LSP7706
1.1A High Voltage Adjustable Current Regulator
Liteon Semiconductor Corp. 20090720_1.0
1/1
GENERAL DESCRIPTION
The LSP7706 is a high voltage, low dropout
current regulator for high power LED lighting. The
LSP can handle the maximum output curren t up to
1.1Amp. The output current can also be varied by
an external resistor. The output sink current could
be switched off via OE pin. And the OE pin can
also be used to control PWM dimming function.
TO-263 green package is av ailable to enhance
the power dissipation of the driver. The LSP7706
also features with build-in thermal protection to
prevent the chip from over heat damage. The
adequate thermal pad in PCB area is required to
control the junction temperature below 125°C.
FEATURES
0.8V Output Drop-out Voltage at 1.1Amp.
1.1Amp. Maximum Output Current.
Output Current Controlled by External
Resistor.
3us Fast Response Output Stage Enable
Control.
Output Pin Sust ain Voltage Up To 75V.
Supply Voltage Range 5V~50V.
Green TO-263-5L package.
TYPICAL APPLICATIONS
High Power LED Driv er
RGB Full Color Power LED driv er
LCD Monitor/TV LED Backlight Driver
LED Lighting
LED Street Lamp / Table Lamp
PIN ASSIGNMENT
TO-263-5L
(Top View)
V
DD
ISET
GND
OE
OUT
TO-220-5L
(Top View)
V
DD
ISET
GND
OE
OUT
1
2
3
4
5
V
DD
ISET
GND
OE
OUT
TO-252-5L
(Top View)
1
2
3
4
5
1
2
3
4
5
PIN DESCRIPTION
Pin Number Pin Name Pin Function
1 VDD Power supply.
2 ISET Output current set input. Connect a resistor from ISET to GND to set the LED bias
current.
3 GND Ground.
4 OE
Output stage enable control pin. High enable the OUT pin. It can be left floating
for normally on. The pin can also be used for PWM dimming function.
5 OUT
Output pin. Sink current is decided by the current on RSET connected to ISET.
500
2.1
500 ×=×=
SET
SETOUT RV
II
Thermal Pad Ground.
LSP7706
1.1A High Voltage Adjustable Current Regulator
Liteon Semiconductor Corp. 20090720_1.0
2/2
TYPICAL APPLICATION CIRCUIT
ABSOLUTE MAXIMUM RATINGS
Parameters Rating Unit
Input Voltage, VDD 50 V
Output Pin Sustain Voltage, VOUT 75 V
Enable Voltage, VOE 13.2 V
Maximum Operating Junction Temperature, TJ 150 °C
Storage Temperature Range -65 to 150 °C
Lead Temperature (soldering, 10 seconds) 260 °C
Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground.
Currents are positive into, negative out of the specified terminal.
THERMAL IMPEDIENCE
TO-263, TO-220 Package:
Thermal Resistance-Junction to Tab, θJT 3 °C /W
Thermal Resistance-Junction to Ambient, θJA 45 °C /W
TO-252 Package:
Thermal Resistance-Junction to Tab, θJT 7 °C /W
Thermal Resistance-Junction to Ambient, θJA 80 °C /W
Junction Temperature Calculation: TJ = TA + (PD × θ JA).
The θJA numbers are guidelines for the thermal performance of the device/pc-board system. Connect the thermal pad to ground using a
large pad or ground plane for better heat dissipation. All of the above assume no ambient airflow.
