Applications Note: SY5830B
Single Stage Flyback And PFC Controller
With Primary Side Control For LED Lighting
General Description
The SY5830B is a single stage Flyback and PFC
controller targeting at LED lighting applications. It is a
primary side controller without applying any secondary
feedback circuit for low cost, and drives the Flyback
converter in the quasi-resonant mode to achieve higher
efficiency. It keeps the Flyback converter in constant on
time operation to achieve high power factor. It adopts
special design to achieve quick start up and reliable
protection for safety requirement.
Features
•
•
•
•
•
•
•
Primary side control eliminates the opto-coupler.
Valley turn-on of the primary MOSFET to achieve
low switching loss
Power factor >0.90 with single-stage conversion.
Reliable short LED and Open LED protection
Quick start up <500ms
Low start up current:15µA typical
Package: SOT23-6
Ordering Information
SY5830
□(□□)□
Tempera ture Code
Packa ge Code
Optional Spec Code
Ordering Number
SY5830BABC
Package type
SOT23-6
Note
----
Applications
•
LED lighting
Typical Applications
Ef
fic
ie
nc
y
(
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)
Figure 1. Schematic Diagram SOT23-6
Figure 2. Efficiency vs Input Voltage
AN_SY5830B Rev.0.1
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1
AN_SY5830B
Pinout
(
top view)
ISEN
1
6
DRV
GND
2
5
VIN
COMP
3
4
VSEN
(SOT23-6)
Top Mark: Jyxyz (device
code: Jy,
x=year code, y=week code, z= lot number code)
Pin Name
SOT23-6
Pin Description
Current sense pin. Connect this pin to the source of the primary switch.
Connect the sense resistor across the source of the primary switch and the
GND pin.
V
×
N
PS
,
k=0.167 )
(current sense resister R : R =k
REF
S
S
ISEN
1
I
OUT
GND
COMP
2
3
VSEN
4
VIN
DRV
5
6
Also this pin used to detect transformer and secondary is short or not.
Ground pin
Loop compensation pin. Connect a RC network across this pin and
ground to stabilize the control loop.
Inductor current zero-crossing detection pin. This pin receives the
auxiliary winding voltage by a resister divider and detects the inductor
current zero crossing point. This pin also provides over voltage protection
and line regulation modification function simultaneously. If the voltage
on this pin is above
V
VSEN,OVP
, the IC would enter over voltage protection
mode. Good line regulation can be achieved by adjusting the upper
resistor of the divider.
Power supply pin. This p n
lso provides output over voltage protection
along with VSEN pin.
Gate driver pin. Connect this pin to the gate of primary MOSFET.
AN_SY5830B Rev.0.1
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AN_SY5830B
Absolute Maximum Ratings
(Note 1)
VIN, DRV ---------------------------------------------------------------------------------------------------------------
Supply Current I
VIN
-----------------------------------------------------------------------------------------------------------
VSEN--------------------------------------------------------------------------------------------------------------
ISEN, COMP -------------------------------------------------------------------------------------------------------------
Power Dissipation, @ T
A
= 25°C SOT23-6 ------------------------------------ ---------------------------------------------
Package Thermal Resistance (Note 2)
SOT23-6,
θ
JA ---------------------------------------------------------------------------------------------------
SOT23-6,
θ
JC ---------------------------------------------------------------------------------------------------
Junction Temperature Range -------------------------------------------------------------------------------------
Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------------
Storage Temperature Range --------------------------------------------------------------------------------------
-0.3V~33V
15mA
- 0.3V ~V
IN
+0.3V
- 0.3~3.6V
0.6W
170°C/W
130°C/W
-
40°C to 150°C
260°C
-
65°C to 150°C
Recommended Operating Conditions
(Note 3)
VIN, DRV ----------------------------------------------------------------------------------------------------------------
Junction Temperature Range -------------------------------------------------------------------------------------
9.5V~27V
-40°C to 125°C
Block Diagram
Figure3. Block Diagram
AN_SY5830B Rev.0.1
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AN_SY5830B
Electrical Characteristics
(V
IN
= 12V (Note 3), T
A
= 25°C unless otherwise specified)
Parameter
Power Supply Section
VIN turn-on threshold
VIN turn-off threshold
VIN OVP voltage
Start up Current
Shunt current in OVP mode
Error Amplifier Section
Internal reference voltage
Current Sense Section
Current limit voltage
Protection limit for TR short
CC Feedforward coefficient
CC Feedforward resistor
COMP section
Pre-charge value
VSEN pin Section
VSEN pin OVP voltage
threshold
Fast start up theshold
Gate Driver Section
Gate driver voltage
Maximum source current
Minimum sink current
Max ON Time
Max OFF Time
Blanking time for ON time
Blanking time for OFF time
Maximum switching frequency
Thermal Section
Thermal Shutdown
Temperature
Symbol
V
V
VIN,ON
Test Conditions
Min
22.5
7.5
27
12
3.8
0.294
0.40
0.85
Typ
25
8.5
30
17
4.7
0.3
0.44
0.9
0.1
340
1.4
Max
27
9.5
33
23
5.7
0.306
0.48
0.97
Unit
V
V
V
µA
mA
V
V
V
Ω
V
V
I
VIN,OFF
VIN,OVP
I
ST
V
V
VIN
<V
VIN,OVP
VIN
>V
VIN,OFF
VIN,OVP
V
V
REF
V
ISEN,LIMIT
ISEN,EX
R
K
2
K2
V
COMP,ST
V
VSEN,OVP
V
1.43
1.5
0.55
1.57
V
V
VSEN,ST
V
I
Gate
9.5
SOURCE
I
T
T
SINK
ON,MAX
V
ISEN
=0V
T
OFF,MAX
ON,BLK
T
OFF,BLK
f
MAX
12
60
250
10
150
350
2
125
13
V
mA
mA
µs
µs
ns
µs
kHz
T
SD
150
°C
Note 1:
Stresses beyond the “Absolute Maximum Ratings” ma y 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
operational sections of the s ecification is not implied. Exposure to absolute maximum rating conditions for extended
periods may affect device reliability.
