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LT1118/ LT1118-2.5

LT1118-2.85/ LT1118-5

Lo w I , Lo w Dro p o ut,

Q

800m A, So urc e a nd Sink

Re g ula to rs Ad justa b le a nd

Fixe d 2.5V, 2.85V, 5V Outp ut

U

FEATURES

DESCRIPTION

The LT^®1118 family of low dropout regulators has the

unique capability of maintaining output regulation while

sourcingorsinkingloadcurrent. The2.85Voutputvoltage

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,

quiescentsupplycurrentis alow600µA,allowingcontinu-

ous connection to the TERMPWR lines. An ultralowpower

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.

■

Regulates While Sourcing or Sinking Current

Provides Termination for up to 27 SCSI Lines

600µA Quiescent Current

Ultra-Low Power Shutdown Mode

Current Limit and Thermal Shutdown Protection

Stable for Any C_LOAD≥ 0.22µF

Fast Settling Time

1V Dropout Voltage

■

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APPLICATIONS

■

Active Negation SCSI Terminations

Computers

Disk Drives

CD-ROM

■

Current limits in both sourcing and sinking modes, plus

on-chip thermal shutdown make the circuit tolerant of

output fault conditions.

■

Supply Splitter

The LT1118 is available in 3-lead SOT-223 and 8-lead SO

packages.

, LTC and LT are registered trademarks of Linear Technology Corporation.

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TYPICAL APPLICATION

Load Transient Response

0.2V

0V

LT1118-2.85 OUT

GND

∆V_OUT

IN

–0.2V

1µF

CERAMIC

800mA

5V

2.2µF

I

LOAD

I_LOAD

1118 TA01

0mA

–400mA

1118 TA02.tif

1

LT1118/ LT1118-2.5

LT1118-2.85/ LT1118-5

W W

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ABSOLUTE MAXIMUM RATINGS

(Note 1)

Supply Voltage (V ) ............................................... 15V

Input Voltage (Enable) ................................–0.2V to 7V

Operating Temperature Range ..................... 0°C to 70°C

Storage Temperature Range ................. –65°C to 150°C

Lead Temperature (Soldering, 10 sec).................. 300°C

CC

Output Voltage................................ –0.2V to V + 0.5V

CC

Short-Circuit Duration ..................................... Indefinite

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PACKAGE/ORDER INFORMATION

FRONT VIEW

TOP VIEW

3

2

1

IN

GND

NC

EN

1

2

3

4

8

7

6

5

GND

IN

OUT

GND

IN

1

2

3

4

8

7

6

5

EN

TAB IS

GND

NC

GND

OUT

IN

FB

ST PACKAGE

3-LEAD PLASTIC SOT-223

S8 PACKAGE

8-LEAD PLASTIC SO

S8 PACKAGE

8-LEAD PLASTIC SO

_JMAX= 125°C, θ_JC= 15°C/W

T

_JMAX= 125°C, θ_JC= 15°C/W

T

_JMAX= 125°C, θ_JC= 15°C/W

ORDER PART NUMBER

LT1118CS8

ORDER PART NUMBER

LT1118CS8-2.5

LT1118CS8-2.85

LT1118CS8-5

LT1118CST-2.5

LT1118CST-2.85

LT1118CST-5

S8 PART MARKING

1118

S8 PART MARKING

111825

111828

11185

Consult factory for Industrial and Military grade parts.

(Note 2)

ELECTRICAL CHARACTERISTICS

PARAMETER

CONDITIONS

MIN

TYP

0.6

1

MAX

1

UNITS

mA

Quiescent Current (V )

V

= 5V

= 0V

●

IN

EN

Quiescent Current in Shutdown (V )

V

10

µA

IN

EN

Enable Input Thresholds

Input Low Level

Input High Level

●

0.4

–1

1.4

V

2

Enable Input Current

0V ≤ V ≤ 5V

●

25

µA

EN

Output Voltage

LT1118-2.5

No Load (25°C)

All Operating Conditions (Note 3)

2.47

2.45

2.5

2.53

2.55

V

LT1118-2.85

LT1118-5

No Load (25°C)

All Operating Conditions (Note 3)

2.82

2.79

2.85

2.88

2.91

V

No Load (25°C)

All Operating Conditions (Note 3)

4.95

4.90

5

5.05

5.1

V

Line Regulation (Note 4)

LT1118-2.5

LT1118-2.85

LT1118-5

I = 0mA, 4.2V ≤ V ≤ 15V

●

6

10

mV

L

IN

I = 0mA, 4.75V ≤ V ≤ 15V

L

IN

I = 0mA, 6.5V ≤ V ≤ 15V

L

IN

2

LT1118/ LT1118-2.5

LT1118-2.85/ LT1118-5

(Note 2)

