LT3519IMS-1#TRPBF Linear Technology, LT3519IMS-1#TRPBF Datasheet - Page 11

• 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
Inductor Selection
The inductor used with the LT3519/LT3519-1/LT3519-2
should have a saturation current rating of 1A or greater.
For buck mode LED drivers, the inductor value should be
chosen to give a ripple current 150mA or more. In the
buck mode, the inductor value can be estimated using
the formula:
V
voltage to the converter, and f
In the boost confi guration, the inductor can be estimated
using the formula:
Table 1. Recommended Inductor Vendors
VENDOR
Sumida
Toko
Cooper
Vishay
Input Capacitor Selection
For proper operation, it is necessary to place a bypass
capacitor to GND close to the V
LT3519-1/LT3519-2. A 1μF or greater capacitor with low
ESR should be used. A ceramic capacitor is usually the
best choice.
In the buck mode confi guration, the capacitor at the input
to the power converter has large pulsed currents. For
best reliability, this capacitor should have low ESR and
LED
L µH
D
L µH
D
BUCK
BOOST
( )
( )
is the voltage across the LED string, V
=
=
=
=
D
f
V
f
OSC
V
OSC
(
BUCK
LED
IN
V
D
LED
BOOST
(MHz) • 0.15A
V
(MHz) • 0.15A
LED
• V
– V
PHONE
[phone]
[phone]
[phone]
[phone]
(
IN
IN
• V
)
– V
IN
OSC
LED
is the switching frequency.
)
⎛
⎜
⎝
⎛
⎜
⎝
µH • A • MHz
µH • A • MHz
IN
pin of the LT3519/
WEB
www.sumida.com
www.toko.com
www.cooperet.com
www.vishay.com
V
V
IN
is the input
⎞
⎟
⎠
⎞
⎟
⎠
ESL and have an adequate ripple current rating. A 2.2μF
ceramic type capacitor is usually suffi cient for LT3519
(400kHz version). A capacitor of proportionately less
value for LT3519-1/LT3519-2 (higher frequency version)
can be used.
Output Capacitor Selection
The selection of output capacitor depends on the load
and converter confi guration, i.e., step-up or step-down
and the operating frequency. For LED applications, the
equivalent resistance of the LED is typically low, and the
output fi lter capacitor should be sized to attenuate the
current ripple.
To achieve the same LED ripple current, the required fi lter
capacitor value is larger in the boost and buck-boost mode
applications than that in the buck mode applications. Lower
operating frequencies will require proportionately higher
capacitor values. For LED buck mode applications, a 1μF
ceramic capacitor is usually suffi cient. For the LED boost
and buck-boost mode applications, a 2.2μF ceramic ca-
pacitor is usually suffi cient. Very high performance PWM
dimming applications may require a larger capacitor value
to support the LED voltage during PWM transitions.
Use only ceramic capacitors with X7R, X5R or better dielec-
tric as they are best for temperature and DC bias stability
of the capacitor value. All ceramic capacitors exhibit loss
of capacitance value with increasing DC voltage bias, so
it may be necessary to choose a higher value capacitor
to get the required capacitance at the operation voltage.
Always check that the voltage rating of the capacitor is
suffi cient.
Table 2. Recommended Ceramic Capacitor Vendors
VENDOR
TDK
Kemet
Murata
Taiyo Yuden
LT3519/LT3519-1/LT3519-2
PHONE
[phone]
[phone]
[phone]
[phone]
WEB
www.tdk.com
www.kemet.com
www.murata.com
www.t-yuden.com
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3519fa