Application Notes: AN_SY5861B
Adaptive LED Current Filter
For LED Lighting
Preliminary datasheet
General Description
The SY5861B is an adaptive linear current regulator to
eliminate low frequency current ripple targeting at LED
lighting applications.
It is applied as a current filter to the output of a LED
driver, especially single stage LED driver. It adopts
adaptive control scheme and no additional electrical
design is needed.
Reliable open/short LED protection and over thermal
protection are all provided.
Features
•
•
•
Current filter for single stage LED driver to eliminate
current ripple
Proprietary scheme for low power loss
≤2.5%
Adaptive for wide output speculation：
Output voltage range from 20V to 100V
Output current≤250mA
Open LED Protection and Short LED protection
Reliable short LED and Open LED protection
Compact package: SO8
•
•
•
Applications
Ordering Information
SY5861
□(□□)□
Tempera ture Code
Packa ge Code
Optional Spec Code
Ordering Number
SY5861BFAC
Package type
SO8
Note
----
•
LED lighting
Typical Applications
Figure 1. Schematic Diagram
AN_SY5861BRev.0.1
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AN_SY5861B
Pinout
(
top view)
(SO8)
Top Mark: AZBxyz (device
code:
AZB,
x=year code, y=week code, z= lot number code)
Pin Name
LEDN
VIN
NC
AVG
GND
Pin Number
1
2
3
4
5/6/7/8
Pin Description
Cathode of LED string.
Power Supply. Cascade a resistor (10KΩ) to this pin and anode of the
LED string.
NC.
Average current filter pin. Bypass a capacitor (100nF) to this pin and
GND.
Ground pin
Absolute Maximum Ratings
(Note 1)
VIN ------------------------------------------------------------------------------------------------------------------------ -0.3V~100V
LEDN -----------------------------------------------------------------------------------------------------------------------
-0.3~100V
Power Dissipation, @ T
A
= 25°C SO8----------------------------------------- ------------------------------------------------
0.6W
Package Thermal Resistance (Note 2)
SO8,
θ
JA
-------------------------------------------------------------------------------------------------------------
88°C/W
SO8,
θ
JC
-------------------------------------------------------------------------------------------------------------
45°C/W
Junction Temperature Range --------------------------------------------------------------------------------------
-
40°C to 150°C
Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------------------------
260°C
Storage Temperature Range ---------------------------------------------------------------------------------------
-
65°C to 150°C
Recommended Operating Conditions
VIN, LEDN ----------------------------------------------------------------------------------------------------------------
20V~100V
AN_SY5861BRev.0.1
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AN_SY5861B
Electrical Characteristics
(V
IN
= 12V, T
A
= 25°C unless otherwise specified)
Parameter
Power Supply Section
VIN turn-on threshold
VIN turn-off threshold
VIN operating current
Thermal Section
Thermal Shutdown Temperature
Thermal Shutdown Temperature
Thermal Hysteresis Temperature
Symbol
V
V
VIN,ON
Test Conditions
Min
9.5
7.2
64
Typ
10
7.8
77
150
100
20
Max
10.5
8.2
90
Unit
V
V
µA
C
C
C
VIN,OFF
I
VIN
T
T
SD1
T
SD2
V
LEDN
<15V
V
LEDN
> 15V
HYS
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 specification 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 subst rate PCB, 2oz
copper, with minimum recommended pad on top layer and thermal vias to bott m layer ground plane.
AN_SY5861BRev.0.1
Silergy Corp. Confidential-Prepared for Customer Use Only
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AN_SY5861B
Operation
The SY5861B is an adaptive linear current regulator to
eliminate low frequency current ripple targeting at LED
lighting applications.
It is applied as a current filter to the output of a LED
driver, especially single stage LED driver. It adopts
adaptive control scheme and no additional electrical
design is needed.
It is adaptive for wide output speculation, the output
voltage is ranging from 20V to 100V; the maximum
output current is 250mA. It adopts proprietary scheme
for low power loss and the efficiency loss is no more
than 2.5%. It also can be operated in parallel to support
higher LED current.
SY5861B provides reliable protections such as Short
LED Protection (SLP), Open LED Protection (OLP), and
Over Temperature Protection (OTP).
SY5861B is available with SO8.
Applications Information
Start up
When V
VIN
rises up over V
VIN-ON
, SY5861B starts to
work. At first, it has 250ms blanking time without
current filter function to build up stable reference
internally. Then the LED current ripple is decreased by
SY5861B gradually.
Shut down
When V
VIN
drops below V
VIN-OFF
, LEDN Pin is
high impedance to GND Pin.
Parallel operation application
SY5861B can be operated in parallel to support higher
LED current. The circuit is shown in below.
Fig. Parallel circuit
AN_SY5861BRev.0.1
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AN_SY5861B
SO8 Package Outline & PCB Layout Design
1.
55
1.27 TYP
5.40
3.80
-
4.00
5.80 - 6.20
0.60
0.30 – 0.50
Recommended Pad Layout
0.25 - 0.50
4
5
4.80 - 5.00
0.2
5ba
se
°
°
8
-
0
0.18 -0.25
1.40 -1.60
0.08 -0.25
0.60 - 0.85
1.27 (TYP)
Notes: All dimensions are
.
in millimeters.
All dimensions don’t include mold flash & metal burr.
AN_SY5861BRev.0.1
Silergy Corp. Confidential-Prepared for Customer Use Only
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