ELECTRICAL CHARACTERISTICS

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Load Regulation (Note 4)

LT1118-2.5

LT1118-2.85

LT1118-5

0mA ≤ I ≤ 800mA

●

10

mV

L

–400mA ≤ I ≤ 0mA

L

0mA ≤ I ≤ 800mA

●

10

mV

L

–400mA ≤ I ≤ 0mA

L

0mA ≤ I ≤ 800mA

●

20

mV

L

–400mA ≤ I ≤ 0mA

L

Dropout Voltage (Note 5)

I = 100mA

I = 800mA

L

0.85

1

1.1

1.3

V

L

Minimum Output Voltage

Ripple Rejection

LT1118

●

2

V

f

= 120Hz, V – V = 2V

60

80

dB

RIPPLE

IN

OUT

V

RIPPLE

= 0.5V

P-P

Load Transient Settling Time,

∆V = 1%

0mA ≤ I ≤ 800mA, C

= 1µF

5

µs

L

LOAD

–400mA ≤ I ≤ 0mA, C

= 1µF

L

LOAD

+

Output Short-Circuit Current

I

V

OUT

= 0V

= V

IN

800

1200

–700

mA

SC

OUT

–

–400

SC

Thermal Shutdown Junction Temperature

Enable Turn-On Delay

No Load

170

50

°C

µs

The

●

denotes specifications which apply over the operating temperature

Note 3: All operating conditions include the combined effects of load

range.

current, input voltage and temperature over each parameter’s full range.

Note 1: Absolute maximum ratings are those values beyond which the life

Note 4: Load and line regulation are tested at a constant junction

of the device may be impaired.

temperature by low duty cycle pulse testing.

Note 2: Unless otherwide specified, testing done at V = 5V

Note 5: Dropout voltage is defined as the minimum input to output voltage

CC

(LT1118-2.5, LT1118-2.85) or V = 7V (LT1118-5). V = V . Output

measured while sourcing the specified current.

CC

EN

CC

C

LOAD

= 1µF, I

= 0.

LOAD

3

LT1118/ LT1118-2.5

LT1118-2.85/ LT1118-5

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TYPICAL PERFORMANCE CHARACTERISTICS

Ripple Rejection vs Frequency

Dropout Voltage vs Output Current

80

60

40

20

0

80

60

40

20

0

1.4

1.2

1

800mA

400mA

T = 75°C

J

T = 25°C

J

10mA

0.8

0.6

0.4

0.2

0

T = 125°C

J

NO LOAD

SOURCING CURRENT

SINKING CURRENT

100

10

100

1k

10k

100k

10

1k

10k

100k

0

200

400

600

800

FREQUENCY (Hz)

OUTPUT CURRENT (mA)

1118 G02

1118 G03

1118 G01

Output Impedance vs Frequency

Feedback Current vs Temperature

Ripple Rejection vs Load Current

10

1

450

400

350

300

250

200

150

100

50

80

60

40

20

0

C

= C

= 1µF

IN

LOAD

NO CURRENT

100mA SOURCE

10mA SOURCE

0.1

0.01

0.001

100mA SINK

10mA SINK

0

2

3

4

5

6

–400 –200

0

200

400

600

800

–55 –35 –15

5

25 45 65 85 105 125

TEMP

10

FREQUENCY (Hz)

10

LOAD CURRENT (mA)

1118 G04

1118 G06

1118 G05

Input Current vs

Output Sink Current

Ground Pin Current vs

Output Source Current

800

700

600

500

400

300

200

100

0

2000

1750

1500

1250

1000

750

500

250

0

400

OUTPUT SOURCING CURRENT (mA)

0

200

600

800

200 250

300 350 400

0

50 100 150

OUTPUT SINK CURRENT (mA)

1118 G08

1118 G07

4

LT1118/ LT1118-2.5

LT1118-2.85/ LT1118-5

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PIN FUNCTIONS

OUT:RegulatedOutputVoltage. Outputcansourceorsink

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_OUTif the ESR of the main

C_OUTis too high.

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.

FB: FeedbackPin. Thefeedbackpinis usedtoprogramthe

output voltage of the adjustable S8 part. The output

voltage is determined by the selection of feedback resis-

tors defined by the following formula:

GND: Ground Pin. The multiple GND pins on the SO-8

package are internally connected, but lowest load regula-

tion errors will result if these pins are tightly connected on

the printed circuit board. This will also aid heat dissipation

at high power levels.

V_OUT= V (1 + R₁/R₂) + I_FBR₁

FB

EN: TTL/CMOS Logic Input. A high level allows normal

operation. A low level reduces supply current to zero. This

LT1118 Adjustable

pin is internally connected to V on 3-lead ST packaged

devices.

