Datasheet

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