LT3519IMS-1#TRPBF Linear Technology, LT3519IMS-1#TRPBF Datasheet - Page 12

• Manufacturer Part Number: LT3519IMS-1#TRPBF
• Description: LED DRIVER WITH INTEGRATED SCHOT
• Manufacturer: Linear Technology
• Type: High Power, Constant Currentr

Specifications of LT3519IMS-1#TRPBF

• Constant Current: Yes
• Constant Voltage: Yes
• Topology: PWM, SEPIC, Step-Down (Buck), Step-Up (Boost)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: Automotive
• Frequency: 800kHz ~ 1.10MHz
• Voltage - Supply: 3 V ~ 30 V
• Mounting Type: Surface Mount
• Package / Case: 16-MSOP
• Operating Temperature: -40°C ~ 125°C
• Current - Output / Channel: 750mA
• Internal Switch(s): Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Efficiency: -

APPLICATIONS INFORMATION
LT3519/LT3519-1/LT3519-2
Open LED Detection
The LT3519/LT3519-1/LT3519-2 provide an open-collector
status pin, OPENLED, that pulls low when the FB pin is
within ~60mV of its 1.22V regulated voltage. If the open
LED clamp voltage is programmed correctly using the FB
pin, then the FB pin should never exceed 1.1V when LEDs
are connected, therefore, the only way for the FB pin to
be within 60mV of the 1.22V regulation voltage is for an
open LED event to have occurred.
Inrush Current
The LT3519/LT3519-1/LT3519-2 have a built-in Schottky
diode for a boost converter. When supply voltage is ap-
plied to V
V
the inductor and the Schottky diode to charge the output
capacitor. The selection of inductor and capacitor value
should ensure the peak of the inrush current to below
10A. In addition, the LT3519/LT3519-1/LT3519-2 turn-on
should be delayed until the inrush current is less than the
maximum current limit. If the peak of the inrush current
is more than 10A, an external Schottky diode should be
used to bypass both the inductor and internal Schottky.
The recommended Schottky diodes for hot plug are shown
on Table 3.
Table 3. Schottky Diodes Recommended for Hot Plug
VENDOR
Diodes, Inc
Zetex
International Rectifi er
12
OUT
generates inrush current fl owing from input through
IN
pin, the voltage difference between V
PART NUMBER
ZLLS10000TA
10MQ060N
DFLS160
V
R
60
40
60
(V)
I
AVE
1.5
IN
1
1
(A)
and
Board Layout
As with all switching regulators, careful attention must be
paid to the PCB board layout and component placement.
To prevent electromagnetic interference (EMI) problems,
proper layout of high frequency switching paths (see
Figure 4) is essential. Minimize the length and area of all
traces connected to the switching node pin (SW). Keep the
sense voltage pins (ISP and ISN) away from the switching
node. The bypass capacitor on the V
should be placed as close as possible to the V
GND. Likewise, place C
not extensively route high impedance signals such as FB
and CTRL, as they may pick up switching noise. Figure 5
shows the recommended component placement.
+
L1
V
IN
Figure 4. High Frequency Path
Figure 5. Suggested Layout
C
IN
L1
GND
OPENLED
PWM
SHDN/UVLO
V
SW
ANODE
GND
V
IN
IN
OUT
SW
CATHODE
next to the CATHODE pin. Do
CTRL
V
GND
GND
ISN
GND
D1
ISP
REF
FB
IN
supply to the LT3519
C
OUT
V
OUT
LOAD
V
3519 F05
OUT
3519 F04
R
IN
S
pin and
3519fa