Datasheet LT1585A Datasheet (Linear Technology)

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Page 1

LT1585A/LT1585A-3.3



FEATURES

■

Fast Transient Response

■

Guaranteed Dropout Voltage at Multiple Currents

■

Load Regulation: 0.05% Typ

■

Trimmed Current Limit

■

On-Chip Thermal Limiting

■

Standard 3-Pin Power Package

APPLICATIONS

■

Pentium® Processor Supplies

■

PowerPCTM Supplies

■

Other 2.5V to 3.6V Microprocessor Supplies

■

Low Voltage Logic Supplies

■

Battery-Powered Circuitry

■

Post Regulator for Switching Supply

LT1585ACT Adjustable LT1585ACT-3.3 3.3V Fixed

5A Low Dropout

Fast Response

Positive Regulators

Adjustable and Fixed

DESCRIPTION

The LT®1585A/LT1585A-3.3 are low dropout 3-terminal regulators with 5A output current capability. Design has been optimized for low voltage applications where transient response and minimum input voltage are critical. Similar to the LT1084 family, these regulators feature lower dropout voltage and faster transient response. These improvements make them ideal for low voltage microprocessor applications requiring a regulated 2.5V to

3.6V output with an input supply below 7V. Current limit is trimmed to ensure specified output current

and controlled short-circuit current. On-chip thermal limiting provides protection against any combination of overload that would create excessive junction temperatures.

The LT1585A/LT1585A-3.3 are available in the industry standard 3-pin TO-220 power package.

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

Pentium is a registered trademark of Intel Corporation. PowerPC is a trademark of IBM Corporation.

TYPICAL APPLICATION

C2* 10µF

3.3V 5A

1585A TA01

≥ 4.75V

* REQUIRED FOR STABILITY

NOTE: MICROPROCESSOR APPLICATIONS WITH LOAD TRANSIENTS OF 3.8A REQUIRE OUTPUT DECOUPLING CAPACITANCE >1300µF ON FIXED VOLTAGE PARTS TO ACHIEVE < 50mV OF DEVIATION FROM NOMINAL OUTPUT. CONSULT FACTORY FOR DETAILS

C1 10µF

LT1585A-3.3

Dropout Voltage vs Output Current3.3V, 5A Regulator

1.5

1.4

1.3

1.2

1.1

1.0

0.9

0.8

0.7

INPUT/OUTPUT DIFFERENTIAL (V)

0.6

0.5 0

OUTPUT CURRENT (A)

FULL LOAD

LT1585A TA02

Page 2

LT1585A/LT1585A-3.3

ABSOLUTE MAXIMUM RATINGS

............................................................................. 7V

Operating Junction Temperature Range

Control Section.................................... 0°C to 125°C

Power Transistor ................................. 0°C to 150°C



PACKAGE/ORDER INFORMATION

FRONT VIEW

3

2

T PACKAGE

3-LEAD PLASTIC TO-220

θJA = 50°C/W

Consult factory for Industrial and Military grade parts.

VIN

ADJ

OUT



ORDER PART

NUMBER

LT1585ACT

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

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

UUU

PRECONDITIONI G

100% Thermal Limit Functional Test

FRONT VIEW

3

2

T PACKAGE

3-LEAD PLASTIC TO-220

θJA = 50°C/W

VIN

OUT

GND



ORDER PART

LT1585ACT-3.3

NUMBER

ELECTRICAL CHARACTERISTICS

PARAMETER CONDITIONS MIN TYP MAX UNITS

Reference Voltage LT1585A (VIN – V

1.5V ≤ (VIN – V

Output Voltage LT1585A-3.3 VIN = 5V, TJ = 25°C, I

Line Regulation LT1585A 2.75V ≤ VIN ≤ 7V, I (Notes 1, 2) LT1585A-3.3 4.75V ≤ VIN ≤ 7V, I

Load Regulation LT1585A (VN – V (Notes 1, 2, 3) LT1585A-3.3 VIN = 5V, TJ = 25°C, 0mA ≤ I

