FEATURES
n
n
n
n
n
n
n
n
LT1118/LT1118-2.5
LT1118-2.85/LT1118-5
Low I
Q
, Low Dropout,
800mA, Source and Sink
Regulators Adjustable and
Fixed 2.5V, 2.85V, 5V Output
DESCRIPTION
The LT
®
1118 family of low dropout regulators has the
unique capability of maintaining output regulation while
sourcing or sinking load current. The 2.85V output voltage
regulator is ideal for use as a Boulay termination of up
to 27 SCSI data lines. The regulator maintains regulation
while both sourcing and sinking current, enabling the use
of active negation drivers for improved noise immunity on
the data lines. Regulation of output voltage is maintained
for TERMPWR voltages as low as 4.0V. When unloaded,
quiescent supply current is a low 600μA, allowing continu-
ous connection to the TERMPWR lines. An ultralow power
shutdown mode is also available on the SO-8 version. In
Shutdown the output is high impedance and supply cur-
rent drops to less than 10μA.
Current limits in both sourcing and sinking modes, plus
on-chip thermal shutdown make the circuit tolerant of
output fault conditions.
The LT1118 is available in 3-lead SOT-223 and 8-lead SO
packages.
Regulates While Sourcing or Sinking Current
Provides Termination for up to 27 SCSI Lines
600μA Quiescent Current
Ultralow Power Shutdown Mode
Current Limit and Thermal Shutdown Protection
Stable for Any C
LOAD
≥ 0.22μF
Fast Settling Time
1V Dropout Voltage
APPLICATIONS
n
n
n
n
n
Active Negation SCSI Terminations
Computers
Disk Drives
CD-ROM
Supply Splitter
L,
LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
Load Transient Response
0.2V
IN
LT1118-2.85 OUT
GND
5V
2.2μF
1μF
CERAMIC
V
OUT
0V
–0.2V
I
LOAD
1118 TA01
800mA
I
LOAD
0mA
–400mA
1118 TA02
1118fd
1
LT1118/LT1118-2.5/
LT1118-2.85/LT1118-5
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Supply Voltage (V
CC
) ................................................15V
Input Voltage (Enable).................................– 0.2V to 7V
Output Voltage ............................... – 0.2V to V
CC
+ 0.5V
Short-Circuit Duration ..................................... Indefinite
Operating Temperature Range...................... 0°C to 70°C
Storage Temperature Range...................– 65°C to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
PIN CONFIGURATION
TOP VIEW
GND 1
NC 2
EN 3
FB 4
8 GND
7 IN
6 OUT
5 IN
IN 1
OUT 2
GND 3
IN 4
TOP VIEW
8 EN
7 GND
6 GND
5 NC
TAB IS
GND
FRONT VIEW
3
2
1
IN
GND
OUT
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 15°C/W
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 15°C/W
ST PACKAGE
3-LEAD PLASTIC SOT-223
T
JMAX
= 125°C,
θ
JC
= 15°C/W
ORDER INFORMATION
LEAD FREE FINISH
LT1118CS8#PBF
LT1118CS8-2.5#PBF
LT1118CS8-2.85#PBF
LT1118CS8-5#PBF
LT1118CST-2.5#PBF
LT1118CST-2.85#PBF
LT1118CST-5#PBF
LEAD BASED FINISH
LT1118CS8
LT1118CS8-2.5
LT1118CS8-2.85
LT1118CS8-5
LT1118CST-2.5
LT1118CST-2.85
LT1118CST-5
TAPE AND REEL
LT1118CS8#TRPBF
LT1118CS8-2.5#TRPBF
LT1118CS8-2.85#TRPBF
LT1118CS8-5#TRPBF
LT1118CST-2.5#TRPBF
LT1118CST-2.85#TRPBF
LT1118CST-5#TRPBF
TAPE AND REEL
LT1118CS8#TR
LT1118CS8-2.5#TR
