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LT1118/LT1118-2.5 LT1118-2.85/LT1118-5 Low IQ, Low Dropout, 800mA, Source and Sink Regulators Adjustable and Fixed 2.5V, 2.85V, 5V Output
FEATURES
s s s s s s s s
DESCRIPTION
The LT(R)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 600A, allowing continuous 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 current drops to less than 10A. 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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Regulates While Sourcing or Sinking Current Provides Termination for up to 27 SCSI Lines 600A Quiescent Current Ultra-Low Power Shutdown Mode Current Limit and Thermal Shutdown Protection Stable for Any CLOAD 0.22F Fast Settling Time 1V Dropout Voltage
APPLICATIONS
s s s s s
Active Negation SCSI Terminations Computers Disk Drives CD-ROM Supply Splitter
TYPICAL APPLICATION
Load Transient Response
0.2V IN LT1118-2.85 OUT GND 5V 2.2F 1F CERAMIC VOUT 0V - 0.2V 800mA ILOAD
1118 TA01
ILOAD
0mA - 400mA
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1118 TA02.tif
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LT1118/LT1118-2.5 LT1118-2.85/LT1118-5
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VCC) ............................................... 15V Input Voltage (Enable) ................................- 0.2V to 7V Output Voltage ................................ - 0.2V to VCC + 0.5V Short-Circuit Duration ..................................... Indefinite
PACKAGE/ORDER INFORMATION
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
1 OUT TAB IS GND FRONT VIEW 3 2 IN GND
S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 125C, JC = 15C/W
S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 125C, JC = 15C/W
ORDER PART NUMBER LT1118CS8
ORDER PART NUMBER LT1118CS8-2.5 LT1118CS8-2.85 LT1118CS8-5 S8 PART MARKING 111825 111828 11185
S8 PART MARKING 1118
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
PARAMETER Quiescent Current (VIN) Quiescent Current in Shutdown (VIN) Enable Input Thresholds Enable Input Current Output Voltage LT1118-2.5 LT1118-2.85 LT1118-5 Line Regulation (Note 4) LT1118-2.5 LT1118-2.85 LT1118-5 VEN = 5V VEN = 0V
(Note 2)
MIN
q q q q q q q q q q q
CONDITIONS
Input Low Level Input High Level 0V VEN 5V No Load (25C) All Operating Conditions (Note 3) No Load (25C) All Operating Conditions (Note 3) No Load (25C) All Operating Conditions (Note 3) IL = 0mA, 4.2V VIN 15V IL = 0mA, 4.75V VIN 15V IL = 0mA, 6.5V VIN 15V
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W
WW U
W
(Note 1)
Operating Temperature Range ..................... 0C to 70C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
ST PACKAGE 3-LEAD PLASTIC SOT-223
TJMAX = 125C, JC = 15C/W
ORDER PART NUMBER LT1118CST-2.5 LT1118CST-2.85 LT1118CST-5
TYP 0.6 1
MAX 1 10 2 25 2.53 2.55 2.88 2.91 5.05 5.1 6 6 10
UNITS mA A V V A V V V V V V mV mV mV
0.4 -1 2.47 2.45 2.82 2.79 4.95 4.90
1.4 1.4 2.5 2.5 2.85 2.85 5 5
LT1118/LT1118-2.5 LT1118-2.85/LT1118-5
ELECTRICAL CHARACTERISTICS
PARAMETER Load Regulation (Note 4) LT1118-2.5 LT1118-2.85 LT1118-5 Dropout Voltage (Note 5) Minimum Output Voltage Ripple Rejection Load Transient Settling Time, V = 1% Output Short-Circuit Current ISC+ ISC- LT1118
(Note 2)
MIN
q q q q q q
CONDITIONS 0mA IL 800mA - 400mA IL 0mA 0mA IL 800mA - 400mA IL 0mA 0mA IL 800mA - 400mA IL 0mA IL = 100mA IL = 800mA
q
TYP
MAX 10 10 10 10 20 20
UNITS mV mV mV mV mV mV V V V dB s s
0.85 1 60 80 5 5 800 1200 - 700 170 50
1.1 1.3 2
fRIPPLE = 120Hz, VIN - VOUT = 2V VRIPPLE = 0.5VP-P 0mA IL 800mA, CLOAD = 1F - 400mA IL 0mA, CLOAD = 1F VOUT = 0V VOUT = VIN No Load No Load
- 400
mA mA C s
Thermal Shutdown Junction Temperature Enable Turn-On Delay
The q denotes specifications which apply over the operating temperature range. Note 1: Absolute maximum ratings are those values beyond which the life of the device may be impaired. Note 2: Unless otherwide specified, testing done at VCC = 5V (LT1118-2.5, LT1118-2.85) or VCC = 7V (LT1118-5). VEN = VCC. Output CLOAD = 1F, ILOAD = 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.