LSP7706
1.1A High Voltage Adjustable Current Regulator
Liteon Semiconductor Corp. 20090720_1.0
3/3
RECOMMENDED OPERATION
Parameter Symbol Min Typ Max Unit
Supply Voltage VDD 5 50 V
Output Sink Current IOUT 0.3 1.1 A
Operating Free-Air Temperature Range TA -40 +85 °C
Operating Junction Temperature TJ +125 °C
ELECTRICAL CHARACTERISTICS
VDD=24V, TA=25°C (Unless otherwise noted)
Parameter Condition Min Typ Max Unit
VOUT=0.5V, RSET=800Ω 750
Output Current
VOUT=0.7V, RSET=600Ω 1000
mA
VOUT=0.5V, RSET=800Ω ±5
Output Current Deviation
VOUT=0.7V, RSET=600Ω ±5
%
ISET Pin Current Range 0.6 2.2 mA
Maximum Output Current VOUT=0.8V, RSET=545Ω 1100 mA
RSET=800Ω, IOUT=750mA 0.5
Output Drop-out Voltage Note 1
RSET=600Ω, IOUT=1A 0.7
V
Load Regulation IOUT=750mA, VOUT=0.5V to 3V 8 mA
Line Regulation IOUT=750mA, VOUT=0.5V,
VDD= 5V to 50V, 6 mA
Thermal Shut-down Junction
Temperature Hysteresis 20℃ 160 ℃
“Low” Input Voltage 0 0.8 V
“High” Input Voltage 2 Min{VDD, 12} V
“Low” Input Current -20 +20 µA
“High” Input Current -5.0 +5.0 µA
Output Enable Delay Time OE from Low to High, VOUT=0.5V,
IOUT=750mA, 50% 5 µS
Output Disable Delay Time OE from High to Low, VOUT =0.5V,
IOUT=750mA, 50% 5 µS
Supply Current Consumption 7 mA
Note1: Output dropout voltage: 90% x IOUT @ VOUT=0.8V
LSP7706
1.1A High Voltage Adjustable Current Regulator
Liteon Semiconductor Corp. 20090720_1.0
4/4
FUNCTIONAL BLOCK DIAGRAM
VDD
Band-gap
Reference
A711
Control
Circuit
VREF
－
＋
OUT
GND
FB
OE
ISET
TYPICAL CHARACTERISTICS
Supply Current vs. Supply Volta ge
0.0
1.0
2.0
3.0
4.0
5.0
6.0
0204060
Supply Voltage (V)
Supply Current (mA)
VDROP=0.8V
TA=25°C
I
OUT
=1100mA
IOUT=900mA
IOUT=500mA
I
OUT
=330mA
I
OUT
=700m A
ISET Voltage vs. Junction Temperature
1.00
1.10
1.20
1.30
1.40
1.50
-50 0 50 100 150
Junction Temperature (°C)
ISET Voltage (V)
V
DD
=24V
Output Curre nt vs. Supply Volta ge
0
200
400
600
800
1000
1200
0204060
Supply Voltage (V)
Output Current (mA)
VDROP=1V
TA=25°C
IOUT=330mA
IOUT=500mA
IOUT=700mA
IOUT=900mA
IOUT=1100mA
Ou tp u t Cu rr ent vs. Dro p o u t Vo ltage
0
200
400
600
800
1000
1200
0.00 1.00 2.00 3.00
Dropout Voltage (V)
Output Current (mA)
IOUT=330mA
VDD=24V
TA=25°C
IOUT=500mA
IOUT=700mA
IOUT=900mA
IOUT=1100mA
LSP7706
1.1A High Voltage Adjustable Current Regulator
Liteon Semiconductor Corp. 20090720_1.0
5/5
RSET vs. Output Current
0
0.5
1
1.5
2
300 500 700 900 1100
Output Current (mA)
RSET (KΩ)
VDROP=1V
TA=25°C
FUNCTION DESCRIPTION
LSP7706 is a high voltage, high current, and low dropout current regulator for maximum output current up to
1.1A. The OE pin is used for enabling/disabling the output stage of the chip. The current could be linearly adjusted
through external resister, RSET, connected to ISET pin, or by PWM control via OE pin. Although the absolute
maximum rating of OUT pin 75V, the dropout voltage between OUT pin and GND pin should not be too large when
current is sinking because of the heat dissipation capability of the package and PCB layout.
1. Setting LED Current
An external resistor RSET connected to ISET pin sets the sink current of OUT pin. The value of RSET is calculated
by the following formula:
500
)(
2.1
500 ⋅
Ω
=⋅= KR V
II
SET
SETOUT (mA)
2. PWM Dimming Control
LSP7706 provides PWM dimming control function through OE pin. Basically, by changing the duty cycle of the
PWM control signal, the ratio of LED ON-time to OFF-time can be changed. Consequently, larger duty cycle results
in larger average current for driving LED and thus higher luminance.
Ideally, the average LED driving current is in linear proportion to the duty cycle of the PWM control signal in
spite of the frequency. However, due to the inherent propagation delay of the chip and the rising/falling time of the
driving current, the deviation of the actual current from theoretical value will become larger when the PWM
frequency gets higher. That is, if the PWM frequency exceeds certain recommended value, the effect of the fixed
propagation delay and the rising/falling time of LED current on the linear relationship between the duty cycle and the
average current will become more apparent. On the other hand, if the PWM frequency is too low, the flicker will
become observable. Therefore, it is important to choose a suitable frequency for the PWM signal.
