|
|
LT3468-2のメーカーはLinearです、この部品の機能は「Photoflash Capacitor Chargers」です。 |
部品番号 | LT3468-2 |
| |
部品説明 | Photoflash Capacitor Chargers | ||
メーカ | Linear | ||
ロゴ | |||
このページの下部にプレビューとLT3468-2ダウンロード(pdfファイル)リンクがあります。 Total 12 pages
LT3468/LT3468-1/LT3468-2
Photoflash Capacitor
Chargers in ThinSOTTM
FEATURES
■ Highly Integrated IC Reduces Solution Size
■ Uses Small Transformers:
5.8mm × 5.8mm × 3mm
■ Fast Photoflash Charge Times:
4.6s for LT3468 (0V to 320V, 100µF, VIN = 3.6V)
5.7s for LT3468-2 (0V to 320V, 100µF, VIN = 3.6V)
5.5s for LT3468-1 (0V to 320V, 50µF, VIN = 3.6V)
■ Controlled Input Current:
500mA (LT3468)
375mA (LT3468-2)
225mA (LT3468-1)
■ Supports Operation from Single Li-Ion Cell, or Any
Supply from 2.5V up to 16V
■ Adjustable Output Voltage
■ No Output Voltage Divider Needed
■ Charges Any Size Photoflash Capacitor
■ Low Profile (<1mm) SOT-23 Package
U
APPLICATIO S
■ Digital / Film Camera Flash
■ PDA / Cell Phone Flash
■ Emergency Strobe
DESCRIPTIO
The LT®3468/LT3468-1/LT3468-2 are highly integrated
ICs designed to charge photoflash capacitors in digital and
film cameras. A patented control technique* allows for the
use of extremely small transformers. Each device contains
an on-chip high voltage NPN power switch. Output voltage
detection* is completely contained within the device,
eliminating the need for any discrete zener diodes or
resistors. The output voltage can be adjusted by simply
changing the turns ratio of the transformer. The LT3468
has a primary current limit of 1.4A, the LT3468-2 has a 1A
limit, and the LT3468-1 has a 0.7A limit. These different
current limit levels result in well controlled input currents
of 500mA for the LT3468, 375mA for the LT3468-2 and
225mA for the LT3468-1. Aside from the differing current
limit, the three devices are otherwise equivalent.
The CHARGE pin gives full control of the part to the user.
Driving CHARGE low puts the part in shutdown. The DONE
pin indicates when the part has completed charging. The
LT3468 series of parts are available in tiny low profile
(1mm) SOT-23 packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
*Protected by U.S. Patents, including 6518733.
TYPICAL APPLICATIO
LT3468 Photoflash Charger Uses
High Efficiency 4mm Tall Transformer
DANGER HIGH VOLTAGE – OPERATION BY HIGH VOLTAGE
TRAINED PERSONNEL ONLY
VIN
2.5V TO 8V
4.7µF
1:10.2
14
25
320V
+
100µF
100k
DONE
VIN SW
LT3468
DONE
GND
CHARGE
CHARGE
346812 TA01
LT3468 Charging Waveform
VIN = 3.6V
COUT = 100µF
VOUT
50V/DIV
AVERAGE
INPUT
CURRENT
1A/DIV
1s/DIV
3468 G01
346812fa
1
1 Page LT3468/LT3468-1/LT3468-2
TYPICAL PERFOR A CE CHARACTERISTICS LT3468 curves use the circuit of Figure 6, LT3468-1
curves use the circuit of Figure 7 and LT3468-2 use the circuit of Figure 8 unless otherwise noted.
