LT1175
ELECTRICAL CHARACTERISTICS
PARAMETER
Current Limit (Note 12)
The
l
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
OUT
= 5V, V
IN
= 7V, I
OUT
= 0, V
SHDN
= 3V, I
LIM2
and I
LIM4
tied to V
IN
.
To avoid confusion with “min” and “max” as applied to negative voltages, all voltages are shown as absolute values except where
polarity is not obvious.
CONDITIONS
V
IN
– V
OUT
= 1V to 12V
I
LIM2
Open
I
LIM4
Open
I
LIM2
, I
LIM4
Open
V
IN
– V
OUT
= 1V to V
IN
= 20V
I
OUT
= 0mA to 500mA
P = 0 to P
MAX
(Notes 4, 9)
T
J
= 25°C to T
JMIN
, or 25°C to T
JMAX
5-Pin Packages
8-Pin Packages
l
l
l
l
l
l
MIN
520
390
260
130
TYP
800
600
400
200
0.003
0.1
0.04
0.1
0.25
MAX
1300
975
650
325
0.015
0.35
0.1
0.2
1.25
UNITS
mA
mA
mA
mA
%/V
%
%/W
%/W
%
Line Regulation (Note 11)
Load Regulation (Note 6, 11)
Thermal Regulation
Output Voltage Temperature Drift
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 LT1175 regulators are tested and specified under pulse load
conditions such that T
J
T
A
. The LT1175C is 100% production tested
at T
A
= 25°C. Performance at 0°C and 125°C is assured by design,
characterization and correlation with statistical process controls. The
LT1175I is guaranteed over the full –40°C to 125°C operating junction
temperature range. The LT1175MP is 100% tested and guaranteed over
the –55°C to 125°C operating junction temperature range.
Note 3:
SHDN
pin maximum positive voltage is 30V with respect to
– V
IN
and 13.5V with respect to GND. Maximum negative voltage is –20V
with respect to GND and –5V with respect to –V
IN
.
Note 4:
P
MAX
= 1.5W for 8-pin packages, and 6W for 5-pin packages.
This power level holds only for input-to-output voltages up to 12V, beyond
which internal power limiting may reduce power. See Guaranteed Current
Limit curve in Typical Performance Characteristics section. Note that all
conditions must be met.
Note 5:
GND pin current increases because of power transistor base
drive. At low input-to-output voltages (<1V) where the power transistor
is in saturation, GND pin current will be slightly higher. See Typical
Performance Characteristics.
Note 6:
With I
LOAD
= 0, at T
J
> 125°C, power transistor leakage could
increase higher than the 10μA to 25μA drawn by the output divider or fixed
voltage SENSE pin, causing the output to rise above the regulated value.
To prevent this condition, an internal active pull-up will automatically turn
on, but supply current will increase.
Note 7:
This is the current required to pull the output voltage to within 1V
of ground during shutdown.
Note 8:
Dropout voltage is measured by setting the input voltage equal to
the normal regulated output voltage and measuring the difference between
V
IN
and V
OUT
. For currents between 100mA and 500mA, with both I
LIM
pins tied to V
IN
, maximum dropout can be calculated from
V
DO
= 0.15 + 1.1Ω (I
OUT
).
Note 9:
Thermal regulation is a change in the output voltage caused by
die temperature gradients, so it is proportional to chip power dissipation.
Temperature gradients reach final value in less than 100ms. Output voltage
changes after 100ms are due to absolute die temperature changes and
reference voltage temperature coefficient.
Note 10:
The lower limit of 0.8V is guaranteed to keep the regulator in
shutdown. The upper limit of 2.5V is guaranteed to keep the regulator
active. Either polarity may be used, referenced to GND pin.
Note 11:
Load and line regulation are measured on a pulse basis with
pulse width of 20ms or less to keep chip temperature constant. DC
regulation will be affected by thermal regulation (Note 8) and chip
temperature changes. Load regulation specification also holds for currents
up to the specified current limit when I
LIM2
or I
LIM4
are left open.
Note 12:
Current limit is reduced for input-to-output voltage above 12V.
See the graph in Typical Performance Characteristics for guaranteed limits
above 12V.
Note 13:
Operating at very large input-to-output differential voltages
(>15V) with load currents less than 5mA requires an output capacitor with
an ESR greater than 1Ω to prevent low level output oscillations.
1175ff
5
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