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PDF LT3485-1 Data sheet ( Hoja de datos )
| Número de pieza | LT3485-1 | |
| Descripción | Photoflash Capacitor Chargers | |
| Fabricantes | Linear Technology | |
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LT3485-0/LT3485-1/
LT3485w-w2w/.DLatTaS3he4et48U.c5om-3
Photoflash Capacitor
Chargers with Output Voltage
Monitor and Integrated IGBT Drive
FEATURES
■ Integrated IGBT Driver
■ Voltage Output Monitor
■ Uses Small Transformers: 5.8mm × 5.8mm × 3mm
■ Operates from Two AA Batteries, Single Cell Li-Ion
or Any Supply from 1.8V up to 10V
■ No Output Voltage Divider Needed
■ No External Schottky Diode Required
■ Charges Any Size Photoflash Capacitor
■ Available in 10-Lead (3mm × 3mm) DFN
Fast Charge Time
VERSION
INPUT CURRENT (mA)
LT3485-3
750
LT3485-0
500
LT3485-2
350
LT3485-1
225
VIN = VBAT = 3.6V
U100µF capacitor, 320V. *50µF capacitor
APPLICATIO S
CHARGE TIME (sec)
2.5
3.7
5.5
4.0*
■ Digital Camera and Cell Phone Flash Charger
DESCRIPTIO
The LT®3485 family of photoflash chargers are highly inte-
grated ICs containing complete charger and IGBT drive
functions. The patented control technique of the LT3485-x
allows it to use extremely small transformers. Output voltage
detection requires no external circuitry. The turns ratio of the
transformer controls the final charge voltage. While charging,
the output voltage on the capacitor may be monitored by a
microcontroller from the monitor pin. Each device contains an
on-chip high voltage NPN power switch, which can withstand
negative voltages on the switch pin without an external
Schottky diode. The device features a VBAT pin, which allows
the use of two AA cells to charge the capacitor. The internal
circuitry operates from the VIN pin. The LT3485-0 has a
primarycurrentlimitof1.4A,whereastheLT3485-3,LT3485-2,
and LT3485-1 have current limits of 2A, 1A and 0.7A respec-
tively. These different current limits result in tightly controlled
input currents.
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 LT3485
series of parts are housed in a leadless (3mm × 3mm) DFN
package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 6636021.
TYPICAL APPLICATIO
LT3485-0 Photoflash Charger Uses High Efficiency 3mm Tall Transformers
DANGER HIGH VOLTAGE – OPERATION BY HIGH VOLTAGE TRAINED PERSONNEL ONLY
VBAT
2 AA OR
1 TO 2 Li-Ion
4.7µF
1:10.2
1• 4
2 •5
VBAT
SW
DONE
CHARGE
GND
LT3485-0
VCC
5V
VIN VMONT
0.22µF
IGBTPWR
TO
MICRO
320V
150µF
PHOTOFLASH
CAPACITOR
1M
2.2µF
600V
TRIGGER T
1
3
2
A
FLASHLAMP
C
IGBTIN IGBTOUT
IGBT
3485 TA01
LT3485-0 Charging Waveform
VOUT
50V/DIV
AVERAGE
INPUT CURRENT
0.5A/DIV VIN = 3.6V
COUT = 100µF
1s/DIV
3485 TA02
34850123fb
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1 page  
LT3485-0/LT3485-1/
LT3485w-w2w/.DLatTaS3he4et48U.c5om-3
TYPICAL PERFOR A CE CHARACTERISTICS LT3485-0 curves use the circuit of Figure 8, LT3485-1
curves use the circuit of Figure 9, LT3485-2 use the circuit of Figure 10 and LT3485-3 use the circuit of Figure 11 unless otherwise noted.
