LT3485-0/LT3485-1/
LT3485-2/LT3485-3
Photoflash Capacitor
Chargers with Output Voltage
Monitor and Integrated IGBT Drive
FEATURES
■
■
■
■
■
■
■
■
DESCRIPTIO
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
VERSION
LT3485-3
LT3485-0
LT3485-2
LT3485-1
INPUT CURRENT (mA)
750
500
350
225
CHARGE TIME (sec)
2.5
3.7
5.5
4.0*
Fast Charge Time
V
IN
= V
BAT
= 3.6V
100µF capacitor, 320V. *50µF capacitor
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 V
BAT
pin, which allows
the use of two AA cells to charge the capacitor. The internal
circuitry operates from the V
IN
pin. The LT3485-0 has a
primary current limit of 1.4A, whereas the LT3485-3, 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.
APPLICATIO S
■
Digital Camera and Cell Phone Flash Charger
TYPICAL APPLICATIO
V
BAT
2 AA OR
1 TO 2 Li-Ion
1:10.2
1
4.7µF
2
V
BAT
DONE
CHARGE
GND
LT3485-0
V
CC
5V
0.22µF
V
IN
IGBTPWR
IGBTIN
IGBTOUT
V
MONT
SW
LT3485-0 Photoflash Charger Uses High Efficiency 3mm Tall Transformers
DANGER HIGH VOLTAGE – OPERATION BY HIGH VOLTAGE TRAINED PERSONNEL ONLY
320V
4
1M
150µF
PHOTOFLASH
CAPACITOR
2.2µF
600V
TRIGGER T
1
2
TO
MICRO
3
C
AVERAGE
INPUT CURRENT
0.5A/DIV
•
•
5
A
V
OUT
50V/DIV
FLASHLAMP
IGBT
3485 TA01
U
LT3485-0 Charging Waveform
V
IN
= 3.6V
C
OUT
= 100µF
1s/DIV
3485 TA02
U
U
34850123fb
1
LT3485-0/LT3485-1/
LT3485-2/LT3485-3
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
CHARGE
V
BAT
V
IN
SW
SW
1
2
3
4
5
11
10 V
MONT
9 DONE
8 IGBTPWR
7 IGBTIN
6 IGBTOUT
V
IN
Voltage .............................................................. 10V
V
BAT
Voltage ............................................................ 10V
SW Voltage ................................................... –1V to 50V
SW Pin Negative Current ...................................... –0.5A
CHARGE Voltage ...................................................... 10V
IGBTIN Voltage ........................................................ 10V
IGBTOUT Voltage ..................................................... 10V
DONE Voltage .......................................................... 10V
IGBTPWR Voltage .................................................... 10V
V
MONT
Voltage ......................................................... 10V
Current into DONE Pin ............................... 0.2mA/–1mA
Maximum Junction Temperature .......................... 125°C
Operating Temperature Range (Note 2) ... –40°C to 85°C
Storage Temperature Range .................. –65°C to 125°C
DD PACKAGE
10-LEAD (3mm
´
3mm) PLASTIC DFN
T
JMAX
= 125°C
θ
JA
= 43°C/W
EXPOSED PAD (11) IS GND, MUST BE SOLDERED TO PCB
ORDER PART NUMBER
LT3485EDD-0
LT3485EDD-1
LT3485EDD-2
LT3485EDD-3
DD PART MARKING
LBRH
LBVN
LBVP
LBTK
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
PARAMETER
Quiescent Current
V
IN
Voltage Range
V
BAT
Voltage Range
Switch Current Limit
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= V
BAT
= V
CHARGE
= 3V, unless otherwise noted.
CONDITIONS
Not Switching
V
CHARGE
= 0V
●
●
MIN
TYP
5
0
2.5
1.7
1.6
1.1
0.75
0.45
1.7
1.2
0.85
0.55
310
210
170
100
31.5
200
45
65
0
MAX
8
1
10
10
1.8
1.3
0.95
0.65
400
300
225
175
32
400
120
100
0.1
UNITS
mA
µA
V
V
A
A
A
A
mV
mV
mV
mV
V
mV
mV
µA
µA
Switch V
CESAT
V
OUT
Comparator Trip Voltage
V
OUT
Comparator Overdrive
DCM Comparator Trip Voltage
CHARGE Pin Current
LT3485-3
LT3485-0
LT3485-2
LT3485-1
LT3485-3, I
SW
= 1.5A
LT3485-0, I
SW
= 1A
LT3485-2, I
SW
= 700mA
LT3485-1, I
SW
= 400mA
Measured as V
SW
– V
IN
300ns Pulse Width
Measured as V
SW
– V
IN
V
CHARGE
= 3V
V
CHARGE
= 0V
●
●
31
10
34850123fb
2
U
W
U
U
W W
W
LT3485-0/LT3485-1/
LT3485-2/LT3485-3
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= V
BAT
= V
CHARGE
= 3V, unless otherwise noted.
