SE8322
Single Stage Flyback and PFC Controller with
Primary Side Regulation Controller for LED
Lighting
DESCRIPTION
FEATURES
Wonderful Compatibility and Performance
Primary Side Regulation (PSR)
Constant Current output (+/- 3%)
Universal Input Voltage Range
Energy Efficient
Boundary Conduction Mode (BCM) with
Valley Switching reduces EMI and enhances
Efficiency
Power Factor Correction (PF>95%)
High Efficiency (>85% achievable)
Low Startup Current: 1.5µA
Low Operating Current: 1.9mA
Low Quiescent Current: 1.2mA
Advanced Protection and Safety Features
The primary-side-control offline LED lighting
controller, SE8322, provides accurate output
current, high power factor and low total harmonic
distortion. High efficiency is achieved by low
operating current and valley turn-on of the primary
MOSFET. Constant on-time control is utilized for a
better PFC performance.
The multi-protection of SE8322, including openLED protection, short-LED protection, cycle-tocycle current limit, VCC UVLO and overtemperature protection, can greatly enhance the
system reliability. Current-limit threshold is
adjusted automatically in a short-LED condition in
order that the output current is minimized.
APPLICATIONS
Isolated LED Driver
LED lighting
Open-LED Protection
Short-LED Protection
Cycle-by-Cycle Current Limit
Over-Temperature Protection
Package
SOP-8 Package Available
Figure 1. Typical Application
SE8322 Rev 1.1
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SE8322
FUNCTIONAL BLOCK DIAGRAM
Figure 2. Functional Block Diagram
PIN FUNCTIONS
Pin #
Name
1
NC
2
ZCD
Zero current detection pin. Connect this pin through a resistor divider from the auxiliary
winding to GND in order to detect the inductor current zero crossing point. This pin
also detects the output voltage for OCP.
3
VCC
Power supply pin. This pin supply power both for IC operating current and GATE
driving current.
4
GATE
Gate drive output pin. The totem pole output stage is able to drive high power
MOSFET.
5
CS
Current sense pin. The MOSFET current is sensed via a resistor for constant current
regulation and cycle-to-cycle current limit.
6
GND
7
NC
8
COMP
SE8322 Rev 1.1
Description
Not connected
Ground.
Not connected
Loop Compensation pin. Connect a compensation network to stabilize the loop.
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SE8322
ORDERING INFORMATION
ORDERING NUMBER
SE8322-SO-L
PINS
8
PACKAGE
SOP
PACKAGE REFERENCE
ABSOLUTE MAXIMUM RATINGS
Item
Symbol
Rating
Unit
Power Supply Voltage
VCC
<30
V
ZCD Pin Input Voltage
VZCD
-0.3 to 7.0
V
CS Pin Input Voltage
VCS
-0.3 to 7.0
V
COMP Pin Input Voltage
VCOMP
-0.3 to 7.0
V
GATE Pin Input Voltage
VGATE
-0.3 to 30.0
V
TJ
<150
°C
Storage Temperature
TSTG
-55 to 150
°C
Lead Temperature (Soldering, 10s)
TLead
<260
°C
Maximum Junction Temperature
SE8322 Rev 1.1
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SE8322
ELECTRICAL CHARACTERISTICS
VCC=20V, TA=+27°C, unless otherwise noted.
Symbol
Parameter
SUPPLY SECTION
VCC
Condition
Min.
Typ.
Max.
