
3. Setting of switching frequency
A noise can be reduced using a spread spectrum function built-in the device. When spread spectrum is controlled, the
switching does not work in frequency FOSC1 decided by RT resistance shown in P.9 Figure 12 and Frequency of FOSC1 × 0.84
as a center, it works at the frequency that modulated 11.1 %. The quantity of modulation frequency FRS and noise decrement
can be calculated from formula listed in P.10. (Because frequency is modulated at the time of the spread spectrum, it
becomes maximum when frequency including the coil current is low. When each fixed number is calculated, please use it.
(Please refer to P.10, 11 for the details.)) When a spread spectrum function is not used, please short-circuit with VREG50
terminal with RS terminal. Because the frequency setting changes, please be careful.
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
31/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
4. Derivation of input peak current IL_MAX (VDCD > 1.21 V)
1. Calculation of output voltage (VOUT)
VF of LED for driving: VF
current setting
voltage: VREF1
𝑉𝑂𝑈𝑇 = 𝑉𝐹 × 𝑁 + 𝑉𝑅𝐸𝐹1 + LED
𝑅𝑂𝑁_𝑃𝑊𝑀𝐹𝐸𝑇
× 𝐼standard
𝐿𝐸𝐷
ON resistance of FET for PWM dimming:
RON_PWMFET
LED current: ILED
Resistance for LED current setting: RSET
Maximum coil current: IL_MAX
Coil mean current: IL_AVE
Ripple current: ΔIL
Power voltage: VCC
Output voltage: VOUT
Efficiency: η
DC / DC oscillation frequency: FOSC
2. Calculation of output current ILED
𝐼𝐿𝐸𝐷 =
𝑉𝑅𝐸𝐹1
𝑅𝑆𝐸𝑇
3. Calculation of input peak current IL_MAX
1
𝐼𝐿_𝑀𝐴𝑋 = 𝐼𝐿_𝐴𝑉𝐸 + 𝛥𝐼𝐿
2
1
𝐼𝐿_𝑀𝐼𝑁 = 𝐼𝐿_𝐴𝑉𝐸 − 𝛥𝐼𝐿
2
𝐼𝐿_𝐴𝑉𝐸 =
𝛥𝐼𝐿 =
𝑉𝑂𝑈𝑇 × 𝐼𝐿𝐸𝐷
𝜂 × 𝑉𝐶𝐶
𝑉𝐶𝐶 (𝑉𝑂𝑈𝑇 − 𝑉𝐶𝐶 )
1
×
×
𝐿
𝑉𝑂𝑈𝑇
𝐹𝑂𝑆𝐶
●Since minimum input voltage is the worst case of VCC, assign minimum input voltage for calculation.
●BD18351EFV-M adopts current mode DC / DC converter control. When I L_Min is positive, it becomes to be in the
consecutive modes, and it will be in the discontinuity mode when I L_MIN is negative. Phase characteristics are easy to
become insufficient in the discontinuous mode, and responsiveness turns worse, and a switching wave pattern becomes
irregular, and stability is easy to turn worse. Therefore it is sufficient validation of phase characteristics are recommended.
●η (efficiency) is about 90 %.
●In the case of VDCD 𝐼𝐿_𝑀𝐴𝑋
𝑅𝐶𝑆
Since values of coil L may vary about ±30 %, set with sufficient margin.
6. Selection of coil L constant value
For the purpose of stabilizing current mode DCDC converter operation, adjustment of L value within the following condition is
recommended.
(𝑉𝑂𝑈𝑇 − 𝑉𝐶𝐶 ) × 𝑅𝐶𝑆 × 𝑅𝑅𝑇 × 10−3
< 13 × 𝑉𝑅𝑇
𝐿 × 106
Reduction of calculated value will increase stability, but may reduce responsiveness such as power voltage variation. Bigger
values which do not satisfy the above formula may cause sub-harmonic oscillation, destabilize switching duty and cause
blinking of LED.
Further, assign VRT = 0.8 V when RS terminal short-circuits with VREG and spread spectrum is not used, and assign
VRT = 0.675 V when capacitor is connected to RS terminal and spectrum is diffused.
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
32/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
7. Setting of LED open protection voltage
LED open detection voltage needs higher voltage setting than overshoot of
output voltage at start up to avoid start up failure. Further, output voltage at
the time of LED open detection (VOUT_ODT) is calculable as shown below by
setting RODT1 and RODT2.
