LT3484-0/LT3484-1/LT3484-2
Photoflash Capacitor
Chargers
FEATURES
■
■
■
DESCRIPTIO
■
■
■
■
■
■
Highly Integrated IC in 2mm
×
3mm DFN Package
Reduces Solution Size
Uses Small Transformers:
5.8mm
×
5.8mm
×
3mm
Fast Photoflash Charge Times:
4.6s for LT3484-0 (0V to 320V, 100µF, V
IN
= 3.6V)
5.7s for LT3484-2 (0V to 320V, 100µF, V
IN
= 3.6V)
5.5s for LT3484-1 (0V to 320V, 50µF, V
IN
= 3.6V)
Operates from Two AA Batteries, or Any Supply from
1.8V up to 16V
Controlled Average Input Current
500mA (LT3484-0)
350mA (LT3484-2)
225mA (LT3484-1)
No Output Voltage Divider Needed
No External Schottky Diode Required
Charges Any Size Photoflash Capacitor
Available in 6-Lead 2mm
×
3mm DFN Package
The LT
®
3484 family of photoflash capacitor charger ICs is
designed for use in digital camera and mobile phone
applications where space is at a premium. The LT3484’s
patented control technique allows it to use extremely small
transformers, and the improved NPN power switch re-
quires no external Schottky diode clamp, reducing solu-
tion size. Output voltage detection requires no external
circuitry as the transformer turns ratio determines final
charge voltage.
The devices feature a V
BAT
pin, which allows the use of 2
alkaline cells to charge the capacitor. The LT3484-0, -2
and -1 have primary current limits of 1.4A, 1A and 0.7A
respectively, resulting in tightly controlled average input
current of 500mA, 350mA and 225mA respectively. The
three versions are otherwise identical.
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
LT3484 series of parts are housed in a tiny low profile
2mm
×
3mm DFN package.
, LTC and LT 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
LT3484-0 Photoflash Charger Uses
High Efficiency 3mm Tall Transformers
DANGER HIGH VOLTAGE – OPERATION BY HIGH VOLTAGE
TRAINED PERSONNEL ONLY
V
BAT
2AA OR
1 TO 2 Li-Ion
1:10.2
1
4.7µF
2
V
BAT
V
IN
0.1µF
100k
LT3484-0
DONE
CHARGE
348412 TA01
LT3484-0 Charging Waveform
V
IN
= 3.6V
C
OUT
= 100µF
4
5
320V
+
SW
V
CC
5V
150µF
PHOTOFLASH
CAPACITOR
V
OUT
50V/DIV
AVERAGE
INPUT
CURRENT
1A/DIV
GND
U
1s/DIV
3484 TA02
U
U
3484012f
1
LT3484-0/LT3484-1/LT3484-2
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
DONE 1
CHARGE 2
V
IN
3
7
6 V
BAT
5 SW
4 SW
V
IN
Voltage .............................................................. 16V
V
BAT
Voltage ............................................................ 16V
SW Voltage ................................................... –1V to 50V
SW Pin Negative Current ...................................... –0.5A
CHARGE Voltage ...................................................... 10V
DONE Voltage .......................................................... 10V
Current into DONE Pin ..........................................
±1mA
Maximum Junction Temperature .......................... 125°C
Operating Temperature Range .................–40°C to 85°C
Storage Temperature Range ..................–65°C to 150°C
DCB6 PACKAGE
6-LEAD (2mm
×
3mm) PLASTIC DFN
T
JMAX
= 125°C
θ
JA
= 73.5°C/W
EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB
ORDER PART NUMBER
LT3484EDCB-0
LT3484EDCB-1
LT3484EDCB-2
DCB6 PART MARKING
LBTM
LBTN
LBTP
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.