Unit
24
V
(TA = -40°C to 125°C)
Operating Range
9
VCC-ON
Turn-On Threshold Voltage
14
16.3
18
V
VCC-OFF
Turn-Off Threshold Voltage
7
8.2
9
V
VCC-HYS
VCC Hysteretic Voltage
7
8.1
9
V
1.6
1.9
2.4
mA
1
1.2
1.55
mA
1.4
1.5
1.6
µA
VCC Over-Voltage-Protection
24
25
25.5
V
OVP Hysteresis
0.9
1
1.05
V
ICC
Operating Current
Switch Period = 15µs
IQ
Quiescent Current
No switch
IST
Startup Current
VCC = VCC-ON - 0.16V
VOVP
VOVP-HYS
CONSTANT ON-TIME SECTION
(TA = -40°C to 125°C)
TON-MIN
Minimum On Time
0.7
1
1.5
µs
TON-MAX
Maximum On Time
20
24
27
µs
ERROR AMPPLIFIER SECTION
GM
Transconductance
120
µA/V
AEA
Voltage Gain
9000
V/V
VCOMP
IC-SOURCE
IC-SINK
COMP Voltage Range
0.9
4
V
Max Source Current
35
48
65
µA
-220
-294
-362
µA
11
13.5
14
V
Max Source Current
0.97
1.2
1.4
A
Max Sink Current
-1.2
-1.7
-2.1
A
Max Sink Current
GATE DRIVER SECTION
VCLAMP
IG-SOURCE
IG-SINK
(TA = -40°C to 125°C)
Output Clamp Voltage
ZERO CURRENT DETECTOR SECTION
VZCD
ZCD Threshold
0.4
V
VZCD_HYS
ZCD Hysteresis
0.5
V
TOFF-MIN
Minimum Off Time
3.6
µs
AUTO START SECTION
TSTART
Auto Start Time
-40°C < TA < 125°C
100
135
190
µs
Continued on the following page...
SE8322 Rev 1.1
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SE8322
ELECTRICAL CHARACTERISTICS
VCC=20V, TA=+27°C, unless otherwise noted.
Symbol
Parameter
Condition
Min.
Typ.
Max.
Unit
OVER-CURRENT PROTECTION SECTION
VOCP-H
CS High Threshold Voltage
for OCP
3
V
VOCP-L
CS Low Threshold Voltage
for OCP
1
V
VHOCP-EN
ZCD Threshold Voltage to
Enable High OCP level
0.9
V
VLOCP-EN
ZCD Threshold Voltage to
Enable Low OCP level
0.6
V
CS Sampling Leading-Edge
Blanking Time
215
ns
TLEB
OVER TEMPERATURE PROTECTION SECTION
TOTP
TOTP-HYS
Over Temperature Protection
140
150
160
°C
OTP Hysteresis
22
25
28
°C
SE8322 Rev 1.1
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SE8322
FUNCTIONAL DESCRIPTION
SE8322 is a single stage Flyback and PFC
controller for LED lighting applications. Primary
side control is applied so that the system is
simplified, and high power factor is achieved by
constant on-time model. Boundary Conduction
Mode (BCM) with valley switching improves
efficiency and EMI performance. The multiprotection function stabilizes system and protects
external components.
not changed. Obviously, the low IST of SE8322
makes it easier to design RST.
Boundary Conduction Mode Operation
Boundary Conduction Mode (BCM) and valley
switching provides low turn-on switching losses.
GATE
TOFF
Startup
The capacitor CST across VBUS and GND is
charged by BUS through a start up resistor RST
once BUS is powered on. After VCC rises up to
VCC-ON, the internal blocks start to work and the
gate driver begins to switch. Then VCC will be
pulled down by internal consumption until the
power supply is taken over by the auxiliary
winding.
IP
TON
IS
VD
VZCD
Figure 3. Startup Sequence
In order that V can rise when start up, and fall
when OVP and OTP, RST should be preset
following this:
Figure 4. Boundary Conduction Mode
The voltage across drain and source of the
external MOSFET is detected by the ZCD pin.
The current of the inductor begins to decrease
linearly as soon as the external MOSFET is
turned off. When the current falls to zero, the
MOSFET Drain-Source Voltage decreases, which
is also detected by the ZCD pin through a resistor
divider. The external MOSFET would be turned on
by a turn on signal sent by the Zero Current
Detector once the ZCD voltage is lower than 0.4V.
Primary Side Constant Current Control
Select CST for an ideal tST:
The output mean current can be represented as
For a more stable VCC, a bigger CST is needed,
and RST should be decreased in order that tST is
SE8322 Rev 1.1
N—The winding turns ratio of primary side to
secondary side of the transformer.
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SE8322
RCS—The
current
SE8322 Rev 1.1
sense
resistor
connected
between the CS pin and GND.
