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BL8333D
Non-isolated Buck Off
Offline LED Driver
Features
Description
The BL8333D is a high precision
on buck constant
current LED driver. It is suitable for 85Vac~265Vac
universal low power offline LED ligh
ghting.
The BL8333D integrates a 500V pow
wer MOSFET.
It doesn’t need the auxiliary windiing for supplying
the chip. It can achieve excellent constant current
performance with very few exterrnal components,
so the system cost and size are miniimized.
The BL8333D utilizes patent pending
ng current control
method. It can achieve ± 3% LED
ED output current
acccuracy The output current does
oes not change with
the inductance and LED output voltage.
age.







Internal 500V Power M
MOSFET
± 3% LED Output Curreent Accuracy
Ultra Low Operating
ng Cu
Current
No Auxiliary Winding
Critical Conduction Mode Operation
LED Short Protection
Available in DIP-8 Pack
ackage
Applications



LED Candle Light
LED Bulb
Other LED Lighting
The BL8333D offers rich protection functions to
improve the system reliability, includ
uding LED open
circuit protection, LED short circuit protection, VCC
under voltage protection, CS resisstor short circuit
protection and thermal regulation func
unction.
Typical Application
BL8333D Datasheet V1.0
1
BL8333D
Non-isolated Buck Off
Offline LED Driver
PIN ASSIGNMENT and DESCRIPTION
PIN NO
SYMBOL
1
2
3
4
5,6
7,8
GND
RADJ
NC
VDD
DRN
ISEN
DESCRIPTION
Ground
Over Voltage Protection SettingPin.Connect a resistor.
No Connection.
Power Supply Pin.
Internal MOSFET Drain.
Current Sense Pin.Connect a resistor
sistor between this pin and GND.
Absolute Maximum Ratin
ngs (note1)
Symbol
Parameters
Ran
nge
Units
VDD
Power Supply
-0.3~20
0.3~20
V
VDRN
Drain Voltage
-0.3~
~500
V
CS
Current sense pin input
nput voltage
-0.3~
~6
V
IDDMAX
Maximum sink current
ent
5
mV
VRADNJ
Over-voltage setting
ng pin
p voltage
-0.3~
~6
V
PDMAX
Power dissipation
450
mW
θJA
Thermal resistance (Junction
(
to Ambient)
145
℃/W
TJ
Operating junction teemperature
-40 tto 150
℃
TSTG
Storage temperaturee range
-55 tto 150
℃
ESD
ESD
2000
000
V
Note 1: Stresses beyond those listed under “absol
olute maximum ratings” may cause permanent damage to the device.
BL8333D Datasheet V1.0
2
BL8333D
Non-isolated Buck Off
Offline LED Driver
Recommended Operation
n Conditions
Symbol
Para
Parameter
Range
Unit
ILED1
Input LED
ED current voltage
[email protected]
@ VOUT =80V
mA
ILED2
Input LED
ED current voltage
[email protected]
@ VOUT =36V
mA
VMIN
Minimum LED
L
Loading Voltage
>15
V
Electrical Characteristics
Symbol
VDD_CLP
IDD
VST
IST
Parameter
VCC Clamp Volt
ltage
VCC Operating Cu
urrent
Conditions
0.8mA
FSYS=65KHz
VCC Turn On Threeshold
VCC Startup Curr
rrent
VCC Rising
VUVLO
VCC Turn off Threshold
Thre
Current Sense Section
Threshold Voltage for Peak
VISEN
Current Limit
VISEN-SHT
Threshold Voltage
age for
Peak Current Limitt When
VDD= VST - 1V
VCC Falling
Output Short
Range
15.8~17.2
Units
V
≤135
12.8~14.2
2.8~14.2
μA
V
≤195
8.1~9.1
μA
V
392~408
mV
198
mV
500
ns
150
ns
Output Shortt
TLEB
TDELAY
MOSFET Section
Leading Edge Blaanking
Time for Current Sense
Switch Off Delay Time
V
BVDSS
Drain-Source Breakdo
akdown
Voltage
VGS=0V/IDS=250uA
500
RSW
Static Drain-source
source Onresistance
VGS=15V/IDS=0.4A
6
Ω
VGS=0V/VDS=500V
0.5
μA
0.55
Power MOSFET Drain
D
Leakage Current
ent
Internal Time Control Section
VRADJ
ROVP Pin Volt
ltage
IDSS
TON_MAX
Maximum ON Time
T
45
TOFF_MAX
TOFF_MIN
Maximum OFF Time
T
Minimum OFF Time
255
V
us
us
5
us
155
℃
Thermal Regulation Section
Thermal Regulation
TR EG
Temperature
BL8333D Datasheet V1.0
3
BL8333D
Non-isolated Buck Off
Offline LED Driver
MOSFET can be calculated bby the equation:
Application Information
The BL8333D is a high performance non-isolated
non
Buck
converter specially designed for LED
LE lighting. The
device integrates a 500V power MOS
SFET. It achieves
excellent line regulation and load regulation.with
regulation.w very
few external components
Start Up
=
400
;
=
×
−
Where, I P is peak currentt of the inductor, L is the
inductance value, VIN is the
he DC bus voltage after the
rectifier bridge,VLED is the vvoltage on the LED.