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
Quiescent Current
V
CC
Voltage Range
V
BAT
Voltage Range
Switch Current Limit
LT3484-0
LT3484-2
LT3484-1
LT3484-0, I
SW
= 1A
LT3484-2, I
SW
= 650mA
LT3484-1, I
SW
= 400mA
Measured as V
SW
– V
IN
300ns Pulse Width
Measured as V
SW
– V
IN
V
CHARGE
= 3V
V
CHARGE
= 0V
V
IN
= V
SW
= 5V, in Shutdown
●
●
●
●
●
ELECTRICAL CHARACTERISTICS
CONDITIONS
Not Switching
V
CHARGE
= 0V
●
●
MIN
TYP
5
0
MAX
8
1
16
16
UNITS
mA
µA
V
V
A
A
A
mV
mV
mV
V
mV
mV
µA
µA
µA
V
V
V
mV
nA
2.5
1.7
1.1
0.75
0.45
1.2
0.85
0.55
330
210
150
31
10
31.5
200
60
65
0
0.01
1
1.3
0.95
0.65
430
280
200
32
400
120
100
0.1
1
0.3
Switch V
CESAT
V
OUT
Comparator Trip Voltage
V
OUT
Comparator Overdrive
DCM Comparator Trip Voltage
CHARGE Pin Current
Switch Leakage Current
CHARGE Input Voltage High
CHARGE Input Voltage Low
DONE Output Signal High
DONE Output Signal Low
DONE Leakage Current
100kΩ from V
IN
to DONE
33µA into DONE Pin
V
DONE
= 3V, DONE NPN Off
3
100
20
200
100
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
3484012f
2
U
W
U
U
W W
W
LT3484-0/LT3484-1/LT3484-2
LT3484-0 curves use the circuit of Figure 6,
LT3484-1 curves use the circuit of Figure 7 and LT3484-2 use the circuit of Figure 8, T
A
= 25°C unless otherwise noted.
LT3484-0 Charging Waveform
V
IN
= 3.6V
C
OUT
= 100µF
TYPICAL PERFOR A CE CHARACTERISTICS
V
IN
= 3.6V
C
OUT
= 50µF
V
OUT
50V/DIV
AVERAGE
INPUT
CURRENT
1A/DIV
1s/DIV
LT3484-0 Charge Time
10
9
8
CHARGE TIME (s)
CHARGE TIME (s)
100µF
CHARGE TIME (s)
7
6
5
4
3
2
1
0
2
50µF
3
4
5
V
IN
(V)
6
LT3484-0 Output Voltage
327
326
325
V
OUT
(V)
V
OUT
(V)
T
A
= –40°C
T
A
= 25°C
T
A
= 85°C
324
323
322
321
320
2
3
4
5
V
IN
(V)
3484 G07
324
323
322
321
320
V
OUT
(V)
6
U W
3484 G01
LT3484-1 Charging Waveform
LT3484-2 Charging Waveform
V
IN
= 3.6V
C
OUT
= 100µF
V
OUT
50V/DIV
V
OUT
50V/DIV
AVERAGE
INPUT
CURRENT
0.5A/DIV
1s/DIV
3484 G02
AVERAGE
INPUT
CURRENT
0.5A/DIV
1s/DIV
3484 G03
LT3484-1 Charge Time
10
9
8
7
6
5
4
3
2
1
0
7
8
3484 G04
LT3484-2 Charge Time
10
9
8
7
6
5
4
3
2
1
0
50µF
50µF
100µF
20µF
2
3
4
5
V
IN
(V)
6
7
8
3484 G05
2
3
4
5
V
IN
(V)
6
7
8
3484 G06
LT3484-1 Output Voltage
327
326
325
325
324
323
322
321
2
3
4
5
V
IN
(V)
3484 G08
LT3484-2 Output Voltage
327
T
A
= –40°C
T
A
= 25°C
T
A
= 85°C
T
A
= –40°C
T
A
= 25°C
T
A
= 85°C
326
7
8
6
7
8
2
3
4
5
V
IN
(V)
6
7
8
3484 G09
3484012f
3
LT3484-0/LT3484-1/LT3484-2
LT3484-0 curves use the circuit of Figure 6,
LT3484-1 curves use the circuit of Figure 7 and LT3484-2 use the circuit of Figure 8, T
A
= 25°C unless otherwise noted.
