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LT3420EMS#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20
4
LT3420/LT3420-1
3420fb
Output Voltage in Refresh Mode,
LT3420-1
TEMPERATURE (°C)
–50
V
OUT
(V)
100
3420 G04
050
335
330
325
320
315
310
305
300
295
–25 25 75 125
FIGURE 2 CIRCUIT
V
CC
= 3.3V
V
BAT
= 3.3V
V
IN
(V)
2.5
V
OUT
(V)
5.5
3420 G05
5.03.0 4.03.5 4.5 6.0
FIGURE 2 CIRCUIT
V
CC
= V
IN
V
BAT
= V
IN
T
A
= 25°C
335
330
325
320
315
310
305
300
295
V
BAT
(V)
2
TIME (s)
6
3420 G06
3
4
5
10
8
6
4
2
0
FIGURE 2 CIRCUIT
V
OUT
CHARGED
FROM 50V TO 320V
T
A
= 25°C
C
OUT
= 100µF
C
OUT
= 40µF
Output Voltage in Refresh Mode,
LT3420-1
Charge Pin Input Current
Primary Current Limit, LT3420
Secondary Current Limit, LT3420
Charge Time, LT3420-1
CHARGE PIN VOLTAGE (V)
2
CURRENT (µA)
10
8
6
4
2
0
57 10
3420 G07
34
6
89
T
A
= 25°C
TEMPERATURE (°C)
–50
CURRENT (A)
3420 G08
0
50
100
1.7
1.5
1.3
1.1
0.9
–25 25 75
125
TEMPERATURE (°C)
–50
CURRENT (mA)
100
3420 G09
050
60
55
50
45
40
35
30
25
20
–25 25 75 125
Efficiency of Figure 1 Circuit,
LT3420
Primary Current Limit, LT3420-1
Secondary Current Limit, LT3420-1
EFFICIENCY (%)
3420 G10
90
80
70
60
50
40
V
OUT
(V)
100 200 300
50 150 350250
V
CC
= V
BAT
= V
IN
V
IN
= 3.3V
V
IN
= 5V
T
A
= 25°C
TEMPERATURE (°C)
–50
CURRENT (A)
3420 G11
0
50
100
1.2
1.1
1.0
0.9
0.8
–25 25 75
125
TEMPERATURE (°C)
–50
CURRENT (mA)
100
3420 G12
050
35
30
25
20
15
10
5
–25 25 75 125
Graphs apply to both the LT3420 and LT3420-1 unless otherwise noted.
TYPICAL PERFOR A CE CHARACTERISTICS
UW
LT3420/LT3420-1
5
3420fb
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Efficiency for Figure 2 Circuit,
LT3420-1 Input Current, LT3420
V
CC
Minimum Operating VoltageQuiescent Current in Refresh Mode V
BAT
Minimum Operating Voltage
Input Current, LT3420-1
EFFICIENCY (%)
3420 G13
90
80
70
60
50
40
V
OUT
(V)
100 200 300
50 150 350250
V
CC
= V
BAT
= V
IN
V
IN
= 3.3V
V
IN
= 5V
T
A
= 25°C
AVERAGE INPUT CURRENT (mA)
3420 G14
1000
900
800
700
600
500
V
OUT
(V)
100 200 300
50 150 350250
FIGURE 1 CIRCUIT
V
CC
= V
BAT
= 3.3V
T
A
= 25°C
V
OUT
(V)
50
300
AVERAGE INPUT CURRENT (mA)
350
400
450
500
600
100
150 200 250
3420 G15
300 350
550
FIGURE 2 CIRCUIT
V
CC
= V
BAT
= 3.3V
T
A
= 25°C
V
CC
(V)
2.5
QUIESCENT CURRENT (µA)
10
3420 G16
5.5 8.5
140
120
100
80
60
4.0 7.0
T
A
= 25°C
TEMPERATURE (°C)
–50
V
CC
PIN VOLTAGE (V)
100
3420 G17
050
2.6
2.5
2.4
2.3
2.2
2.1
2.0
1.9
1.8
–25 25 75 125
V
+
V
–
ENABLE VOLTAGE
IS HYSTERETIC
TEMPERATURE (°C)
–50
V
BAT
PIN VOLTAGE (V)
100
3420 G18
050–25 25 75 125
2.0
1.8
1.6
1.4
1.2
1.0
V
+
V
–
ENABLE VOLTAGE
IS HYSTERETIC
Graphs apply to both the LT3420 and LT3420-1 unless otherwise noted.
6
LT3420/LT3420-1
3420fb
UU
U
PI FU CTIO S
R
REF
(Pin 1): Reference Resistor Pin. Place a resistor (R2)
from the R
REF
pin to GND. 2k is recommended.
V
BAT
(Pin 2): Battery Voltage Input. This pin should be
connected to the power supply or battery, which supplies
power to transformer T1. Must be locally bypassed.
R
FB
(Pin 3): Feedback Resistor Pin. Place a resistor (R1)
from the SW pin to the R
FB
pin. Set R1 according to the
following formula:
R
R
N
RNV V
SEC OUT D
1
2
14 2
2
=++
[]
(. • ) ( )
(LT3420)
R
R
N
RNV V
SEC OUT D
1
2
2
2
=++
[]
()( )
(LT3420-1)
V
OUT
: Desired Output Voltage
N: Transformer Turns Ratio
R
SEC
: Transformer Secondary Resistance
V
D
: Diode Forward Voltage Drop
R2: Resistor from the R
REF
Pin to GND. 2k is a Typical
Choice
V
CC
(Pin 4): Input Supply Pin. Must be locally bypassed
with a 4.7µF or larger ceramic capacitor.
GND (Pin 5): Ground. Tie directly to local ground plane.
SW (Pin 6): 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.
SEC (Pin 7): Transformer Secondary Pin. Tie one end of
the transformer secondary to this pin. Take care to use the
correct phasing of the transformer (Refer to Figures 1
and 2).
DONE (Pin 8): Done Output Pin. Open collector NPN
output. DONE is pulled low whenever the chip is delivering
power to the output and goes high when power delivery
stops.
CHARGE (Pin 9): Charge Pin. Drive CHARGE high (1.5V or
more) to commence charging of the output capacitor.
Drive to 0.2V or less to put the part in shutdown mode.
C
T
(Pin 10): Refresh Timer Capacitor Pin. Place a capacitor
from the C
T
pin to GND to set the refresh timer sample rate
according to the following formula:
C
T
= 2.5 • 10
–6
• t
REFRESH
t
REFRESH
: Desired Refresh Period in Seconds.
EXPOSED PAD (Pin 11) (DD Package only): GND. Must be
soldered to local ground plane on PCB.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20

LT3420EMS#PBF

Mfr. #:
Buy LT3420EMS#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators 1.4A Photoflash Capacitor Charger
Lifecycle:
New from this manufacturer.
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