LC5710S DATA SHEET
LC5710S
DATA SHEET
Rev.1.9
Rev.1.9
SANKEN ELECTRIC CO., LTD.
http://www.sanken-ele.co.jp
Copy Right: SANKEN ELECTRIC CO., LTD.
Page.1
LC5710S DATA SHEET
Rev.1.9
CONTENTS
General Descriptions................................................................................................................. 3
1. Absolute Maximum Ratings ............................................................................................ 4
2. Recommended Operation Conditions............................................................................. 4
3. Electrical Characteristics ................................................................................................. 5
4. Functional Block Diagram ............................................................................................... 7
5. Pin Assign & Functions .................................................................................................... 7
6. Typical Application Circuit ............................................................................................. 8
7. Package Information ........................................................................................................ 9
8. Functional Description ................................................................................................... 10
8.1 Settlement of the operating frequency ................................................................. 10
8.2 PMW Current Control.......................................................................................... 10
8.3 LED Dimming ........................................................................................................ 11
8.4 Overcurrent Protection Function (OCP) ............................................................ 12
8.5 Overvoltage Protection Function (OVP) ............................................................. 13
8.6 Selection of application circuit ............................................................................. 13
8.7 Setting of External Inductor ................................................................................. 15
8.8 The Internal Power Dissipation Pd ...................................................................... 18
8.9 Phase Compensation (COMP terminal) .............................................................. 20
8.10 LED Cross-Connection Protection Function .................................................... 24
8.11 Peripheral Parts Design ...................................................................................... 25
8.12 Reference Design Example ................................................................................. 26
9. Example Pattern Layout ................................................................................................ 27
10. Design Considerations .................................................................................................. 29
11. Typical Caracteristics(Ta=25℃) ................................................................................. 31
12. The contents of packing specification ......................................................................... 40
IMPORTANT NOTES ........................................................................................................... 41
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Page.2
LC5710S DATA SHEET
Rev.1.9
General Descriptions
Package
SOP8
The LC5710S product is the power IC for LED
driver which incorporates a power MOSFET and a
controller IC in a package.
This product is a DC/DC converter which features
are; wide input voltage range, 100kHz to 500kHz
operating frequency, and Buck/ Boost/ Buck-Boost
converter can be selected with external circuit
configuration.
LED string current can be set with the external
resistor, and LED dimming can be controlled by the
digital input signal or DC-bias. The rich set of
protection features helps to realize low component
counts, and high performance-to-cost power supply.
Characteristics
Features
Input voltage range
RDS(ON)
Operation Types: The following converter types
are applicable by the external circuit configuration
・Buck Converter
・Boost Converter
・Buck-Boost Converter
High Efficienby: η > 90%(TYP)
Operation Frequency:
100kHz to 500kHz(adjustable)
LED string current setting with an external resistor.
Current Detection voltage of LED string:
100mV±3%
Thus, low power loss and high accuracy LED
string current can be achieved by setting of an
external resistor.
PWM Dimming Frequency: available to
20000Hz(MAX)
Analog Dimming by the DC-bias(0 to 2V)
Package: HSOP8
Heat slag in the back can increase heat dissipation
effect by connecting it to GND pattern
Protection Functions
・Overcuurent Protection Function (OCP)
------ Pulse-by-pulse basis
・OvervoltageProtection Function (OVP)
------ Auto restart
・Thermal Shutdown Protection Function (TSD)
------ Auto restart
･LED cross protection
5V (MIN)～58V(MAX)
550mΩ(TYP)
Applications
LED lighting fixtures
LED light bulbs
Marking
Product number
LC5710
SK YMW
xxxx
Lot number
Y=The last digit of the year (0 to 9)
M=Month (Jan to Sep:1 to 9，O=”10”，N=”11”，D=”12”)
W=Week(1 to 3)
Date = 1 to 10:1
Date = 11 to 20:2
Date = 21 to 31:3
*Our control number (4 digit)
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Page.3
LC5710S DATA SHEET
Rev.1.9
1.Absolute Maximum Ratings
Certain details refer to the specification sheet of this product.
The polarity value for current specifies a sink as “+”, and a source as “−”, referencing the IC.
Unless specifically noted, Ta is 25°C
Table.1
Characteristic
Pins
Symbol
Rating
Unit
VIN Pin Voltage
5－3
VIN
−0.3 to 60.0
V
SW Pin Voltage
4―3
VSW
−0.3 to 60.0
V
CSP Pin Voltage
6―3
VCSP
−0.3 to 60.0
V
CSN Pin Voltage
Differential Voltage
bwteen CSP and CSN Pins
COMP Pin Voltage
7―3
VCSN
−0.3 to 60.0
V
6―7
VCSP-CSN
−0.3 to 3.3
V
1―3
VCOMP
−0.3 to 3.3
V
DIM Pin Voltage
8―3
VDIM
−0.3 to 3.3
V
2―3
VRT
−0.3 to 3.3
V
(2)
―
PD
1.2
W
(3)
―
TJ
125
°C
(2)
―
θj-a
82.8
℃/W
―
θj-pin
59.0
℃/W
―
Top
−40 to 125
°C
―
TSTG
−40 to 150
°C
RT Pin Voltage
Allowable Power Dissipation
of MOSFET
Junction Temperature
in Operation
Thermal Resistance
(1)
(junction-ambient air)
Thermal Resistance
(junction- Pin No. 3)
Operating ambient
temperature
Notes
(1)
Storage Temperature
(1)
However, it is limited by Junction temperature.
(2)
When mounted on a 40×40mm Glass-epoxy board (copper area in a 25×25mm).
(3)
Thermal shutdown temperature is approximately 150°C
2.Recommended Operation Conditions
Recommended Operation Conditions are the required operating conditions to maintain the normal circuit
functions described in the electrical characteristics. In actual operation, it should be within these conditions.
The polarity value for current specifies a sink as “+” and a source as “−” referencing the IC.
Unless specifically noted, Ta is 25°C
Table.2
Characteristic
VIN Pin Voltage
Output current
DIM Terminal Voltage
DIM Terminal Dimming
Frequency
Peak to Peak Inductor Ripple
current
(4)
Pins
Symbol
MIN
MAX
Unit
5−3
VIN
5
58
V
―
Io
0
1
8−3
A
Notes
(5)
Buck
(5)
Boost/Buckboost
0
0.5
VDIM
VDIM(OFF)
2.5
V
Analogue Dimming
8−3
fDIM
100
20000
Hz
Digital Dimming
―
⊿IL
0.1
0.4
A
Operating ambient
(4)
-40
+85
Top
―
℃
temperature
(4)
To be used within the allowable package power dissipation characteristics (fig. 1)
(5)
Buck circuit：1A, Boost circuit／Buck-boost circuit：0.5A, Each condition is ⊿IL ≦0.4A.
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Page.4
LC5710S DATA SHEET
Rev.1.9
3.Electrical Characteristics
Certain details refer to the specification sheet of this product.
The polarity value for current specifies a sink as “+” and a source as “−”, referencing the IC.