IN

R

1

V

IN

OUT

FB

V

OUT

= V 1 +

+ I

R

IN

FB

FB 1

(

)

R

2

1µF

LT1118

GND

R

1

EN

R

2

1118 TA06

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OPERATIO

Output Capacitor

Worst case transient response of the LT1118 regulators

occurs atzerooutputcurrent. Inordertoobtainthefastest

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.

The LT1118 family of voltage regulators require an output

capacitor for stability. The regulators are stable with

output capacitors larger than 0.2µF. Load transient re-

sponse is very sensitive to output capacitor value and

dielectricchoice. LowESRceramiccapacitors arethebest

choice for fast settling to load transients. Output capaci-

tors between 0.2µF and 1µF give good performance in

mostapplications. Largertantalumoutputcapacitors may

be used to reduce load transient amplitudes. Larger ca-

pacitors should be paralleled with a 0.1µF ceramic capaci-

tor 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 re-

sults from their use.

Thermal Considerations

The LT1118 regulators are packaged in plastic SOT-223

and fused lead S8 packages. These small footprint pack-

ages are unable to convectively dissipate the heat gener-

ated 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

5

LT1118/ LT1118-2.5

LT1118-2.85/ LT1118-5

U

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 pack-

age is:

When the regulator is sinking load current, power dissipa-

tion is nearly independent of V and can be calculated as:

IN

P_D= V_OUT• I_LOAD

.

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

P_D= (V – V_OUT) • I_LOAD

.

IN

S8 Package

SOT-223

Free Air

1 Sq Inch Copper

120°C/W

55°C/W

95°C/W

53°C/W

4 Sq Inch Copper

35°C/W

38°C/W

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TYPICAL APPLICATIONS

SCSI Active Terminator

110Ω

•

TERMPWR

110Ω

27 LINES

LT1118-2.85 OUT

GND

IN

•

110Ω

+

5V

2.2µF

1µF

1118 TA03

Power Supply Splitter

V

5V

IN

5V

ANALOG

COMMON

2.5V

LT1118-2.5 OUT

IN

1µF

GND

1µF

1118 TA04

6

LT1118/ LT1118-2.5

LT1118-2.85/ LT1118-5

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PACKAGE DESCRIPTION

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)

0.033 – 0.041

(0.84 – 1.04)

0.090

(2.29)

NOM

10° – 16°

0.010 – 0.014

(0.25 – 0.36)

10°

0.071

(1.80)

MAX

10° – 16°

0.0008 – 0.0040

(0.0203 – 0.1016)

0.025 – 0.033

(0.64 – 0.84)

0.012

(0.31)

MIN

0.181

(4.60)

NOM

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

(0.254 – 0.508)

7

5

8

6

× 45°

0.053 – 0.069

(1.346 – 1.752)

0.004 – 0.010

(0.101 – 0.254)

0.008 – 0.010

(0.203 – 0.254)

0°– 8° TYP

0.150 – 0.157**

(3.810 – 3.988)

0.228 – 0.244

(5.791 – 6.197)

0.016 – 0.050

0.406 – 1.270

0.050

(1.270)

TYP

0.014 – 0.019

(0.355 – 0.483)

*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH

SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

SO8 0996

**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD

FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE

1

3

4

2

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 represen-

tationthattheinterconnectionofits circuits as describedhereinwillnotinfringeonexistingpatentrights.

7

LT1118/ LT1118-2.5

LT1118-2.85/ LT1118-5

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TYPICAL APPLICATION

Variable 2V to 10V Regulator with Digital Control

12V

0.1µF

IN

OUT

FB

V

OUT

1µF

0.22µF

R

22k

LT1118

GND

1

V

CC

D

IN

R

5.1k

2

V

DAC

µP

V

OUT

LTC1257

CLK

EN

R

6.2k

3

GND

V

REF

LOAD

1118 TA05

R

1

R

1

V

OUT

= 1.225 1 +

– V

DAC

R

|| R

R

2

3

)

(

RELATED PARTS

PART NUMBER

DESCRIPTION

Logic Controlled Regulator

800mA Low Dropout Regulator

COMMENTS

LT1005

5V, 1A Main Output Plus 35mA Auxilliary Output

Fixed 2.85V, 3.3V, 5V or Adjustable Outputs

20µA Supply Current, 2.5V Reference Output

Reverse Voltage and Reverse Current Protection

LT1117

LT1120A

LT1121

Micropower Regulator with Comparator and Shutdown

Micropower Low Dropout Regulator with Shutdown

1118fa LT/TP 0598 2K REV A • PRINTED IN USA

LINEAR TECHNOLOGY CORPORATION 1995

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

8

●

(408)432-1900 FAX:(408)434-0507 www.linear-tech.com

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