Dropout Voltage LT1585A ∆V

LT1585A-3.3 ∆V

LT1585A ∆V LT1585A-3.3 ∆V

Current Limit LT1585A (VIN – V (Note 3) LT1585A-3.3 (V

Adjust Pin Current LT1585A ● 55 120 µA Adjust Pin Current LT1585A 1.5V ≤ (V

Change (Note 3) Minimum LT1585A 1.5V ≤ (V

Load Current Quiescent Current LT1585A-3.3 V

4.75V ≤ V

) = 3V, TJ = 25°C, I

OUT

= 1%, I

REF

= 1%, I

OUT

= 1%, I

REF

= 1%, I

OUT

OUT)

– V

OUT)

= 5V ● 813 mA

) ≤ 5.75V, 10mA ≤ I

OUT

= 0mA 3.267 (–1%) 3.300 3.333 (+1%) V

≤ 7V, 0mA ≤ I

) = 3V, TJ = 25°C, 10mA ≤ I

– V

OUT

= 10mA

OUT

= 0mA

OUT

= 3A

OUT

= 3A

OUT

= 5A

OUT

= 5A

OUT

= 5.5V = 5.5V

) ≤ 5.75V, 10mA ≤ I

OUT

) ≤ 5.75V ● 210 mA

OUT

= 10mA 1.238 (–1%) 1.250 1.262 (+1%) V

OUT

≤ 5A ● 3.235 (– 2%) 3.300 3.365 (+2%) V

OUT

≤ I

OUT

≤ 5A ● 1.225 (–2%) 1.250 1.275 (+2%) V

OUT

● 0.005 0.2 %

≤ I

OUT

FULL LOAD

≤ I

OUT

FULL LOAD

● 0.05 0.5 %

● 1.150 1.300 V

● 1.200 1.400 V

● 5.0 6.0 A

● 0.2 5 µA

0.05 0.3 %

Page 3

LT1585A/LT1585A-3.3

ELECTRICAL CHARACTERISTICS

PARAMETER CONDITIONS MIN TYP MAX UNITS

Ripple Rejection LT1585A f = 120Hz, C

= 5A

OUT

LT1585A-3.3 f = 120Hz, C

= 5A

OUT

Thermal LT1585A TA = 25°C, 30ms Pulse Regulation LT1585A-3.3 TA = 25°C, 30ms Pulse

Temperature Stability ● 0.5 % Long-Term Stability TA = 125°C, 1000 Hrs. 0.03 1.0 % RMS Output Noise TA = 25°C, 10Hz ≤ f ≤ 10kHz 0.003 %

(% of V

OUT

)

Thermal Resistance LT1585A T Package: Control Circuitry/Power Transistor 0.7/3.0 °C/W Junction to Case

= 25µF Tant., (V

OUT

= 25µF Tant., VIN = 6.3V,

OUT

– V

OUT

) = 3V,

● 60 72 dB

0.004 0.02 %/W

The ● denotes specifications which apply over the specified operating temperature range.

Note 1: See thermal regulation specifications for changes in output voltage due to heating effects. Load and line regulation are measured at a constant junction temperature by low duty cycle pulse testing.

Note 2: Line and load regulation are guaranteed up to the maximum power dissipation 28.8W for the LT1585A in T package. Power dissipation is

determined by input/output differential and the output current. Guaranteed maximum output power will not be available over the full input/output voltage range.

Note 3: I

FULL LOAD

as a function of input-to-output voltage. I LT1585A/LT1585A-3.3. The LT1585A has constant current limit with changes in input-to-output voltage.

TYPICAL PERFORMANCE CHARACTERISTICS

LT1585A Dropout Voltage vs Output Current

1.5 GUARANTEED

1.4

TEST POINTS

1.3

1.2

1.1

1.0

0.9

0.8

DROPOUT VOLTAGE (V)

0.7

0.6

0.5

OUTPUT CURRENT (A)

T = 25°C

T = –5°C

T = 125°C

LT1585A • TPC01

LT1585A Short-Circuit Current vs Temperature

6.0

5.5

5.0

4.5

SHORT-CIRCUIT CURRENT (A)