3.1 Electrical Characteristics of Control Part (MIC) Unless specifically noted, Ta is 25°C, VIN=15V
Table.3
Parameter
Terminal
Symbol
Operation Start Voltage
5−3
Operation Stop Voltage
Operation Hysteresis Voltage
Ratings
Units
MIN
TYP
MAX
VIN(ON)
3.8
4.1
4.5
V
5−3
VIN(OFF)
3.4
3.7
4.2
V
5−3
VIN(HYS)
0.25
0.37
0.50
V
Remarks
Supply Current
(6)
5−3
IIN(ON)
―
1.6
―
mA
Supply Current in No Operation
(6)
5−3
IIN(OFF)
―
0.24
―
mA
VIN= 3V
Oscillator Frequency1
―
fOSC1
80
100
135
kHz
RRT=180kΩ
Oscillator Frequency2
―
fOSC2
350
500
650
kHz
RRT=18kΩ
Minimum On Time
―
tON(MIN)
100
200
300
ns
Maximum Duty Cycle
―
DMAX
84
90
95
%
VCOMP= 0V
VCOMP= 2.8
V
Current Sense Voltage
6−7
VCS
97
100
103
mV
SW Current Limit
4−3
ISW(LIM)
1.4
1.8
2.2
A
CSP Input Current
6−3
ICSP
22
35
50
µA
CSN Input Current
7−3
ICSN
5
9.5
18
µA
COMP Terminal Source Current
1−3
ICOMP(SO)
-65
-50
-35
µA
COMP Terminal Sink Current
1−3
ICOMP(SI)
35
50
65
µA
―
GM
―
4.2
―
mS
6−7
VCS(OVP)
140
150
160
mV
―
TWDT
―
30
―
mS
8−3
VDIM(ON)
0.17
0.20
0.23
V
8−3
VDIM(OFF)
0.12
0.15
0.18
V
8−3
VDIM(HYS)
10
50
100
mV
(6)
―
TSD
―
165
―
°C
(6)
―
TSD(HYS)
―
22
―
°C
Error Amplifier Conductance
(6)
Over Voltage Threshold
Setup time of Watch Dog Timer
DIM Voltage in LED On at
Dimming mode
DIM Voltage in LED Off at
Dimming mode
DIM Hysteresis Voltage at
Dimming mode
Thermal Shutdown
Thermal Shutdown
(6)
Hysteresis
(6)
Guaranteed by design, not tested.
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Page.5
VCS=20mV
VCOMP=2V
VCS=180mV
VCOMP=2V
VCS=70
~130mV
Vcomp=2.5V
Vcs=short
LC5710S DATA SHEET
Rev.1.9
3.2 Allowable package power dissipation
When mounted on a 40×40mm Glass-epoxy board (copper area in a 25×25mm).
fig.1
Package power dissipation of LC5710S
(Thermal Derating Curve)
Note1 : The power dissipation in fig.1 is calculated at the junction temperature 125 ℃.
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Page.6
LC5710S DATA SHEET
Rev.1.9
4. Functional Block Diagram
fig.2 Block diagram
5. Pin Assign & Functions
Table.4
Pin No.
Symbol
1
COMP
2
RT
3
GND
4
SW
5
VIN
6
CSP
7
CSN
8
DIM
Functions
DIM
EN/DIM
COMP
VDD
NC
RT
CSN
GND
CSP
SW
VIN
fig.3 Pin Assign
External phase compensation terminal.
For adjust switching frequency,Connect RRT resisitor to
ground.
Ground terminal.
Switching Output. Switching node that drives the external
inductor.
Supply Input.
Input capacitor CIN is connected between VIN and GND.
Current Sense Input Positive. Reference potential for the
current sense input.
Current Sense Input Negative. Connect current sense resistor
to sense output current.
PWM Dimming Signal Input. And Analog Dimming is
possible as to input of DC voltage that is :
VDIM (OFF) <VDIM<2.5V. LC5710S continues off-condition
when this pin is held in the one under VDIM (OFF).
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Page.7
LC5710S DATA SHEET
Rev.1.9
6. Typical Application Circuit
Examples for LED lighting power supply
A)Buck application
B)Boost application
fig.4 Typical Application Circuit of LC5710S
C)Buck-Boost application
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Page.8
LC5710S DATA SHEET
Rev.1.9
7. Package Information
SOP8 Package
Top view
8
1
7
2
6
5
3
4
side view1
side view2
NOTES2:
1) All dimensions are in Millimeter
2) Pb-free. Device composition compliant with the RoHS directive
3) Drawing is not to scale.
fig.5 SOP8 package outline
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Page.9
LC5710S DATA SHEET
Rev.1.9
8. Functional Description
All of the parameter values used in these descriptions are typical values of the electrical characteristics, unless they
are specified as minimum or maximum.
With regard to current direction, “+” indicates sink current (toward the IC) and “–” indicates source current (from the IC).
8.1 Settlement of the operating frequency
The operating frequency of the LC5710S is adjustable with the value of “setup resistor RRT” that is connected
between RT terminal (2 pin) and GND terminal (3 pin). This frequency Fosc can be calculated with an equation (1).
The relations of the frequency to the resistance value of RRT are shown in the fig. 6.
Fosc(Hz)={4.74／(24×RRT)＋0.365E-6}／21.5E-12 ･･･(1)
*Unit of RRT=(Ω)
Operating Frequency Fosc(kHz)
LC5710S RRT vs. Fosc characteristic
600
500
400
300
200
100
0
10
100
RRT(kΩ)
fig.6 RRT vs. Fosc
8.2 PWM Current Control
The current control circuit is shown in fig.7.
CS
RS
1
Osillator
COMP
+
CSP 6
RCS
－
ROVP
－
Q
S
+
－
External components
CSN 7
VCS
LED
COUT
Output
voltage
R
SW 4
+
+
Σ
－
fig.7 Current control circuit
For enhanced response speed and stability, current mode control (peak current mode control) is used for constant
current control of the output current. The operating frequency, FOSC is adjustable between 100kHz and 500kHz by the
setting resistor RRT.
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Page.10
LC5710S DATA SHEET
Rev.1.9
LED string current is detected by the current detection resistor, RCS.
The voltage of RCS is detected by both CSP and CSN pins. This IC compares this voltage with the Current Detection
Voltage, VCS, and makes a target value for current control.
The constant current is controlled so that the detection voltage of peak current of internal power MOSFET is close to
the target value, and thus the LED string current is constant.
The constant current of LED string, IOUT, is calculated by the following with RCS as the current detection resistor and
ROVP as the resistor for overvoltage protection in the case that LED string is open.
IOUT
where;
VCS ICSN (RCS ROVP)
RCS
･･･(2)
ICSN : the CSN Pin Sink Current, 9.5μA.
VCS : the Current Detection Voltage, 100mV.
Also, IOUT can be expressed by the following, if ICSN×(RCS+ROVP) is negligibly small against VCS.
IOUT
VCS
RCS
･･･(3)
ROVP value should be chosen so that IOUT is within the acceptable accuracy range referring to the calculation in “8.5
Overvoltage Protection Function (OVP)”.
8.3 LED Dimming
8.3.1 Analog dimming
The dimming of LC5710S copes with both of Analog (the input of a DC voltage) and PWM-digital-Dimming.
Though it is Analog-dimming first, there are relations of the fig.8(A),(B) in the input DC voltage of the DIM pin and
the dimming-ratio. Moreover,Dimming by the Pull-down resistor RDIM is possible by using a internal current-source
of the IC, too. The relations of the DIM pin voltage and RDIM are shown by the figure 8 (B). Dimming ratio is 100%
when the DIM pin voltage is more than DC 2V.
fig.8(A) DIM Pin voltage vs. LED Current
fig.8(B) Pull-down resistor RDIM vs. DIM pin voltage
Though LC5710S doesn't have an exclusive
"Remote ON/OFF pin",
But,"Remote ON/OFF function" is as well as
possible by using a DIM pin.
fig.8I The connection of RDIM and remote ON／OFF application
From the port of the microcomputer of the use and so on, and if the DIM pin of LC5710S is held continuously to
the “Low” level,LC5710S continues suspension of a movement. The “Low level” voltage must be lower voltage
than VDIM (OFF). For reverse logic, put one small signal Transistor as the fig8I.
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Page.11
LC5710S DATA SHEET
Rev.1.9
8.3.2 PWM digital dimming
LED dimming is controlled by the duty cycle of PWM digital signal which is input to DIM terminal.
The constant current output turns ON/OFF by the following signal input voltage to DIM pin which is within the
absolute maximum rating; −0.3V to 3.3V.
