Applications Note: SY5019
Flyback controller
For adapters or chargers
General Description
SY5019 is a PWM/PFM controller with several features
to enhance performance of Flyback converters that
targeting at adapter or charger applications. It drives
Flyback controller in the Quasi-Resonant mode for
higher efficiency and better EMI performance. SY5019
adopt burst mode control for improved efficiency and
the output current is detected by internal primary
detection technology to achieve more reliable Over
Current Protection and Short Circuit Protection. The
output voltage is achieved by secondary side control
technology for good load and line regulation. SY5019
provides a fast internal HV start up circuit without
consuming any standby power to achieve lowest no-load
power consumption.
Features
•
Quasi-Resonant (QR) mode operation: Valley turn-
on of the primary MOSFET to achieve low
switching losses
•
Output current is monitored by primary detection for
reliable Over Current Protection and Short Circuit
Protection
•
PWM/PFM control for higher average efficiency
•
Burst mode control for low no load loss and
efficiency
•
HV start up circuit is used to reduce no-load.
•
Internal high current MOSFET driver: 120mA
•
Auto-Recovery for OVP/OCP/SCP/OTP
•
Maximum frequency limitation 125kHz
•
Compact package: SO8
Ordering Information
SY5019
□
(□□
□
□□)□
□□
Temperature Code
Package Code
Optional Spec Code
Applications
•
•
•
•
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Typical Applications
AN_SY5019 Rev.0.9B
Silergy Corp. Confidential- Prepared for Customer Use Only
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Fig.1 Schematic Diagram
en
Ordering Number
SY5019FAC
Package type
SO8
Note
----
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AC/DC Adapters
Battery Chargers
Consumer Electronics
Auxiliary power supplies
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AN_SY5019
Pinout
(
top view)
(SO8)
Top Mark: BAExyz (device
code:
BAE,
x=year code, y=week code, z= lot number code)
Pin
1
2
3
4
5
6
7
8
Name
GND
DRV
NC
HV
VIN
VSEN
COMP
ISEN
Description
Ground pin.
Gate driver pin. Connect this pin to the gate of primary MOSFET.
Not Connect
Connect an internal HV start up circuit. Connect this pin to Bus or Drain Pin of Primary MOSFET.
Power supply pin.
Inductor current zero-crossing detection pin. This pin receives the auxiliary winding voltage by a
resistor divider and detects the inductor current zero crossing point.
Feedback input pin. The PWM ducy cycle is determined by voltage level into this pin.It’s connected to a
optocoupler.
Current sense pin. Connect this pin to the source of the primary switch.
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HV
HV Start
up
circuit
VIN
en
Bias
Supply
l-P
Block Diagram
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VREF
IREF
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VIN_OVP
V
VSEN
_OVP
IPK_SEN
IPK_SET
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PWM
Protection
on
IOUT_SEN
V
OUT
Detection
Cable Comp
.
V
VSEN
_OVP
V
VSEN
_FB
VCC
Logic
VIN_OK
VIN_OVP
VSEN
.C
VSEN
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ISEN
IOUT
Calculator
IPK_SEN
IOUT_SEN
PWM
Generator
DRIVER
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VREF
OCP
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20k
2.5V
COMP
COMP Behavior
( Frequency_set、 _set、
Ipk
Fast Transient Response )
COMP
Fig.2 Block Diagram
AN_SY5019 Rev.0.9B
Silergy Corp. Confidential- Prepared for Customer Use Only
GND
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Hiccup
ST
DRV
Flimit_SET
2
AN_SY5019
Absolute Maximum Ratings
(Note 1)
HV------------------------------------------------------------------------------------------------------------------------------------ 600V
VIN---------------------------------------------------------------------------------------------------------------------------- -0.3V~21V
Supply Current I
VIN
-----------------------------------------------------------------------------------------------------------------20mA
VSEN ----------------------------------------------------------------------------------------------------------------- -0.3V~V
VIN
+0.3V
DRV ------------------------------------------------------------------------------------------------------------------------- -0.3V~15V
ISEN, COMP
----------------------------------------------------------------------------------------------------------- -0.3V~3.6V
Power Dissipation, @ TA = 25°C SO8 ----------------------------------------------------------------------------------------- 1.1W
Package Thermal Resistance (Note 2)
SO8,θ
JA
----------------------------------------------------------------------------------------------------------------------125°C/W
SO8, θ
JC
----------------------------------------------------------------------------------------------------------------------60°C/W
Junction Temperature Range -----------------------------------------------------------------------------------------
-
45°C to 150°C
Lead Temperature (Soldering, 10 sec.) ---------------------------------------------------------------------------------------- 260°C
Storage Temperature Range ------------------------------------------------------------------------------------------
-
65°C to 150°C
AN_SY5019 Rev.0.9B
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Silergy Corp. Confidential- Prepared for Customer Use Only
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VIN -------------------------------------------------------------------------------------------------------------------------- 9V~17.5V