Please refer to the following timing chart & table for the limitation of maximum dimming frequency. It is
determined by the minimum duty ratio, DMIN, and the minimum LED “ON” time, tON,MIN. The maximum dimming
frequency, fPWM, can be calculated by the following formula:
MIN
MINON
MAXPWM D
t
f,
,
1=
Where, duty ratio is defined as:
OFFON
ON
tt t
D+
=
LSP7706
1.1A High Voltage Adjustable Current Regulator
Liteon Semiconductor Corp. 20090720_1.0
6/6
OE 50%*VOE
tON tOFF
VOE
tpLH tpHL tR
ILED 50%*IOUT
tF
IOUT
Characteristic Symbol Min Typ Max Unit
LED “ON” Period (OE Pin Control Signal) tON 5 us
LED “OFF” Period (OE Pin Control Signal) tOFF 5 us
Propagation Delay Time (Output Current from “L” to “H”) tpLH 1.5 3 us
Propagation Delay Time (Output Current from “H” to “L”) tpHL 1.5 3 us
Output Current Rising Time (Rising from 10% to 90%) tR 1.5 3 us
Output Current falling Time (Falling from 90% to 10%) tF 1.5 3 us
3. DC Voltage Input
Any DC voltage level between 5V to 50V could be adopted as power source VDD for typical application of
LSP7706 as long as VDD is larger than the total forward voltage drop of the LED string by the minimum dropout
voltage (between OUT pin and GND pin) needed for the expecting current.
If 50V ~ 100V voltage level is adopted as power source to positive end of the LED string, one Zener shunt
regulator could be used to provide appropriate voltage (lower than 50V) to VDD pin. The supply voltage to VDD pin
and LED+ end could also be separated. Note that, heat-sink area on PCB is required if the dropout voltage between
OUT pin and GND pin is too large. Please refer to the “Thermal Consideration” section.
LSP7706
1.1A High Voltage Adjustable Current Regulator
Liteon Semiconductor Corp. 20090720_1.0
7/7
4. Application for LED Lighting
LSP7706 could coordinate with any type of DC-to-DC converter through feedback path to realize LED lighting
module. The number of LEDs in the string is variable even with certain fixed power source since the output voltage
of the DC-to-DC converter could be modulated according to feedback signal. In the following figure, DFB is used to
feed the dropout voltage of OUT pin of the LSP7706 back to DC/DC converter; and RFB is the pull-high resistor for
DFB.
5. AC Voltage Input
LSP7706 could work with any kind of well-developed switch-mode power supply system. Simply cut off the
internal feedback path of the power supply system and then feed the signal from LSP7706 back to the power supply
system instead.
LSP7706
1.1A High Voltage Adjustable Current Regulator
Liteon Semiconductor Corp. 20090720_1.0
8/8
6. Output Capacitor CO
If the LED string and LSP7706 is located in separate PCBs, or the length of the routing path L1>10cm or
L2>3cm, the output capacitor CO should be added. Typically, capacitance of 0.1uF ~ 1uF is recommended and 1uF
is needed when L2 is much longer than 3cm.
The output capacitor CO may be neglected under certain condition. If the LED string and LSP7706 are located
in the same PCB, and the length of the routing path L1<10cm & L2<3cm, the output capacitor CO can be neglected.
LSP7706
1.1A High Voltage Adjustable Current Regulator
Liteon Semiconductor Corp. 20090720_1.0
9/9
THERMAL IMPEDIENCE
The Maximum Power Dissipation on Current Regulator
PD(MAX) = VOUT(MAX) × I
OUT(NOM) + VIN(MAX) × I
DD
VOUT(MAX) = the maximum voltage on output pin;
IOUT(NOM) = the nominal output current;
IDD = the quiescent current the regulator consumes at IOUT(NOM);
VIN(MAX) = the maximum input voltage.
Thermal Consideration
The LSP7706 has internal power and thermal limiting circuitry designed to protect the device under overload
conditions. However, maximum junction temperature ratings should not be exceeded under continuous normal load
conditions. The thermal protection circuit of LSP7706 prevents the device from damage due to excessive power
dissipation. When the device junction temperature rises to approximately 160°C, the regulator will be turned off.