・When the DIM terminal Voltage is higher than “LED-ON-Threshold (VDIM(ON)≧0.2V)” , IOUT flows.
・DIM terminal voltage hysteresis VDIM(HYS)=50mV.
The Dimming-ratio depends on the duty ratio of the PWM-digital-dimming signal pulse (fig.9).
PWM Dimming with 1kHz, Duty 50%
PWM Dimming with 1kHz, Duty 25%
CH2: Dimming signal (2V/div)
CH3: LED current
(0.2A/div)
CH1: SW pin voltage (10V/div)
PWM Dimming with 1kHz, Duty 75%
fig.9
PWM Dimming with Duty 100%
Actual waveform in Dimming operation
As well as the case of the analog-dimming, if the signal of the “Low” level lower than VDIM (off) is inputted
to DIM-pin continuously, the suspension of a movement is continued. As for the fig9 as well, when a Dimming
signal (CH2:pale-blue ) is a “Low” level, the switch-pin voltage waveform(CH1:blue) isn‟t switching.
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Page.12
LC5710S DATA SHEET
Rev.1.9
8.4 Overcurrent Protection Function (OCP)
The IC incorporates Overcurrent Protection Function (OCP) limited the current flowing to SW terminal (fig.10).
When the current to SW terminal reaches ISW(LIM)= 1.8A, the internal power MOSFET turns off on pulse-by-pulse
basis.This protection is activated in case of the constant current detection failure or the output end shorted.
SW 4
PWM
LOGIC
+
OCP
－
GND 3
fig.10
Overcurrent protecton circuit
8.5 Overvoltage Protection Function (OVP)
If LED string is open and the constant current loop is cut, the output voltage increases more than the controlled
voltage. As shown in fig.11, the OVP Function with the circuit connected ROVP and a zener diode, DZOVP, is done
OVP protection. After LED string is open, when DZOVP is conducted, the output voltage is limited to the sum voltage
of the zener voltage of DZOVP and the Overvoltage Protection (OVP) Threshold Voltage, VCS=150mV.
CSP
6
RCS
ICSN
CSN
CSP
COUT
7
CSN
6
RCS
ICSN
7
ROVP
COUT
ROVP
IDZ
IOUT
DZOVP
DZOVP
LED
Normal operation
fig.11
LED string is open
Overvoltage protection circuit
The allowable current of DZOVP, IDZ, can be expressed by the following with PDZ as the allowable dissipation and VDZ
as the zener voltage of DZOVP.
IDZ
PDZ
VDZ
･･･(4)
The ROVP value, by which the loss of DZOVP is less than the allowable dissipation, is chosen by the following with
ICSN as the CSN Pin Sink Current and RCS as the constant current detection resistor.
ROVP
VCS ( OVP)
RCS
IDZ ICSN
･･･(5)
Also, when ICSN is negligibly small against IDZ, the approximate equation of Equation (4) becomes as follows.
ROVP
VCS ( OVP)
RCS
IDZ
･･･(6)
ROVP value should be chosen so that the loss of DZOVP is less than the allowable dissipation in OVP protection, and
IOUT is within the acceptable accuracy range.
DZOVP value, VDZ, should be chosen to be higher than the maximum output voltage of LED string to avoid DZ OVP
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Page.13
LC5710S DATA SHEET
Rev.1.9
conduction during the normal operation.
For example,when these conditions are VCS=150mV,ICSN=9.5μA,IDZ=5mA,RCS=0.33Ω, Because of ICSN << IDZ,
ROVP becomes 29.67Ω (≒ 30Ω) that is calculated following the equation(6).
8.6 Selection of application circuit
Select application circuit properly in the relations with the LED strings voltage and the input voltage VIN in the Table
5.
Table.5
Relations between the input voltage and the LED string voltage .
VIN＞(n × VFLED)＋Vcs
VIN＜(n × VFLED)＋Vcs
VIN(Low)＜(n × VFLED)＋Vcs＜VIN(High)
Circuit type
Buck
Boost
Buckboost
The number of LED which can be serial connection in LC5710S becomes as follows in the Table 6 in each circuit
type. But, there are the following 1) – 4) as a factor which a movement condition is restricted to.
1) Settlement of the input voltage under VIN (ON) ･･･The setup that VIN is under 5V is impossible by the start
condition of the IC.
2) VIN(MAX) or Vsw(MAX) ･･･As an example, the condition that VIN or Vsw voltage reaches 48V by
80%-derating against 60V which is the absolute maximum ratings.
3) A limitation (0.15<Duty<0.84) by the minimum or maximum ON-duty.
4) The input and output condition that “Inductor peak current ILp” reaches threshold of “SW current limit ISW
(LIM) =1.4A (Min)” .
Table.6
VIN(or Vsw)＜48V(60V×0.8), 0.15＜Duty＜0.84 are common condition.
Range of the VIN(V)
Number of
Buck-type
Boost-type
Buckboost-type
Vout or
LED (pcs)
LED strings
ILED=1.0A，
ILED=0.5A，
ILED=0.5A，
(Serial
voltage(V)
⊿IL=0.4A
⊿IL=0.4A
⊿IL=0.4A
connection)
MIN(V)
MAX(V)
MIN(V)
MAX(V)
MIN(V)
MAX(V)
1
3.6
5.00
24.00
5
20.4
2
7.1
8.45
47.33
5.00
6.04
5.1
39.9
3
10.6
12.62
48.00
5.00
9.01
7.6
37.4
4
14.1
16.79
48.00
6.60
11.99
10.1
33.9
5
17.6
20.95
48.00
8.30
14.96
12.7
30.4
6
21.1
25.12
48.00
9.90
17.94
15.1
26.9
7
24.6
29.29
48.00
11.60
20.91
17.6
23.4
8
28.1
33.45
48.00
13.20
23.89
9
31.6
37.62
48.00
14.90
26.86
10
35.1
41.79
48.00
16.50
29.84
11
38.6
45.95
48.00
18.20
32.81
12
42.1
19.80
35.79
13
45.6
21.50
38.76
For non ･･･In case of following condition, VIN under VIN(ON), VIN or Vsw reaches 48V, and ILp reaches I SW(LIM),
it is the setup which doesn‟t become utility. When a table 6 is graphed, they are shown in the fig12 – the fig14.
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Page.14
LC5710S DATA SHEET
Rev.1.9
Number of LEDs serial connection n(pcs)
Buck-type Number of LEDs serial connection vs．Range of VIN
×11
×10
×9
×8
×7
×6
×5
×4
×3
×2
×1
0
5
10
15
20
25
30
35
Input voltage VIN(V)
40
45
50
fig.12
Number of LEDs serial connection n(pcs)
Boost-type Number of LEDs serial connection vs．Range of VIN
×13
×12
×11
×10
×9
×8
×7
×6
×5
×4
×3
×2
×1
0
5
10
15
20
25
30
35
Input voltage VIN(V)
40
45
50
fig.13
Number of LEDs serial connection n(pcs)
Buckboost-type Number of LEDs serial connection vs．Range of
VIN
×7
×6
×5
×4
×3
×2
×1
0
5
10
15
20
25
30
Input voltage VIN(V)
35
40
45
50
fig.14
The fig12 – the fig14 are based on the calculation. You must reduce ILED,frequency and Vout when surge voltage
is big in the waveform of the SW terminal, and when the heat generation of the IC is high. And, you must use it
within the range of “Thermal Derating Curve” of the fig1.
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Page.15
LC5710S DATA SHEET
Rev.1.9
8.7 Setting of External Inductor
The each operation of Buck, Boost and Buck-Boost converter is explained as follows.
The inductance value is designed so that the operation becomes Continuous Conduction Mode (CCM) which the
inductance current flows continuously, because the load current of LED lighting application is constant.
The duty, D, is set within the following range, based on “3. Electrical Characteristics”.
tON(MIN)×FOSC ＜ D ＜DMAX
･･･(7)
Therefore, Duty-D is within the range of 0.84 from 0.15 ( 0.15＜ D ＜0.84).
