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PDF ADT6780 Data sheet ( Hoja de datos )
| Número de pieza | ADT6780 | |
| Descripción | Thermally enhanced Low VFB Step-Down LED Driver (EN) | |
| Fabricantes | ADTECH | |
| Logotipo |  |
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Thermally enhanced Low VFB Step-Down LED Driver
ADT6780
Thermally enhanced
Low VFB Step-Down LED Driver
ADT6780
General Description
The ADT6780 is a thermally enhanced current mode step down LED driver. That is designed
to deliver constant current to high power LEDs. The device is suitable for various high power
LED application due to the wide operating range(VIN 4.5V~28V) and high output
capability(continuous 2A). with a very low feedback voltage(VFB=0.2V) power dissipation can
be minimized. Fault condition protection includes cycle-by-cycle current limiting and thermal
shutdown.
The package is available in a standard SOP8-PP(with Exposed pad) package.
Features
• Feedback reference voltage : 0.2V
• Current mode buck LED driver with 925kHz
fixed frequency
• Input voltage range : 4.5V to 28V
• Continuous output current : 2A
• Up to 93% efficiency
• Integrated Power MOSFET switch : 80mΩ
• 10㎂ shutdown mode
• Thermal shutdown & current limit protection
• Under Voltage LOckout
www.DataSheet.net/
Applications
• High power LED/IR-LED Lighting
• Automotive and Marine Lighting
• Architecture Lighting
• General Lighting Solutions
Typical Application Circuit
C5
1 BST
SW 3
VIN
EN
2 VIN
C1 U1
FB 5
7 EN
COMP 6
8 SS
C4
4
GND
L1
D1
C2
D2
R1
C3
R2 C6
OPTION
Jul. 12. 2012 / Preliminary
Figure 1. Typical Application Circuit
* This specifications are subject to be changed without notice
1/13
VOUT
http://www.ad-tech.co.kr
Datasheet pdf - http://www.DataSheet4U.co.kr/
1 page  
Thermally enhanced Low VFB Step-Down LED Driver
ADT6780
Typical Operating Characteristics
VIN=12V, Load : 1A / one 4W White LED and Ta=25℃, unless otherwise noted
Efficiency
100%
95% VIN=6V
90%
85% VIN=12V
80% VIN=24V
75%
70%
65%
60%
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
LED Current (A)
1
VSW
10V/div
VOUT(AC)
20mV/div
IINDUCTOR
0.5A/div
Steady State Operation
1㎲/div
VFB vs Die Temperature
0.216
0.212
0.208
0.204
0.200
0.196
0.192
0.188
0.184
-40 -20
0 20 40 60 80 100 120
Temperature (℃)
Output Short
Switching Frequency vs Die Temperature
1050
1000
950
www.DataSheet.net/
900
850
800
750
-40 -20
0 20 40 60 80 100 120
Temperature (℃)
Peak Current vs Duty
4.0
VOUT
2V/div
3.5
3.0
VSW
10V/div
IINDUCTOR
2A/div
2.5
2.0
1.5
Jul. 12. 2012 / Preliminary
4㎲/div
1.0
0
20 40
60 80 100
Duty (%)
* This specifications are subject to be changed without notice
5/13 http://www.ad-tech.co.kr
Datasheet pdf - http://www.DataSheet4U.co.kr/
5 Page 
Thermally enhanced Low VFB Step-Down LED Driver
ADT6780
APPLICATION INFORMATION (continued)
Table1 and Table2 list the typical values of compensation components and external components for general
applications.
Table 1. Components values for IRLED application (Refer to the Typical Application Circuit, for other components.)
VIN (V) # of series IRLEDs
12 1 ~ 5
VOUTMAX (V)
10
R2 (㏀)
2
C3 (㎋)
8.2
C6 (㎊)
None
L1 (uH)
6.8 ~ 10
C2 (㎌)
10
24 1 ~ 8
16
2
8.2
None 15 ~ 22
10
Table 2. Components values for WLED application (Refer to the Typical Application Circuit, for other components.)
VIN (V)
12
24
# of series WLEDs
1~2
1~4
VOUTMAX (V)
8
16
R2 (㏀)
2
2
C3 (㎋)
8.2
8.2
C6 (㎊)
None
None
L1 (uH)
6.8 ~ 10
15 ~ 22
C2 (㎌)
10
10
The output voltage is calculated by the below equation.
VOUT = n × VF + VFB
Where, n is the number of LEDs connected in series, VF is the forward voltage of the LED and VFB is the
voltage drop across the current sense resistor.
A general procedure to choose the compensation componentswww.DataSheet.net/ for conditions is following:
1. Select the desired crossover frequency. Set the crossover frequency to be equal or less than 1/10 of
switching frequency.
2. Select R2 (compensation resistor) to operate the desired crossover frequency in a given condition. R2
value is calculated by the following equation:
R2
=
2π × FC × C2 × R LED
GEA × GCS × R1
3. Select C3 (compensation capacitor) to achieve the desired loop phase margin. C3 determines the desired
first system zero, fZ1. Typically, set fZ1 below 1/4 of the Fc to provides sufficient phase margin. C3 value is
calculated by:
C3
≥
2π
×
4
FC
×
R2
4. If the ESR output zero (fZ2) is located at less than one-half the switching frequency, use the (optional)
secondary compensation capacitor (C6) to cancel it. As fP3=fZ2, then:
C6
=
C2
× ESR
R2
Jul. 12. 2012 / Preliminary
* This specifications are subject to be changed without notice
11/13
http://www.ad-tech.co.kr
Datasheet pdf - http://www.DataSheet4U.co.kr/
11 Page | ||
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| PDF Descargar | [ Datasheet ADT6780.PDF ] | |
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