Datasheet
LT3420/LT3420-1
3
3420fb
V
BAT
(V)
2
TIME (s)
3420 G03
453
6
10
8
6
4
2
0
V
OUT
CHARGED
FROM
50V TO 320V
T
A
= 25°C
FIGURE 1 CIRCUIT
UNLESS OTHERWISE
NOTED.
C
OUT
= 220µF
C
OUT
= 100µF
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: Rated breakdown with LT3420 in power delivery mode and power
switch off.
Note 3: The LT3420/LT3420-1 are guaranteed to meet performance
specifications from 0°C to 70°C. Specifications over the –40°C to 85°C
PARAMETER CONDITIONS MIN TYP MAX UNITS
Primary Side Current Limit LT3420 (Note 5) 1.20 1.4 1.60 A
LT3420-1 (Note 5) 0.75 0.9 1.05 A
Secondary Side Current Limit LT3420 (Note 5) 20 40 50 mA
LT3420-1 (Note 5) 5 15 25 mA
Leakage Blanking Pulse Width LT3420 200 ns
LT3420-1 0 ns
Refresh Timer Charge/Discharge Current V
CT
= 0.75V 1.5 2.5 3.5 µA
Refresh Timer Upper Threshold 0.9 1.0 1.1 V
Refresh Timer Lower Threshold 0.45 0.5 0.55 V
Switch V
CESAT
LT3420, SW = 1A (Note 5) 220 340 mV
LT3420-1, SW = 0.5A (Note 5) 130 230 mV
Switch Leakage Current V
SW
= 38V (LT3420), V
SW
= 50V (LT3420-1) 0.01 1 µA
CHARGE Input Voltage High 1.5 V
CHARGE Input Voltage Low 0.2 V
CHARGE Pin Bias Current V
CHARGE
= 3V 4.5 15 µA
V
CHARGE
= 0V 0.01 0.1 µA
DONE Output Signal High 100k from V
CC
to DONE 3.3 V
DONE Output Signal Low 33µA into DONE Pin 100 200 mV
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= V
BAT
= 3.3V, V
CHARGE
= V
CC
unless otherwise noted. (Note 3)
operating temperature range are assured by design, characterization and
correlation with statistical process controls.
Note 4: Bias current flows out of R
FB
pin.
Note 5: Current limit and V
CESAT
guaranteed by design and/or correlation
to static test for DD package.
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Output Voltage in Refresh Mode,
LT3420
Output Voltage in Refresh Mode,
LT3420
Charge Time, LT3420
TEMPERATURE (°C)
–50
V
OUT
(V)
100
3420 G01
050
335
330
325
320
315
310
305
300
295
–25 25 75 125
FIGURE 1 CIRCUIT
V
CC
= 3.3V
V
BAT
= 3.3V
V
IN
(V)
2.5
V
OUT
(V)
3420 G02
4.03.53.0 5.55.04.5 6.0
FIGURE 1 CIRCUIT
V
CC
= V
IN
V
BAT
= V
IN
T
A
= 25°C
335
330
325
320
315
310
305
300
295
Graphs apply to both the LT3420 and LT3420-1 unless otherwise noted.