LT3484-0 Switch Current Limit
1.5
0.70
TYPICAL PERFOR A CE CHARACTERISTICS
1.4
CURRENT LIMIT (A)
CURRENT LIMIT (A)
0.62
CURRENT LIMIT (A)
100
1.3
1.2
1.1
– 40 – 20
40
20
0
60
TEMPERATURE (°C)
LT3484-0 Input Current
800
V
IN
= 2.4
V
IN
= 3.6
V
IN
= 4.2
600
300
400
CURRENT (mA)
CURRENT (mA)
400
200
CURRENT (mA)
200
0
0
50
100
150
200
250
300
3484 G13
V
OUT
(V)
LT3484-0 Efficiency
90
85
80
75
90
85
80
75
EFFICIENCY (%)
EFFICIENCY (%)
70
65
60
55
50
45
40
50
100
200
150
V
OUT
(V)
V
IN
= 2.4
V
IN
= 3.6
V
IN
= 4.2
250
300
3484 G16
70
65
60
55
50
45
40
50
100
200
150
V
OUT
(V)
V
IN
= 2.4
V
IN
= 3.6
V
IN
= 4.2
250
300
3484 G17
EFFICIENCY (%)
4
U W
80
100
3484 G10
LT3484-1 Switch Current Limit
1.00
LT3484-2 Switch Current Limit
0.66
0.96
0.92
0.58
0.88
0.54
0.84
0.50
– 40 – 20
40
20
0
60
TEMPERATURE (°C)
80
0.80
– 40 – 20
40
20
0
60
TEMPERATURE (°C)
80
100
3484 G11
3484 G12
LT3484-1 Input Current
600
V
IN
= 2.4
V
IN
= 3.6
V
IN
= 4.2
450
LT3484-2 Input Current
V
IN
= 2.4
V
IN
= 3.6
V
IN
= 4.2
300
100
150
0
0
50
100
150
200
250
300
3484 G14
0
0
50
100
150
200
250
300
3484 G15
V
OUT
(V)
V
OUT
(V)
LT3484-1 Efficiency
90
85
80
75
70
65
60
55
50
45
40
LT3484-2 Efficiency
V
IN
= 2.4
V
IN
= 3.6
V
IN
= 4.2
50
100
200
150
V
OUT
(V)
250
300
3484 G18
3484012f
LT3484-0/LT3484-1/LT3484-2
LT3484-0 curves use the circuit of Figure 6,
LT3484-1 curves use the circuit of Figure 7 and LT3484-2 use the circuit of Figure 8, T
A
= 25°C unless otherwise noted.
LT3484-0 Switching Waveform
V
IN
= 3.6V
V
OUT
= 100V
TYPICAL PERFOR A CE CHARACTERISTICS
V
SW
10V/DIV
I
PRI
1A/DIV
1µs/DIV
3484 G19
LT3484-0 Switching Waveform
V
IN
= 3.6V
V
OUT
= 300V
V
SW
10V/DIV
I
PRI
1A/DIV
1µs/DIV
SWITCH CURRENT (mA)
U W
LT3484-1 Switching Waveform
V
IN
= 3.6V
V
OUT
= 100V
V
SW
10V/DIV
I
PRI
1A/DIV
1µs/DIV
LT3484-2 Switching Waveform
V
IN
= 3.6V
V
OUT
= 100V
V
SW
10V/DIV
I
PRI
1A/DIV
3484 G22
1µs/DIV
3484 G21
LT3484-1 Switching Waveform
V
IN
= 3.6V
V
OUT
= 300V
LT3484-2 Switching Waveform
V
IN
= 3.6V
V
OUT
= 300V
V
SW
10V/DIV
I
PRI
1A/DIV
3484 G20
V
SW
10V/DIV
I
PRI
1A/DIV
1µs/DIV
3484 G23
1µs/DIV
3484 G24
LT3484-0/LT3484-1/LT3484-2
Switch Breakdown Voltage
10
SW PIN IS RESISTIVE UNTIL BREAKDOWN
9 VOLTAGE DUE TO INTEGRATED
RESISTORS. THIS DOES NOT INCREASE
8 QUIESCENT CURRENT OF PART
7
6
5
4
3
2
1
0
0
V
IN
= V
CHARGE
= 5V
10 20 30 40 50 60 70 80 90 100
SWITCH VOLTAGE (V)
3484 G25
T = 25°C
T = –40°C
T = 85°C
3484012f
5
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