LT1118CS8-2.85#TR
LT1118CS8-5#TR
LT1118CST-2.5#TR
LT1118CST-2.85#TR
LT1118CST-5#TR
PART MARKING
1118
111825
111828
11185
111825
111828
11185
PART MARKING*
1118
111825
111828
11185
111825
111828
11185
PACKAGE DESCRIPTION
8-Lead Plastic SO
8-Lead Plastic SO
8-Lead Plastic SO
8-Lead Plastic SO
3-Lead Plastic SOT-223
3-Lead Plastic SOT-223
3-Lead Plastic SOT-223
PACKAGE DESCRIPTION
8-Lead Plastic SO
8-Lead Plastic SO
8-Lead Plastic SO
8-Lead Plastic SO
3-Lead Plastic SOT-223
3-Lead Plastic SOT-223
3-Lead Plastic SOT-223
TEMPERATURE RANGE
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
TEMPERATURE RANGE
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
1118fd
2
LT1118/LT1118-2.5
LT1118-2.85/LT1118-5
ELECTRICAL CHARACTERISTICS
PARAMETER
Quiescent Current (V
IN
)
Quiescent Current in Shutdown (V
IN
)
Enable Input Thresholds
Enable Input Current
Feedback Voltage
Output Voltage
CONDITIONS
V
EN
= 5V
V
EN
= 0V
Input Low Level
Input High Level
0V ≤ V
EN
≤ 5V
No Load (25°C) (LT1118)
All Operating Conditions (Note 3)
No Load (25°C) (LT1118-2.5)
All Operating Conditions (Note 3)
No Load (25°C) (LT1118-2.85)
All Operating Conditions (Note 3)
No Load (25°C) (LT1118-5)
All Operating Conditions (Note 3)
Line Regulation (Note 4)
I
L
= 0mA, 4.2V ≤ V
IN
≤ 15V (LT1118)
I
L
= 0mA, 4.2V ≤ V
IN
≤ 15V (LT1118-2.5)
I
L
= 0mA, 4.75V ≤ V
IN
≤ 15V (LT1118-2.85)
I
L
= 0mA, 6.5V ≤ V
IN
≤ 15V (LT1118-5)
0mA ≤ I
L
≤ 800mA (LT1118)
– 400mA ≤ I
L
≤ 0mA
0mA ≤ I
L
≤ 800mA (LT1118-2.5)
– 400mA ≤ I
L
≤ 0mA
0mA ≤ I
L
≤ 800mA (LT1118-2.85)
– 400mA ≤ I
L
≤ 0mA
0mA ≤ I
L
≤ 800mA (LT1118-5)
– 400mA ≤ I
L
≤ 0mA
Dropout Voltage (Note 5)
FB Pin Bias Current
Minimum Output Voltage
Ripple Rejection
Load Transient Settling Time,
ΔV
= 1%
Output Short-Circuit Current
Thermal Shutdown Junction Temperature
Enable Turn-On Delay
I
L
= 100mA
I
L
= 800mA
LT1118
LT1118
f
RIPPLE
= 120Hz, V
IN
– V
OUT
= 2V
V
RIPPLE
= 0.5V
P-P
0mA ≤ I
L
≤ 800mA, C
LOAD
= 1μF
–400mA ≤ I
L
≤ 0mA, C
LOAD
= 1μF
V
OUT
= 0V, Sourcing
V
OUT
= V
IN
, Sinking
No Load
No Load
800
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 2)
MIN
TYP
0.6
1
0.4
–1
1.213
1.200
2.47
2.45
2.82
2.79
4.95
4.90
1.225
1.225
2.5
2.5
2.85
2.85
5
5
1.4
1.4
MAX
1
10
2
25
1.237
1.250
2.53
2.55
2.88
2.91
5.05
5.10
6
6
6
10
6
6
12
12
12
12
25
25
0.85
1
0.35
60
80
5
5
1200
–700
170
50
–400
1.1
1.3
1
2.1
UNITS
mA
μA
V
V
μA
V
V
V
V
V
V
V
V
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
V
V
μA
V
dB
μs
μs
mA
mA
°C
μs
Load Regulation (Note 4)
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:
Unless otherwide specified, testing done at V
CC
= 5V
(LT1118-2.5, LT1118-2.85) or V
CC
= 7V (LT1118-5). V
EN
= V
CC
.
,
Output C
LOAD
= 1μF I
LOAD
= 0.
Note 3:
All operating conditions include the combined effects of load
current, input voltage and temperature over each parameter’s full range.
Note 4:
Load and line regulation are tested at a constant junction
temperature by low duty cycle pulse testing.
Note 5:
Dropout voltage is defined as the minimum input to output voltage
measured while sourcing the specified current.
