Diodes ZXLD1374 - Manual (Page 37)

ZXLD1374
Document number: DS35032 Rev. 3 - 2
37 of 39
www.diodes.com
September 2012
© Diodes Incorporated
ZXLD1374
A Product Line of
Diodes Incorporated
Application Information
(cont.)
350mA Buck-boost LED driver
In this application example, ZXLD1374 is
connected as a Buck-boost LED driver with
schematic and parts list shown below. The LED
driver is able to deliver 350mA of LED current into
4/5 high brightness LED with input voltage ranged
from 7V to 20V. In order to increase the driving
voltage level for the internal MOSFET during low
voltage input, bootstrap circuit formed by R6 D2
and C6 are used to supply higher voltage to the
VAUX pin.
Since the Buck-boost LED driver can handle an
input voltage range below and above the LED
voltage, this versatile input voltage range makes it
ideal for automotive lighting applications.
Figure 52 Application Circuit of 350mA Buck-Boost LED Driver
Bill of Material
Ref No. Value Part No. Manufacturer
U1 60V LED driver ZXLD1374 Diodes Inc
Q1 60V MOSFET 2N7002A Diodes Inc
D1 100V 3A Schottky PDS3100-13 Diodes Inc
D2 100V 1A Schottky B1100 Diodes Inc
Z1 47V 410mW Zener BZT52C47 Diodes Inc
L1 47µH 2.6A 744771147 Wurth Electronik
C1 100pF 50V SMD 0805/0603 Generic
C3 C4 C5 4.7µF 50V X7R SMD1210 Generic
C2 C6 1µF 50V X7R SMD1206 Generic
R1 R2 300mΩ 1% SMD1206 Generic
R3 120kΩ 1% SMD 0805/0603 Generic
R4 36kΩ 1% SMD 0805/0603 Generic
R5 2.7kΩ SMD 0805/0603 Generic
R6 1kΩ SMD 1206 Generic
Typical Performance
Efficiency vs Input Voltage
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
7 8 9 10 11 12 13 14 15 16 17 18 19 20
Input Voltage
Ef
fi
ci
ency
4 LED VF=12.5V
5 LED VF=15.6V
Figure 53 Efficiency
LED Current vs Input Voltage
0
50
100
150
200
250
300
350
400
7 8 9 10 11 12 13 14 15 16 17 18 19 20
Input Voltage
L
E
D Cu
rr
en
t
4 LED VF=12.5V
5 LED VF=15.6V
Figure 54 Line Regulation