4.0 –50

–75

–25

0 TEMPERATURE (°C)

100

125

LT1585A • TPC02

is defined as the maximum value of output load current

FULL LOAD

is equal to 5A for the

LT1585A Load Regulation vs Temperature

0.10

∆I = 5A

0.05

–0.05

–0.10

–0.15

OUTPUT VOLTAGE DEVIATION (%)

150

175

–0.20

–25 25 75 125

TEMPERATURE (°C)

LT1585A • TPC03

175–50–75 0 50 100 150

Page 4

LT1585A/LT1585A-3.3

TEMPERATURE (°C)

–75

QUIESCENT CURRENT (mA)

125

LT1585A • TPC09

4 3

–25

–50 150

100

175

TEMPERATURE (°C)

–75

OUTPUT VOLTAGE (V)

3.33

3.34

3.35

125

LT1585A • TPC06

3.32

3.31

3.30

3.29

3.28

3.27

3.26

3.25 –25

–50 150

100

175

OUT

= 3.3V

TYPICAL PERFORMANCE CHARACTERISTICS

LT1585A Reference Voltage vs Temperature

1.275

1.270

1.265

1.260

1.255

1.250

1.245

1.240

REFERENCE VOLTAGE (V)

1.235

1.230

1.225 –25

–50 150

–75

TEMPERATURE (°C)

LT1585A Minimum Load Current vs Temperature

MINIMUM LOAD CURRENT (mA)

–25

–75

–50 150

TEMPERATURE (°C)

Output Voltage vs Temperature Using Adjustable LT1585A

3.70 V

SET WITH 1% RESISTORS

OUT

3.65

3.60

3.55

3.50

3.45

3.40

3.35

OUTPUT VOLTAGE (V)

3.30

3.25

100

125

175

LT1585A • TPC04

3.20 –25

–50 150

–75

= 3.6V

OUT

= 3.45V

OUT

= 3.38V

OUT

= 3.3V

OUT

0 TEMPERATURE (°C)

100

125

LT1585A • TPC05

175

LT1585A Adjust Pin Current vs Temperature

100

90 80 70

60 50 40 30

ADJUST PIN CURRENT (µA)

20 10

100

125

175

LT1585A • TPC07

–25

–50 150

–75

0 TEMPERATURE (°C)

100

125

LT1585A • TPC08

175

LT1585A-3.3 Output Voltage vs Temperature

LT1585A-3.3 Quiescent Current vs Temperature

RIPPLE REJECTION (dB)

10 1k 10k 100k

LT1585A-3.3 Ripple Rejection vs Frequency

LT1585A-3.3: (VIN – V

0.5V ≤ V

RIPPLE

= I

OUT

FULL LOAD

100

FREQUENCY (Hz)

≤ 2V

OUT

) ≤ 3V

LT1585A • TPC10

LT1585A Maximum Power Dissipation*

POWER (W)

60 70

*AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE

90 110 120 130 140 150

80 100

CASE TEMPERATURE (˚C)

LT1585A • TPC11

Page 5

SI PLIFIED SCHE ATIC

THERMAL

LIMIT

ADJ

GND

FOR FIXED VOLTAGE DEVICE

LT1585A/LT1585A-3.3

–

OUT

LT1585A • BD

WUU

APPLICATIONS INFORMATION

General

The LT1585A/LT1585A-3.3 3-terminal regulators are easy to use and have all the protection features expected in high performance linear regulators. The devices are short-circuit protected, safe-area protected and provide thermal shutdown to turn off the regulators should the junction temperature exceed about 150°C. The regulators include an adjustable and a fixed 3.3V version.

These ICs are pin compatible with the LT1083/LT1084/ LT1085 family of linear regulators but offer lower dropout voltage and faster transient response. The trade-off for this improved performance is a 7V maximum supply voltage. Similar to the LT1083/LT1084/LT1085 family, the LT1585A/LT1585A-3.3 regulators require an output capacitor for stability. However, the improved frequency compensation permits the use of capacitors with much lower ESR while still maintaining stability. This is critical in addressing the needs of modern, low voltage, high speed microprocessors.