When power consumption is over about 1.22W (TO-263 and TO-220 package, at TA=70°C), additional heat sink is
required to control the junction temperature below 125°C.
The junction temperature is:
TJ = PD (θJT +θTS +θSA ) + TA
PD : Dissipated power.
θJT: Thermal resistance from the junction to the mounting tab of the package.
For TO-263 package, θJT = 3.0 oC /W.
θTS: Thermal resistance through the interface between the IC and the surface on which it is mounted.
(typically, θTS < 1.0°C /W)
θSA: Thermal resistance from the mounting surface to ambient (thermal resistance of the heat sink).
If PC Board copper is going to be used as a heat sink, below table can be used to determine the appropriate
size of copper foil required. For multi-layered PCB, these layers can also be used as a heat sink. They can be
connected with several through-hole vias.
PCB θSA (°C /W) 59 45 38 33 27 24 21
PCB heat sink size (mm2) 500 1000 1500 2000 3000 4000 5000
1
2
3
4
5
VDD
ISET
GND
OE
OUT
Recommended figure of PCB area used as a heat sink.
Thermal-pad of TO-263
Through hole vias
LSP7706
1.1A High Voltage Adjustable Current Regulator
Liteon Semiconductor Corp. 20090720_1.0
10/10
ORDERING INFORMATION
MARKING INFORMATION
TO263-5L TO252-5L
Package:
D: TO252
K: TO263
T: TO220
Output Voltage:
Blank: A dj Packing:
A: Tape & Real Temperature Grade:
d: -40～85℃
LSP7706X X X X
LSP7706
1.1A High Voltage Adjustable Current Regulator
Liteon Semiconductor Corp. 20090720_1.0
11/11
PACKAGE INFORMATION
5-Pin Surface Mount TO-263
INCHES MILLIMETERS
MIN TYP MAX MIN TYP MAX
A 0.395 - 0.420 10.03 - 10.67
B 0.325 - 0.361 8.25 - 9.17
C 0.171 - 0.181 4.34 - 4.59
D 0.045 - 0.055 1.14 - 1.40
E 0.013 - 0.017 0.330 - 0.432
F 0.029 - 0.035 0.737 - 0.889
G 0.062 - 0.072 1.57 - 1.83
I - - 0.065 - - 1.65
K 0.575 0.635 14.60 16.13
L 0.090 0.110 2.29 2.79
M7° 7°
N3° 3°
FE
G
B
I
A
M
K
D
C
N
L
5-Pin Plastic TO-220
INCHES MILLIMETERS
MIN TYP MAX MIN TYP MAX
A 0.560 - 0.650 14.23 - 16.51
B 0.380 - 0.420 9.66 - 10.66
C 0.140 - 0.190 3.56 - 4.82
D 0.018 - 0.035 0.46 - 0.89
F 0.140 - 0.160 3.56 - 4.06
G 0.134 - - 3.40 - -
J 0.012 - 0.045 0.31 - 1.14
K 0.500 - 0.580 12.70 - 14.73
N 0.268 TYP 6.80 TYP
R 0.080 - 0.115 2.04 - 2.92
S 0.045 - 0.055 1.14 - 1.39
T 0.230 - 0.270 5.85 - 6.85
K
D
G
N
R
J
B
T
F
C
S
A
LSP7706
1.1A High Voltage Adjustable Current Regulator
Liteon Semiconductor Corp. 20090720_1.0
12/12
TO-252-5L
Dimensions in Millimeters Dimensions in Inches
Symbol
MIN MAX MIN MAX
A 2.200 2.400 0.087 0.094
A1 0.000 0.127 0.000 0.005
B 0.400 0.600 0.016 0.024
C 0.430 0.580 0.017 0.023
c1 0.430 0.580 0.017 0.023
D 6.350 6.650 0.250 0.262
D1 5.200 5.400 0.205 0.213
E 5.400 5.700 0.213 0.224
E 1.270 TYP 0.050 TYP
e1 2.540 TYP 1.000 TYP
L1 9.500 9.900 0.374 0.390
L2 1.400 1.780 0.055 0.070
L3 2.550 2.900 0.100 0.114
V 3.800 REF 0.150 REF
UPDATE HISTORY
Date Version Description
July 20, 2009 1.0 New generation
