SC4505EVB SEMTECH [Semtech Corporation], SC4505EVB Datasheet - Page 11

• Manufacturer Part Number: SC4505EVB
• Description: High Efficiency Boost Converter for Backlight/Flash LED Driver
• Manufacturer: SEMTECH [Semtech Corporation]

As shown in Figure 5, R
divider. R
triggering point adjustment. It is noted that the resistance
of the internal resistor divider formed by R
around 500k
will be applied to VO pin to quickly discharge the output
capacitor. Any large value of R
discharge process at OVP condition. Generally speaking,
small value of R
However, small value of the resistor divider formed by
R
often use R
the OVP specification. In this case, the OVP triggering
threshold estimation equation can be rewritten as
follows:
Set
We can get
The tolerance of the R
in determining the OVP triggering point. Usually there is
about 5%~8% difference between the calculated value
and the measure OVP triggering threshold.
POWER MANAGEMENT
Applications Information
3
2006 Semtech Corp.
VIN
and R
4
3
L1
and R
would cause additional power loss. People
4
=100k
COMP
V
Figure 5. OVP Tweaking
3
OVP
When OVP happens, a strong pulldown
4
R
is preferred in applications.
are external resistor divider for OVP
3
SC4505
V
3
R
and then select R3 according to
OVP
and R
D1
R
1
R
R
4
V
28V
R
//500K
and R
4
OVP
1
2
4
//500K
100K
4
I
should also be considered
1
2
1
are the internal resistor
VO
3
83.3K
R
will slow down the
3
VOUT
R
R
3
4
28V
I
2
1
and R
C
OUT
2
is
11
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SC4505