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elecTrical characTerisTics
erature range, otherwise specifications are at T
PARAMETER
SW Pin Leakage
SW Pin Current Limit
SW Pin Voltage Drop
SS Pull-Up Current
Error Amplifier
Full-Scale Current Sense Threshold ( V
Current Sense Threshold at CTRL = 1V ( V
Current Sense Threshold at CTRL = 0.5V ( V
Current Sense Threshold at CTRL = 0.1V ( V
CTRL Range for Current Sense Threshold Adjustment
CTRL Input Bias Current
Current Sense Amplifier Input Common Mode
Range ( V
)
ISN
ISP/ISN Short-Circuit Threshold ( V
ISP/ISN Short-Circuit Fault Sensing Common Mode
Range ( V
)
ISN
ISP/ISN Input Bias Current (Combined)
LED Current Sense Amplifier g
m
V
Output Impedance
C
V
Standby Input Bias Current
C
FB Regulation Voltage (V
)
FB
FB Amplifier g
m
FB Pin Input Bias Current
FB Voltage Loop Active Threshold
FB Overvoltage Threshold
Oscillator
Switching Frequency
SW Minimum Off-Time
SW Minimum On-Time
Linear Regulator
INTV
Regulation Voltage
CC
Dropout (V
– INTV
)
IN
CC
INTV
Undervoltage Lockout
CC
INTV
Current Limit
CC
INTV
Current in Shutdown
CC
The
= 25°C. V
A
IN
CONDITIONS
SW = 48V
I(SW) = 2A
Current Out of Pin
)
FB = 0V, ISP = 48V, CTRL ≥ 1.2V
(ISP–ISN)
)
CTRL = 1V, FB = 0V, ISP = 48V
(ISP–ISN)
)
CTRL = 0.5V
(ISP–ISN)
)
CTRL = 0.1V, FB = 0V, ISP = 48V
(ISP–ISN)
Current Out of Pin, CTRL = 0V
)
ISN = 0V
(ISP–ISN)
PWM = 5V (Active), ISP = ISN = 48V
PWM = 0V (Standby), ISP = ISN = 48V
1V < V
< 2V
C
PWM = 0V
ISP = ISN = 0V, 48V
FB = V
, ISP = ISN
FB
Current Out of Pin, FB = 1V
VMODE Falling
PWMOUT Falling
R
= 100k
T
R
= 10k
T
I
= –10mA, V
INTVCC
EN/UVLO = 0V, INTV
denotes the specifications which apply over the full operating temp-
l
= 24V, EN/UVLO = 24V, CTRL = 2V, PWM = 5V, unless otherwise noted.
= 7V
IN
= 7V
CC
LT3956
MIN
TYP
MAX
5
10
3.3
3.9
4.6
l
220
8
10
13
240
250
257
l
217
225
231
l
96
100
103
l
–2.5
0
4.5
l
0
1.1
50
100
2.9
80
300
335
370
0
3
80
0
0.1
120
15000
–20
20
1.220
1.250
1.270
l
1.232
1.250
1.265
480
40
100
V
–
V
–
V
FB
FB
FB
65mV
50mV
40mV
V
+ 50mV
V
+
V
FB
FB
FB
60mV
80mV
90
100
125
l
925
1000
1050
170
200
7
7.15
7.3
1
4.1
4.4
l
14
17
25
8
12
UNITS
µA
A
mV
µA
mV
mV
mV
mV
V
nA
V
mV
V
µA
µA
µS
kΩ
nA
V
V
µS
nA
–
V
+
V
kHz
kHz
ns
ns
V
V
V
mA
µA
3956f
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