LT3585-0 LINER [Linear Technology], LT3585-0 Datasheet - Page 15

• Manufacturer Part Number: LT3585-0
• Description: Photofl ash Chargers with Adjustable Input Current and IGBT Drivers
• Manufacturer: LINER [Linear Technology]

APPLICATIO S I FOR ATIO
Board Layout
The high voltage operation of these parts demand care-
ful attention to board layout. You will not get advertised
performance with careless layout. Figure 10 shows the
recommended component placement. Keep the area for the
high voltage end of the secondary as small as possible. Also
note the larger than minimum spacing for all high voltage
nodes in order to meet breakdown voltage requirements for
the circuit board. It is imperative to keep the electrical path
formed by C1, the primary of T1, and the LT3585 series IC
as short as possible. If this path is haphazardly made long,
U
IGBTPWR
IGBTIN
U
V
GND
V
BAT
IN
W
C2
1
2
3
4
5
THERMAL
VIAS
Figure 10. LT3585 Suggested Layout
R1
11
GND
U
C1
10
9
8
7
6
TO GATE OF IGBT
DONE CHRG
R2
it will effectively increase the leakage inductance of T1,
which may result in an overvoltage condition on the SW
pin. The CHRG/IADJ pin trace should be kept as short as
possible while minimizing the adjacent edge with the SW
pin trace. This will eliminate false toggling of the CHRG/IADJ
pin during sharp transitions on the SW pin. Thermal vias
should be added underneath the Exposed Pad, Pin 11, to
enhance the LT3585’s thermal performance. These vias
should go directly to a large area of ground plane. Acting
as a heat sink, the thermal vias/ground plane will lower
the device’s operating temperature.
V
T1
BAT
LT3585-0/LT3585-1
LT3585-2/LT3585-3
3585 F10
D1 (DUAL DIODE)
PHOTOFLASH
CAPACITOR
V
OUT
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3585f