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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

DESCRIPTIO
Regulates While Sourcing or Sinking Current Provides Termination for up to 27 SCSI Lines 600A Quiescent Current Ultralow Power Shutdown Mode Current Limit and Thermal Shutdown Protection Stable for Any CLOAD 0.22F Fast Settling Time 1V Dropout Voltage
APPLICATIO S

Active Negation SCSI Terminations Computers Disk Drives CD-ROM Supply Splitter
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.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
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
AXI U RATI GS
Supply Voltage (VCC) ............................................... 15V Input Voltage (Enable) ................................- 0.2V to 7V Output Voltage ................................ - 0.2V to VCC + 0.5V Short-Circuit Duration ..................................... Indefinite
PACKAGE DESCRIPTIO
TOP VIEW GND 1 NC 2 EN 3 FB 4 8 GND 7 IN 6 OUT 5 IN
S8 PACKAGE 8-LEAD PLASTIC SO
TJMAX = 125C, JC = 15C/W
ORDER PART NUMBER LT1118CS8
S8 PART MARKING 1118
ORDER PART NUMBER LT1118CS8-2.5 LT1118CS8-2.85 LT1118CS8-5
Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 2)
PARAMETER Quiescent Current (VIN) Quiescent Current in Shutdown (VIN) Enable Input Thresholds Enable Input Current Feedback Voltage Output Voltage LT1118 LT1118-2.5 LT1118-2.85 LT1118-5 CONDITIONS VEN = 5V VEN = 0V 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) No Load (25C) All Operating Conditions (Note 3)

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WW
W
(Note 1)
Operating Temperature Range ..................... 0C to 70C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
TOP VIEW IN 1 OUT 2 GND 3 IN 4 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
ST PACKAGE 3-LEAD PLASTIC SOT-223
TJMAX = 125C, JC = 15C/W
TJMAX = 125C, JC = 15C/W
S8 PART MARKING 111825 111828 11185
ORDER PART NUMBER LT1118CST-2.5 LT1118CST-2.85 LT1118CST-5
ST PART MARKING 111825 111828 11185
MIN
TYP 0.6 1
MAX 1 10 2 25 1.237 1.250 2.53 2.55 2.88 2.91 5.05 5.1
UNITS mA A V V A V V V V V V V V
0.4 -1 1.213 1.200 2.47 2.45 2.82 2.79 4.95 4.90
1.4 1.4 1.225 1.225 2.5 2.5 2.85 2.85 5 5
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LT1118/LT1118-2.5 LT1118-2.85/LT1118-5
ELECTRICAL CHARACTERISTICS
The denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 2)
PARAMETER Line Regulation (Note 4) LT1118 LT1118-2.5 LT1118-2.85 LT1118-5 LT1118 LT1118-2.5 LT1118-2.85 LT1118-5 Dropout Voltage (Note 5) FB Pin Bias Current Minimum Output Voltage Ripple Rejection Load Transient Settling Time, V = 1% Output Short-Circuit Current ISC+ ISC- LT1118 LT1118 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 800
CONDITIONS IL = 0mA, 4.2V VIN 15V IL = 0mA, 4.2V VIN 15V IL = 0mA, 4.75V VIN 15V IL = 0mA, 6.5V VIN 15V 0mA IL 800mA - 400mA IL 0mA 0mA IL 800mA - 400mA IL 0mA 0mA IL 800mA - 400mA IL 0mA 0mA IL 800mA - 400mA IL 0mA IL = 100mA IL = 800mA

MIN
TYP
MAX 6 6 6 10 6 6 12 12 12 12 25 25
UNITS mV mV mV mV mV mV mV mV mV mV mV mV V V A V dB s s
Load Regulation (Note 4)
0.85 1 0.35 60 80 5 5 1200 - 700 170 50
1.1 1.3 1 2.1
- 400
mA mA C s
Thermal Shutdown Junction Temperature Enable Turn-On Delay
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 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) 10mA SOURCE 0.1
300 250 200 150 100 50 450 400
RIPPLE REJECTION (dB)
1 ZOUT (mA)
0.01
100mA SINK 10mA SINK
0.001 102
103
104 105 FREQUENCY (Hz)
Input Current vs Output Sink Current
2000 1750
GROUND PIN CURRENT (A) INPUT CURRENT (A)
800 700 600 500 400 300 200 100 0
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
80
Ripple Rejection vs Load Current
CIN = CLOAD = 1F 60
350
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
0
400 200 600 OUTPUT SOURCING CURRENT (mA)
800
1118 G08
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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.
VIN 1F EN
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: 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 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: VOUT = VFB (1 + R1/R2) + IFBR1
LT1118 Adjustable
IN LT1118 FB R2
1118 TA06
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 APPLICATIO S
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
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LT1118/LT1118-2.5 LT1118-2.85/LT1118-5
PACKAGE DESCRIPTIO U
ST Package 3-Lead Plastic SOT-223
(LTC DWG # 05-08-1630)
.248 - .264 (6.30 - 6.71) .114 - .124 (2.90 - 3.15) .059 MAX .129 MAX .248 BSC .039 MAX .059 MAX .090 BSC .181 MAX .0905 (2.30) BSC .033 - .041 (0.84 - 1.04) RECOMMENDED SOLDER PAD LAYOUT 10 - 16 .071 (1.80) MAX 10 MAX .010 - .014 (0.25 - 0.36) 10 - 16 .024 - .033 (0.60 - 0.84) .181 (4.60) BSC .012 (0.31) MIN .0008 - .0040 (0.0203 - 0.1016)
ST3 (SOT-233) 0502
.264 - .287 (6.70 - 7.30) .130 - .146 (3.30 - 3.71)
S8 Package 8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
.045 .005 .050 BSC
8 .189 - .197 (4.801 - 5.004) NOTE 3 7 6 5
.245 MIN
.160 .005 .228 - .244 (5.791 - 6.197)
.150 - .157 (3.810 - 3.988) NOTE 3
.030 .005 TYP
RECOMMENDED SOLDER PAD LAYOUT .010 - .020 x 45 (0.254 - 0.508) .008 - .010 (0.203 - 0.254) 0- 8 TYP
1
2
3
4
.053 - .069 (1.346 - 1.752)
.004 - .010 (0.101 - 0.254)
.016 - .050 (0.406 - 1.270)
NOTE: 1. DIMENSIONS IN
INCHES (MILLIMETERS) 2. DRAWING NOT TO SCALE 3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
.014 - .019 (0.355 - 0.483) TYP
.050 (1.270) BSC
SO8 0303
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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 APPLICATIO
12V
IN 1F LT1118 EN
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
8
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 FAX: (408) 434-0507
U
Variable 2.1V to 6.5V Regulator with Digital Control
0.1F OUT R1 13.3k R2 6.19k FB R3 6.19k 0.22F VCC VDAC VOUT LTC1257 GND VREF DIN CLK LOAD
1118 TA05
VOUT
GND
P
VOUT = 1.225 1 +
( R2 || R3 )
R1
- VDAC
R1 R2
1118fc LT/LWI 0706 REV C * PRINTED IN USA
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 1995

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