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ILD8150 80 V high side buck LED driver IC with hybrid dimming
Circuit description
Output frequency is determined by the following equation:
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frequencies. Figure 3 shows the frequency curves not including the delay in blue and including the delay in red.
100
90
80
70
60
50
40
30
20
10
0
Typical frequency change character curve over output voltage, V
Figure 3
1.5 kΩ, C
= 180 pF
fltr
R
and C
are the RC filter, which reduces the noise from R
fltr
fltr
2.2
Cycle-by-cycle current limitation
Because ILD8150 operates in current mode, it does not allow operation with higher current than it sets. Output
current is limited cycle-by-cycle. Thus, it safely operates even when the LED output gets shorted. R
circuit may cause damage.
2.2.1
OTP
ILD8150 has integrated OTP based on the junction temperature measurement on the chip. OTP is required to
prevent the IC from operating at a critical temperature. The high threshold when the IC turns off is T
low threshold when the IC turns on is T
2.2.2
UVLO
ILD8150 has hysteretic UVLO protection against operation at insufficient supply voltage. ILD8150 also has UVLO
that shuts down the IC when the minimum supply voltage drops below the internal threshold, typically
V
, and releases the IC from lockout at V
VIN_UVLO,OFF
Application Note
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. This part is negligible for low frequencies but it has a strong effect at high
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Input voltage 80 V
8
12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76
Without delay
.
OT,ON
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and ��
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, where ��
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Output voltage, V
With delay
, which can lead to unwanted operation.
CS
.
VIN_UVLO,ON
5 of 28
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.
is the delay contribution, with
= 80 V, L = 680 µH, R
IN
CS
= 0.36 Ω, R
=
fltr
short-
CS
; the
OT,OFF
V 1.0
2019-01-23
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