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SE8322
FUNCTIONAL DESCRIPTION
Power Factor Correction
Internal Constant On-Time Block affords a
constant gate on-time TON, which is in proportion
to COMP potential. The peak current of the
primary side winding is
VCC Under-Voltage Lockout (UVLO)
When the VCC voltage drops below VCC-OFF
(typically 8V), the whole chip shuts down, and
GATE switching stops. The system would not
work again until VCC capacitor is charged to VCCON through the external startup resistor.
Auto Start
LP—The primary inductance.
As LP and TON is constant, IP is accordingly in
proportion to VBUS (as shown in Figure 5).
A auto start block is integrated in SE8322 to avoid
unnecessary shut down. The auto start block
starts timing as soon as the external MOSFET
turns on in every period. If the ZCD pin fails to
send a turn on signal after TSTART (typically 140µs),
the auto start block would turn on GATE
automatically.
When the GATE is turned on, auto start timing
stops.
Minimum Off Time
To limit the maximum switching frequency and to
obtain a better EMI performance, a internal block
is integrated to limit the minimum GATE off time.
The external MOSFET cannot turn on again in
less than 3.6µs after its latest turning off.
Leading Edge Blanking (LEB)
Figure 5. Power Factor Correction
As a result, the input current IIN of the system
follows the input voltage VIN, and the Power
Factor is improved.
SE8322 Rev 1.1
An internal leading edge blanking (LEB) block is
employed in order to avoid the premature
termination of the GATE switching pulse due to
the peak voltage of the CS pin caused by the
parasitic capacitor discharging when the external
MOSFET turns on. VCS sampling is disabled
during the LEB time.
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SE8322
FUNCTIONAL DESCRIPTION
Open-LED Protection
When the load of the system is open, the output
capacitor is charged up rapidly. Consequently,
VCC rises up quickly since the VCC capacitor is
charged by the auxiliary winding and its voltage
reflects the output voltage.
The whole chip enters fault state, in which GATE
will never be turned on, as soon as the voltage of
the VCC pin rises up to VOVP (typically 25V). As
the external MOSFET is always off in the fault
state, the auxiliary winding cannot support the VCC
consumption, and VCC will drop. This fault state
will last until UVLO.
A lower OCP voltage can protect the external
MOSFET as well as reduce power dissipation. As
output voltage is low in the short-LED condition,
the auxiliary winding cannot charge the VCC
capacitor, and VCC will consequently drop until
UVLO.
Over-Temperature Protection (OTP)
When the junction temperature is above 150°C,
the chip enters fault state, and GATE driver is
shut down. The UVLO signal can relive the
system of fault state if the junction temperature
drops below 125°C.
Short-LED Protection
The voltage of the ZCD pin reflects the output
voltage when the switch is on. The short-LED
situation can be detected through the ZCD pin
and the OCP threshold would be changed in that
case.
If the ZCD voltage in GATE on period is lower
than 0.6V, the cycle-by-cycle current limit would
be 1V. The current limit threshold voltage
becomes up to 3V when the ZCD voltage in GATE
on period is higher than 0.9V. Figure 7 shows this
function.
Figure 6. OCP Function
SE8322 Rev 1.1
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SE8322
PACKAGE INFORMATION
Symbol
A
B
C
D
E
F
G
H
I
J
θ
SE8322 Rev 1.1
Dimensions in Millimeters
Min
Max
1.350
1.750
0.100
0.250
1.350
1.550
0.330
0.510
0.170
0.250
4.700
5.100
3.800
4.000
5.800
6.200
1.270(BSC)
0.400
1.270
0°
8°
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Dimensions in Inches
Min
Max
0.053
0.069
0.004
0.010
0.053
0.061
0.013
0.020
0.006
0.010
0.185
0.200
0.150
0.157
0.228
0.244
0.050(BSC)
0.400
1.270
0°
8°
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SE8322
SOLDERING INDICATION
This section gives a very brief insight to a complex technology. There is no soldering method that is ideal for
all surface mount IC packages. Wave soldering can still be used for certain surface mount ICs, but it is not
suitable for fine pitch SMDs. In these situations reflow soldering is recommended.
Reflow Soldering
Reflow soldering requires solder paste (a suspension of fine solder particles, flux and binding agent) to be
applied to the printed-circuit board by screen printing, stenciling or pressure-syringe dispensing before
package placement.