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LT1118/LT1118-2.5 LT1118-2.85/LT1118-5 TYPICAL PERFORMANCE CHARACTERISTICS
Dropout Voltage vs Output Current
1.4 1.2 TJ = 25C TJ = 75C RIPPLE REJECTION (dB) 60 80 800mA RIPPLE REJECTION (dB) 10mA 60
DROPOUT VOLTAGE
1 0.8 0.6 0.4 0.2 TJ = 125C
0 0 200 400 600 OUTPUT CURRENT (mA) 800
1118 G01
Output Impedance vs Frequency
10 NO CURRENT 100mA SOURCE
CURRENT (nA)
ZOUT (mA)
10mA SOURCE 0.1
300 250 200 150 100 50
RIPPLE REJECTION (dB)
1
0.01
100mA SINK 10mA SINK
0.001 102
103
104 105 FREQUENCY (Hz)
Input Current vs Output Sink Current
2000 1750 800 700
GROUND PIN CURRENT (A)
INPUT CURRENT (A)
1500 1250 1000 750 500 250 0 0 50 100 150 200 250 300 350 400 OUTPUT SINK CURRENT (mA)
1118 G07
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UW
Ripple Rejection vs Frequency
80
Ripple Rejection vs Frequency
400mA 10mA
40 NO LOAD 20 SOURCING CURRENT 0 10 100 1k 10k FREQUENCY (Hz) 100k
1118 G02
40 NO LOAD 20 SINKING CURRENT 0 10 100 1k 10k FREQUENCY (Hz) 100k
1118 G03
Feedback Current vs Temperature
450 400 350
60 80
Ripple Rejection vs Load Current
CIN = CLOAD = 1F
40
20
106
1118 G04
0 -55 -35 -15
5
25 45 TEMP
65
85 105 125
1118 G05
0 -400
-200
0 200 400 LOAD CURRENT (mA)
600
800
1118 G06
Ground Pin Current vs Output Source Current
600 500 400 300 200 100 0 0 400 200 600 OUTPUT SOURCING CURRENT (mA) 800
1118 G08
LT1118/LT1118-2.5 LT1118-2.85/LT1118-5
PIN FUNCTIONS
IN: Input Supply Pin. This pin should be decoupled with a 1F 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 connects 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 VIN on 3-lead ST packaged devices. 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. COUT 0.22F to guarantee stability. A 0.1F ceramic capacitor may be needed in parallel with COUT if the ESR of the main COUT is too high. FB: Feedback Pin. The feedback pin is used to program the output voltage of the adjustable S8 part. The output voltage is determined by the selection of feedback resistors defined by the following formula: VOUT = VFB (1 + R1/R2) + IFBR1
LT1118 Adjustable
VIN 1F EN IN LT1118 FB R2
1118 TA06
OPERATIO
Output Capacitor
The LT1118 family of voltage regulators require an output capacitor for stability. The regulators are stable with output capacitors larger than 0.2F. 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 0.2F and 1F give good performance in most applications. Larger tantalum output capacitors may be used to reduce load transient amplitudes. Larger capacitors should be paralleled with a 0.1F ceramic capacitor to maintain quick settling time performance and to insure stability of the regulator control loop. Capacitors larger than 10F may be safely used with the regulators, but little transient settling performance improvement results from their use.
