LT3958
4
3958f
ELECTRICAL CHARACTERISTICS The l denotes the specications which apply over the full operating temp-
erature range, otherwise specications are at TA = 25°C. VIN = 24V, EN/UVLO = 24V, SENSE2 = 0V, unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
INTVCC Current Limit
VIN = 80V
VIN = 20V
19
24
50
29
mA
INTVCC Load Regulation (ΔVINTVCC /VINTVCC)
0 < IINTVCC < 10mA, VIN = 8V
–1
–0.4
%
INTVCC Line Regulation (ΔVINTVCC /[ΔVIN VINTVCC]) 8V < VIN < 80V
0.005
0.025
%/V
Dropout Voltage (VIN – VINTVCC)VIN = 6V, IINTVCC = 10mA, VC = 0V
500
mV
INTVCC Current in Shutdown
EN/UVLO = 0V, INTVCC = 8V
16
μA
INTVCC Voltage to Bypass Internal LDO
7.5
V
Logic Inputs
EN/UVLO Threshold Voltage Falling
VIN = INTVCC = 8V
l
1.17
1.22
1.27
V
EN/UVLO Voltage Hysteresis
20
mV
EN/UVLO Input Low Voltage
IVIN 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 specications
from the 0°C to 125°C junction temperature. Specications 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 VFBX 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 VFBX(OVERVOLTAGE) relative
to regulated VFBX(REG).
Note 5: For 5V < VIN < 6V, the EN/UVLO pin must not exceed VIN.
Note 6: EN/UVLO = 1.33V when VIN = 5V.
TYPICAL PERFORMANCE CHARACTERISTICS
Positive Feedback Voltage
vs Temperature, VIN
Negative Feedback Voltage
vs Temperature, VIN
Quiescent Current
vs Temperature, VIN
TA = 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
VIN = 80V
VIN = 24V
VIN = 8V
VIN = INTVCC = 5V
TEMPERATURE (°C)
–50
–804
REGULATED
FEEDBACK
VOLTAGE
(mV)
–802
–800
–798
–792
–794
0
50
75
–796
–25
25
100
125
3958 G02
VIN = 80V
VIN = 24V
VIN = 8V
VIN = INTVCC = 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
VIN = 80V
VIN = 24V
VIN = INTVCC = 5V