The output voltage, VOUT, can be calculated by the following with VOUT as the output voltage, IL as the inductor
current, and ΔIL as the ripple current of inductor current.
Vout= n×VFLED＋VCS
･･･(8)
where; VFLED : Forward voltage drop of a LED(･･･VF=3.5V／1PCS)
n : The number of LED in series
VCS : Current Detection Voltage, VCS= 100mV
Table.7
Equations to calculate Necessary Inductance L
Buck type
Boost type
Buckboost type
VIN
Vout
VIN＋Vout
SW terminal voltage
Vsw
ON-duty “D”
＋
Inductor average
current ILAVE
ILED
Inductor peak current
ILp
＋
Necessary Inductance L
⊿
⊿
＋
⊿
⊿
＋
⊿
⊿
In case of Buck-type, as for the Drain-current which flows into the SW terminal, Drain-current becomes equal to LED
current. But, in case of Boost-type, or in case of Buckboost-type, for example when the Duty-D is 0.5, if it is same
inductor-ripple current, Drain-current is doubled from Buck-type. Be careful to this point.
Inductor-ripple-current is the range of “⊿IL=0.1A to 0.4A”, it is based on a recommendation. And, by the condition
of internal-over-current-protection, because it is required that Inductor-peak-current “ILp” doesn‟t reach
“ISW (LIM) =1.4A (MIN)”. Substantially, the current which can be supplied to LED becomes as follows (you must
satisfy together a temperature limitation referring to the fig.1).
*Buck- type ･･･ 1.0A
*Boost-type/Buckboost-type ･･･ 0.5A
A calculation example graph is shown as follows (Refer to the fig15－ the fig17).
And, a VF of white-LED for the lighting is prescribed with 3.5V, and calculated with 5pcs series-connection
(Vout=17.6V).
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Page.16
LC5710S DATA SHEET
Rev.1.9
Buck-type Necessary Inductance L calculation example
LED=5pcs series,VIN=24V
Fosc=500kHz
Fosc=300kHz
Fosc=100kHz
Necessary Inductance L(μH)
1000
100
10
1
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Inductor-ripple current ⊿IL(A)
fig.15
Boost-type Necessary Inductance L calculation ezample
LED=5pcs series,VIN=12V
Fosc=500kHz
Fosc=300kHz
Fosc=100kHz
Necessary Inductance L(μH)
1000
100
10
1
0.1
0.15
0.2
0.25
0.3
Inductor-ripple current⊿IL(A)
fig.16
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Page.17
0.35
0.4
LC5710S DATA SHEET
Rev.1.9
Buckboost-type Necessary Inductance L calculation example
LED=5pcs series,VIN=Vout±20%
Fosc=500kHz
Fosc=300kHz
Fosc=100kHz
Necessary Inductance L(μH)
1000
100
10
1
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Inductor-ripple current⊿IL(A)
fig.17
fig15－fig17 Necessary Inductance L calculation example
*FOSC = 100kHz,300kHz,500kHz
*Number of LED = 5pcs series
The value of graph is calculated following the equation in the Table7
Note:
*Necessary inductance value grows big by the setup whose “⊿IL is small”.
As a tendency of characteristics of the Inductor,
・In case of big Inductance value, allowable current limits decrease.
・The contour of Inductor becomes large with the core size when allowable current is satisfied and Inductance is
kept.
As a circuit application of the LED driver, it has Buck-type, Boost-type and Buckboost-type as same as the DC/DC
converter,
As a setup of ⊿IL, generally, it is said that the cost performance of 20%-30 % of the setups of output current is the
best.
When it says easily,”⊿IL=Iout×α(α=0.2 to 0.3)” is best choice.
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Page.18
LC5710S DATA SHEET
Rev.1.9
8.8 The Internal Power Dissipation Pd
8.8.1 The loss Pcont of the control circuit
The loss Pcont of the control circuit depends on the input voltage and frequency. (fig.18) .
The loss of control circuit Pcont (mW)
LC5710S VIN vs. Pcont characteristics
Fosc=100kHz
Fosc=300kHz
Fosc=500kHz
100
90
80
70
60
50
40
30
20
10
0
0
5
10
15
20
25
30
VIN(V)
35
40
45
50
fig.18
The loss of the control circuit is prescribed with containing the steady loss by circuit static electric current Iq and
the drive loss which drives internal PowerMOSFET. A fig.18 is the total of the loss of circuit electric current and
the drive loss. Read near value in the fig.18, and substitute it when you calculate a loss.
8.8.2 The switching-speed of internal PowerMOSFET
As for the fig.19, in the calculation of the switching-time of internal PowerMOSFET, this is based on the
assumption with no influence such as Prasitic-Inductance in main-circuit. It is prescribed with “turn-on time tr” and
“turn-off time tf” being the same speeds.
The switching time(Tsw:tr,tf) (nsec)
LC5710S SW terminal voltage vs. Tsw characteristics
45
40
35
30
25
20
15
10
5
0
0
5
10
15
20
25
30
35
SW terminal voltage Vsw(V)
40
45
50
fig.19
However,actually,The internal PowerMOSFET is connected with the main-circuit of the voltage conversion part.
By the condition of pattern wiring, the switching-speed becomes fast, or becomes slow.
･In case of the pattern which Parasitic-Inductance inheres in, probably it becomes fast.
･In case of the pattern which high-impedance inheres in, probably it becomes slow.
Approve it in advance.
There is no problem if actual measurement value is substituted when an actual movement wave form can be
observed with oscilloscope and so on.
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Page.19
LC5710S DATA SHEET
Rev.1.9
8.8.3 The loss of internal PowerMOSFET .
As the loss of internal-PowerMOSFET, there are the loss of “steady-ON” by the ON-resistance “Ron” between the
“source” and “drain”, and the switching-loss by the switching-time in the fig.19.
Buck-type, Boost-type and Buckboost-type, the loss of PowerMOSFET of each type are shown the approximation
in the Table8.
Table.8
Loss of “Steady-ON” Pon
Switching loss Psw
Buck type
Ron×(ILED)2×Ton×Fosc
2×{VIN×(ILED／2)×Tsw×Fosc}
Boost type
Ron×(ILAVE)2×Ton×Fosc
2×{Vout×(ILAVE／2)×Tsw×Fosc}
Buckboost
type
Ron×(ILAVE)2×Ton×Fosc
2×{(VIN＋Vout)×(ILAVE／2)×Tsw×Fosc}
*
･Ton=(1／Fosc)×D･･･D=Duty (Refer to Table7.)
･Tsw is prescribed by the value (sec) of the figure 19 with “turn-on time tr” and “turn-off time tf” being the
same
speeds. In the same period, switching occurs twice. There is no problem if actual measurement value is
substituted when an actual movement wave form can be observed with oscilloscope and so on.
･Fosc= oscillating frequency (Hz)
･In case of the Buck-type, ILED(A)=ILAVE(A)
･Refer to a Table 7 for ILAVE (A).
･Ron is “ON-resistance(Ω)” of the internal PowerMOSFET, between drain and source.
8.8.4 Power dissipation in the IC, Pd
The internal loss is to follow a equation (9).
Pd=Pcont＋Pon＋Psw
･･･(9)
(Calculation example in the Buck-type)
Conditions:Fosc=300kHz､VIN=24V､LED strings voltage=17.6V(5LEDs)､ILED=1A､Ron=0.5Ω.
･Pcont=44mW (It was referred from fig.16.)
･Pon=0.5(Ω)×1(A)×1(A)×2.444E-6(sec)×300E+3(Hz) ≒0.367W
･Psw=2×{24(V)×(1(A)／2)×20E-9(sec)×300E+3(Hz)} ≒0.144W
∴Pd=0.044(W)＋0.367(W)＋0.144(W) =0.555W
(Calculation example in the Boost-type)
Conditions:Fosc=300kHz､VIN=12V､LED strings voltage=17.6V(5LEDs)､ILED=0.5A､Ron=0.5Ω.
