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3231
WS
WS3231
WS3231 High PF PSR Constant Current LED Driver
General Description
Features
�
±5% LED Current Accuracy
WS3231 is a high PF primary-side feedback and
�
Primary-side Sensing and Regulation Without
regulation controller for LED lighting, optimized for flyback
TL431 and Opto-coupler
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
�
QR mode
eliminated. And WS3231 does not need the auxiliary
�
600V MOS integrated
winding for sensing the output current and supplying the
�
Ultra low operating current
chip. The low component counts and small system size
�
LED Open/Short Circuit Protection
are realized.
�
CS Resistor Short Circuit Protection
Since using the high accurate current sense method,
�
VCC over voltage protection & under voltage
WS3231 realizes ±5% accuracy of LED current along with
lockout( UVLO)
excellent line and load regulation.
Over Temperature Protection
WS3231
�
offers
comprehensive
protection
including
Cycle-by-Cycle current limiting (OCP), LED open/short
circuit protection, CS resistor short circuit protection, VCC
Applications
UVLO,OVP and Clamp, and over temperature protection.
�
GU10 LED driver
WS3231 is available in SOP-8 package.
�
LED spot light
�
Other LED lighting
Typical Application Circuit
NP
NS
AC
1 VCC
GND 8
2 NC
GND 7
3
COMP
4 CS
D 6
D 5
W/T-S035-Rev.A/0 Dec.2013
Copyright@Winsemi Microelectronics Co., Ltd., All right r eserved.
1213
3231
WS
WS3231
Pin Definition and Device Marking
WS3231 is available in SOP-8 package:
NC
2
c om p 3
CS
4
8 GND
WS3231S8P
1
AXB YM
VC C
WS3231S8P: Product code
7 GND
6
5
D
A:
Die Code
X:
Internal Code
B:
Area Code
YM：Year, Month
D
Pin Function Description
Pin
Pin
Name
Number
VCC
1
Power Supply
NC
2
NC
Comp
3
Loop Compensation
CS
4
Current Sense
D
5/6
Drain
GND
7/8
Ground
Pin Type
Function Description
Power supply.
Floating
Loop compensation pin. Connect a RC network across this pin and
ground to stabilize the control loop.
Current sense. This pin connects a current sense resistor to GND to
detect the primary current of transformer.
Drain of Power MOS
Ground.
Block Diagram
VCC
B G &Internal
Power Supply
OVP
OTP
D
To n s
G ate
CC&Logic Control
15V
9 . 0 V 1 3 .8 V
0 .8 V
O CP
L in e
Compensation
CS
sampling
UVLO
G m 0 . 5 V CS*3*Tons/T
R E SE T
To n s
C om p
0
Valley 、To n s
G ate
Detect
GND
2/7
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3231
WS
WS3231
Ordering Information
Package
SOP-8,
Pb-free
IC Marking Information
Purchasing Device Name
WS3231S8P
WS3231S8P
Recommended Operating Condition
Symbol
Parameter
Value
Unit
VCC
VCC supply voltage
9~14
V
TA
Operating temperature
-20~85
℃
Pout
Output power
<5
W
Absolute Maximum Ratings
Symbol
Parameter
Value
Unit
Icc_max
VCC pin maximum sink current
5
mA
D
Drain of power MOS
-0.3~600
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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3231
WS
WS3231
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
300
400
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
Power MOS Section
Rds_on
ON-resistor
V GS=10V,ID=0.5A
Vds_BD
Breakdown voltage
ID=250μA
15
600
Ω
V
Over Temperature Protection
Tsd
Thermal shutdown threshold
150
℃
Tsd_hys
Thermal shutdown hysteresis
25
℃
4/7
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3231
WS
WS3231
Function Description
WS3231 is a high PF offline QR PSR controller, optimized
for
low power
in
Once the parameters of the transformer and the current
regulation. Consequently,
sense resistor Rcs is determined, so is the output current.
opto-coupler and TL431 could be eliminated, thus reduce
And the output current can be set by adjusting the current
the cost.
sense resistor Rcs.
Startup Current
Internal pre-charge design for quick start up
Startup current of WS3231 is designed to as low as 60uA.