𝑉𝑂𝑈𝑇_𝑂𝐷𝑇
VOUT
RODT1
(𝑅𝑂𝐷𝑇1 + 𝑅𝑂𝐷𝑇2 )
=
× 1.5𝑉(𝑇𝑦𝑝)
𝑅𝑂𝐷𝑇2
ODT
ODT resistor will be the current discharge path for the output capacitor
when PWM = Low Recommended value for RODT1 is 600 kΩ to 1000 kΩ as
Vout ripple may be large and cause LED flickering when PWM = Low with
inadequate ohmic value range.
Sufficient verification for LED flickering is required with actual application
as behavior differs by characteristic of output capacitor and LED.
(Vout drop can be prevented by inserting bigger output capacitor or ODT
resistance.)
+
RODT2
-
1.5V/1.4V
Figure 49. ODT terminal Equivalent Circuit
8. Selection of power element, diode D1, MOSFET Q1 and Q2
VCC
L
Di
VOUT
SWDRV
Q1
COUT
RSET
CS
RCS
IMP
IMN
VREF1
PWMOUT
Q2
Figure 50. Boost Application Circuit
Selection of MOSFET Q1
Select MOSFET (Q1) to have VDS rating higher than the Max output voltage which LED open function is activated.
𝑉𝑂𝑈𝑇_𝑂𝐷𝑇_𝑀𝐴𝑋 >
(𝑅𝑂𝐷𝑇1 +𝑅𝑂𝐷𝑇2 )
𝑅𝑂𝐷𝑇2
× 1.575𝑉(𝑀𝑎𝑥 )
VDS: Voltage between drain and source
In addition, the RMS current limit flowing between drain - sources of Q1 can be calculated as follows.
𝐼𝐷𝑆_𝑅𝑀𝑆 = 1.3 × √(𝐼𝐿_𝐴𝑉𝐸 )^2 × 𝐷𝑆𝑊
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
DSW : Switching Duty
33/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
A loss of Q1 is calculated next. The loss of Q1 will be the Ploss2 which is switching loss and Ploss1 the On resistance of Q1.
Switching loss Ploss1 and Q1 On resistance loss Ploss2 can be calculated as follows.
𝑃𝑙𝑜𝑠𝑠1 =
(𝑇𝑟 +𝑇𝑓 )
2
× 𝐹𝑂𝑆𝐶 × (𝑉𝑂𝑈𝑇 + 𝑉𝐷𝑖 ) × 𝐼𝐿_𝐴𝑉𝐸
𝑃𝑙𝑜𝑠𝑠2 = 𝐼𝐿_𝐴𝑉𝐸 2 × 𝑅𝑜𝑛 × 𝐷𝑆𝑊
Tr / Tf: Drain source rise / fall time
Ron: Ron of Q1
Selection of rectifier diode Di
For power consumption reduction, please use a Schottky Barrier diode for rectification diode Di. The withstand voltage rating
of the diode shall be higher than the LED Open protection voltage. In addition, Schottky Barrier diode with low leakage
current shall be selected if PWM dimming is used. Because the leakage current increases with higher temperature
environment, the output capacitor can be discharged in PWM = Low which may result that LED current will be unstable.
The current limit of Di can be calculated in following formula.
𝐼𝐷𝑖 = 𝐼𝐿_𝐴𝑉𝐸 × (1 − 𝐷𝑆𝑊 ) × 1.5
Selection of MOSFET Q2
Consider margin and set the rated voltage rather higher than the actual usage condition for LED current and output voltage.
9. Selection of output capacitor COUT
Output capacity includes two purposes. The first is to reduce output ripple. The second is to supply current to LED when
MOSFET (Q1) is switched on. The output voltage ripple is influenced by both bulk capacity and ESR. (When a ceramic
capacitor is used, bulk capacity causes most of the ripple.) Bulk capacity and the ESR can be calculated in lower formula.
