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3230
WS
WS3230
WS3230 High PF PSR Constant Current LED Driver
General Description
Features
�
±5% LED Current Accuracy
WS3230 is a high precision QR primary-side feedback
�
Primary-side Sensing and Regulation Without
and regulation controller for LED lighting, optimized for
TL431 and Opto-coupler
flyback converter with the output power less than 30W.
�
No Auxiliary Winding For Sensing And Supplying
Since adopting primary sense and feedback control
�
High Power Factor Correction
technology, the secondary sense and feedback circuit is
�
Ultra low operating current
eliminated. And WS3230 does not need the auxiliary
�
LED Open/Short Circuit Protection
winding for sensing the output current and supplying the
�
CS Resistor Short Circuit Protection
chip. The low component counts and small system size
�
VCC over voltage protection & under voltage
are realized.
lockout( UVLO)
Since using the high accurate current sense method,
Over Temperature Protection
WS3230 realizes ±5% accuracy of LED current along with
�
excellent line and load regulation.
WS3230
offers
comprehensive
protection
including
Cycle-by-Cycle current limiting (OCP), LED open/short
Applications
circuit protection, CS resistor short circuit protection, VCC
�
GU10 LED driver
UVLO,OVP and Clamp, and over temperature protection.
�
LED spot light
WS3230 is available in SOT23-5 package.
�
Other LED lighting
Typical Application Circuit
NP
AC
5 VC C
G a te 2
4 Com p
1 GND
CS
3
W/T-Y026-Rev.A/0 Aug.2013
[email protected] Microelectronics Co., Ltd., All right r eserved.
NS
3230
WS
WS3230
Pin Definition and Device Marking
WS3230 is available in SOT23-5 package:
30: WS3230
Y: Year Code (1:2011; 2:2012……)
M: Month Code (1-12)
Pin Function Description
Pin
Pin
Name
Number
GND
1
Ground
Ground.
Gate
2
Output
Totem-pole gate drive output for the power MOSFET.
CS
3
Current Sense
Comp
4
Loop Compensation
VCC
5
Power Supply
Pin Type
Function Description
Current sense. This pin connects a current sense resistor to GND to
detect the primary current of transformer.
Loop compensation pin. Connect a RC network across this pin and
ground to stabilize the control loop.
Power supply.
Block Diagram
VCC
B G &Internal
Power Supply
OVP
OTP
To n s
CC&Logic Control
15V
9 . 0 V 1 3 .8 V
G ate
G a te
0 .8 V
O CP
L in e
Compensation
CS
sampling
UVLO
G m 0 .5 V
R E SE T
C om p
CS*3*Tons/T
0
Valley 、To n s
G ate
To n s
Detect
GND
2/7
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3230
WS
WS3230
Ordering Information
Package
IC Marking Information
Purchasing Device Name
SOT23-5, Pb-free
30 YMB
WS3230YP
Recommended Operating Condition
Symbol
Parameter
Value
Unit
VCC
VCC supply voltage
9~14
V
TA
Operating temperature
-20~85
℃
Absolute Maximum Ratings
Symbol
Parameter
Value
Unit
Icc_max
VCC pin maximum sink current
5
mA
Gate
Driver output
-0.7~40
V
CS
CS pin input voltage
-0.3~7
V
Comp
Comp pin input voltage
-0.3~7
V
TJ
Operating junction temperature
-40~150
℃
TSTG
Min./Max. Storage temperature
-55~150
℃
Note
Note: Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. These
are stress ratings only, functional operation of the device at these or any other conditions beyond those indicated in the
Recommended Operating Conditions section are not implied. Exposure to absolute maximum-rated conditions for
extended periods may affect device reliability.
3/7
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3230
WS
WS3230
Electrical Characteristics (TA=25℃,VCC=14V, if not otherwise noted)
symbol
parameter
Test condition
Min
Typ
Max
Unit
Supply Voltage (VCC)
I_VCC_ST
Start up current
VCC=UVLO_ON-1V
60
100
uA
I_OP
Operation Current
Fop=7Khz
170
300
uA
UVLO_ON
Turn on threshold Voltage
VCC rising
12.7
V
UVLO_OFF
Turn-off threshold Voltage
VCC falling
10
V
VCC_Clamp
VCC Clamp voltage
Icc=5mA
15
V
500
ns
Current Sense Section
TLEB
Leading edge Blanking Time
V TH_OC
OCP threshold
Tdelay
Switch off delay time
485
500
515
mV
200
ns
Frequency Section
Ton_max
Max Primary On Time
24
us
Toff_max
Max Primary Off Time
224
us
Driver Section
Isource
Gate sourcing current
VCC=14V,Gate=0V
284
mA
Isink
Gate sinking current
VCC=Gate=14V
202
mA
VOH
Output voltage high
VCC=14V,Io=20mA
VOL
Output voltage low
VCC=14V,Io=-20mA
Tr
Rising time
VCC=14V,Cgate=1nF
183
ns
Tf
Falling time
VCC=14V,Cgate=1nF
69.5
ns
9.5
V
0.45
V
Over Temperature Protection
Tsd
Thermal shutdown threshold
150
℃
Tsd_hys
Thermal shutdown hysteresis
25
℃
4/7
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3230
WS
WS3230
Function Description
WS3230 is a high-integrated offline QR PSR controller,
=(Vcs*Tons/T)*0.5*(Nps/Rcs)
optimized for low power LED driver. WS3230 operates in
=0.083*(Nps/Rcs)
primary-side
sensing and
regulation. Consequently,
Once the parameters of the transformer and the current
opto-coupler and TL431 could be eliminated, thus reduce
sense resistor Rcs is determined, so is the output current.
the cost.