Current generation microprocessors cycle load current from almost zero to amps in tens of nanoseconds. Output voltage tolerances are tighter and include transient response as part of the specification. The LT1585A/ LT1585A-3.3 are specifically designed to meet the fast current load-step requirements of these microprocessors and save total cost by needing less output capacitance in order to maintain regulation.

Stability

The circuit design in the LT1585A/LT1585A-3.3 requires the use of an output capacitor as part of the frequency compensation. For all operating conditions, the addition of a 22µ F solid tantalum or a 100µ F aluminum electrolytic on the output ensures stability. Normally, the LT1585A/ LT1585A-3.3 can use smaller value capacitors. Many different types of capacitors are available and have widely varying characteristics. These capacitors differ in capaci-

Page 6

LT1585A/LT1585A-3.3

WUU

APPLICATIONS INFORMATION

tor tolerance (sometimes ranging up to ±100%), equivalent series resistance, equivalent series inductance and capacitance temperature coefficient. The LT1585A/ LT1585A-3.3 frequency compensation optimizes frequency response with low ESR capacitors. In general, use capacitors with an ESR of less than 1Ω.

On the adjustable LT1585A, bypassing the adjust terminal improves ripple rejection and transient response. Bypassing the adjust pin increases the required output capacitor value. The value of 22µF tantalum or 100µF aluminum covers all cases of bypassing the adjust terminal. With no adjust pin bypassing, smaller values of capacitors provide equally good results.

Normally, capacitor values on the order of several hundred microfarads are used on the output of the regulators to ensure good transient response with heavy load current changes. Output capacitance can increase without limit and larger values of output capacitance further improve the stability and transient response of the LT1585A/ LT1585A-3.3.

Large load current changes are exactly the situation presented by modern microprocessors. The load current step contains higher order frequency components that the output decoupling network must handle until the regulator throttles to the load current level. Capacitors are not ideal elements and contain parasitic resistance and inductance. These parasitic elements dominate the change in output voltage at the beginning of a transient load step change. The ESR of the output capacitors produces an instantaneous step in output voltage (∆V = ∆I • ESR). The ESL of the output capacitors produces a droop proportional to the rate of change of output current (V = L • ∆I/∆t). The output capacitance produces a change in output voltage proportional to the time until the regulator can respond (∆V = ∆t • ∆I/C). These transient effects are illustrated in Figure 1.

The use of capacitors with low ESR, low ESL and good high frequency characteristics is critical in meeting the output voltage tolerances of these high speed micropro-

ESR EFFECTS

ESL EFFECTS

SLOPE, =

V

∆I

POINT AT WHICH REGULATOR

TAKES CONTROL

Figure 1

CAPACITANCE EFFECTS

LT1585A • F01

cessors. These requirements dictate a combination of high quality, surface mount tantalum capacitors and ceramic capacitors. The location of the decoupling network is critical to transient response performance. Place the decoupling network as close as possible to the processor pins because trace runs from the decoupling capacitors to the processor pins are inductive. The ideal location for the decoupling network is actually inside the microprocessor socket cavity. In addition, use large power and ground plane areas to minimize distribution drops.

A possible stability problem that occurs in monolithic linear regulators is current limit oscillations. The LT1585A/ LT1585A-3.3 essentially have a flat current limit over the range of input supply voltage. The lower current limit rating and 7V maximum supply voltage rating for these devices permit this characteristic. Current limit oscillations are typically nonexistent, unless the input and output decoupling capacitors for the regulators are mounted several inches from the terminals.

Protection Diodes

In normal operation, the LT1585A/LT1585A-3.3 do not require any protection diodes. Older 3-terminal regulators require protection diodes between the output pin and the input pin or between the adjust pin and the output pin to prevent die overstress.

On the adjustable LT1585A, internal resistors limit internal current paths on the adjust pin. Therefore, even with bypass capacitors on the adjust pin, no protection diode is needed to ensure device safety under short-circuit conditions.