LT3485-0 Efficiency
90
80
70
60
50
40
50
2.5V
3.6V
4.2V
100 150 200 250 300
VOUT (V)
3485 G10
LT3485-3 Efficiency
90
80
70
60
50
40
50
2.5V
3.6V
4.2V
100 150 200 250 300
VOUT (V)
3485 G13
LT3485-2 Output Voltage
328
327
–40°C
326 25°C
85°C
325
324
323
322
234 56
VIN (V)
78
3485 G16
LT3485-1 Efficiency
90
80
70
60
50
40
50
2.5V
3.6V
4.2V
100 150 200 250 300
VOUT (V)
3485 G11
LT3485-0 Output Voltage
322
321
320
319
318
317
234 56
VIN (V)
–40°C
25°C
85°C
78
3485 G14
LT3485-3 Output Voltage
322
321
320
319
318
317
234 56
VIN (V)
–40°C
25°C
85°C
78
3485 G17
LT3485-2 Efficiency
90
80
70
60
50
40
50
2.5V
3.6V
4.2V
100 150 200 250 300
VOUT (V)
3485 G12
LT3485-1 Output Voltage
322
321
320
319
318
317
234 56
VIN (V)
–40°C
25°C
85°C
78
3485 G15
LT3485 Switch Current Limits
2000
1600
1200
800
LT3485-3
LT3485-0
LT3485-2
LT3485-1
400
0
–40 –20
0 20 40 60
TEMPERATURE (°C)
80 100
3485 G18
34850123fb
5
5 Page 
LT3485-0/LT3485-1/
LT3485w-w2w/.DLatTaS3he4et48U.c5om-3
APPLICATIO S I FOR ATIO
Note that the absolute maximum rating of the SW pin is
not exceeded. Make sure to check the SW voltage wave-
form with VOUT near the target output voltage, as this is the
worst case condition for SW voltage. Figure 4 shows the
various limits on the SW voltage during switch turn off.
It is important not to minimize the leakage inductance to
a very low level. Although this would result in a very low
leakage spike on the SW pin, the parasitic capacitance of
the transformer would become large. This will adversely
affect the charge time of the photoflash circuit.
Linear Technology has worked with several leading mag-
netic component manufacturers to produce pre-designed
flyback transformers for use with the LT3485-0/LT3485-
1/LT3485-2/LT3485-3. Table 2 shows the details of sev-
eral of these transformers.
Capacitor Selection
For the input bypass capacitors, high quality X5R or X7R
types should be used. Make sure the voltage capability of
the part is adequate.
Output 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:
VPK−R = VOUT + (N • VIN)
IPRI
1A/DIV 2
VSW
10A/DIV
VIN = 5V
VOUT = 320V
100ns/DIV
3485 F03
Figure 3. LT3485 SW Voltage Waveform
“A”
VSW
“B”
MUST BE
LESS THAN 50V
MUST BE
LESS THAN 40V
0V
3485 F04
Figure 4. New Transformer Design Check (Not to Scale)
Table 2. Pre-Designed Transformers – Typical Specifications Unless Otherwise Noted
FOR USE WITH
TRANSFORMER
NAME
SIZE
LPRI LPRI-LEAKAGE
(W × L × H) mm (µH)
(nH)
N
RPRI
(mΩ)
LT3485-0/LT3485-2
LT3485-1
SBL-5.6-1
SBL-5.6S-1
5.6 × 8.5 × 4.0 10 200 Max 10.2 103
5.6 × 8.5 × 3.0 24 400 Max 10.2 305
RSEC
(Ω)
26
55
LT3485-0
LT3485-1
LT3485-2
LT3485-3
LT3485-0/LT3485-1
LT3485-1
LT3485-3
LDT565630T-001
LDT565630T-002
LDT565630T-003
LDT565630T-041
T-15-089
T-15-083
T-17-109A
5.8 × 5.8 × 3.0 6 200 Max 10.4 100 Max 10 Max
5.8 × 5.8 × 3.0 14.5 500 Max 10.2 240 Max 16.5 Max
5.8 × 5.8 × 3.0 10.5 550 Max 10.2 210 Max 14 Max
5.8 × 5.8 × 3.0 4.7 150 Max 10.4 90 Max 6.4 Max
6.4 × 7.7 × 4.0 12 400 Max 10.2 211 Max 27 Max
8.0 × 8.9 × 2.0 20 500 Max 10.2 675 Max 35 Max
6.5 × 7.9 × 4.0 5.9 300 Max 10.2 78 Max 18.61 Max
VENDOR
Kijima Musen
Hong Kong Office
852-2489-8266 (ph)
[email protected] (email)
TDK
Chicago Sales Office
(847) 803-6100 (ph)
www.components.tdk.com
Tokyo Coil Engineering
Japan Office
0426-56-6262 (ph)
www.tokyo-coil.co.jp
34850123fb
11
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet LT3485-1.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LT3485-0 | Photoflash Capacitor Chargers | Linear Technology |
| LT3485-1 | Photoflash Capacitor Chargers | Linear Technology |
| LT3485-2 | Photoflash Capacitor Chargers | Linear Technology |
| LT3485-3 | Photoflash Capacitor Chargers | Linear Technology |
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