𝐶𝑂𝑈𝑇 ≥ 𝐼𝐿𝐸𝐷 ×
𝑅𝐸𝑆𝑅 <
𝐷𝑠𝑤
∆𝑉𝐶𝑂𝑈𝑇 × 𝐹𝑂𝑆𝐶
ΔVCOUT: influence with the capacitor among output ripple
ΔVESR: Ripple which occurs in the ESR of the output capacitor
∆𝑉𝐸𝑆𝑅
𝐼𝐿_𝑀𝐴𝑋
The total output ripple permitted here can be expressed as product of LED current ripple and the equivalent resistance of the
LED. This equivalent resistance is defined as "ΔV / ΔI of the LED current", and it is necessary to calculate from I-V properties
in the data sheet of the selected LED. Assuming that number of the driven LED = 8 pcs (equivalent resistance 0.2 Ω / LED),
LED current = 1 A (IL_MAX = 4.5 A), switching Duty = 60 %, switching frequency = 300 kHz, it is supposed that LED current
ripple is 5%.Then the total output ripple can be calculated as follows.
𝑉𝑂𝑈𝑇_𝑟𝑖𝑝𝑝𝑙𝑒 = 1𝐴 × 5% × (0.2𝛺 × 8) = 80𝑚𝑉
If bulk capacity causes 95 % among total output ripple, the output capacitor is calculated as follows.
𝐶𝑂𝑈𝑇 ≥ 1 ×
𝑅𝐸𝑆𝑅 <
0.6
1
×
= 26.4𝜇𝐹
0.08 × 0.95 300𝑘𝐻𝑧
(0.08 × 0.05)
𝑉𝑂𝑈𝑇_𝑟𝑖𝑝𝑝𝑙𝑒
=
= 0.88𝑚𝛺
𝐼𝐿_𝑀𝐴𝑋
4.5
However the capacitance of output capacitor mentioned above is minimum capacitance. Therefore please select
components considering the tolerance of the capacitor and DC bias properties. Furthermore, because small external
component connected to output may lead to bigger ripple on output voltage, which may result in LED flickering, sufficient
verification of the actual application is required. Increase output capacitors if judged to be required from the verification. In
addition, an acoustic noise may be produced by the piezoelectric effect of the ceramic capacitor during PWM dimming.
Electrolytic capacitor used together with a ceramic capacitor may reduce this noise. But capacitance may largely decrease
with a change of the voltage with the ceramic capacitor and may not accord with the numerical value calculated from theory.
Thorough consideration is required.
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
34/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
10. Setting of TDISC terminal
Output discharge time and Output short protection time can be set by connecting capacitor to TDISC terminal.
Recommended range of capacitor will be 0.01 μF to 0.47 μF, however if capacitor at TDISC (CTDISC) is smaller, output
discharge time will be short which may result in LED flashing when restarting the supply voltage. On the other hand if CTDISC
is large discharge time will be longer. If Vout is high and discharge time is longer, heat generation of LSI will be larger
therefore verification with actual application is required with caution.
11. Selection of input capacitor
In DC / DC converter, since peak current flows between input and output, a capacitor is also required in the input side.
Therefore, low ESR capacitors with capacitor of no less than 10 µF and ESR component of no more than 100 mΩ are
recommended as input capacitors. Selection of capacitors out of the range may cause malfunction of IC because excessive
ripple voltage will overlap input voltage.
12. Setting of phase compensation circuit
●Concerning stability condition of application
Stability condition for system with negative feedback is as shown below.
Phase-lag when gain is 1 (0 dB) is no more than 150 ° (namely, phase margin is no less than 30 °).
Further, since DC / DC converter application is sampled by switching frequency, GBW of the entire system is set to be
no more than 1 / 10 of switching frequency. To wrap up, target characteristics of application are as shown below.
●Phase-lag when gain is 1 (0 dB) is no more than 150 ° (namely, phase margin is no less than 30 °)
●GBW at the time (namely, frequency when gain is 0 dB) is no more than 1/10 of switching frequency. Therefore, in
order to raise responsiveness by limiting GBW, higher switching frequency is required.
The knack for securing stability by phase compensation is to insert phase-lead FZ1 near GBW. GBW is determined by COUT
and phase-lag fp1 due to output impedance RL (= VOUT / ILED).
They are shown in the following formulae.
