LT3420EMS-1#TRPBF Linear Technology, LT3420EMS-1#TRPBF Datasheet - Page 12

• Manufacturer Part Number: LT3420EMS-1#TRPBF
• Description: IC PHOTOFLASH CAP CHARGER 10MSOP
• Manufacturer: Linear Technology

Specifications of LT3420EMS-1#TRPBF

• Applications: Photoflash Capacitor Charger
• Current - Supply: 90µA
• Voltage - Supply: 2.2 V ~ 16 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

LT3420/LT3420-1
APPLICATIO S I FOR ATIO
efficiency of the circuit. In addition, the effective capaci-
tance on the primary is largely dominated by the actual
secondary capacitance. This is simply a result of any
secondary capacitance being multiplied by N
flected to the primary. Since N is generally 10 or higher, a
small capacitance of 10pF on the secondary is 100 times
larger, or 1.0nF, on the primary. This capacitance forms a
resonant circuit with the primary leakage inductance of the
transformer. As such, both the primary leakage induc-
tance and secondary side capacitance should be mini-
mized.
Table 2 shows various predesigned transformers along
with relevant parameters. Contact the individual trans-
former manufacturer for additional information or
customization.
Table 2a. Predesigned Transformers, LT3420
PART
SRW10EPC
-U01H003
6375-T108
SBL-6.4
Table 2b. Predesigned Transformers, LT3420-1
PART
SBL-5.6S-2
LDT565630T 1:10.2 14.5
-002
12
TURNS
TURNS
RATIO
RATIO (µH)
1:12
1:12
1:12
1:10
(µH) LxWxH (mm) VENDOR
17.5
24
15
15
U
L
L
10.9x10.8x5.2 TDK
10.8x9.5x3.6
10.3x6.4x5.2
LxWxH (mm) VENDOR
5.6x8.5x3.0
5.8x5.8x3.0
U
SIZE
SIZE
W
[phone]
www.components.tdk.com
Sumida
[phone]
www.sumida.com
Kijima Musen
852-2489-8266
[e-mail]
Kijima Musen
852-2489-8266
[e-mail]
TDK
[phone]
www.components.tdk.com
2
U
when re-
DIODE SELECTION
The rectifying diode(s) should be low capacitance type
with sufficient reverse voltage and forward current rat-
ings. The peak reverse voltage that the diode(s) will see is
approximately:
The peak current of the diode is simply:
For the circuit of Figure 1 with V
and I
can work with the LT3420/LT3420-1. These are chosen for
low capacitance and high reverse blocking voltage. Use
the appropriate number of diodes to achieve the necessary
reverse breakdown voltage.
Table 3
PART
GSD2004S
(Dual diode)
BAS21
(Single diode)
MMBD3004S
I
I
V
PK-SEC
PK-SEC
PK-R
PK-SEC
≈
=
=
(
is 116mA. Table 3 shows various diodes that
MAX REVERSE CAPACITANCE
V
1 4
1 0
VOLTAGE (V)
OUT
.
.
N
N
2x300
2x300
A
A
250
+
(
(
( •
LT
LT
N V
3420
3420 1
BAT
)
−
) • . 1 65
(pF)
1.5
)
5
5
BAT
)
of 3.3V, V
VENDOR
Vishay
[phone]
www.vishay.com
Philips Semiconductor
[phone]
www.philips.com
Diodes Inc.
[phone]
www.diodes.com
PK-R
is 590V
3420fb