･Pcont=22mW (It was referred from fig.16.)
･Pon=0.5(Ω)×0.73(A)×0.73(A)×1.061E-6(sec)×300E+3(Hz) ≒0.084W
･Psw=2×{17.6(V)×(0.73(A)／2)×15E-9(sec)×300E+3(Hz)} ≒0.057W
∴Pd=0.022(W)＋0.084(W)＋0.057(W) =0.163W
(Calculation example in the Buckboost-type)
Conditions:Fosc=300kHz､VIN=17V､LED strings voltage=17.6V(5LEDs)､ILED=0.5A､Ron=0.5Ω.
･Pcont=33mW (It was referred from fig.16.)
･Pon=0.5(Ω)×1.018(A)×1.018(A)×1.696E-6(sec)×300E+3(Hz) ≒0.264W
･Psw=2×{(17(V)＋17.6(V))×(1.018(A)／2)×28.8E-9(sec)×300E+3(Hz)} ≒0.305W
∴Pd=0.033(W)＋0.264(W)＋0.305(W) =0.602W
Notes:
The thermal resistance θj-a of the package is becomes 82.8(℃／W). Thermal shutdown( protection
function:TSD) may activate by the condition of Pd.
When ambient temperature is defined as “Ta”, Junction temperature “Tj” is shown with a equation (10).
Tj=(Pd×θj-a)＋Ta
･･･(10)
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Page.20
LC5710S DATA SHEET
Rev.1.9
The “ON-resistance” Ron of internal PowerMOSFET has a positive temperature coefficient.
When Tj is nearing 100(℃) , Ron has the possibility to increase about 1.5 times from condition of Tj=25(℃).
*Be careful.
When temperature of the IC is high, you must have the following item reduced.
･Oscillating frequency
･Value of the ILED
･The number of LED serial connection
Or, you must establish the input voltage condition again, you must put Pd within the area of “Thermal Derating
Curve” in the fig.1.
8.9 PHASE COMPENSATION (COMP terminal)
8.9.1 The calculation of the Phase compensation “fixed-number” .
In the page8, the fig.4 of sixth clauses – Typcal application circuit example, as for the Phase-compensation
fixed-number of the COMP terminal connection, “Rs, Cs, Cp”, they are calculated in accordance with the equation
of the Table9.
Table.9
Rs
Cp
Requirement decision
Cs
(←When a left equation satisfies a
condition.) Cp
Rled
Fz2
Fc of the Buck-type
Fc of the Boost-type
*Co : Capacitance of output capacitor (F), Vout : Output voltage (V), Fc : Crossover frequency (Hz), ESR : The
equivalent serial resistance of the output capacitor (Ω), Rled : The resistance when LED was considered a
resistance load (Ω), ILED : Average current of LED (A), Fz2 : The zero point frequency which is characteristic of
Boost-type (Hz) ・・・ This does the function of the zero in the gain-characteristics, and this does the function of
the pole in the phase-compensation. L : Inductance of the main inductor (H), D : Duty (On-period/period of a
cycle), refer to Table5. *Cp is necessary because ESR is big when a output capacitor COUT is aluminum
electrolytic capacitor.
The setup of crossover-frequency Fc is different in the Buck-type and the Boost-type.In this IC, at the case of
Buck-type, Fc is set up in less than 1/50 of Fosc.
But, it has the condition of „a righthalf plane zero‟ in case of Boost-type of the Current-Mode.
Therefore you must calculate Fz2 by the equation of Fz2 of the Table9, and you must set up Crossover-frequency
Fc in less than 1/50 of Fz2.
*” K” is the multiplier which is characteristic of the feedback loop of LC5710S.
K=2.497E-4
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Page.21
LC5710S DATA SHEET
Rev.1.9
8.9.2 Rs,Cs, calculation example (COUT: ceramics capacitor)
Table.10 Buck-type ,Fosc=500kHz, ILED=1A, ⊿IL=0.4A
Number
Inductance
Co total
of LED
Vout(V)
VIN(V)
L
capacitance(
serial
connection
1
2
3
4
5
6
7
8
9
10
3.6
7.1
10.6
14.1
17.6
21.1
24.6
28.1
31.6
35.1
5
12
15
18
24
28
36
42
42
48
Co total
ESR
(μ H)
μ F)
(mΩ )
5.6
15
18
18
27
27
39
39
43
47
1
1
1
1
1
1
1
1
1
1
10
10
10
10
10
10
10
10
10
10
Fc(kHz)
Rs(kΩ )
Cs(nF)
10
10
10
10
10
10
10
10
10
10
0.91
1.79
2.67
3.55
4.43
5.31
6.19
7.07
7.95
8.83
70.348
35.669
23.892
17.961
14.389
12.002
10.294
9.012
8.014
7.215
*The numerical value in the table shows value in calculation.
*Select a part from the near fixed-number , because numerical value doesn‟t agree completely in the geometric
progression such as E12 series and E24 series.
* Decide a fixed-number after you surely confirm a movement in the experiment.
*The capacity of Cout and ESR are the expressions of „the total‟. When Ceramics capacitor of the little size more
than one are connected in parallel , it is shown that it becomes the numerical value of the table in the total.
*Table13 and Table17 are the same situations,too.
Table.11 Buck-type, Fosc=300kHz, ILED=1A, ⊿IL=0.4A
Number
Inductance
Co total
of LED
Vout(V)
VIN(V)
L
capacitance(
serial
connection
1
2
3
4
5
6
7
8
9
10
3.6
7.1
10.6
14.1
17.6
21.1
24.6
28.1
31.6
35.1
5
12
15
18
24
28
36
42
42
48
1
2
3
4
5
6
7
3.6
7.1
10.6
14.1
17.6
21.1
24.6
5
12
15
18
24
28
36
Fc(kHz)
Rs(kΩ )
Cs(nF)
10
10
10
10
10
10
10
10
10
10
6
6
6
6
6
6
6
6
6
6
2.55
5.04
7.52
10.00
12.48
14.96
17.45
19.93
22.41
24.89
41.577
21.081
14.120
10.615
8.504
7.093
6.084
5.326
4.736
4.264
Co total
ESR
Fc(kHz)
Rs(kΩ )
Cs(nF)
2
2
2
2
2
2
2
1.81
3.57
5.33
7.09
8.85
10.61
12.37
175.872
89.174
59.730
44.903
35.973
30.006
25.737
(μ H)
μ F)
(mΩ )
9.1
27
27
27
43
47
68
82
68
82
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
Table.12 Buck-type, Fosc=100kHz, ILED=1A, ⊿IL=0.4A
Number
Inductance
Co total
of LED
Vout(V)
VIN(V)
L
capacitance(
serial
connection
Co total
ESR
(μ H)
μ F)
(mΩ )
27
75
82
82
120
150
200
10
10
10
10
10
10
10
10
10
10
10
10
10
10
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Page.22
LC5710S DATA SHEET
8
9
10
28.1
31.6
35.1
42
42
48
270
200
270
Rev.1.9
10
10
10
Table.13 Boost-type, Fosc=500kHz, ILED=0.5A, ⊿IL=0.4A
Number
Inductance
Co total
of LED
Vout(V)
VIN(V)
L
capacitance(
serial
connection
2
3
3
4
4
5
6
6
7
7
7
8
8
9
10
7.1
10.6
10.6
14.1
14.1
17.6
21.1
21.1
24.6
24.6
24.6
28.1
28.1
31.6
35.1
5
5
7
7
9
12
12
15
12
15
18
15
18
18
24
2
3
3
4
4
5
6
6
7
7
7
8
8
9
10
7.1
10.6
10.6
14.1
14.1
17.6
21.1
21.1
24.6
24.6
24.6
28.1
28.1
31.6
35.1
5
5
7
7
9
12
12
15
12
15
18
15
18
18
24
2
3
7.1
10.6
5
5
14.13
15.89
17.66
22.531
20.036
18.038
Co total
ESR
Fc(kHz)
Rs(kΩ )
Cs(μ F)
μ F)
(mΩ )
7.5
15
12
18
18
20
27
22
33
33
27
36
33
39
39
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
2.990
1.001
2.454
1.230
2.033
2.606
1.610
3.087
1.130
1.765
3.107
1.417
2.225
1.675
2.680
0.53
0.27
0.65
0.44
0.72
1.15
0.85
1.64
0.70
1.09
1.92
1.00
1.57
1.33
2.37
0.398
2.382
0.396
1.187
0.434
0.211
0.463
0.125
0.806
0.330
0.106
0.449
0.181
0.285
0.100
Co total
ESR
Fc(kHz)
Rs(kΩ )
Cs(μ F)
(μ H)
F)
(mΩ )
15
22
20
33
27
33
43
36
51
51
43
62
56
68
68
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
1.495
0.683
1.472
0.671
1.355
1.579
1.011
1.887
0.731
1.142
1.951
0.823
1.311
0.96
1.537
1.25
0.86