Phase-lead
VOUT
1
𝐹𝑍1 =
IMP
2𝜋 × 𝐶𝑃𝐶 × 𝑅𝑃𝐶
CURRENT
SENSE
Phase-lag
𝐹𝑃 =
𝑅𝐿 =
IMN
1
-
ERRAMP
COMP
+
VOUT
DISC
CPC
RPC
2𝜋 × 𝑅𝐿 × 𝐶𝑂𝑈𝑇
𝑉𝑂𝑈𝑇
𝐼𝐿𝐸𝐷
Figure 51. ERRAMP Equivalent Circuit
As described above, please secure phase margin. For RL value at max load should be inserted. In addition, with boost
DC/DC, right half plane zero (RHP zero) is to be considered. This zero has a characteristic of zero as a gain and as the pole
with phase. Because it causes an oscillation when this zero effects on a control loop, it is necessary to bring GBW just before
RHP zero. RHP zero can be calculated with an equation below and shows good characteristic by setting GBW to be lower
than 1 / 10 of RHP zero.
𝐹𝑍2 =
𝑉
𝑅𝐿 × (𝑉 𝐶𝐶 )2
𝑂𝑈𝑇
2𝜋 × 𝐿
Particularly when supply voltage rises and gets close to output voltage, the switching output becomes irregular and ripple of
the output voltage increases. Ripple of the LED current may thereby get bigger.
Since this setting is obtained by simplified, not strict, calculation, adjustment by actual equipment may be required in some
cases.
Further, since these characteristics will vary depending upon substrate layout, load condition, etc., confirm satisfactorily with
actual equipment when planning mass production.
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
35/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
13. Soft start time and confirmation of the boot-time
A soft start function is incorporated, and an inrush current can be prevented by inserting an external capacitor. Charge
current of the soft start is 5 μA (Typ) and charges it without depending on PWM. The inrush current can be suppressed by
increasing soft start capacity, but boot-time becomes longer. On the other hand, as for the boot-time, it becomes faster by
lowering soft start capacity, but an inrush current grows bigger and it leads to the sound rumble of the coil in the startup,
therefore attention is necessary. 0.01 μF to 1 μF is recommended to control overshoot of the LED current in the startup.
In addition, the boot-time varies according to PWM dimming control condition. Refer to details described in P11 and 12.
14. Confirmation of actual equipment operation
Select external components based on verification with actual equipment since characteristics will vary depending on various
factors such as load current, input voltage, output voltage, inductor value, load capacity, switching frequency and mounting
pattern.
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
36/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
PCB Application Circuit diagram
VCC = 9 V to 16 V, LED drive stage number: 7 (VOUT ≈ 23 V), LED current: 500 mA,
DC / DC oscillation frequency: 280 kHz, SSCG mode ON
VCC
CIN1
VREG50 VFAIL
CN1
CVREG51
VCC
VFAIL
CVREG50
L1
VREG50
RFL
FAIL
VOUT1
CIN2
CEN
RODT1
FAIL
VCC
EN
VREG50
EN
REN1
ODT
VREG25
REN2
RODT2
RT
DCD
VOUT
RDCD1
RRT
VOUT
DCD
DRL
U1
RDCD3
RDCD2
DRL
COUT1
RS
CRS
COMP
BD18351EFV-M
SWDRV
RPC
RSW
COUT3
COUT4
COUT5
RSET
DGND DGND DGND DGND DGND
M1
RCS1
CPC
COUT2
CS
SS
VREG50
RVOUT
DI
RCS2
CSS
CN2
RDISC1
RIMP
IMP
DISC
RIMN
CR
DGND
CCR
GND
IMN
CR
TDISC
RDISC2
PWMOUT
CTDISC
Figure 52. Boost application (PWM Dimming Application)
About the attention point at the time of the PCB layout
VCC
L
Di
VOUT
SWDRV
Q1
COUT
7.
RSET
CS
1
RCS
IMP
IMN
VREF1
PWMOUT
Q2
Figure 53. Boost High Side PWM Dimming Application
1. Please locate the decoupling capacitor of CIN2, CVREG50, CVREG51 close to an LSI pin as much as possible
2. RRT locates it close to RT pin, and prevent there from being capacity
3. Because high current may flow in DGND, please lower impedance.
4. Prevent noise to be applied to EN, DRL, COMP, SS, RT, DCD, IMP, and IMN terminals.
5. As the CR, DISC, RS, SWDRV, PWMOUT terminals are switching, please be careful not to affect the neighboring patterns.
6. There is heat dissipation PAD on the back side of the package.
7. For noise reduction, DGND of RCS1, RCS2 and DGND of COUT recommend to have one common grounds. In addition, consider
the PCB layout so that the current path of M1 → RCS1, RCS2 → DGND and the current path of Di → COUT → DGND are the
shortest and with the lowest impedance.