Page 7

LT1585A/LT1585A-3.3

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APPLICATIONS INFORMATION

A protection diode between the input and output pins is usually not needed. An internal diode between the input and output pins on the LT1585A/LT1585A-3.3 can handle microsecond surge currents of 50A to 100A. Even with large value output capacitors it is difficult to obtain those values of surge currents in normal operation. Only with large values of output capacitance, such as 1000µF to 5000µF, and with the input pin instantaneously shorted to ground can damage occur. A crowbar circuit at the input of the LT1585A/LT1585A-3.3 can generate those levels of current, and a diode from output to input is then recommended. This is shown in Figure 2. Usually, normal power supply cycling or system “hot plugging and unplugging” will not generate current large enough to do any damage.

The adjust pin can be driven on a transient basis ±7V with respect to the output, without any device degradation. As with any IC regulator, exceeding the maximum input-tooutput voltage differential causes the internal transistors to break down and none of the protection circuitry is then functional.

D1

1N4002

(OPTIONAL)

LT1585A-3.3

C1 10µF

IN OUT

GND



C2 10µF

OUT

Ripple Rejection

The typical curve for ripple rejection reflects values for the LT1585A-3.3 fixed output voltage part. In applications that require improved ripple rejection, use the adjustable device. A bypass capacitor from the adjust pin to ground reduces the output ripple by the ratio of V

/1.25V. The

OUT

impedance of the adjust pin capacitor at the ripple frequency should be less than the value of R1 (typically in the range of 100Ω to 120Ω) in the feedback divider network in Figure 2. Therefore, the value of the required adjust pin capacitor is a function of the input ripple frequency. For example, if R1 equals 100Ω and the ripple frequency equals 120Hz, the adjust pin capacitor should be 22µ F. At 10kHz, only 0.22µF is needed.

Output Voltage

The LT1585A adjustable regulator develops a 1.25V reference voltage between the output pin and the adjust pin (see Figure 3). Placing a resistor R1 between these two terminals causes a constant current to flow through R1 and down through R2 to set the overall output voltage. Normally, this current is the specified minimum load current of 10mA. The current out of the adjust pin adds to the current from R1 and is typically 55µA. Its output voltage contribution is small and only needs consideration when very precise output voltage setting is required.

D1

1N4002

(OPTIONAL)

C1 10µF

LT1585A

IN OUT

ADJ



ADJ

OUT

C2 10µF

LT1585A • F02

C1 10µF

= V

OUT

(1 + R2/R1) + I

REF

Figure 3. Basic Adjustable Regulator

55µA

LT1585A



ADJ

OUT

(R2)

REF

OUT

C2 10µF

LT1585A • F03

Figure 2

Page 8

LT1585A/LT1585A-3.3

WUU

APPLICATIONS INFORMATION

Load Regulation

It is not possible to provide true remote load sensing because the LT1585A/LT1585A-3.3 are 3-terminal devices. Load regulation is limited by the resistance of the wire connecting the regulators to the load. Load regulation per the data sheet specification is measured at the bottom of the package.

For fixed voltage devices, negative side sensing is a true Kelvin connection with the ground pin of the device returned to the negative side of the load. This is illustrated in Figure 4.

For adjustable voltage devices, negative side sensing is a true Kelvin connection with the bottom of the output divider returned to the negative side of the load. The best

LT1585A-3.3

IN OUT

GND

load regulation is obtained when the top of resistor divider R1 connects directly to the regulator output and not to the load. Figure 5 illustrates this point. If R1 connects to the load, the effective resistance between the regulator and the load is:

RP(1 + R2/R1), RP = Parasitic Line Resistance

The connection shown in Figure 5 does not multiply RP by the divider ratio. As an example, RP is about four milliohms per foot with 16-gauge wire. This translates to 4mV per foot at 1A load current. At higher load currents, this drop represents a significant percentage of the overall regulation. It is important to keep the positive lead between the regulator and the load as short as possible and to use large wire or PC board traces.