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OUT 1F R1
VOUT = VFB 1 +
(
R1 + IFB R1 R2
)
GND
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
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LT1118/LT1118-2.5 LT1118-2.85/LT1118-5
OPERATIO
thermally connected to the die substrate. Table 1 shows measured thermal resistance from junction to ambient for the LT1118 connected to various sized PC board ground planes. The power dissipated in the LT1118 varies with input voltage and loading. When the regulator is sourcing current the power which must be dissipated by the package is: PD = (VIN - VOUT) * ILOAD.
TYPICAL APPLICATIONS
SCSI Active Terminator
110 * * * * 110 110 IN LT1118-2.85 OUT GND 2.2F 1F
1118 TA03
VIN 5V
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When the regulator is sinking load current, power dissipation is nearly independent of VIN and can be calculated as: PD = VOUT * ILOAD. Heat sinking to the IC package must consider the worst case power dissipation which may occur.
Table 1. Measured Thermal Resistance from Junction to Ambient for the LT1118
S8 Package Free Air 1 Sq Inch Copper 4 Sq Inch Copper 120C/W 55C/W 35C/W SOT-223 95C/W 53C/W 38C/W
TERMPWR 27 LINES 110 * * * 110 *
+
5V
Power Supply Splitter
5V
1F
IN
LT1118-2.5 OUT GND 1F
ANALOG COMMON 2.5V
1118 TA04
LT1118/LT1118-2.5 LT1118-2.85/LT1118-5
PACKAGE DESCRIPTION U
Dimensions in inches (millimeters) unless otherwise noted.
ST Package 3-Lead Plastic SOT-223
(LTC DWG # 05-08-1630)
0.248 - 0.264 (6.30 - 6.71) 0.116 - 0.124 (2.95 - 3.15)
0.264 - 0.287 (6.71 - 7.29) 0.130 - 0.146 (3.30 - 3.71)
0.090 (2.29) NOM
0.033 - 0.041 (0.84 - 1.04)
10 - 16 0.071 (1.80) MAX 10 MAX 0.010 - 0.014 (0.25 - 0.36)
10 - 16 0.025 - 0.033 (0.64 - 0.84) 0.181 (4.60) NOM 0.012 (0.31) MIN 0.0008 - 0.0040 (0.0203 - 0.1016)
ST3 (SOT-233) 0792
S8 Package 8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 - 0.197* (4.801 - 5.004) 0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254) 0- 8 TYP 0.228 - 0.244 (5.791 - 6.197) 0.150 - 0.157** (3.810 - 3.988) 0.053 - 0.069 (1.346 - 1.752) 0.004 - 0.010 (0.101 - 0.254) 8 7 6 5
0.016 - 0.050 0.406 - 1.270
0.014 - 0.019 (0.355 - 0.483)
0.050 (1.270) TYP
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
SO8 0996
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Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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LT1118/LT1118-2.5 LT1118-2.85/LT1118-5
TYPICAL APPLICATION
12V 0.1F IN 1F LT1118 EN FB R3 6.2k OUT R1 22k 0.22F R2 5.1k VCC VDAC VOUT LTC1257 GND VREF DIN CLK LOAD
1118 TA05
RELATED PARTS
PART NUMBER LT1005 LT1117 LT1120A LT1121 DESCRIPTION Logic Controlled Regulator 800mA Low Dropout Regulator Micropower Regulator with Comparator and Shutdown Micropower Low Dropout Regulator with Shutdown COMMENTS 5V, 1A Main Output Plus 35mA Auxilliary Output Fixed 2.85V, 3.3V, 5V or Adjustable Outputs 20A Supply Current, 2.5V Reference Output Reverse Voltage and Reverse Current Protection
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Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
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Variable 2V to 10V Regulator with Digital Control
VOUT
GND
P
VOUT = 1.225 1 +
( R2 || R3 )
R1
- VDAC
R1 R2
1118fa LT/TP 0598 2K REV A * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1995

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