1.84
1.12
2.26
3.29
2.52
4.71
2.13
3.32
5.67
2.73
4.36
3.59
6.38
0.339
1.090
0.234
0.849
0.208
0.122
0.249
0.071
0.409
0.167
0.057
0.283
0.111
0.184
0.064
Co total
ESR
Fc(kHz)
Rs(kΩ )
Cs(μ F)
0.575
0.221
1.03
0.59
1.078
4.895
Table.15 Boost-type, Fosc=100kHz, ILED=0.5A, ⊿IL=0.4A
Number
Inductance
Co total
of LED
Vout(V)
VIN(V)
L
capacitance(
serial
connection
2
2
2
(μ H)
Table.14 Boost-type, Fosc=300kHz, ILED=0.5A, ⊿IL=0.4A
Number
Inductance
Co total
of LED
Vout(V)
VIN(V)
L
capacitance(μ
serial
connection
10
10
10
(μ H)
μ F)
(mΩ )
39
68
10
10
10
10
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Page.23
LC5710S DATA SHEET
3
4
4
5
6
6
7
7
7
8
8
9
10
10.6
14.1
14.1
17.6
21.1
21.1
24.6
24.6
24.6
28.1
28.1
31.6
35.1
7
7
9
12
12
15
12
15
18
15
18
18
24
62
91
82
100
150
120
180
150
120
180
180
200
200
Rev.1.9
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
0.475
0.243
0.446
0.521
0.290
0.566
0.207
0.388
0.699
0.283
0.408
0.327
0.523
1.27
0.86
1.58
2.31
1.54
3.00
1.28
2.40
4.33
2.00
2.88
2.6
4.61
1.059
3.035
0.902
0.529
1.429
0.374
2.399
0.682
0.210
1.122
0.541
0.751
0.264
*In theBuckboost-type, Relations between “Duty D” and the movement mode are as the following.
D＞0.5：Boost mode
D＜0.5：Buck mode
Referring to the Table10 – the Table15, adjust compensation value in accordance with the condition of the use,
under the actual movement .
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Page.24
LC5710S DATA SHEET
Rev.1.9
8.10 LED Cross-Connection Protection Function
fig.20-1 The normal connection of LED
fig.20-2 Mis-wiring (Cross-connection)
With the application when each-string of LED-ASSY is driven by using LC5710S for the plural,
against the normal connection of the fig20-1, by mis-wiring of the connector part which connects harness to
LED-ASSY and so on,
it may become a connection like a fig20-2. This is prescribed as “Cross-connection”.
“LED Cross-connection protection function” is built in the LC5710S to avoid the saturation of Inductor and the
damage, by the heat-generation when the over-load condition with “Cross-connection”.
In the LC5710S, in case of the above-mentioned “Cross-connection”,the “watch-dog-timer (30msec : typ)”
watches the decline of VCS (CSP-CSN voltage) and rise in the COMP terminal voltage.
When the same condition goes on beyond 30msec, movement of LC5710S becomes the burst-mode, and it is
possible that the heat-generation is restrained.
When it is seen from LC5710S, because “Cross-connection” is the persistently abnormal condition of the
peripheral circuit.
Even if “Cross-connection protection” activates as well as the “thermal protection”, a stress may be given to the
peripheral part and IC itself, and so on.
This condition isn‟t assured for a long time because a user recognizes mis-wiring and it is the protection which is
the simple target until wiring is amended.
Be careful.
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Page.25
LC5710S DATA SHEET
Rev.1.9
8.11 Peripheral Parts Design
Take care to use properly rated and proper type of components.
The following circuit symbols refer to “6. Typical Application Circuit”. In page.9.
Inductor L
This is a choke coil for smoothing LED current.
When the 26illimeter is larger, the output ripple current is smaller, and the current stability is improved.
In actual operation, it should be considered so that the coil is not saturated by the peak of ripple current.
If the coil is saturated, the surge current beyond expectations flows. Thus LED, IC and peripheral circuit will be
damaged.
Diode DS
This is a free-wheel diode for Buck converter, and this is a boost diode for Boost and Buck-Boost converter.
For diode selection, the withstanding voltage and the recovery time (trr) are important. In case that diode with a
long trr is used, the large surge current flows into power MOSFET when power MOSFET turns on. Thus, it may
cause noise increasing, malfunction and efficiency decreasing.
It is recommended to choose from Schottky barrier diode and Ultra-fast diode according to the withstanding
voltage.
Current detection resistor RCS
If the current detection resistor with high inductance is used, it may cause malfunctioning because of the high
frequency current flowing through it.
It is recommended to choose a low equivalent series inductance and high surge tolerant type for the current
detection resistor.
Input capacitor CIN
This is a smoothing capacitor for main power supply. When the capacitance is larger, the ripple voltage is smaller.
It is recommended to choose the capacitance according to the output power because the ripple voltage becomes
bigger when the output power increases even if the same capacitance.
Output capacitor COUT
By the ipple current specification of LED string, it is recommended to determine whether COUT is needed or not, or
to determine the capacitance value.
If large ripple current can be set, the inductance of L can be smaller, the COUT capacitance can be smaller or the
COUT can be removed. Thus, the power supply will be downsized and reduced the cost.
If the small ripple current is set, the inductance of L is increased or COUT is connected in parallel with LED string.
Thus, the heat generation of LED string, which is caused by ripple current variation, can be reduced.
In addition, if LED string is far from the output edge of power supply, COUT is connected close to LED string in
parallel so that the ripple voltage and ripple current can be reduced.
Phase compensation network CP, CS, RS
These are the “phase compensation parts” of a control-loop to connect to the COMP terminal. Connect the GND
side of the “phase compensation parts” to GND Pin of the IC at shortest wiring. When it is far from GND of the
IC,
noise appears in the COMP terminal by the influence such as parasitic-inductance of the pattern, and the faulty
operation occurs often. Be careful.
Setup resistor (RRT) of oscillating frequency
The oscillating-frequency of LC5710S is possible to adjust between 100kHz and 500kHz by the connection of R RT.
Connect the GND side of the frequency-setup-resistor RRT to GND Pin of the IC at shortest wiring.
This is to avoid the unstable movement of the IC by the influence of the noise.
Copy Right: SANKEN ELECTRIC CO., LTD.
Page.26
LC5710S DATA SHEET
Rev.1.9
8.12 Reference Design Example
4) Buck-type
Fosc=300kHz
ILED=500mA
Inductor ripple current ⊿IL=0.4A
Number of LED=5LEDs(Vout=17.6V)
VIN=24V
Vsw=24V
Cout(ESR)=10mΩ/ceramics capacitor
Cp(C4)：Open
*SJPB-L6 being used as the D1 is
manufactured by "Sanken-electric Co".
