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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 1µ A 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
00=DNN
00= : Product Code
DNN : Date Code
Applications
E27, PAR, Light Bar, Offline LED Lights
Pin Configuration
(TOP VIEW)
SENSE VC AND
654
23
VCC GND GATE
TSOT-23-6
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
DS8487-02 October 2017
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
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RT8487
Simplified Application Circuit
Buck type:
Bridge Rectifier
+
-
R1
R2
CIN
R3B
C1
AND
VCC
RT8487
VC GATE
GND
SENSE
C2
Q1
RS L1
D2
Bootstrap Diode
D1
COUT
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
www.richtek.com
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is a registered trademark of Richtek Technology Corporation.
DS8487-02 October 2017

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RT8487
Functional Pin Description
Pin No.
Pin Name
Pin Function
1 VCC
Supply voltage input. For good bypass, a ceramic capacitor near the VCC
pin is required.
2 GND
Ground.
3 GATE Gate driver output for external MOSFET switch.
4 AND
AND function pin.
5 VC
Close loop compensation node.
6
SENSE
LED current sense input. The typical sensing threshold is 250mV between
the SENSE and GND pin.
Functional Block Diagram
VCC
SENSE
Regulator
+
EA
-
V 250mV
State Machine
A
GATE
GND
VC AND
Operation
The RT8487 senses true average output current and
keeps the system driving constant output current. The
VC pin is the compensation node in this close loop
system and dominates the frequency response. To
stabilize the system and achieve better PFC / THDi,
proper selection of a compensation network is needed.
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
DS8487-02 October 2017
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
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RT8487
Absolute Maximum Ratings (Note 1)
Supply Input Voltage (VCC) ------------------------------------------------------------------------------------------ 0.3V to 40V
Power Dissipation, PD @ TA = 25C
TSOT-23-6 ---------------------------------------------------------------------------------------------------------------- 0.5W
Package Thermal Resistance (Note 2)
TSOT-23-6, JA ---------------------------------------------------------------------------------------------------------- 197.4C/W
Lead Temperature (Soldering, 10 sec.) ---------------------------------------------------------------------------- 260C
Junction Temperature -------------------------------------------------------------------------------------------------- 150C
Storage Temperature Range ----------------------------------------------------------------------------------------- 65C to 150C
ESD Susceptibility (Note 3)
HBM (Human Body Model) ------------------------------------------------------------------------------------------- 2kV
Recommended Operating Conditions (Note 4)
Supply Input Voltage, VCC ------------------------------------------------------------------------------------------- 10V to 30V
Ambient Temperature Range ---------------------------------------------------------------------------------------- 40C to 85C
Junction Temperature Range ---------------------------------------------------------------------------------------- 40C to 125C
Electrical Characteristics
(VCC = 24V, TA = 25C, unless otherwise specified)
Parameter
Symbol
Test Conditions
Min Typ Max Unit
VCC UVLO ON
VUVLO_ON
17 18 19 V
VCC UVLO OFF
VUVLO_OFF
6.4 7.2
8
V
VCC Shutdown Current
ISD
VCC = VUVLO_ON 3V
-- -- 1 A
VCC Quiescent Current
IQC
Gate stands still
-- 0.5 5 mA
VCC Operating Current
ICC
By CGATE = 1nF, Freq.= 20kHz
-- 1 5 mA
VCC OVP Level
VOVP
32 34 39.5 V
Sense Pin Leakage Current ISENSE
VSENSE = 3V
-- 1 5 A
Current Sense Threshold
VSENSE
242.5 250 257.5 mV
AND Pin Leakage Current
IAND
VAND = 5V
-- 1 2 A
GATE Voltage High
VGATE_H
IGATE = 0mA
IGATE = 10mA
10 12
--
V
8 10 --
Rising Time tr
GATE Driver
Falling Time tf
-- 50 --
ns
-- 25 --
Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the
operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may affect
device reliability
Note 2. JA is measured under natural convection (still air) at TA = 25C with the component mounted on a high
effective-thermal-conductivity four-layer test board on a JEDEC 51-7 thermal measurement standard.
Note 3. Devices are ESD sensitive. Handling precaution recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
www.richtek.com
4
is a registered trademark of Richtek Technology Corporation.
DS8487-02 October 2017

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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 © 2017 Richtek Technology Corporation. All rights reserved.
DS8487-02 October 2017
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
5