LED2000PUR STMicroelectronics, LED2000PUR Datasheet - Page 28

• Manufacturer Part Number: LED2000PUR
• Description: LED Lighting Drivers 3.0V to 18V 850kHz 100mV 95mOhm HS
• Manufacturer: STMicroelectronics

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

Application information
7.4
28/40
V
The typical output voltage is:
Equation 36
R
For the calculation we can estimate R
consequence of Tj increase during the operation.
T
I
The overall losses are:
Equation 37
Equation 38
The junction temperature of the device is:
Equation 39
where T
ambient. The junction-to-ambient (Rth
HSO8 package and mounted on the board is about 40 °C/W.
Assuming the ambient temperature is around 40 °C, the estimated junction temperature is:
Short-circuit protection
In overcurrent protection mode, when the peak current reaches the current limit threshold,
the device disables the power element and it is able to reduce the conduction time down to
the minimum value (approximately 100 nsec typical) to keep the inductor current limited.
This is the pulse-by-pulse current limitation to implement the constant current protection
feature.
In overcurrent condition, the duty cycle is strongly reduced and, in most applications, this is
enough to limit the switch current to the current threshold.
Q
T
P
SW_EQ
IN
DSON_HS
J
P
T
TOT
has a typical value of 1.5 mA @ V
=12 V, V
=
V
TOT
J
OUT
=
60
=
T
+
=
A
A
is approximately 12 ns.
0.14
=
0.205
is the ambient temperature and Rth
R
+
has a typical value of 95 m and R
DSON_HS
n
Rth
FW_LED
LED
J A
0.7
–
40
2
V
=3.5 V, n
FW_LED
0.6
P
68 C
TOT
I
OUT
+
0.1
+
2
V
LED
FB
0.7
Doc ID 023432 Rev 3
D
=2, I
+
=
2
R
7.1V
DSON_LS
0.4
LED
IN
DSON_HS
J-A
+
= 12 V.
=700 mA
12
) thermal resistance of the device assembled in the
0.7
I
J-A
OUT
DSON_LS
= 140 m and R
12
is the thermal resistance junction-to-
2
10
1 D
–
is 69 m @ 25 °C.
–
9
850
+
V
IN
DSON_LS
10
I
3
OUT
+
12
= 100 m as a
f
SW
1.5
T
10
SW
–
3
+
LED2000
V
205mW
IN
I
Q