PARAMETER
Switch Leakage Current
CHARGE Input Voltage High
CHARGE Input Voltage Low
Minimum Charge Pin Low Time
DONE Output Signal High
DONE Output Signal Low
DONE Leakage Current
IGBT Input Voltage High
IGBT Input Voltage Low
IGBT Output Rise Time
IGBT Output Fall Time
V
OUT
Monitor Accuracy
Monitor Output Current
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
C
OUT
= 4000pF, IGBTPWR = 5V, 10%→90%
C
OUT
= 4000pF, IGBTPWR = 5V, 90%→10%
SW – V
BAT
= 20V
SW – V
BAT
= 30V
High→Low→High
100kΩ from V
IN
to DONE
33µA into DONE Pin
V
DONE
= 3V, DONE NPN Off
●
●
ELECTRICAL CHARACTERISTICS
CONDITIONS
V
IN
= V
SW
= 5V, in Shutdown
MIN
●
●
●
TYP
0.01
MAX
1
0.3
UNITS
µA
V
V
µs
V
1
20
3
140
20
1.5
0.3
450
340
625
940
200
200
100
mV
nA
V
V
ns
ns
mV
mV
µA
610
920
640
960
Note 2:
The LTC3485E-X is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
34850123fb
3
LT3485-0/LT3485-1/
LT3485-2/LT3485-3
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 Charging Waveform
LT3485-1 Charging Waveform
LT3485-2 Charging Waveform
TYPICAL PERFOR A CE CHARACTERISTICS
V
OUT
50V/DIV
AVERAGE
INPUT
CURRENT
1A/DIV V
IN
= 3.6V
C
OUT
= 50µF
0.5s/DIV
LT3485-3 Charging Waveform
CHARGE TIME (SECONDS)
V
OUT
50V/DIV
4
3
2
1
INPUT CURRENT (mA)
AVERAGE
INPUT
CURRENT
1A/DIV V = 3.6V
IN
C
OUT
= 50µF
0.5s/DIV
LT3485-1 Input Current
250
400
200
INPUT CURRENT (mA)
INPUT CURRENT (mA)
INPUT CURRENT (mA)
150
100
50
0
0
50
100
150 200
V
OUT
(V)
250
300
3485 G07
4
U W
2.5V
3.6V
4.2V
V
OUT
50V/DIV
V
OUT
50V/DIV
3485 G01
AVERAGE
INPUT
CURRENT
0.5A/DIV V
IN
= 3.6V
C
OUT
= 50µF
0.5s/DIV
3485 G02
AVERAGE
INPUT
CURRENT
0.5A/DIV V = 3.6V
IN
C
OUT
= 50µF
0.5s/DIV
3485 G03
Charge Time
6
LT3485-0 Input Current
C
OUT
= 50µF
600
500
LT3485-1
5
LT3485-2
400
300
200
100
2.5V
3.6V
4.2V
0
50
100
150 200
V
OUT
(V)
250
300
3485 G06
3485 G04
LT3485-0
0
2
3
4
LT3485-3
5
V
IN
(V)
6
7
8
1635 G05
0
LT3485-2 Input Current
900
800
300
LT3485-3 Input Current
700
600
500
400
300
200
100
0
0
50
100
150 200
V
OUT
(V)
250
300
3485 G09
200
100
2.5V
3.6V
4.2V
0
0
50
100
200
V
OUT
(V)
150
250
300
3485 G08
2.5V
3.6V
4.2V
34850123fb
LT3485-0/LT3485-1/
LT3485-2/LT3485-3
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
90
TYPICAL PERFOR A CE CHARACTERISTICS
LT3485-1 Efficiency
80
EFFICIENCY (%)
EFFICIENCY (%)
EFFICIENCY (%)
70
60
50
40
50
100
150
200
V
OUT
(V)
250
LT3485-3 Efficiency
90
322
80
EFFICIENCY (%)
V
OUT
(V)
60
319
V
OUT
(V)
70
50
40
50
100
150
200
V
OUT
(V)
250
LT3485-2 Output Voltage
328
327
326
V
OUT
(V)
325
324
323
322
318
–40°C
25°C
85°C
322
CURRENT LIMIT (mA)
V
OUT
(V)
2
3
4
5
V
IN
(V)
6
U W
2.5V
3.6V
4.2V
300
3485 G10
LT3485-2 Efficiency
90
80
80
70
70
60
60
50
2.5V
3.6V
4.2V
50
100
150
200
V
OUT
(V)
250
300
3485 G11
50
2.5V
3.6V
4.2V
50
100
150
200
V
OUT
(V)
250
300
3485 G12
40
40
LT3485-0 Output Voltage
322
LT3485-1 Output Voltage
321
321
320
320
319
2.5V
3.6V
4.2V
300
3485 G13
318
–40°C
25°C
85°C
2
3
4
5
V
IN
(V)
6
7
8
3485 G14
318
–40°C
25°C
85°C
2
3
4
5
V
IN
(V)
6
7
8
3485 G15
317
317
LT3485-3 Output Voltage
2000
LT3485 Switch Current Limits
LT3485-3
321
1600
LT3485-0
LT3485-2
800
LT3485-1
400
320
1200
319
–40°C
25°C
85°C
2
3
4
5
V
IN
(V)
6
7
8
3485 G17
317
7
8
3485 G16
0
–40
–20
40
20
0
60
TEMPERATURE (°C)
80
100
3485 G18
34850123fb
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