Semiconductor
http:// www.auk.co.kr
SN8500D
Switching Type (Buck) LED Driver IC
◈
Description
The SN8500D is a high power PWM LED driver IC using a buck converter topology that is capable of driving up
to 1.5A of output current. it operates from an input voltage range of
current to single LED or a LED string.
3Vdc to 40Vdc and generates a regulated
programmable constant output current for high power LEDs. external resistor controlled the maximum output
◈
Features
•
Operation from 3.0V to 40V input.
•
Low Standby Current
•
High efficiency
•
Output Switch Current to 1.5A
•
Halogen-Free Package is Available
◈
Application
•
Automotive and Marine Lighting
•
High Power LED Driver
•
Constant Current Source
◈
Pin Assignment & Description (Top View)
OSC
OUT
GND
CS
VCC
Package : TO-252-5L
5
4
3
2
1
Pin
1
2
3
4
5
Symbol
VCC
CS
GND
OUT
OSC
Description
Input Voltage
Peak Current Sense Pin
Ground
Output Pin
Oscillator Timing pin
◈
Ordering Information
Package Type
TO-252-5L
(1) Device Code, (2) Year & Week Code
Device Name
SN8500D
Marking
SN8500---(1)
YYWW---(2)
KSD-I6T002-000
1
SN8500D
◈
Absolute maximum ratings
Characteristic
Power Supply Voltage
Output Current
Thermal Resistance Junction-Ambient
Power Dissipation
Operating Temperature Range
Storage Temperature Range
[Ta=25℃]
Symbol
V
CC(MAX)
I
OUT(MAX)
Rth(j-a)*
P
D
*
T
opr
T
stg
Rating
40
1.5
96.1
1.3
-40 ~ +85
-55 ~ +150
Unit
V
A
℃/W
W
℃
℃
* Mounted on a glass epoxy circuit board of 30x30mm Pad dimension of 50mm
2
◈
Recommended operating conditions
Characteristic
Power Supply Voltage
Output Current
Dimming Frequency
Symbol
V
CC
I
OUT
F
DIM
Rating
Min
7
-
-
Max
40
1.5
10
Unit
V
A
kHz
◈
Electrical Characteristics (Ta=25
℃
, unless otherwise noted.)
Characteristic
Supply Current 1
Supply Current 2
Dropout Voltage
Current Sense Voltage
Maximum duty cycle
Current Sense Off Current
OSC ON Voltage
OSC OFF Voltage
OSC Charge Current
OSC Discharge Current
Symbol
I
CC1
I
CC2
Vdrop
V
CS
T
DC
I
CS(OFF)
V
OSC
(on)
V
OSC
(off)
I
CH
I
DCH
Condition
V
CC
=4V, Out=open
V
CC
=40V, Out=open
V
CC
=10V, Iout=1A
V
CC
=10V, Rout=820kΩ
-
V
CC
=40V, V
OSC
=1.5V
V
CC
=4V~40V
V
CC
=4V~40V
Vcc=5V, V
OSC
=0.5V
Vcc=5V, V
OSC
=1.5V
Min. Typ. Max. Unit
-
-
-
270
-
-
-
1.5
24
140
2.0
2.0
1
300
85
200
-
-
35
180
4.0
4.0
1.3
330
-
1000
0.5
-
42
260
mA
mA
V
mV
%
µA
V
V
µA
µA
KSD-I6T002-000
2
S8500D
◈
Functional block diagram
OUT
CS
-
+
0.3V
VCC
CONTROL
Driver
OSC
OSC
SN8500
GND
◈
Typical Application
L
CS
R
SENSE
OUT
Supply Voltage
7~40V
SN8500
VCC
D
F
Power LED
OSC
C
IN
GND
+
C
T
KSD-I6T002-000
3
SN8500D
◈
Application Information
1) Input Capacitor
The input capacitor (C
IN
) reduces the ripple of the input current drawn from the input supply
and reduces noise injection into the IC. The reflected ripple voltage will be smaller when an
input capacitor with larger capacitance is used. The capacitors should be placed close to the
V
CC
and GND.
2) Current-Sense Resistor
The snese resistor Rsense can be obtained as follows
Rsense = 300mV / (I
AVG
+ 0.5
x
I
RIPPLE
)
Thus target average LED current 700mA and ripple current 100mA then the result
Rsense= 300mV/ (700mA + 0.5
x
100mA) = 0.4Ω
When selecting the sense resistor, low–inductance resistors, such as surface–mount metal
film resistors, are preferred.
3) Output inductor
The value of the inductor is not fixed and can be adjusted freely in order to make tradeoffs
among size, cost, and efficiency. Although lower inductor values will minimize size and cost,
they will also reduce efficiency due to higher peak currents. On the other hand, higher
inductor values will increase efficiency, but at some point the resistive losses due to the extra
turns of wire will exceed the benefit gained from lower AC current levels. Also, high
inductor values can affect the load–transient response of the converter.
4) Freewheeling diode
The schottky barrier diode SDB30A40(40V, 3A) was recommended for freewheeling diode
KSD-I6T002-000
4
SN8500D
◈
Application Guide
L=220uH
CS
R
SENSE
OUT
Supply Voltage
7~40V
SN8500
VCC
OSC
D
F
(SDB30A40)
Power LED x n
C
IN
=47uF
GND
+
C
T
=470pF
<Application 1. Constant Current Power LED Driver Circuit in Series>
L=220uH
CS
R
SENSE
OUT
Supply Voltage
7~40V
SN8500
VCC
OSC
D
F
(SDB30A40)
Power LED x n
C
IN
=47uF
GND
+
C
T
=470pF
<Application 2. Constant Current Power LED Driver Circuit in Parallel>
KSD-I6T002-000
5
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