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PDF RT8487 Data sheet ( Hoja de datos )
| Número de pieza | RT8487 | |
| Descripción | High Efficiency BCM LED Driver Controller | |
| Fabricantes | Richtek | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de RT8487 (archivo pdf) en la parte inferior de esta página. Total 13 Páginas | ||
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RT8487
High Efficiency BCM LED Driver Controller for High Power
Factor Offline Applications
General Description
The RT8487 is a Boundary mode high PF floating buck
constant LED current output controller with an internal
gate driver.
The RT8487 features a ZCS detector which keeps
system operating in BCM and obtaining excellent
power efficiency, better EMI performance.
The RT8487 achieves high power factor correction
(PFC) and low total harmonic distortion of current
(THDi) by a smart internal line voltage compensation
circuit which has minimized system component counts;
saved both PCB size and total system cost.
Especially, the RT8487 can use a cheap simple drum
core inductor in the system instead of an EE core to
obtain high efficiency.
The RT8487 is housed in a TSOT-23-6 package. Thus,
the components in the whole LED driver system can be
made very compact.
Features
Support High Power Factor and THDi
Consideration Applications
Programmable Constant LED Current with Highly
Precision Current Regulation
Extremely Low Quiescent Current Consumption
and 1µA Shutdown Current
True Low System BOM Cost and Economical
Floating Buck Converter Solution
Unique Programmable AND Pin for ZVS Setting
to Achieve Best Power Efficiency
Universal Input Voltage Range with Off-Line
Topology
Built-in Over Thermal Protection
Built-in Over Voltage Protection
Output LED String Open Protection
Output LED String Short Protection
Output LED String Over Current Protection
Ordering Information
RT8487
Package Type
J6 : TSOT-23-6
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
RoHS compliant and compatible with the current
requirements of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
Marking Information
Applications
E27, PAR, Light Bar, Offline LED Lights
Pin Configurations
(TOP VIEW)
SENSE VC AND
654
23
VCC GND GATE
TSOT-23-6
00=DNN
00= : Product Code
DNN : Date Code
Copyright © 2015 Richtek Technology Corporation. All rights reserved.
DS8487-00 March 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1
1 page  
Typical Application Circuit
Buck :
Bridge Rectifier
+
-
CIN
0.1μF/500V
R1
511K
R2
511K
C1
4.7μF/50V
R3B
100k
4
AND
1
VCC
RT8487
5 VC
GATE 3
2
GND
SENSE 6
C2
1μF
RT8487
Q1
MTN4N60
RS
0.8
L1
470μH
RB
10
D2
RS1M
D1
ES2J
COUT
270μF/63V
Copyright © 2015 Richtek Technology Corporation. All rights reserved.
DS8487-00 March 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
5
5 Page 
OCP threshold which is about seven times of the sense
voltage threshold.
Thermal Protection (OTP)
A thermal protection feature is included to protect the
RT8487 from excessive heat damage. When the
junction
temperature exceeds a threshold of 150C, the thermal
protection OTP will be triggered and the GATE will be
turned off.
Thermal Considerations
For continuous operation, do not exceed absolute
maximum junction temperature. The maximum power
dissipation depends on the thermal resistance of the IC
package, PCB layout, rate of surrounding airflow, and
difference between junction and ambient temperature.
The maximum power dissipation can be calculated by
the following formula :
PD(MAX) = (TJ(MAX) TA) / JA
where TJ(MAX) is the maximum junction temperature,
TA is the ambient temperature, and JA is the junction to
ambient thermal resistance.
For recommended operating condition specifications,
the maximum junction temperature is 125C. The
junction to ambient thermal resistance, JA, is layout
dependent. For TSOT-23-6 package, the thermal
resistance, JA, is 197.4C/W on a standard JEDEC
51-7 four-layer thermal test board. The maximum
power dissipation at TA = 25C can be calculated by
the following formula :
PD(MAX) = (125C 25C) / (197.4C/W) = 0.5W for
TSOT-23-6 package
The maximum power dissipation depends on the
operating ambient temperature for fixed TJ(MAX) and
thermal resistance, JA. The derating curve in Figure 1
allows the designer to see the effect of rising ambient
temperature on the maximum power dissipation.
RT8487
0.6
Four-Layer PCB
0.5
0.4
0.3
0.2
0.1
0.0
0
25 50 75 100
Ambient Temperature (°C)
125
Figure 1. Derating Curve of Maximum Power
Dissipation
Layout Considerations
For best performance of the RT8487, the following
layout guidelines should be strictly followed.
The hold up capacitor, C1, must be placed as close
as possible to the VCC pin.
The compensation capacitor, C2, and delay resistor,
R3B, must be placed as close as possible to the VC
and the AND pin.
The IC GATE and GND pin are high frequency
switching nodes. Both traces must be as wide and
short as possible.
Keep the main traces with switching current as short
and wide as possible.
Place CIN, L1, Q1, RS, COUT, and D1 as close to
each other as possible.
Copyright © 2015 Richtek Technology Corporation. All rights reserved.
DS8487-00 March 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
11
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet RT8487.PDF ] | |
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