After VCC exceeds UVLO_ON, Vcomp is pre-charged by
The VCC capacitor will be charged through the start-up
an internal current source. The PWM block will not start to
resistor when the system is powered on. Once the VCC
output PWM signals until Vcomp is over 0.45V. Such
voltage reaches the start-up threshold, the WS3231 will
design is meant to reduce the start up time. The voltage
start to switch. The WS3231 integrates a 15V zener for
pre-charged Vcomp in start-up procedure can be
VCC clamping. Due to the ultra-low operating current, the
programmed b y,
primary-side
LED driver. WS3231 operates
=0.083*（Nps/Rcs）
sensing and
auxiliary winding is not need to supply the IC.
Vcomp=0.4V-300uA*Rcomp
Where Rcomp is the series resistor of Comp pin.
Quasi-Resonant Operation
Operation switching frequency
Quasi-Resonant switching mode is applied in WS3231.
When the voltage across drain and source of the primary
The frequency of WS3231 is decided by load condition
MOSFET is at voltage valley, the MOSFET would be
and QR mode. When the output power decreases, the
turned on, reducing the switching losses and improving
switching frequency can become rather high. The
EMI performance.
maximum switching frequency in WS3231 is internally
limited to 120Khz.
CC Operation
Current Sensing and Leading Edge Blanking
WS3231 is designed to produce good CC control
characteristic. In DCM mode, the output current Io can be
Cycle-by-Cycle current limiting is offered in WS3231. The
represented b y,
switch current is detected by a sense resistor into the
Io=0.5*Ips*Tons/T
sense pin. An internal leading edge blanking circuit chops
Where Ips is the peak current of the secondary side; Tons
off the sense voltage spike at initial MOSFET on state due
is the turn on time of secondary side; T is the switching
to snubber diode reverse recovery so that the external RC
period.
filtering on sense input is no longer required. The current
Ips=Ipp*Nps=(Vcs/Rcs)*Nps
limit comparator is disabled and thus cannot turn off the
Where Ipp is the primary peak current; Vcs is the voltage
external MOSFET during the blanking period.
on CS resistor; Rcs is primary current detection resistor;
Nps is the turns ratio of primary to secondary of the
Protection Controls
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,
Excellent
system
comprehensive
stability
protection
is
of
achieved
WS3231.
by
the
Including
Io=0.5*(Vcs/Rcs)*Nps*Tons/T
Cycle-by-Cycle current limiting (OCP), LED open/short
=(Vcs*Tons/T)*0.5*（Nps/Rcs）
circuit protection, CS resistor short circuit protection, VCC
5/7
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3231
WS
WS3231
UVLO,OVP and Clamp, over temperature protection, and
shutdown circuitry in the WS3231 senses the die
so on.
temperature after start up, and the thermal protection
When the LED is open circuit, it will trigger over-voltage
threshold is set to 150℃ with a 25℃ hysteresis. When the
protection logic and latch, the system stops switching
temperature on die of WS3231 rises and reaches the
immediately; When the LED short circuit is detected, the
threshold, the power MOSFET will be shut down
system works at low frequency(Fop=5Khz), so the power
immediately
loss is low. At some catastrophic fault condition, such as
temperature on die falls 25℃ from thermal protection
shorted CS resistor or flyback transformer saturation, the
trigger point.
and
maintained
switch
off
until
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,
the system will recover to normal operation.The thermal
6/7
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3231
WS
WS3231
SOP-8 Package Information
B2
0 . 5 * 0.125±0. 05
球形标记
A1
A2
D
D1
B
B1
A
C4
A3
R2
C
C1
θ4
θ2
C2
θ1
C3
θ3
R1
Winsemi
Symbol
Dimensions in Millimeters
Dimensions in Inches
Min
Max
Min
Max
A
4.70
5.10
0.185
0.201
B
3.70
4.10
0.146
0.161
C
1.30
1.50
0.051
0.059
A1
0.35
0.48
0.014
0.019
A2
1.27TYP
0.05TYP
A3
0.345TYP
0.014TYP
B1
5.80
B2
6.20
0.228
5.00TYP
0.244
0.197TYP
C1
0.55
0.70
0.022
0.028
C2
0.55
0.70
0.022
0.028
C3
0.05
0.225
0.002
0.009
C4
0.203TYP
0.008TYP
D
1.05TYP
0.041TYP
D1
0.40
0.80
0.016
0.031
7/7
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