PARASITIC

LINE RESISTANCE

LT1585A • F04

Figure 4. Connection for Best Load Regulation



LT1585A

*CONNECT R1 TO CASE CONNECT R2 TO LOAD

Figure 5. Connection for Best Load Regulation

ADJ



LINE RESISTANCE

OUTINV

PARASITIC

R1*

R2*

LT1585A • F05

Page 9

LT1585A/LT1585A-3.3

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APPLICATIONS INFORMATION

Thermal Considerations

The LT1585A/LT1585A-3.3 family protects the device under overload conditions with internal power and thermal limiting circuitry. However, for normal continuous load conditions, do not exceed maximum junction temperature ratings. It is important to consider all sources of thermal resistance from junction-to-ambient. These sources include the junction-to-case resistance, the caseto-heat sink interface resistance and the heat sink resistance. Thermal resistance specifications have been developed to more accurately reflect device temperature and ensure safe operating temperatures. The Electrical Characteristics section provides a separate thermal resistance and maximum junction temperature for both the control circuitry and the power transistor. Older regulators, with a single junction-to-case thermal resistance specification, use an average of the two values provided here and allow excessive junction temperatures under certain conditions of ambient temperature and heat sink resistance. Calculate the maximum junction temperature for both sections to ensure that both thermal limits are met.

Junction-to-case thermal resistance is specified from the IC junction to the bottom of the case directly below the die. This is the lowest resistance path for heat flow. Proper mounting ensures the best thermal flow from this area of the package to the heat sink. Linear Technology strongly recommends thermal compound at the case-to-heat sink interface. Use a thermally conductive spacer if the case of the device must be electrically isolated and include its contribution to the total thermal resistance. Please consult “Mounting Considerations for Power Semiconduc-

tors”

1990 Linear Applications Handbook, Volume I

Pages RR3-1 to RR3-20. The output connects to the case of both the LT1585A and the LT1585A-3.3.

For example, using an LT1585ACT-3.3 (TO-220, commercial) and assuming:

VIN(Max Continuous) = 5.25V (5V + 5%), V I

= 5A

OUT

TA = 70°C, θ

CASE-TO-HEAT SINK

Power dissipation under these conditions is equal to:

PD = (V

Junction temperature will be equal to:

TJ = TA + PD(θ

For the Control Section:

TJ = 70°C + 9.75W (3°C/W + 1°C/W + 0.7°C/W) = 115.8°C

115.8°C < 125°C = T cial range)

For the Power Transistor:

TJ = 70°C + 9.75W (3°C/W + 1°C/W + 3°C/W) = 138.3°C

138.3°C < 150°C = T mercial Range)

In both cases the junction temperature is below the maximum rating for the respective sections, ensuring reliable operation.

– V

HEAT SINK

OUT

HEAT SINK

= 3°C/W

= 1°C/W (with Thermal Compound)

)(I

) = (5.25 – 3.3)(5) = 9.75W

OUT

+ θ

CASE-TO-HEAT SINK

(Control Section Commer-

JMAX

(Power Transistor Com-

JMAX

OUT

+ θJC)

= 3.3V,

Page 10

LT1585A/LT1585A-3.3

TYPICAL APPLICATIONS N

Minimum Parts Count LT1585A Adjustable Circuit

for the Intel 120MHz Pentium Processor

4.75V TO

5.25V C1 TO C3

220µF

10V

AVX TPS

3 EACH

50mV/DIV

2A/DIV

AVX X7R 0805

OUT

THERMALLOY

7020B-MT

OUT

330nF

16V

C4

LT1585ACT

ADJ

R1 110Ω

0.1%

R2 197Ω

0.1%

LT1585A Transient Response

for 3.8A Load Current Step*

PLACE IN MICROPROCESSOR

SOCKET CAVITY

3.50V 5A

C5 TO C10

100µF 10V AVX TPS 4 EACH

AVX CORP. (803) 448-9411 THERMALLOY INC. (214) 243-4321

DO NOT SUBSTITUTE COMPONENTS.