Note 2:
ſ
JA
is measured in the natural convection at T
A
= 25°C on a low effective single layer thermal con ductivity
test board of JEDEC 51-3 thermal measurement standard. Test condition: Device mounted on 2” x 2” FR-4 substrate
PCB, 2oz copper, with minimum recommended pad on top layer and thermal vias to bottom layer ground plane.
Note 3:
Increase VIN pin voltage gradually higher than V
VIN,ON
voltage then turn down to 12V.
AN_SY5830B Rev.0.1
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AN_SY5830B
Operation
SY5830B is a constant current Flyback controller with
primary side control and PFC function that targets at
LED lighting applications.
The device provides primary side control to eliminate
the opto-couplers or the secondary feedback circuits,
which would cut down the cost of the system.
High power factor is achieved by constant on
operation mode, with which the control scheme and
the circuit structure are both simple.
Start up process is optimized inside SY5830B, and
quick start up (less than 500ms) is achieved without
any additional circuit
In order to reduce the switching losses and improve
EMI performance, Quasi-Resonant switching mode is
applied, which means to turn on the power MOSFET
at voltage valley; the start up current of SY5830B is
rather small (15µA typically) to reduce the standby
power loss further; the maximum switching frequency
is clamped to 125kHz to reduce switching losses and
improve EMI performance when the converter is
operated at light load condition.
SY5830B provides reliable protections such as Short
Circuit Protection (SCP), Open LED Protection (OLP),
Over Temperature Protection (OTP), transformer
shorted protection and power diode shorted protection,
etc.
.
SY5830B is available with SOT23-6
Fig. Start up
This operation is aimed to build up enough output
voltage for auxiliary winding bias supply as quickly as
possible. It is enabled only one time just when V
VIN
is
over V
VIN,ON
.
V
V
is pre-charged by internal current source to
COMP,IC
and hold at this level until fast start up
process is finished.
COMP
The start up resistor R
ST
and C
VIN
are designed by
rules below:
(a)
Preset start-up resistor R
ST
, make sure that the
current through R
ST
is larger than I
ST
and smaller than
I _
V
VIN OVP
BUS
V
BUS
I
VIN_OVP
<R
ST
<
I
ST
Where V
BUS
is the BUS line voltage.
Applications Information
Start up
After AC supply or DC BUS is powered on, the
capacitor C
VIN
across VIN and GND pin is charged up
by BUS voltage through a start up resistor R
ST
. Once
V
VIN
ises up to V
VIN-ON
, the internal blocks start to
work and PWM output is enabled.
The output voltage is feedback by VSEN pin, which
is taken as V
FB
. If V
FBV
is lower than certain
threshold V
VSEN,ST
, which means the output voltage
is not built up, V
COMP
is pulled up to high clamped; if
V
FBV
is higher than V
VSEN,ST
, V
COMP
is under
charge of the internal gain modulator.
(b)
Select C
VIN
to obtain an ideal start up time t
ST,
and
ensure the output voltage is built up at one time.
(
C
VIN
=
V
BUS
R
ST
-I
ST
)
×
t
ST
V
VIN_ON
(d)
If the C
VIN
is not big enough to build up the output
voltage at one time. Increase C
VIN
and decrease R
ST
,
go back to step (a) and redo such design flow until the
ideal start up procedure is obtained.
AN_SY5830BRev.0.1
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