1118fd
3
LT1118/LT1118-2.5/
LT1118-2.85/LT1118-5
TYPICAL PERFORMANCE CHARACTERISTICS
Dropout Voltage vs Output Current
1.4
1.2
T
J
= 25°C
DROPOUT VOLTAGE (V)
1
0.8
0.6
0.4
0.2
SOURCING CURRENT
0
0
200
400
600
OUTPUT CURRENT (mA)
800
1118 G01
Ripple Rejection vs Frequency
80
800mA
80
Ripple Rejection vs Frequency
400mA
RIPPLE REJECTION (dB)
60
10mA
T
J
= 75°C
RIPPLE REJECTION (dB)
60
10mA
T
J
= 125°C
40
NO LOAD
20
40
NO LOAD
20
SINKING CURRENT
0
10
100
1k
10k
FREQUENCY (Hz)
100k
1118 G02
0
10
100
1k
10k
FREQUENCY (Hz)
100k
1118 G03
Output Impedance vs Frequency
10
NO CURRENT
100mA SOURCE
CURRENT (nA)
10mA SOURCE
Z
OUT
(Ω)
0.1
300
250
200
150
100
50
10
6
1118 G04
Feedback Current vs Temperature
450
400
RIPPLE REJECTION (dB)
80
Ripple Rejection vs Load Current
C
IN
= C
LOAD
= 1μF
60
1
350
40
0.01
100mA SINK
10mA SINK
20
0.001
10
2
10
3
10
4
10
5
FREQUENCY (Hz)
0
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1118 G05
0
–400
–200
0
200
400
LOAD CURRENT (mA)
600
800
1118 G06
Input Current
vs Output Sink Current
2000
1750
INPUT CURRENT (μA)
1500
1250
1000
750
500
250
0
0
50
100 150 200 250 300 350 400
OUTPUT SINK CURRENT (mA)
1118 G07
Ground Pin Current
vs Output Source Current
800
700
GROUND PIN CURRENT (μA)
600
500
400
300
200
100
0
0
400
200
600
OUTPUT SOURCING CURRENT (mA)
800
1118 G08
1118fd
4
LT1118/LT1118-2.5
LT1118-2.85/LT1118-5
PIN FUNCTIONS
IN:
Input Supply Pin. This pin should be decoupled with
a 1μF or larger low ESR capacitor. The two IN pins on the
SO-8 package must be directly connected on the printed
circuit board to prevent voltage drops between the two
inputs. When used as a SCSI active termination, IN con-
nects to term power. When used as a supply splitter, IN is
also the positive supply output.
GND:
Ground Pin. The multiple GND pins on the SO-8
package are internally connected, but lowest load regulation
errors will result if these pins are tightly connected on the
printed circuit board. This will also aid heat dissipation at
high power levels.
EN:
TTL/CMOS Logic Input. A high level allows normal
operation. A low level reduces supply current to zero. This
pin is internally connected to V
IN
on 3-lead ST packaged
devices.
V
IN
1μF
EN
OUT:
Regulated Output Voltage. Output can source or sink
current. Current limit for sourcing and sinking current is
provided to protect the device from fault conditons. The
output must have a low ESR output filter capacitor. C
OUT
≥ 0.22μF to guarantee stability. A 0.1μF ceramic capacitor
may be needed in parallel with C
OUT
if the ESR of the main
C
OUT
is too high.
FB:
Feedback Pin. The feedback pin is used to program
the output voltage of the adjustable S8 part. The output
voltage range that can be achieved is 2.1V to 6.5V. The
output voltage is determined by the selection of feedback
resistors defined by the following formula:
V
OUT
= V
FB
(1 + R
1
/R
2
) + I
FB
R
1
LT1118 Adjustable
IN
LT1118
FB
R
2
1118 TA06
OUT
1μF
R
1
V
OUT
= V
FB
1 +
(
R
1
+ I
FB
R
1
R
2
)
GND
OPERATION
Output Capacitor
The LT1118 family of voltage regulators require an output
capacitor for stability. The regulators are stable with out-
put capacitors larger than 0.2μF Load transient response
.
is very sensitive to output capacitor value and dielectric
choice. Low ESR ceramic capacitors are the best choice
for fast settling to load transients. Output capacitors
between 0.2μF and 1μF give good performance in most
applications. Larger tantalum output capacitors may be
used to reduce load transient amplitudes. Larger capaci-
tors should be paralleled with a 0.1μF ceramic capacitor
to maintain quick settling time performance and to insure
stability of the regulator control loop. Capacitors larger
than 10μF may be safely used with the regulators, but
little transient settling performance improvement results
from their use.
Worst case transient response of the LT1118 regulators
occurs at zero output current. In order to obtain the fastest
transient settling performance, the regulator output may
be preloaded with a small current. The preload current
reduces the regulator output impedance, reducing output
voltage settling time.
Thermal Considerations
The LT1118 regulators are packaged in plastic SOT-223 and
fused lead S8 packages. These small footprint packages
are unable to convectively dissipate the heat generated
when the regulator is operating at high current levels. In
order to control die operating temperatures, the PC board
layout should allow for maximum possible copper area at
the ground pins of the LT1118. The ground pins and the
tab on the SOT-223 package are electrically and thermally
1118fd
5
ADI 工业技术
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