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
37/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
List of PCB board attaching externally parts
Bom_No
Value
Parts No
Product Maker
CIN1
10μF
GCM32EC71H106KA01
Murata
CIN2
0.1μF
GCM188R11H104KA01
Murata
CVREG50
2.2μF
GCM21BR71C225KA49
Murata
CVREG51
1000pF
GCM155R11H102KA01
Murata
REN1
100kΩ
MCR03
Rohm
REN2
39kΩ
MCR03
Rohm
CEN
1000pF
GCM155R11H102KA01
Murata
RRT
30kΩ
MCR03
Rohm
CRS
0.047μF
GCM188R11H473KA01
Murata
RPC
5.1kΩ
MCR03
Rohm
CPC
0.047μF
GCM188R11H473KA01
Murata
RDISC1
100kΩ
MCR03
Rohm
RDISC2
20kΩ
MCR03
Rohm
CCR
0.1μF
GCM188R11H104KA01
Murata
CSS
0.1μF
GCM188R11H104KA01
Murata
CTDISC
0.1μF
GCM188R11H104KA01
Murata
RFL
100kΩ
MCR03
Rohm
L1
10µH
IHLP-3232DZ-11
Vishay
RODT1
680kΩ
MCR03
Rohm
RODT2
33kΩ
MCR03
Rohm
RDCD1
12kΩ
MCR03
Rohm
RDCD2
100kΩ
MCR03
Rohm
RDCD3
100kΩ
NTCG104EF104F
TDK
M1
-
RSD150N06FRA
Rohm
RSW
22Ω
MCR03
Rohm
RCS1
150mΩ
LTR18
Rohm
RCS2
150mΩ
LTR18
Rohm
Di
-
RB058L150
Rohm
RIMP
0Ω
MCR03
Rohm
RIMN
0Ω
MCR03
Rohm
COUT1
0.1µF
GCM188R11H104KA01
Murata
COUT2
10μF
GCM32EC71H106KA01
Murata
COUT3
10μF
GCM32EC71H106KA01
Murata
COUT4
10μF
GCM32EC71H106KA01
Murata
COUT5
10μF
GCM32EC71H106KA01
Murata
RVOUT
0Ω
LTR18
Rohm
RSET
680mΩ
LTR10
Rohm
M2
-
RTR020N05
Rohm
IC
-
BD18351EFV-M
Rohm
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
38/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
I/O Equivalent Circuits
1. COMP
2. SS
4. DCD
VREG50
VREG50
VREG50
SS
CM
COMP
DCD
COMP
5. VREG25
6. RT
7. RS
VREG50
VREG50
VREG50
RS
CM
VREG25
RT
8. CR, 9. DISC
10. FAIL
11. TDISC
VREG50
CR
FAIL
TDISC
DISC
×1
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
39/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
I/O Equivalent Circuits - Continued
12. PWMOUT
13. IMN, 14. IMP
17. CS
VREG50
IMP
VREG50
VREG50
IMP
IMN
PWMOUT
CS
18. SWDRV
19. ODT
20. VREG50
VCC
VREG50
ODT
VREG50
SWDRV
Internal
Circuit
22. DRL
23. EN
24. VCC
VCC
VREG50
EN
DRL
BG
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
40/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Operational Notes
1.
Reverse Connection of Power Supply
Connecting the power supply in reverse polarity can damage the IC. Take precautions against reverse polarity when
connecting the power supply, such as mounting an external diode between the power supply and the IC’s power
supply pins.
2.
Power Supply Lines
Design the PCB layout pattern to provide low impedance supply lines. Separate the ground and supply lines of the
digital and analog blocks to prevent noise in the ground and supply lines of the digital block from affecting the analog
block. Furthermore, connect a capacitor to ground at all power supply pins. Consider the effect of temperature and
aging on the capacitance value when using electrolytic capacitors.
3.
Ground Voltage
Ensure that no pins are at a voltage below that of the ground pin at any time, even during transient condition.
4.