C11 TO C20 1µF 16V AVX Y5V 0805 24 EACH

LT1585A TA04

100µs/DIV

*TRANSIENT RESPONSE MEASURED WITH AN INTEL

POWER VALIDATOR. V POWER VALIDATOR

IS MEASURED AT THE

OUT

LT1584A • TA05

Page 11

TYPICAL APPLICATIONS N

Guaranteed LT1585A Circuit for the Intel 100MHz and Higher Frequency Pentium Processors

(Meets Intel Specifications with Worst-Case Tolerances)

LT1585A/LT1585A-3.3

SEE NOTE 5

C2 TO C4

220µF 10V AVX TPS 3 EACH

THERMALLOY

7021B-MT

LT1585A

ADJ

C1

0.1µF

OUT

C5

33pF

NPO

R1 1k

COMP COL

LT1431S

SGND FGND

R3D 83Ω

SEE NOTE 7

R3E

117Ω

SGND PGND

REF

R2

C6

0.01µF

SEE NOTE 6

R3C 800Ω 

R3B

1.35k

 R3A

1.15k



LT1585A/LT1431 Transient Response

for 3.8A Load Current Step*

C7 100µF 10V

OUT

SENSE

PGND

LT1584 • TA06

PLACE IN MICROPROCESSOR

SOCKET CAVITY

C8 TO C13 100µF

10V AVX TPS 4 EACH

NOTES: UNLESS OTHERWISE SPECIFIED

1. ALL RESISTOR VALUES ARE OHMS,  1/8W, 5%

2. ALL CAPACITORS ARE 50V, 20%

3. ALL POLARIZED CAPACITORS ARE AVX  TYPE TPS OR EQUIVALENT

4. INPUT CAPACITANCE MAY BE REDUCED  IF THE 5V SUPPLY IS WELL BYPASSED

5. FOR 100MHz PENTIUM PROCESSOR, INPUT VOLTAGE MUST BE AT LEAST

4.85V AT THE REGULATOR INPUT

6. FOR PENTIUM VRE PROCESSOR,  R4 NOT INSTALLED – FOR 3.3V OUTPUT, INSTALL 0Ω JUMPER RESISTOR R4

7. R3A TO R3E ARE B.I. TECHNOLOGY 627V100

C14 TO C23 1µF 16V AVX Y5V 0805 24 EACH

OUT

50mV/DIV

OUT

2A/DIV

100µs/DIV

*TRANSIENT RESPONSE MEASURED WITH AN INTEL

POWER VALIDATOR. V POWER VALIDATOR

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.

IS MEASURED AT THE

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LT1584A • TA06

Page 12

LT1585A/LT1585A-3.3

PACKAGE DESCRIPTION

Dimensions in inches (millimeters) unless otherwise noted.

T Package

3-Lead Plastic TO-220

0.390 – 0.415

(9.906 – 10.541)

(11.684 – 12.700)

0.980 – 1.070

(24.892 – 27.178)

(13.208 – 14.478)

0.460 – 0.500

0.520 – 0.570

0.090 – 0.110

(2.286 – 2.794)

0.028 – 0.038

(0.711 – 0.965)

0.147 – 0.155

(3.734 – 3.937)

0.230 – 0.270

(5.842 – 6.858)

(14.478 – 15.748)

0.330 – 0.370

(8.382 – 9.398)

0.218 – 0.252

(5.537 – 6.401)

0.050

(1.270)

TYP

DIA

0.570 – 0.620

0.165 – 0.180

(4.293 – 4.699)

0.013 – 0.023

(0.330 – 0.584)

0.045 – 0.055

(1.143 – 1.397)

0.095 – 0.115

(2.413 – 2.921)

T3 (TO-220) 0595

RELATED PARTS

PART NUMBER DESCRIPTION COMMENTS

LTC1430 High Power Step-Down Switching Regulator 5V to 3.3V at 10A LT1580 7A Very Low Dropout Linear Regulator 0.54V Dropout at 7A, Fixed 2.5V LT1584 7A Low Dropout Fixed and Adjustable Linear Regulators Fast Transient Response for Microprocessor Applications LT1587 3A Low Dropout Fixed and Adjustable Linear Regulators Fast Transient Response for Microprocessor Applications

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7487

(408) 432-1900

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FAX

: (408) 434-0507

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TELEX

: 499-3977

 LINEAR TECHNOLOGY CORPORATION 1995

and Adjustable

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LT/GP 1095 10K • PRINTED IN USA

Datasheet LT1585A Datasheet (Linear Technology)

Specifications and Main Features

Frequently Asked Questions

User Manual