Junction Temperature Range ----------------------------------------------------------------------------------------- -40°C to 125°C
Ambient Temperature Range ---------------------------------------------------------------------------------------- -40°C to 105°C
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Recommended Operating Conditions
(Note 3)
ST
3
AN_SY5019
Electrical Characteristics
(V
IN
= 12V, T
A
= 25°C unless otherwise specified)
Parameter
Symbol
Power Supply Section
Input voltage range
V
VIN
VIN turn-on threshold
V
VIN_ON
VIN turn-off threshold
V
VIN_OFF
VIN OVP voltage
V
VIN_OVP
HV start up current
I
HV_ON
HV leakage current
I
HV_OFF
Start up current
I
ST
Operating current
I
VIN
Quiescent current
I
Q
Shunt current in OVP mode
I
VIN_OVP
Current Feedback Modulator Section
Internal reference voltage
V
REFI
ISEN Pin Section
Current limit voltage
Latch voltage for ISEN
CC feedforward resistor
VSEN Pin Section
OVP voltage threshold
COMP Section
Internal voltage bias
Sleep mode voltage ON threshold
V
ISEN_LIM
V
ISEN_EX
R
k2
V
VSEN_OVP
V
CVB
V
COMP_ON
Test Conditions
Min
9
13.7
6.3
17.5
V
HV
=373V
V
VIN
<V
VIN_OFF
C
L
=100pF,f=100kHz
100
V
VIN
>V
VIN_OVP
0.413
V
FBV
<0.4V
V
FBV
>0.4V
Typ
Max
17.5
15.7
8.3
19.5
Unit
V
V
V
V
mA
µA
µA
mA
µA
mA
V
V
V
V
Ω
V
V
V
rP
0.42
0.7
1
2
300
1.45
2.5
0.4
ST
14.7
7
18.5
1.5
3
1.2
1.5
300
9
4
600
0.426
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0.9
1.1
375
1.52
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1.37
Sleep mode voltage OFF threshold
V
COMP_OFF
0.45
V
Internal pull-up resistor
R
COMP
20
kΩ
Gate Driver Section
Gate driver voltage
V
GATE
12
V
Maximum. source current
I
SOURCE_MAX
120
mA
Maximum. sink current
I
SINK_MAX
500
mA
Max ON Time
T
ON_MAX
V
COMP
=2.5V
24
µs
Min ON Time
T
ON_MIN
100
300
400
ns
Max OFF Time
T
OFF_MAX
400
500
650
µs
Min OFF Time
T
OFF_MIN
1.2
µs
Minimum switching period
T
PERIOD_MIN
7
8
9
µs
Thermal Section
Thermal shutdown temperature
T
SD
150
°C
Note 1:
Stresses beyond the “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
operational sections of the specification is not implied. Exposure to absolute maximum rating conditions for extended
periods may affect device reliability.
Note 2:
θ
JA
is measured in the natural convection at T
A
= 25°C on a low effective single layer thermal conductivity 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_SY5019 Rev.0.9B
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Silergy Corp. Confidential- Prepared for Customer Use Only
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AN_SY5019
Operation
SY5019 is a PWM/PFM controller with several features
to enhance performance of Flyback converters.
To achieve higher efficiency and better EMI performance,
SY5019 drives Flyback converters in the Quasi-Resonant
mode; the start up current of the device is rather
small(4µA max) to reduce the standby power loss further
and the maximum switching frequency is limited below
125kHz.
In order to improve the stability, the self-adaption
compensation is applied.
The output current is monitored by primary side detection
technology, and the maximum output current can be
programmed in Over Current Protection and Short Circuit
Protection. In addition to SY5019 provides Over Voltage
Protection (OVP), Over Temperature Protection (OTP),
VSEN pin short protection, etc..
SY5019 can be applied in AC/DC adapters, Battery
Chargers and other consumer electronics.
SY5019 is available with SO8package.
Fig.3 Start up
The C
VIN
are designed by rules below:
(a)
Select C
VIN
to obtain an ideal start up time t
ST,
and
ensure the output voltage is built up at one time.
(I
HV_ON
−
I
ST
−
I
HV_OFF
)
×
t
ST
(1)
C
VIN
=
V
VIN_ON
(b)
If the C
VIN
is not big enough to build up the output
voltage at one time. Increase C
VIN
until the ideal start up
procedure is obtained.
Applications Information
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Start up
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After AC supply or DC BUS is powered off, the energy
stored in the BUS capacitor will be discharged. When
the auxiliary winding of Flyback transformer cannot
supply enough energy to VIN pin, V
VIN
will drop down.
Once V
VIN
is below V
VIN_OFF
, the IC will stop working.
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The whole start up procedure is divided into two sections
shown in Fig.3. t
STC
is the C
VIN
charged up section, and
t
STO
is the output voltage built-up section. The start up
time t
ST
composes of t
STC
and t
STO
, and usually t
STO
is
much smaller than t
STC
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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 HV start up circuit. Once V
VIN
rises up to
V
VIN_ON
, the internal blocks start to work. V
VIN
will be
pulled down by internal consumption of IC until the
auxiliary winding of Flyback transformer could supply
enough energy to maintain V
VIN
above V
VIN
_
OFF
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Quasi-Resonant Operation(valley detection)
QR mode operation provides low turn-on switching
losses for Flyback converter.
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Fig.4 QR mode operation
Shut down
The voltage across drain and source of the primary
MOSFET is reflected by the auxiliary winding of the
AN_SY5019 Rev.0.9B
Silergy Corp. Confidential- Prepared for Customer Use Only
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