(B)Boost-type
Fosc=300kHz
ILED=500mA
Inductor ripple current ⊿IL=0.4A
Number of LED=7LEDs(Vout=24.6V)
VIN=12V
Vsw=24.6V
Cout(ESR)=10mΩ/ ceramics capacitor
Cp(C4)：Open
*SJPB-L6 being used as the D1 is
manufactured by "Sanken-electric Co".
IBuckboost-type
Fosc=300kHz
ILED=500mA
Inductor ripple current ⊿IL=0.4A
Number of LED=5LEDs(Vout=17.6V)
VIN=12V～18V
Vsw=29.6V～35.6V
Cout(ESR)=10mΩ/ ceramics capacitor
Cp(C4)：Open
*SJPB-L6 being used as the D1 is
manufactured by "Sanken-electric Co".
*The above reference design example is only a guide. Decide the fixed-number on your circuit board after you
confirm a movement in the actual working,experiment adjustment.
Fig.21 (a) – (c)Reference design example
Copy Right: SANKEN ELECTRIC CO., LTD.
Page.27
LC5710S DATA SHEET
Rev.1.9
9. Example Pattern Layout
For the LC5710S,the LC5711S and the LC5720S, the circuit board pattern of demonstration-board
by our company is shown in the following.
9.1
manufactured
pattern layout
For Buck-type (parts mounting side)
For Buck-type(back side)
For Boost-type/Buckboost-type
(parts mounting side)
For Boost-type/Buckboost-type(back side)
fig.22 Demo-board pattern layout
9.1.1 Foot print drawing
fig.23 Footprint drawing
for LC5710S
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Page.28
LC5710S DATA SHEET
Rev.1.9
9.2 Circuit diagram of Demonstration-Board
9.2.1
For Buck-type
J1
fig.24
*LC5710S/LC5720S : R5 and R6 must be open. Jumper-J1 must be inserted. C7 and R7 are used only with LC5710S.
9.2.2
For Boost-type and Buckboost-type
J2
J1
fig.25
*The setup of Jumper
For Boost-type:
J1= Insert, J2= Open
For Buckboost-type: J1= Open, J2= Insert
* C7 and R7 are used only with LC5710S.
Copy Right: SANKEN ELECTRIC CO., LTD.
Page.29
LC5710S DATA SHEET
Rev.1.9
10. Design Considerations
10.1Trace and Component Layout Design
PCB circuit trace design and component layout affect IC functioning during operation. Unless they are proper,
malfunction, significant noise, and large power dissipation may occur.
Circuit loop traces flowing high frequency current, as shown in fig.26, should be designed as wide and short as
possible to reduce trace impedance.
In addition, earth ground traces affect radiation noise, and thusshould be designed as wide and short as possible.
Switching mode power supplies consist of current traces with high frequency and high voltage, and thus trace design
and component layout should be done in compliance with all safety guidelines.
Furthermore, because an integrated power MOSFET is being used as the switching device, take account of the
positive thermal coefficient of RDS(ON) for thermal design.
(B)Boost-type
(A)Buck-type
(C)Buckboost-type
fig.26 High frequency current loops（hatched portion）
Fig.26 shows practical trace design examples and considerations. In addition, observe the following:
IC peripheral circuit
(1) Main Circuit Traces
Main circuit traces carry the switching current; therefore, widen and shorten them as much as possible.
The loop formed with CIN, VIN pin, and GND pin should be small in order to reduce the inductances of the
traces against high frequency current.
1) Traces around GND pin
Main circuit GND and Control circuit GND should be connected to the vicinity of GND pin with dedicated
traces respectively, in order to avoid interference of the switching current with the control circuit.
1) Traces around the current detection resistor, RCS
The traces of RCS should be connected to CSP pin and CSN pin with dedicated traces respectively, in order to
reduce noises when the current is detected. When the noise between CSP and CSN is high, a filter capacitor
Cf can be added like a “Page9, sixth clauses-application circuit example”,too.
(4)Peripheral components
The components for phase compensation such as C P, CS, RS should be connected close to COMP pin and
GND pin. Also,frequency-setup-resistor RRT should be connected close to RT pin and GND pin.
(5) When COUT is used, it should be connected close to LED string.
* As for the GND pattern, be careful that routes for the Main-circuit(switching current flows), and the routes for
the small-signal don‟t become common impedance.
Copy Right: SANKEN ELECTRIC CO., LTD.
Page.30
LC5710S DATA SHEET
Rev.1.9
5) Buck-type
If it is possible,in each type,the GND for Main-circut and
the GND for small-signal should be separated as the
starting point to the GND pin of the IC. It is recommended
to separate the GND of "dimming-signal" and GND of
"Main-circuit",too.
*A Bold line is a main-circuit.
(B)Boost-type
Ibuckboost-type
fig.27 The trace of the pattern
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Page.31
LC5710S DATA SHEET
Rev.1.9
11. Typical characteristics (Ta=25℃)
11.1 Efficiency
fig.28-1 Buck-mode
ILED=1.0A L=220uH
FOSC=100kHz
fig.28-2 Buck-mode
ILED=1.0A L=47uH
FOSC=500kHz
fig.28-3 Buck-mode
ILED=0.5A L=220uH
FOSC=100kHz
Copy Right: SANKEN ELECTRIC CO., LTD.
Page.32
LC5710S DATA SHEET
Rev.1.9
fig.28-4 Buck-mode
ILED=0.5A L=47uH
FOSC=500kHz
fig.28-5 Boost-mode
ILED=0.5A L=100uH
FOSC=100kHz
fig.28-6 Boost-mode
ILED=0.5A L=22uH
FOSC=500kHz
Copy Right: SANKEN ELECTRIC CO., LTD.
Page.33
LC5710S DATA SHEET
Rev.1.9
fig.28-7 Buckboost-mode
ILED=0.5A L=100uH
FOSC=100kHz
fig.28-8 Buckboost-mode
ILED=0.5A L=22uH
FOSC=500kHz
11.2 UVLO (Under Voltage Lock Out)
fig.28-9 Buck-mode
5LEDs ILED=0.5A
UVLO
Stop→
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←Startup
Page.34
LC5710S DATA SHEET
Rev.1.9
11.3 Switching Frequency Settings
fig.28-10 RRT Resistance
vs. Switching Frequency
11.4 Digital Dimming characteristics
fig.28-11 Dimming
Frequency=1kHz,
Duty vs. ILED
11.5 Analogue Dimming characteristics
fig.28-12 DIM Voltage
VDIM vs. ILED
Copy Right: SANKEN ELECTRIC CO., LTD.
Page.35
LC5710S DATA SHEET
Rev.1.9
11.6 CS Threshould voltage Temperature characteristics
fig.28-13 VCS vs. Ta
11.7 CS Threshould voltage VIN Regulation (5LEDs)
fig.28-14 VCS vs. VIN
11.8 TSD (Thermal Shut Down)
fig.28-15 VCS vs. Ta at
TSD(VIN=24V,5LEDs,
ILED=10mA)
Copy Right: SANKEN ELECTRIC CO., LTD.
