ZXLD1370_11 DIODES [Diodes Incorporated], ZXLD1370_11 Datasheet - Page 19

• Manufacturer Part Number: ZXLD1370_11
• Description: 60V HIGH ACCURACY BUCK/BOOST/BUCK-BOOST LED DRIVER CONTROLLER
• Manufacturer: DIODES [Diodes Incorporated]

Suitable coils for use with the ZXLD1370 may be selected from the MSS range manufactured by Coilcraft, or the NPIS range
manufactured by NIC components.
The following websites may be useful in finding suitable components
ZXLD1370
Document number: DS32165 Rev. 3 - 2
Applications Information
MOSFET Selection
The ZXLD130 requires an external NMOS FET as the main power switch with a voltage rating at least 15% higher than the
maximum transistor voltage to ensure safe operation during the ringing of the switch node.
recommended to be at least 10% higher than the average transistor current. The power rating is then verified by calculating
the resistive and switching power losses.
Resistive power losses
The resistive power losses are calculated using the RMS transistor current and the MOSFET on-resistance.
Calculate the current for the different topologies as follows:
Buck mode
Boost / Buck-boost mode
The approximate RMS current in the MOSFET will be:
Buck mode
www.coilcraft.com
www.niccomp.com
www.wuerth-elektronik.de
P
I
I
I
MOSFET
MOSFET
MOSFET
=
P
resistive
−
−
−
MAX
MAX
RMS
Figure 26. 350mA Buck-Boost mode inductor selection for target frequency > 500kHz
15
13
11
+
=
=
=
9
7
5
3
1
I
P
D
1
LED
0
switching
−
MAX
D
D
MAX
D
MAX
x
I
LED
x
L=22uH
I
LED
10
(Continued)
ZXLD1370 Boost Mode 350mA Minimum Recommended Inductor
L=33uH
20
Target Switching frequency > 500kHz
L=47uH
Supply Voltage (V)
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19 of 35
30
40
Diodes Incorporated
A Product Line of
50
60
The current rating is
© Diodes Incorporated
ZXLD1370
February 2011