operating current of the IC is as low as 180uA. It
doesn’t need the auxiliary winding for VCC supply.
It can achieve excellent constant current performance
with very few external components, so the system
cost and size are minimized.
BP9918C utilizes patent pending current control
method. It can achieve precise output current and
excellent line regulation. The driver operates in
critical conduction mode, the output current does not
change with the inductance and output voltage.
The BP9918C offers rich protections to improve the
system reliability, including LED short circuit
protection, VCC under voltage protection and
thermal regulation function.
Non-isolated Buck Offline LED Driver
Features
Internal 500V Power MOSFET
Integrated HV JFET for VCC Power Supply
Critical Conduction Mode Operation
Low Operating Current
± LED Output Current Accuracy
5%
LED Short Protection
VCC Under Voltage Protection
Thermal Regulation Function
Available in
SOT23-3
Package
Applications
LED Candle Light
LED Bulb
Other LED Lighting
Typical Application
AC
1
DRAIN
BP9918C
2
VCC
CS
3
Figure 1. Typical application circuit for BP9918C
BP9918C_EN _DS_Rev.1.3
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BP9918C
晶丰明源半导½
Ordering Information
Part Number
BP9918C
Package
SOT23-3
Operating
Temperature
-40 ℃ to 105 ℃
3,000 Pcs/Reel
Packing Method
Tape
9918C
Marking
Non-isolated Buck Offline LED Driver
Pin Configuration and Marking Information
3
CS
9918C
DRAIN
1
2
VCC
Figure 2. Pin configuration
Pin Definition
Pin No.
1
2
3
Name
DRAIN
VCC
CS
Description
Internal HV Power MOSFET Drain.
Power Supply Pin.
IC GND Pin, also for Current Sense. Connect a sense resistor between
this pin and power GND.
BP9918C_EN _DS_Rev.1.3
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BP9918C
晶丰明源半导½
Absolute Maximum Ratings
(note1)
Symbol
DRAIN
I
D
_max
VCC
P
DMAX
θ
JA
T
J
T
STG
Parameters
Internal HV MOSFET drain voltage
Maximum Drain Current@ T
J
=100℃
Power Supply voltage
Power dissipation (note 2)
Thermal resistance (Junction to Ambient)
Operating junction temperature
Storage temperature range
ESD (note 3)
Range
-0.3~500
500
-0.3~8.5
0.3
220
-40 to 150
-55 to 150
2
Units
V
mA
V
W
℃/W
℃
℃
KV
Non-isolated Buck Offline LED Driver
Note 1:
Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. Under “recommended operating
conditions” the device operation is assured, but some particular parameter may not be achieved. The electrical characteristics table defines the operation
range of the device, the electrical characteristics is assured on DC and AC voltage by test program. For the parameters without minimum and maximum
value in the EC table, the typical value defines the operation range, the accuracy is not guaranteed by spec.
Note 2:
The maximum power dissipation decrease if temperature rise, it is decided by T
JMAX
, θ
JA
, and environment temperature (T
A
). The maximum power
dissipation is the lower one between P
DMAX
= (T
JMAX
- T
A
)/ θ
JA
and the number listed in the maximum table.
Note 3:
Human Body mode, 100pF capacitor discharge on 1.5KΩ resistor
Recommended Operation Conditions
Symbol
I
LED max
V
LED min
Parameter
Maximum Output LED current
Minimum LED Loading Voltage
Range
200
>10
Unit
mA
V
BP9918C_EN _DS_Rev.1.3
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BP9918C
晶丰明源半导½
Non-isolated Buck Offline LED Driver
Electrical Characteristics (Notes 4, 5)
(Unless otherwise specified, V
CC
=7V and T
A
=25
℃)
Symbol
V
CC
V
CC_ON
V
CC_UVLO
I
ST
I
OP
Parameter
V
CC
Operating Voltage
V
CC
Turn On Threshold
V
CC
Turn off Threshold
V
CC
Startup Current
V
CC
Operating Current
Threshold Voltage for
Peak Current Limit
Leading Edge Blanking
Time for Current Sense
Switch Off Delay Time
Minimum OFF Time
Maximum OFF Time
Maximum On Time
Static Drain-source
On-resistance
Drain-Source
Breakdown Voltage
Thermal Regulation
Temperature
Conditions
Drain=100V
V
CC
Rising
V
CC
Falling
V
CC
= V
CC-ON
- 1V
Min
Typ
7.3
6.6
5.7
0.65
110
1.2
180
Max
Units
V
V
V
mA
uA
Supply Voltage Section
Current Sense Section
V
CS_TH
T
LEB
T
DELAY
T
OFF_MIN
T
OFF_MAX
T
ON_MAX
MOSFET Section
R
DS_ON
BV
DSS
V
GS
=7V/I
DS
=0.1A
V
GS
=0V/I
DS
=250uA
500
12
Ω
V
580
600
500
200
2.5
300
50
620
mV
ns
ns
us
us
us
Internal Time Control Section
Thermal Regulation Section
T
REG
140
℃
Note 4:
production testing of the chip is performed at 25°
C.
Note 5:
the maximum and minimum parameters specified are guaranteed by test, the typical value are guaranteed by design, characterization and statistical
analysis
BP9918C_EN _DS_Rev.1.3
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BP9918C
晶丰明源半导½
Internal Block Diagram
DRAIN
VCC
VCC Supply
Non-isolated Buck Offline LED Driver
VCC UVLO &
Power on Reset
Thermal
Regulation
CC &
logic
Control
ZCD
LEB
+
Current
Sense
S/H
-
0.6V
CS
Figure 3. BP9918C Internal Block Diagram
Application Information
The BP9918C is a high performance non-isolated
Buck converter specially designed for LED lighting.
The device integrates a 500V power MOSFET. With
very few external components, the converter
achieves excellent constant current control. And it
does not need auxiliary winding for powering the IC
or voltage sensing, hence the system size and cost is
greatly reduced.
Start Up
After system powered up, the VCC pin capacitor is
charged up by internal HV JEFT. When the VCC pin
voltage reaches the turn on threshold, the internal
circuits start operating. The HV JEFT will still
BP9918C_EN _DS_Rev.1.3
supply operating current when the IC is working and
keep the VCC voltage at 7.3V.
Constant Current Control
Cycle by Cycle current sense is adopted in BP9918C,
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