After the power MOSFET
ET is switched off, the
current in the inductor decre
reases. When the inductor
After system powered up, the VDD
DD pin capacitor is
charged up by the start up resistor. When the VDD
pin voltage reaches the turn on thresshold, the internal
circuits start operating.
Due to the ultra-low operating curreent, the auxiliary
winding is not needed to supply the IC.
C.
current reaches zero, the power MOSFET is turned
on again by IC internal llogic. The off time of the
MOSFET is given by:
=
×
The inductance can be calcu
culated by the equation:
Constant Current Control
The BL8333D works under CRM mode with a
internal 400mV reference voltage and the voltage on
CS pin is compared with the peak indu
uctor current
The peak inductor current is given by:
=
400
2
Where, I LED is driving current, RISEN is the current
=
× (
×
−
×
)
The F is the system swittching frequency, which is
proportional to the input
nput voltage. So the minimum
switching frequency is seet at lowest input voltage,
and the maximum switching
ng frequency is set at highest
input voltage.
The minimum and maximuum off time of BL8333D is
set at 50KHZ and 120KHZ
KHZ, respectively. Referring to
the
sense resistor value.
Inductor Selection
The BL8333D works under CRM mode.
m
When the
power MOFET is switched on, the
he current
cu
in the
inductor rises up from zero, the on time of the
BL8333D Datasheet V1.0
4
BL8333D
Non-isolated Buck Off
Offline LED Driver
small, the tOFF may be smaller than the
he minimum off
time, system will operate in
n discontinuous
conduction mode and the output current
cu
will be
smaller than the designed value. If the
he inductance is
too large, the tOFF may be larger than
han the maximum
off time, the system will operate in continuous
conduction mode and the output current
cu
will be
higher than the designed value. So itt is important to
choose a proper inductance.
Over Voltage Protection
When the LED is open circuit, the
he output voltage
increases gradually, and the demagne
agnetization time
gets shorter. The over voltage pro
otection can be
programmed by the RADJ resistor
≈
× × 15
× 10 ( ohm)
×
After the system enters intoo fault condition, the VCC
voltage will decrease unti
til it reaches the UVLO
threshold, then the system will re-start again. If the
fault condition is removed, tthe system will recover to
normal operation.
The BL8333D integrates thermal regulation function.
When the system is over temperature, the output
current is gradually reduced; the output power and
thermal dissipation are also reduced. The system
temperature is regulated and the system reliability is
improved. Thee thermal regulation temperature is set
to 155℃ internally.
PCB Layout
The following rules should be followed in BL8333D
PCB layout:
The bypass capacitor on VDD pin should be as close as
possible to the VDD Pin and GN
GND pin.
The area of main current loop should be as small as
possible to reduce EMI radiation, such as the
inductor, the power MOSFET, the output diode and the
bus capacitor loop.
Where,
V
is the ISEN turn off threshold (400mV)
L is the inductance value
RISEN is the current sense resistor value.
ue.
Vovp is the open circuit protection voltage.
voltage
The power ground path for current sense should be short,
and the power ground path should be separated from
small signal ground path before connecting to the
negative node of the bulk capacitor.
Protection Function
The RADJ resistor should bee as close as possible to the
RADJ Pin.
The BL8333D offers rich protection
on functions to
improve the system reliability, including LED
open/short protection, ISEN resistor short protection,
VDD under/over voltage protection, the
hermal regulation.
When the LED is open circuit, the
t
system will
trigger the over voltage protec
ection and stop
switching.
When the LED short circuit is detec
ected, the system
works at low frequency (5kHz), So the
he system power
consumption is very low. At some
so
catastrophic
fault condition, such as ISEN resisstor shorted or
inductor saturated, the internal fastt fault detection
circuit will be triggered, the system
m stops
s
switching
immediately.
BL8333D Datasheet V1.0
The NC pin should be conneccted to GND (pin1).
To increase the copper area of DRAIN pin for better
thermal dissipation. However too large copper area may
compromise EMI performance.
5
BL8333D
Non-isolated Buck Off
Offline LED Driver
PACKAGE OUTLINE
DIP8
DIP-88 DIMENSION
1.Top View
2.Side View
MILLIMETERS
SYMBOL
MIN
MAX
A
9.070
9.320
B
6.220
6.480
C
3.180
4.430
D
0.350
0.550
G
BL8333D Datasheet V1.0
2.54BSC
J
0.150
0.290
K
3.145
3.245
L
7.750
8.000
M
---
10
N
8.000
9.000
6