LT3468 Charging Waveform
VIN = 3.6V
COUT = 100µF
LT3468-1 Charging Waveform
VIN = 3.6V
COUT = 50µF
LT3468-2 Charging Waveform
VIN = 3.6V
COUT = 100µF
VOUT
50V/DIV
VOUT
50V/DIV
AVERAGE
INPUT
CURRENT
1A/DIV
1s/DIV
3468 G01
VOUT
50V/DIV
AVERAGE
INPUT
CURRENT
0.5A/DIV
1s/DIV
3468 G02
AVERAGE
INPUT
CURRENT
0.5A/DIV
1s/DIV
3468 G03
LT3468 Charge Time
10 TA = 25°C
9
8
7
6
5
4 COUT = 100µF
3
2
1 COUT = 50µF
0
23456
VIN (V)
7
89
3468 G04
LT3468 Input Current
800 TA = 25°C
600
VIN = 2.8V
VIN = 4.2V
400
VIN = 3.6V
200
LT3468-1 Charge Time
10 TA = 25°C
9
8
7
6
5
COUT = 50µF
4
3
2
1 COUT = 20µF
0
234567
VIN (V)
89
3468 G05
LT3468-1 Input Current
400 TA = 25°C
300
VIN = 2.8V
200 VIN = 4.2V
VIN = 3.6V
100
LT3468-2 Charge Time
10
TA = 25°C
9
8
7
6
5 COUT = 100µF
4
3
2
COUT = 50µF
1
0
23 4 5 6 7
VIN (V)
89
3468 G06
LT3468-2 Input Current
600 TA = 25°C
450
VIN = 2.8V
VIN = 4.2V
300 VIN = 3.6V
150
0
0 50 100 150 200 250 300
VOUT (V)
3468 G07
0
0 50 100 150 200 250 300
VOUT (V)
3468 G08
0
0 50 100 150 200 250 300
VOUT (V)
3468 G09
346812fa
3
3Pages LT3468/LT3468-1/LT3468-2
PI FU CTIO S
SW (Pin 1): Switch Pin. This is the collector of the internal
NPN Power switch. Minimize the metal trace area con-
nected to this pin to minimize EMI. Tie one side of the
primary of the transformer to this pin. The target output
voltage is set by the turns ratio of the transformer.
Choose Turns Ratio N by the following equation:
N=
VOUT + 2
31.5
Where: VOUT is the desired output voltage.
You must tie a Schottky diode from GND to SW, with the
anode at GND for proper operation of the circuit. Please
refer to the applications section for further information.
GND (Pin 2): Ground. Tie directly to local ground plane.
DONE (Pin 3): Open NPN Collector Indication Pin. When
target output voltage is reached, NPN turns on. This pin
needs a pull-up resistor or current source.
CHARGE (Pin 4): Charge Pin. This pin must be brought
high (>1V) to enable the part. A low (<0.3V) to high (>1V)
transition on this pin puts the part into power delivery
mode. Once the target output voltage is reached, the part
will stop charging the output. Toggle this pin to start
charging again. Ground to shut down. You may bring this
pin low during a charge cycle to halt charging at any time.
VIN (Pin 5): Input Supply Pin. Must be locally bypassed
with a good quality ceramic capacitor. Input supply must
be 2.5V or higher.
BLOCK DIAGRA
TO BATTERY
C1
T1 D1
PRIMARY
SECONDARY
D2
VOUT
DONE
3
5 VIN
R2
60k
SW
1
Q3 DCM COMPARATOR
MASTER
LATCH
Q
S
Q1
ENABLE
Q
R
+
A2
–
Q2
R1
2.5k
1.25V
REFERENCE
CHARGE
4
ONE-
SHOT
VOUT COMPARATOR
CHIP ENABLE
LT3468: RSENSE = 0.015Ω
LT3468-2: RSENSE = 0.022Ω
LT3468-1: RSENSE = 0.03Ω
ONE-
SHOT
+
A3
–
–+ 36mV
S
RQ
DRIVER
Q1
Figure 1
+
A1
–
20mV
+–
RSENSE
GND
2
3486 BD
6
+ COUT
PHOTOFLASH
CAPACITOR
346812fa
6 Page | |||
ページ | 合計 : 12 ページ | ||
|
PDF ダウンロード | [ LT3468-2 データシート.PDF ] |
データシートを活用すると、その部品の主な機能と仕様を詳しく理解できます。 ピン構成、電気的特性、動作パラメータ、性能を確認してください。 |
部品番号 | 部品説明 | メーカ |
LT3468-1 | Photoflash Capacitor Charger in ThinSOT | Linear Technology |
LT3468-2 | Photoflash Capacitor Chargers | Linear |