And the output current can be set by adjusting the current
sense resistor Rcs.
Startup Current
Internal pre-charge design for quick start up
Startup current of WS3230 is designed to as low as 60uA.
The VCC capacitor will be charged through the start-up
After VCC exceeds UVLO_ON, Vcomp is pre-charged by
resistor when the system is powered on. Once the VCC
an internal current source. The PWM block will not start to
voltage reaches the start-up threshold, the WS3230 will
output PWM signals until Vcomp is over 0.45V. Such
start to switch. The WS3230 integrates a 15V zener for
design is meant to reduce the start up time. The voltage
VCC clamping. Due to the ultra-low operating current, the
pre-charged Vcomp in start-up procedure can be
auxiliary winding is not need to supply the IC.
programmed b y,
Vcomp=0.4V-300uA*Rcomp
Quasi-Resonant Operation
Where Rcomp is the series resistor of Comp pin.
Quasi-Resonant switching mode is applied in WS3230.
Operation switching frequency
When the voltage across drain and source of the primary
MOSFET is at voltage valley, the MOSFET would be
The frequency of WS3230 is decided by load condition
turned on, reducing the switching losses and improving
and QR mode. When the output power decreases, the
EMI performance.
switching frequency can become rather high. The
maximum switching frequency in WS3230 is internally
CC Operation
limited to 120Khz.
WS3230 is designed to produce good CC control
Current Sensing and Leading Edge Blanking
characteristic. In DCM mode, the output current Io can be
represented b y,
Cycle-by-Cycle current limiting is offered in WS3230. The
Io=0.5*Ips*Tons/T
switch current is detected by a sense resistor into the
Where Ips is the peak current of the secondary side; Tons
sense pin. An internal leading edge blanking circuit chops
is the turn on time of secondary side; T is the switching
off the sense voltage spike at initial MOSFET on state due
period.
to snubber diode reverse recovery so that the external RC
Ips=Ipp*Nps=(Vcs/Rcs)*Nps
filtering on sense input is no longer required. The current
Where Ipp is the primary peak current; Vcs is the voltage
limit comparator is disabled and thus cannot turn off the
on CS resistor; Rcs is primary current detection resistor;
external MOSFET during the blanking period.
Nps is the turns ratio of primary to secondary of the
flyback transformer. The relationship of Vcs, To ns and T is
controlled
to
be
constant
by
internal
circuit,
3*Vcs*Tons/T=0.5V. Thus, Io can be represented b y,
Io=0.5*(Vcs/Rcs)*Nps*Tons/T
Protection Controls
Excellent
system
stability
is
achieved
by
the
comprehensive protection of WS3230. Including
5/7
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3230
WS
WS3230
Cycle-by-Cycle current limiting (OCP), LED open/short
the system will recover to normal operation.
circuit protection, CS resistor short circuit protection, VCC
The thermal shutdown circuitry in the WS3230 senses the
UVLO,OVP and Clamp, over temperature protection, and
die temperature after start up, and the thermal protection
so on.
threshold is set to 150℃ with a 25℃ hysteresis. When the
When the LED is open circuit, it will trigger over-voltage
temperature on die of WS3230 rises and reaches the
protection logic and latch, the system stops switching
threshold, the power MOSFET will be shut down
immediately; When the LED short circuit is detected, the
immediately
system works at low frequency(Fop=5Khz), so the power
temperature on die falls 25℃ from thermal protection
loss is low. At some catastrophic fault condition, such as
trigger point
and
maintained
switch
off
until
the
shorted CS resistor or flyback transformer saturation, the
internal fast fault detection circuit will trigger and latch, the
system stops switching immediately.
After the system enters into fault latch condition, the VCC
voltage will fall until it reaches UVLO threshold. Then the
.
system will re-start again. If the fault condition is removed,
6/7
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3230
WS
WS3230
Package Information
5 Package Outline Dimensions
SOT23SOT23-5
D
e1
E
E1
L
0 .2 5
e
B
B
θ
b
b1
c1 c
BASE METAL
A3
A
A2
W IT H PLAT ING
A1
SECT IO N B-B
Symbol
Dimensions In Mil
Milllimeters
Dimensions in Inches
Min
Max
Min
Max
A
-
1.35
-
0.0531
A1
0.04
0.15
0.0016
0.0059
A2
1.00
1.20
0.0394
0.0472
A3
0.55
0.75
0.0217
0.0295
b
0.38
0.43
0.0150
0.0169
b1
0.37
0.43
0.0146
0.0169
c
0.11
0.21
0.0043
0.0083
c1
0.10
0.16
0.0039
0.0063
D
2.72
3.12
0.1071
0.1228
E
2.60
3.00
0.1024
0.1181
E1
1.40
1.80
0.0551
0.0709
e
0.95 BSC
0.0374BSC
e1
1.90 BSC
0.075BSC
L
0.30
0.60
0.0118
0.0236
θ
0°
8°
0°
8°
7/7
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