lt3468es5-trpbf Linear Technology Corporation, lt3468es5-trpbf Datasheet - Page 10

• Manufacturer Part Number: lt3468es5-trpbf
• Description: Lt3468-1 - Photoflash Capacitor Chargers In Thinsot?
• Manufacturer: Linear Technology Corporation

LT3468/LT3468-1/LT3468-2
APPLICATIO S I FOR ATIO
should be a Schottky diode with at least a 500mA peak
forward current capability. The diode forward voltage drop
should be 600mV or less at 500mA of forward current.
Reverse voltage rating should be 40V or higher. Table 4
shows various recommended clamping diodes.
Table 4. Recommended Clamp Diodes
PART
ZHCS400
B0540W
MA2Z720
Board Layout
The high voltage operation of the LT3468/LT3468-1/
LT3468-2 demands careful attention to board layout. You
will not get advertised performance with careless layout.
Figure 5 shows the recommended component placement.
10
TYPICAL APPLICATIO S
2.5V TO 8V
C1: 4.7µF, X5R OR X7R, 10V
T1: KIJIMA MUSEN PART# SBL-5.6-1, L
D1: VISHAY GSD2004S DUAL DIODE CONNECTED IN SERIES
D2: ZETEX ZHCS400 OR EQUIVALENT
R1: PULL UP RESISTOR NEEDED IF DONE PIN USED
CHARGE
DONE
V IN
100k
Figure 6. LT3468 Photoflash Charger Uses
High Efficiency 4mm Tall Transformer
R1
C1
4.7µF
MAX REVERSE VOLTAGE
DONE
CHARGE
V
IN
U
LT3468
(V)
40
40
40
U
PRI
SW
GND
= 10µH, N = 10.2
1
2
1:10.2
T1
U
D2
W
4
5
www.panasonic.co.jp
D1
www.diodes.com
[phone]
www.zetex.com
[phone]
[phone]
Diodes Inc.
Panasonic
VENDOR
+
Zetex
C
PHOTOFLASH
CAPACITOR
3468 F06
320V
OUT
U
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 break-
down voltage requirements for the circuit board. It is
imperative to keep the electrical path formed by C1, the
primary of T1, and the LT3468/LT3468-1/LT3468-2 as
short as possible. If this path is haphazardly made long, it
will effectively increase the leakage inductance of T1,
which may result in an overvoltage condition on the SW
pin.
CHARGE
Figure 5. Suggested Layout: Keep Electrical Path Formed by C1,
Transformer Primary and LT3468/LT3468-1/LT3468-2 Short
DONE
2.5V TO 8V
C1: 4.7µF, X5R OR X7R, 10V
T1: KIJIMA MUSEN PART# SBL-5.6S-1, L
D1: VISHAY GSD2004S DUAL DIODE CONNECTED IN SERIES
D2: ZETEX ZHCS400 OR EQUIVALENT
R1: PULL UP RESISTOR NEEDED IF DONE PIN USED
V
IN
CHARGE
DONE
V IN
R1
100k
Figure 7. LT3468-1 Photoflash Charger Uses
High Efficiency 3mm Tall Transformer
R1
4
5
C1
4.7µF
DONE
CHARGE
V
IN
LT3468-1
3
2
1
C1
SW
GND
PRI
4
3
= 24µH, N = 10.2
D2
1:10.2
T1
•
D2
5
6
T1
D1
•
+
(DUAL DIODE)
PHOTOFLASH
CAPACITOR
C OUT
PHOTOFLASH
CAPACITOR
D1
320V
C
OUT
346812fa
3468 F05
3468 F07
+