Ground Wiring Pattern
When using both small-signal and large-current ground traces, the two ground traces should be routed separately but
connected to a single ground at the reference point of the application board to avoid fluctuations in the small-signal
ground caused by large currents. Also ensure that the ground traces of external components do not cause variations
on the ground voltage. The ground lines must be as short and thick as possible to reduce line impedance.
5.
Thermal Consideration
Should by any chance the power dissipation rating be exceeded the rise in temperature of the chip may result in
deterioration of the properties of the chip. The absolute maximum rating of the Pd stated in this specification is when
the IC is mounted on a 70mm x 70mm x 1.6mm glass epoxy board. In case of exceeding this absolute maximum rating,
increase the board size and copper area to prevent exceeding the Pd rating.
6.
Recommended Operating Conditions
These conditions represent a range within which the expected characteristics of the IC can be approximately obtained.
The electrical characteristics are guaranteed under the conditions of each parameter.
7.
Inrush Current
When power is first supplied to the IC, it is possible that the internal logic may be unstable and inrush
current may flow instantaneously due to the internal powering sequence and delays, especially if the IC
has more than one power supply. Therefore, give special consideration to power coupling capacitance,
power wiring, width of ground wiring, and routing of connections.
8.
Operation Under Strong Electromagnetic Field
Operating the IC in the presence of a strong electromagnetic field may cause the IC to malfunction.
9.
Testing on Application Boards
When testing the IC on an application board, connecting a capacitor directly to a low-impedance output pin may
subject the IC to stress. Always discharge capacitors completely after each process or step. The IC’s power supply
should always be turned off completely before connecting or removing it from the test setup during the inspection
process. To prevent damage from static discharge, ground the IC during assembly and use similar precautions during
transport and storage.
10. Inter-pin Short and Mounting Errors
Ensure that the direction and position are correct when mounting the IC on the PCB. Incorrect mounting may result in
damaging the IC. Avoid nearby pins being shorted to each other especially to ground, power supply and output pin.
Inter-pin shorts could be due to many reasons such as metal particles, water droplets (in very humid environment) and
unintentional solder bridge deposited in between pins during assembly to name a few.
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
41/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Operational Notes – continued
11. Unused Input Pins
Input pins of an IC are often connected to the gate of a MOS transistor. The gate has extremely high impedance and
extremely low capacitance. If left unconnected, the electric field from the outside can easily charge it. The small
charge acquired in this way is enough to produce a significant effect on the conduction through the transistor and
cause unexpected operation of the IC. So unless otherwise specified, unused input pins should be connected to the
power supply or ground line.
12. Regarding the Input Pin of the IC
This monolithic IC contains P+ isolation and P substrate layers between adjacent elements in order to keep them
isolated. P-N junctions are formed at the intersection of the P layers with the N layers of other elements, creating a
parasitic diode or transistor. For example (refer to figure below):
When GND > Pin A and GND > Pin B, the P-N junction operates as a parasitic diode.
When GND > Pin B, the P-N junction operates as a parasitic transistor.
Parasitic diodes inevitably occur in the structure of the IC. The operation of parasitic diodes can result in mutual
interference among circuits, operational faults, or physical damage. Therefore, conditions that cause these diodes to
operate, such as applying a voltage lower than the GND voltage to an input pin (and thus to the P substrate) should be
avoided.
Resistor
Transistor (NPN)
Pin A
Pin B
C
E
Pin A
N
P+
P
N
N
P+
N
Pin B
B
Parasitic
Elements
N
P+
N P
N
P+
B
N
C
E
Parasitic
Elements
P Substrate
P Substrate
GND
GND
Parasitic
Elements
GND
Parasitic
Elements
GND
N Region
close-by
Figure 54. Example of monolithic IC structure
13. Ceramic Capacitor
When using a ceramic capacitor, determine the dielectric constant considering the change of capacitance with
temperature and the decrease in nominal capacitance due to DC bias and others.
14. Area of Safe Operation (ASO)
Operate the IC such that the output voltage, output current, and power dissipation are all within the Area of Safe
Operation (ASO).
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.
