Datasheet

LT3958
4
3958f
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating temp-
erature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= 24V, EN/UVLO = 24V, SENSE2 = 0V, unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
INTV
CC
Current Limit V
IN
= 80V
V
IN
= 20V
19 24
50
29 mA
mA
INTV
CC
Load Regulation (ΔV
INTVCC
/V
INTVCC
)
0 < I
INTVCC
< 10mA, V
IN
= 8V –1 –0.4 %
INTV
CC
Line Regulation (ΔV
INTVCC
/[ΔV
IN
• V
INTVCC
])
8V < V
IN
< 80V 0.005 0.025 %/V
Dropout Voltage (V
IN
– V
INTVCC
)V
IN
= 6V, I
INTVCC
= 10mA, VC = 0V 500 mV
INTV
CC
Current in Shutdown EN/UVLO = 0V, INTV
CC
= 8V 16 µA
INTV
CC
Voltage to Bypass Internal LDO 7.5 V
Logic Inputs
EN/UVLO Threshold Voltage Falling V
IN
= INTV
CC
= 8V
l
1.17 1.22 1.27 V
EN/UVLO Voltage Hysteresis 20 mV
EN/UVLO Input Low Voltage I
VIN
Drops Below 1µA 0.4 V
EN/UVLO Pin Bias Current Low EN/UVLO = 1.15V 1.7 2 2.5 µA
EN/UVLO Pin Bias Current High EN/UVLO = 1.33V 10 100 nA
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LT3958E is guaranteed to meet performance specifi cations
from the 0°C to 125°C junction temperature. Specifi cations over the –40°C
to 125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LT3958I is guaranteed over the full –40°C to 125°C operating junction
temperature range.
Note 3: The LT3958 is tested in a feedback loop which servos V
FBX
to the
reference voltages (1.6V and –0.8V) with the VC pin forced to 1.3V.
Note 4: FBX overvoltage lockout is measured at V
FBX(OVERVOLTAGE)
relative
to regulated V
FBX(REG)
.
Note 5: For 5V < V
IN
< 6V, the EN/UVLO pin must not exceed V
IN
.
Note 6: EN/UVLO = 1.33V when V
IN
= 5V.
TYPICAL PERFORMANCE CHARACTERISTICS
Positive Feedback Voltage
vs Temperature, V
IN
Negative Feedback Voltage
vs Temperature, V
IN
Quiescent Current
vs Temperature, V
IN
T
A
= 25°C, unless otherwise noted.
TEMPERATURE (°C)
–50
1.590
REGULATED FEEDBACK VOLTAGE (V)
1.592
1.596
1.598
1.600
1.604
0
50
75
1.594
1.602
–25
25
100
125
3958 G01
V
IN
= 80V
V
IN
= 24V
V
IN
= 8V
V
IN
= INTV
CC
= 5V
TEMPERATURE (°C)
–50
–804
REGULATED FEEDBACK VOLTAGE (mV)
–802
–800
–798
–792
–794
0
50
75
–796
–25
25
100
125
3958 G02
V
IN
= 80V
V
IN
= 24V
V
IN
= 8V
V
IN
= INTV
CC
= 5V
TEMPERATURE (°C)
–50
1.4
QUIESCENT CURRENT (mA)
1.6
1.8
0
50
75
1.5
1.7
–25
25
100
125
3958 G03
V
IN
= 80V
V
IN
= 24V
V
IN
= INTV
CC
= 5V