LT3478IFE Ver la hoja de datos (PDF) - Linear Technology
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LT3478IFE Datasheet PDF : 24 Pages
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LT3478/LT3478-1
ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. SW = open, VIN = VS = L = VOUT = ⎯S⎯H⎯D⎯N = 2.7V, LED = open, SS = open,
PWM = CTRL1, CTRL2 = 1.25V, VREF = open, VC = open, RT = 31.6k.
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Frequency: fOSC 2.25MHz
Line Regulation fOSC
Nominal RT Pin Voltage
Maximum Duty Cycle
LED Current to VC Current Gain
LED Current to VC Voltage Gain
VC to Switch Current Gain
VC Source Current (Out of Pin)
VC Sink Current
VC Switching Threshold
VC High Level (VOH)
VC Low Level (VOL)
Inductor Current Limit
Switch Current Limit
RT = 9.09k
RT = 31.6k, 2.7V < VIN < 36V
RT = 31.6k
RT = 200k
RT = 9.09k
(Note 6)
(Note 6)
CTRL1 = 0.4V, VC = 1V
CTRL1 = 0V, VC = 1V
CTRL1 = 0.4V
CTRL1 = 0V
2.7V < VS < 36V
2
2.25
2.6
MHz
0.05
0.2
%/V
0.64
V
● 80
88
%
97
%
73
%
770
µA/A
400
V/A
13
A/V
40
µA
40
µA
0.65
V
1.5
V
0.2
V
● 4.5
6
6.8
A
● 4.5
6.3
7.5
A
Switch VCE SAT
Switch Leakage Current
VOUT Overvoltage Protection (OVP)
(Rising)
ISW = 4.5A
SW = 42V, VC = 0V
OVPSET = 1V
OVPSET = 0.3V
270
mV
1
µA
41
V
12.3
V
Full Scale LED Current (LT3478-1)
700mA LED Current (LT3478-1)
CTRL1 = VREF, Current Out of LED Pin
CTRL1 = 700mV, Current Out of LED Pin
1010 1050 1090
mA
● 655
700
730
mA
350mA LED Current (LT3478-1)
CTRL1 = 350mV, Current Out of LED Pin
325
350
375
mA
100mA LED Current (LT3478-1)
CTRL1 = 100mV, Current Out of LED Pin
70
100
130
mA
Full Scale LED Current VSENSE (LT3478) CTRL1 = VREF, VSENSE = VVOUT – VLED
CTRL1 = 700mV, VSENSE (LT3478)
CTRL1 = 700mV, VSENSE = VVOUT – VLED
CTRL1 = 350mV, VSENSE (LT3478)
CTRL1 = 350mV, VSENSE = VVOUT – VLED
CTRL1 = 100mV, VSENSE (LT3478)
CTRL1 = 100mV, VSENSE = VVOUT – VLED
CTRL1, 2 Input Currents
CTRL1 = 100mV, CTRL2 = 1.25V or
CTRL2 = 100mV, CTRL1 = 1.25V (Current Out of Pin)
101
105
109
mV
● 67
70.5
74
mV
33
35.5
38
mV
7
10
13
mV
40
nA
OVPSET Input Current
PWM Switching Threshold
OVPSET = 1V, VOUT = 41V (Current Out of Pin)
200
nA
0.8
1
1.2
V
VC Pin Current in PWM Mode
OUT Pin Current in PWM Mode
VC = 1V, PWM = 0
PWM = 0
1
50
nA
1
100
nA
SS Low Level (VOL)
SS Reset Threshold
SS High Level (VOH)
Soft-Start (SS) Pin Charge Current
Soft-Start (SS) Pin Discharge Current
I(SS) = 20µA
VC = 0V
VC = 0V
SS = 1V, Current Out of Pin, VC = 0V
SS = 0.5V, VC = 0V
0.15
V
0.25
V
1.5
V
12
µA
350
µA
34781f
3
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