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
42/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Ordering Information
B
D
1
8
3
5
1
Part Number
E
F
V
Package
EFV: HTSSOP-B24
-
M
E
2
Packaging and forming specification
M : High reliability
E2 : Embossed tape and reel
(HTSSOP-B24)
Marking Diagrams
HTSSOP-B24 (TOP VIEW)
Part Number Marking
D18351EF
LOT Number
1PIN MARK
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
43/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Physical Dimension, Tape and Reel Information
Package Name
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
HTSSOP-B24
44/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
BD18351EFV-M
Revision history
Date
Revision
2016.3.4
001
2016.5.12
002
2018.11.7
003
2019.09.02
004
Changes
New Release
P.11 Figure 16. Erratum modified
P.13 (4), P14 Output short detection function (SCP)
Previous rev. ”IMN terminal GND short-circuits”→ Revised ”When LED anode short to GND”
P.19 Thermal resistance
Previous74.2mm(square) → Revised 74.2mm x 74.2mm
P.20 Recommended operation condition
CRTIMER output Duty Min Previous rev. ”5%”→ Revised ”2%”
P.27 Figure 43. Erratum modified
P.31 Figure 48. Erratum modified
P.39,40 Modified equivalent circuit
P.1 Previous rev. “Minimum PWM Dimming Pulse Width: 100 µs”
Revised “Minimum PWM Dimming Pulse Width: 50 µs”
P.4 Previous rev. “(PWM min pulse width=100 µs)”
Revised “(PWM min pulse width=50 µs)”
P.6 Previous rev. “Minimum pulse width is 100 µs”
Revised “Minimum pulse width is 50 µs”
P.8 VOUT_MAX, VF_MAX, The number of drivable LED series stages Formula revised.
P.20 Previous rev. “Operating Condition (External Constant Range)”
Revised “Recommended External Constant Range”
P.20 Add (Note3), (Note4), (Note5).
P.21 Electrical Characteristics LED Open Detection Voltage Min
Previous rev. ”1.35” Revised ”1.42”.
P.21 Electrical Characteristics LED Open Detection Voltage Max
Previous rev. ”1.65” Revised ”1.575”.
P.21 Electrical Characteristics PWM Minimum Pulse Width Min
Previous rev. ”100” Revised “50”.
P.33 VOUT_ODT_MAX Formula revised.
P.21 Output short detection function (SCP)
Previous rev. ”CVREG50 = 2.2 μF”→ Revised ” CVREG50 = 2.2 μF IVREG50 = 0mA to 20 mA ”
P.32 6. Selection of coil L constant value Formula revised.
www.rohm.com
©2016 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
45/45
TSZ02201-0T3T0C700130-1-2
02.Sep.2019 Rev.004
Notice
Precaution on using ROHM Products
1.
If you intend to use our Products in devices requiring extremely high reliability (such as medical equipment (Note 1),
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
CLASSⅡb
CLASSⅢ
CLASSⅢ
CLASSⅣ
CLASSⅢ
2.
ROHM designs and manufactures its Products subject to strict quality control system. However, semiconductor
products can fail or malfunction at a certain rate. Please be sure to implement, at your own responsibilities, adequate
safety measures including but not limited to fail-safe design against the physical injury, damage to any property, which
a failure or malfunction of our Products may cause. The following are examples of safety measures:
[a] Installation of protection circuits or other protective devices to improve system safety
[b] Installation of redundant circuits to reduce the impact of single or multiple circuit failure
3.
Our Products are 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 (Exclude cases where no-clean type fluxes is used.
However, recommend sufficiently about the residue.); 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
© 2015 ROHM Co., Ltd. All rights reserved.
Rev.004
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 Cl 2, 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
© 2015 ROHM Co., Ltd. All rights reserved.
Rev.004
Datasheet
General Precaution
1. Before you use our Products, you are requested to carefully read this document and fully understand its contents.
ROHM shall not be in any way responsible or liable for failure, malfunction or accident arising from the use of any
ROHM’s Products against warning, caution or note contained in this document.
2. All information contained in this document is current as of the issuing date and subject to change without any prior
notice. Before purchasing or using ROHM’s Products, please confirm the latest information with a ROHM sales
representative.
3.
The information contained in this document is provided on an “as is” basis and ROHM does not warrant that all
information contained in this document is accurate and/or error-free. ROHM shall not be in any way responsible or
liable for an y damages, expenses or losses incurred b y you or third parties resulting from inaccuracy or errors of or
concerning such information.
Notice – WE
© 2015 ROHM Co., Ltd. All rights reserved.
Rev.001