LTC3255
3
3255f
For more information www.linear.com/LTC3255
The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V unless otherwise noted. (Notes 2, 3)
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IN
Input Voltage Range (Note 7)
l
4 48 V
V
OUT
Output Voltage Range
l
2.4 12.5 V
V
UVLO_BK
V
IN
Undervoltage Lockout Threshold
with Shunt Disabled
V
IN
Rising, SHUNT = GND
Hysteresis, SHUNT = GND
2.4
50
2.7 V
mV
V
UVLO_SH
V
IN
Undervoltage Lockout Threshold
with Shunt Enabled
V
IN
Rising, SHUNT= BIAS
Hysteresis, SHUNT= BIAS
5
200
5.7 V
mV
I
VIN
V
IN
Quiescent Current
EN Low
EN High, SHUNT = GND
EN High, SHUNT = BIAS
Shutdown
Enabled, Output in Regulation
Enabled, Output in Regulation
3
16
30
6
35
45
µA
µA
µA
I
VOUT
Available Output Current
Shunt Disabled
Shunt Enabled
SHUNT = GND
SHUNT = BIAS, I
VIN
= 4mA, V
OUT
= 3.3V
l
l
50
7.4
7.8
mA
mA
V
FB
Regulated Feedback Voltage
l
1.176 1.200 1.224 V
I
FB
FB Pin Leakage V
FB
= 1.3V ±10 nA
V
EN_VIH
EN High Level Input Voltage
l
1.4 V
V
EN_VIL
EN Low Level Input Voltage
l
0.4 V
I
EN
EN Pin Input Current V
EN
= 12V
V
EN
= 0V
0
0
±1
±1
µA
µA
I
LIM
V
OUT
Current Limit 120 mA
f
OSC
Oscillator Frequency 500 kHz
V
PGTHRESH
PGOOD Rising Threshold % of Final Regulation Voltage
l
90 94 98 %
V
PG(LOW)
PGOOD Output Low Voltage I
PGOOD
= 200µA 0.1 0.4 V
PGOOD High Impedance Leakage V
PGOOD
= 12V
l
1 µA
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: All voltages are referenced to GND unless otherwise specified.
Note 3: The LTC3255E is guaranteed to meet performance specifications
from 0°C to 85°C operating junction temperature. Specifications over
the –40°C to 125°C operating junction temperature range are assured by
design,
characterization and correlation with statistical process controls.
The LTC3255I is guaranteed over the –40°C to 125°C operating junction
temperature range. The LTC3255H is guaranteed over the –40°C to 150°C
operating junction temperature range. The LTC3255MP is guaranteed over
the –55°C to 150°C operating junction temperature range. High junction
temperatures degrade operating lifetimes; operating lifetime is derated
for junction temperatures greater than 125°C. Note that
the maximum
ambient temperature consistent with these specifications is determined by
specific operating conditions in conjunction with board layout, the rated
package thermal resistance and other environmental factors.
The junction temperature (T
J
, in °C) is calculated from the ambient
temperature (T
A
, in °C) and power dissipation (P
D
, in Watts) according to
the formula:
T
J
= T
A
+ (P
D
• θ
JA
)
where θ
JA
(in °C/W) is the package thermal impedance.
Note 4: The LTC3255 has an internal diode that conducts whenever V
OUT
is pulled below GND. When so pulled, absolute maximum current out of
V
OUT
is 50mA.
Note 5: The LTC3255 has an internal diode that conducts whenever
PGOOD is pulled below GND. When so pulled, absolute maximum current
out
of PGOOD is 100µA.
Note 6: This IC has overtemperature protection that is intended to protect
the device during momentary overload conditions. Junction temperatures
will exceed 150°C when overtemperature protection is active. Continuous
operation above the specified maximum operating junction temperature
may impair device reliability.
Note 7: This IC has input overvoltage protection that shuts down the
device whenever V
IN
exceeds the specified input voltage range. Shutdown
typically occurs when V
IN
exceeds 52V. V
IN
subsequently must fall below
50V (typical) for the IC to re-enable.