Page.36
←Shut Down
Restart →
←Normal→
LC5710S DATA SHEET
Rev.1.9
11.9 Supply Current IIN(ON)
fig.28-16 IIN(ON) vs. VIN
(RDIM=120kΩ)
11.10Supply Current IIN(OFF)
fig.28-17 Input Supply
Current IIN(OFF) vs.VIN
(VDIM=0V)
11.11 Waveform of Digital Dimming (1kHz／Duty=5%)
VDIM
fig.28-18 PWM Dimming
Duty=5%,VDIM,VSW,ILED
(1kHz)
VSW
VDIM：2V/Div
VSW：10V/Div
ILED：500mA/Div
Time：1msec/Div
ILED
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Page.37
LC5710S DATA SHEET
Rev.1.9
11.12 Waveform of Digital Dimming (1kHz／Duty=5%)
VDIM
fig.28-19 PWM Dimming
Duty=50%,VDIM,VSW,ILED
(1kHz)
VDIM：2V/Div
VSW：10V/Div
ILED：500mA/Div
Time：1msec/Div
VSW
ILED
11.13 Steady state operation Buck-mode VIN=30V,5LEDs,Fosc=100kHz
fig.28-20 Buck-mode
CH1：VSW：20V/Div
CH2：VIN：10V/Div
CH4：ILED：200mA/Div
Time：5μS/Div
ILED
VIN
VSW
11.14 Steady state operation Buck-mode VIN=30V,5LEDs,Fosc=500kHz
fig.28-21 Buck-mode
CH1：VSW：20V/Div
CH2：VIN：10V/Div
CH4：ILED：200mA/Div
Time：5μS/Div
ILED
VIN
VSW
Copy Right: SANKEN ELECTRIC CO., LTD.
Page.38
LC5710S DATA SHEET
Rev.1.9
11.15 Steady state Operation Boost-mode VIN=15V,5LEDs,Fosc=100kHz
fig.28-22 Boost-mode
ILED
CH1：VSW：10V/Div
CH2：VIN：10V/Div
CH4：ILED：200mA/Div
Time：5μS/Div
VIN
VSW
11.16 Steady state operation Boost-mode VIN=15V,5LEDs,Fosc=500kHz
fig.28-23 Boost-mode
ILED
CH1：VSW：10V/Div
CH2：VIN：10V/Div
CH4：ILED：200mA/Div
Time：5μS/Div
VIN
VSW
11.17 Steady state operation Buck-boost-mode VIN=20V,5LEDs,Fosc=100kHz
ILED
fig.28-24
Buck-boost-mode
CH1：VSW：10V/Div
CH2：VIN：10V/Div
CH4：ILED：200mA/Div
Time：5μS/Div
VIN
VSW
Copy Right: SANKEN ELECTRIC CO., LTD.
Page.39
LC5710S DATA SHEET
Rev.1.9
11.18 Steady state operation Buck-boost-mode VIN=20V,5LEDs,Fosc=500kHz
fig.28-25
Buck-boost-mode
ILED
CH1：VSW：10V/Div
CH2：VIN：10V/Div
CH4：ILED：200mA/Div
Time：5μS/Div
VIN
VSW
Copy Right: SANKEN ELECTRIC CO., LTD.
Page.40
LC5710S DATA SHEET
Rev.1.9
12. Packing specifications
12.1 Taping & Reel outline
Pocket
5.55
12.0
φ1.55
5.5
0.3
1.75
Round
Sprocket
Holes
φ2.05
6.7
2.47
8.0
4.0
EIAJ No.TE1208
2.0
fig. 29 Taping outline
Notes:
1) All dimensions in 41illimeters
2) Surface resistance：under 109Ω
3) Drawing is not to scale
Notes:
1) All dimensions in
millimeters
2) Drawing is not to
scale.
φ13
±0.2
EIAJ No.RRM-12DC
13.5 ±0.5
17.5 ±1.0
fig. 30 Reel outline
Copy Right: SANKEN ELECTRIC CO., LTD.
φ330±2
±0.8
φ80±1
φ21
Page.41
Quantity
4000pcs／reel
LC5710S DATA SHEET
Rev.1.9
IMPORTANT NOTES
●All data, illustrations, graphs, tables and any other information included in this document as to Sanken’s products
listed herein (the “Sanken Products”) are current as of the date this document is issued. All contents in this document
are subject to any change without notice due to improvement, etc. Please make sure that the contents set forth in this
document reflect the latest revisions before use.
●The Sanken Products are intended for use as components of general purpose electronic equipment or apparatus (such
as home appliances, office equipment, telecommunication equipment, measuring equipment, etc.). Prior to use of the
Sanken Products, please put your signature, or affix your name and seal, on the specification documents of the Sanken
Products and return them to Sanken. If considering use of the Sanken Products for any applications that require higher
reliability (transportation equipment and its control systems, traffic signal control systems or equipment,
disaster/crime alarm systems, various safety devices, etc.), you must contact a Sanken sales representative to discuss
the suitability of such use and put your signature, or affix your name and seal, on the specification documents of the
Sanken Products and return them to Sanken, prior to the use of the Sanken Products. Any use of the Sanken Products
without the prior written consent of Sanken in any applications where extremely high reliability is required (aerospace
equipment, nuclear power control systems, life support systems, etc.) is strictly prohibited.
●In the event of using the Sanken Products by either (i) combining other products or materials therewith or (ii)
physically, chemically or otherwise processing or treating the same, you must duly consider all possible risks that
may result from all such uses in advance and proceed therewith at your own responsibility.
●Although Sanken is making efforts to enhance the quality and reliability of its products, it is impossible to completely
avoid the occurrence of any failure or defect in semiconductor products at a certain rate. You must take, at your own
responsibility, preventative measures including using a sufficient safety design and confirming safety of any
equipment or systems in/for which the Sanken Products are used, upon due consideration of a failure occurrence rate
or derating, etc., in order not to cause any human injury or death, fire accident or social harm which may result from
any failure or malfunction of the Sanken Products. Please refer to the relevant specification documents and Sanken‟s
official website in relation to derating.
●No anti-radioactive ray design has been adopted for the Sanken Products.
●No contents in this document can be transcribed or copied without Sanken’s prior written consent.
●The circuit constant, operation examples, circuit examples, pattern layout examples, design examples, recommended
examples and evaluation results based thereon, etc., described in this document are presented for the sole purpose of
reference of use of the Sanken Products and Sanken assumes no responsibility whatsoever for any and all damages
and losses that may be suffered by you, users or any third party, or any possible infringement of any and all property
rights including intellectual property rights and any other rights of you, users or any third party, resulting from the
foregoing.
●All technical information described in this document (the “Technical Information”) is presented for the sole purpose
of reference of use of the Sanken Products and no license, express, implied or otherwise, is granted hereby under any
intellectual property rights or any other rights of Sanken.
●Unless otherwise agreed in writing between Sanken and you, Sanken makes no warranty of any kind, whether express
or implied, as to the quality of the Sanken Products (including the merchantability, or fitness for a particular purpose
or a special environment thereof), and any information contained in this document (including its accuracy, usefulness,
or reliability).
●In the event of using the Sanken Products, you must use the same after carefully examining all applicable
environmental laws and regulations that regulate the inclusion or use of any particular controlled substances,
including, but not limited to, the EU RoHS Directive, so as to be in strict compliance with such applicable laws and
regulations.
●You must not use the Sanken Products or the Technical Information for the purpose of any military applications or use,
including but not limited to the development of weapons of mass destruction. In the event of exporting the Sanken
Products or the Technical Information, or providing them for non-residents, you must comply with all applicable
export control laws and regulations in each country including the U.S. Export Administration Regulations (EAR) and
the Foreign Exchange and Foreign Trade Act of Japan, and follow the procedures required by such applicable laws
and regulations.
●Sanken assumes no responsibility for any troubles, which may occur during the transportation of the Sanken Products
including the falling thereof, out of Sanken’s distribution network.
●Although Sanken has prepared this document with its due care to pursue the accuracy thereof, Sanken does not
warrant that it is error free and Sanken assumes no liability whatsoever for any and all damages and losses which may
be suffered by you resulting from any possible errors or omissions in connection with the contents included herein.
●Please refer to the relevant specification documents in relation to particular precautions when using the Sanken
Products, and refer to our official website in relation to general instructions and directions for using the Sanken
Products.
Copy Right: SANKEN ELECTRIC CO., LTD.
Page.42