LED2000PUR STMicroelectronics, LED2000PUR Datasheet - Page 29
LED2000PUR
Manufacturer Part Number
LED2000PUR
Description
LED Lighting Drivers 3.0V to 18V 850kHz 100mV 95mOhm HS
Manufacturer
STMicroelectronics
Datasheet
1.LED2000DR.pdf
(40 pages)
Specifications of LED2000PUR
Rohs
yes
Input Voltage
3 V to 18 V
Operating Frequency
850 kHz
Maximum Supply Current
3 A
Mounting Style
SMD/SMT
Package / Case
VFQFPN-8L
Power Dissipation
2 W
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
LED2000
The inductor current ripple during ON and OFF phases can be written as:
●
Equation 40
●
Equation 41
where DCR
The pulse-by-pulse current limitation is effective to implement constant current protection
when:
Equation 42
From
current protection becomes more critical the lower the V
In fact, in short-circuit condition the voltage applied to the inductor during the OFF-time
becomes equal to the voltage drop across parasitic components (typically the DCR of the
inductor and the R
the voltage applied at the inductor is maximized and is approximately equal to V
In general, the worst case scenario is heavy short-circuit at the output with maximum input
voltage.
Equation 43
considering T
Equation 44
where T
At higher input voltage I
escalate. As a consequence, the system typically meets
higher than the nominal value thanks to the increased voltage drop across stray
components. In most of the application conditions the pulse-by-pulse current limitation is
effective to limit the inductor current. Whenever the current escalates, a second level current
protection called “Hiccup mode” is enabled. Hiccup protection offers an additional protection
against heavy short-circuit conditions at very high input voltage even considering the spread
I
I
L TOFF
L TON
I
I
I
ON phase
OFF phase
L TON
L TON
L TON
Equation 40
SW
Equation 40
=
=
=
=
=
=1/f
V
------------------------------------------------------------------------------------------------------- T
L
–
------------------------------------------------------------------- - T
–
---------------------------------------------------------------------------------------------- - T
V
------------------------------------------------------------------------------ - T
IN
is the series resistance of the inductor.
ON
IN
DCR
V
I
L TOFF
SW
–
OUT
–
V
which has already been reduced to its minimum.
DCR
OUT
L
and
DSON
and considering the nominal f
+
+
R
and
L
DCR
–
L
DSON LS
Equation 41
+
DCR
L
of the low-side switch) since VOUT is negligible, while during T
R
L TON
Equation 41
DSON HS
L
L
L
+
L
R
+
Doc ID 023432 Rev 3
DSON LS
R
may be higher than I
DSON HS
I
SW
it can be seen that the implementation of the constant
I
–
in overcurrent conditions can be simplified to:
ON MIN
90ns
I
I
OFF
ON
–
------------------------------------------------------------------- - 1.18 s
V
--------- 90ns
SW
L
DCR
IN
.
L
L TOFF
+
R
OUT
L
Equation 42
DSON LS
and so the inductor current can
and the higher the V
Application information
I
at a current level
IN
IN
.
.
29/40
ON