Several methods exist for reflowing; for example, convection or convection/infrared heating in a conveyor
type oven. Throughput times (preheating, soldering and cooling) vary between 100 and 200 seconds
depending on heating method.
Typical reflow peak temperatures range from 215 to 250°C. The top-surface temperature of the packages
should preferable be kept below 220°C for thick/large packages, and below 235°C for small/thin packages.
Wave Soldering
Conventional single wave soldering is not recommended for surface mount devices (SMDs) or printed-circuit
boards with a high component density, as solder bridging and non-wetting can present major problems.
To overcome these problems the double-wave soldering method was specifically developed.
If wave soldering is used, the following conditions must be observed for optimal results:
Use a double-wave soldering method comprising a turbulent wave with high upward pressure followed
by a smooth laminar wave.
For packages with leads on two sides and a pitch:
– larger than or equal to 1.27 mm, the footprint longitudinal axis is preferred to be parallel to the
transport direction of the printed-circuit board;
– smaller than 1.27 mm, the footprint longitudinal axis must be parallel to the transport direction of the
printed-circuit board.
The footprint must incorporate solder thieves at the downstream end.
For packages with leads on four sides, the footprint must be placed at a 45° angle to the transport
direction of the printed-circuit board. The footprint must incorporate solder thieves downstream and at
the side corners.
During placement and before soldering, the package must be fixed with a droplet of adhesive. The adhesive
can be applied by screen printing, pin transfer or syringe dispensing. The package can be soldered after the
adhesive is cured.
Typical dwell time is 4 seconds at 250°C.
A mildly-activated flux will eliminate the need for removal of corrosive residues in most applications.
SE8322 Rev 1.1
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SE8322
Manual Soldering
Fix the component by first soldering two diagonally-opposite end leads. Use a low voltage (24 V or less)
soldering iron applied to the flat part of the lead. Contact time must be limited to 10 seconds at up to 300°C.
When using a dedicated tool, all other leads can be soldered in one operation within 2 to 5 seconds between
270 and 320°C.
Suitability of Surface Mount IC Packages for Wave and Reflow Soldering Methods
Package
BGA, HBGA, LFBGA, SQFP, TFBGA
HBCC, HLQFP, HSQFP, HSOP, HTQFP, HTSSOP, HVQFN, SMS
PLCC (3), SO, SOJ
LQFP, QFP, TQFP
SSOP, TSSOP, VSO
Soldering Method
(1)
Wave
Reflow
(2)
Not suitable
Suitable
Not suitable
Suitable
Suitable
Suitable
(3)(4)
Not recommended
Suitable
(5)
Not recommended
Suitable
Notes
1.
2.
3.
4.
5.
All surface mount (SMD) packages are moisture sensitive. Depending upon the moisture content, the
maximum temperature (with respect to time) and body size of the package, there is a risk that internal or
external package cracks may occur due to vaporization of the moisture in them (the so called popcorn
effect).
These packages are not suitable for wave soldering as a solder joint between the printed-circuit board
and heatsink (at bottom version) can not be achieved, and as solder may stick to the heatsink (on top
version).
If wave soldering is considered, the package must be placed at a 45° angle to the solder wave direction.
The package footprint must incorporate solder thieves downstream and at the side corners.
Wave soldering is only suitable for LQFP, TQFP and QFP packages with a pitch equal to or larger than
0.8 mm; it is definitely not suitable for packages with a pitch equal to or smaller than 0.65 mm.
Wave soldering is only suitable for SSOP and TSSOP packages with a pitch equal to or larger than 0.65
mm; it is definitely not suitable for packages with a pitch equal to or smaller than 0.5 mm.
SE8322 Rev 1.1
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SE8322
Star Micro Electronic Technology Co.Ltd
Tel: 13028827398
Email: 1030.wj@163.com
IMPORTANT NOTICE
“Preliminary” product information describes products that are in production, but for which full characterization data is not yet available. SMET Ltd. believes that the information
contained in this document is accurate and reliable. However, the information is subject to change without notice and is provided “AS IS” without warranty of any kind (express or
implied). Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All
products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, patent infringement, and limitation
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SE8322 Rev 1.1
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