LT1175
elecTrical characTerisTics
Note 8:
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 9:
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 10:
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 11:
Current limit is reduced for input-to-output voltage above 12V.
See the graph in Typical Performance Characteristics for guaranteed limits
above 12V.
Note 12:
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.
Typical perForMance characTerisTics
Typical Current Limit
Characteristics
1.0
CURRENT LIMIT CHANGES ONLY SLIGHTLY
WITH TEMPERATURE SO CURVES ARE
REPRESENTATIVE OF ALL TEMPERATURES
I
LIM2
, I
LIM4
TIED TO V
IN
CURRENT (A)
0.4
0.3
0.2
0.1
0
I
LIM4
TIED TO V
IN
I
LIM2
TIED TO V
IN
I
LIM2
, I
LIM4
OPEN
5
15
20
0
25
10
INPUT-TO-OUTPUT DIFFERENTIAL VOLTAGE (V)
1175 G01
Guaranteed Current Limit
0.6
I
LIM2
, I
LIM4
TIED TO V
IN
0.5
I
LIM4
TIED TO V
IN
CURVES REPRE-
SENT MINIMUM
GUARANTEED
LIMITS AT ALL
TEMPERATURES
VOLTAGE (V)
5.05
Output Voltage Temperature Drift
OUTPUT
FIXED 5V PART
0.8
CURRENT (A)
5.00
0.6
4.95
I
LIM2
TIED TO V
IN
0.4
3.84
FEEDBACK VOLTAGE
ADJUSTABLE PART
0.2
I
LIM2
, I
LIM4
OPEN
3.80
0
0
25
5
10
15
20
INPUT-TO-OUTPUT DIFFERENTIAL VOLTAGE (V)
1175 G02
3.76
–50
50
25
0
75 100
–25
JUNCTION TEMPERATURE (°C)
125
1175 G03
Minimum Input-to-Output Voltage
1.0
INPUT-TO-OUTPUT VOLTAGE (V)
INPUT-TO-OUTPUT VOLTAGE (V)
T
J
= 25°C
V
IN
REDUCED
UNTIL OUTPUT
VOLTAGE
DROPS 1%
I
LIM2
, I
LIM4
OPEN
I
LIM4
TIED
TO V
IN
I
LIM2
, I
LIM4
TIED TO V
IN
0
0.1
0.2 0.3 0.4
0.5
OUTPUT CURRENT (A)
0.6
0.7
1.0
Minimum Input-to-Output Voltage
V
IN
REDUCED UNTIL OUTPUT
VOLTAGE DROPS 1%.
I
LIM2
, I
LIM4
TIED TO V
IN
CURRENT (nA)
100
SENSE Bias Current
(Adjustable Part)
0.8
0.8
80
0.6
I
LIM2
TIED
TO V
IN
0.6
T
J
= 125°C
0.4
T
J
= 25°C
60
0.4
40
0.2
0.2
T
J
= –55°C
20
0
0
0
0.1
0.2 0.3 0.4
0.5
OUTPUT CURRENT (A)
0.6
0.7
0
–50
–25
50
25
0
75
TEMPERATURE (°C)
100
125
1175 G04
1175 G05
1175 G06
1175fe
LINER [ LINEAR TECHNOLOGY ]
