ZXLD1374_11 DIODES [Diodes Incorporated], ZXLD1374_11 Datasheet - Page 18

• Manufacturer Part Number: ZXLD1374_11
• Description: 60V HIGH ACCURACY 1.5A BUCK/BOOST/BUCK-BOOST
• Manufacturer: DIODES [Diodes Incorporated]

ZXLD1374
Document number: DS35032 Rev. 2 - 2
Applications Information
For example, as in the typical application circuit, in order to get I
Setting R
This will result in:
Table 1 shows typical resistor values used to determine GI
Table 1
The values shown have been chosen so that they do not load REF too much or create offset errors due to the GI pin input
current. A ZXLD1374 calculator is available from http://www.diodes.com/destools/calculators.html that will help with
component selection.
INDUCTOR/FREQUENCY SELECTION
Recommended inductor values for the ZXLD1374 are in the range 22µH to 100µH. The chosen coil should have a
saturation current higher than the peak sensed current and a continuous current rating above the required mean sensed
current by at least 50%.
The inductor value should be chosen to maintain operating duty cycle and switch 'on'/'off' times within the recommended
limits over the supply voltage and load current range.
The frequency compensation mechanism inside the chip tends to keep the frequency within the range 300kHz ~ 400kHz in
most of the operating conditions. Nonetheless, the controller allows for higher frequencies when either the number of LEDs
or the input voltage increases.
The graphs below can be used to select a recommended inductor to maintain the ZXLD1374 switching frequency within a
predetermined range when used in different topologies.
GI
0.2
0.25
0.3
0.35
0.4
0.45
0.5
RATIO
GI1
= 33kΩ it results
100kΩ
RGI1
30kΩ
33kΩ
39kΩ
30kΩ
51kΩ
30kΩ
(Continued)
120kΩ
100kΩ
150kΩ
91kΩ
56kΩ
62kΩ
30kΩ
RGI2
I
60V HIGH ACCURACY 1.5A BUCK/BOOST/BUCK-BOOST
LED
I
R
RS
s
R
=
GI
=
(R
2
GI
=
V
V
R
R
ADJ
1
www.diodes.com
GI
GI
GI
+
R
( 1
1
RATIO
18 of 37
GI
=
V
V
ADJ
) 2
LED DRIVER CONVERTER WITH AEC-Q100
GI
(R
LED
225
with E24 series resistors:
GI
I
LED
−
R
1
= 350mA with I
) 1
mV
GI
+
R
1
=
GI
110
=
) 2
150
k
≈
Ω
m
. 0
Ω
23
Diodes Incorporated
RS
A Product Line of
=1.5A the ratio has to be set as:
© Diodes Incorporated
ZXLD1374
March 2011