Linear Technology LT1585-1.5, LT1585A-1.5 Datasheet

FEATURES

LT1585-1.5/LT1585A-1.5

Fixed 1.5V, 4.6A and 5A

Low Dropout, Fast Response

GTL+ Regulators

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DESCRIPTIO

■

Fast Transient Response

■

Guaranteed Dropout Voltage at Multiple Currents

■

Load Regulation: 0.05% Typ

■

Trimmed Current Limit

■

On-Chip Thermal Limiting

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APPLICATIO S

■

GTL+ Power Supply

■

Low Voltage Logic Supplies

■

Battery-Powered Circuitry

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TYPICAL APPLICATIO

The LT®1585-1.5/LT1585A-1.5 are low dropout, 3-termi­nal regulators with 4.6A and 5A output current capability
respectively, and a fixed 1.5V output voltage. The designs
are optimized for low voltage applications where transient
response and minimum input voltage are critical. Similar to
the LT1084, they have lower dropout and faster transient
response. These improvements make them ideal for low
voltage microprocessor applications, especially as the
regulator in an Intel processor GTL+ supply.

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 creates excessive junction temperatures.

The LT1585-1.5/LT1585A-1.5 are available in the through­hole 3-pin TO-220 power package and 3-pin plastic DD.

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

3.3V

LT1585A-1.5

V

C1, C2

+

100µF
10V

NOTE: LTC RECOMMENDS CENTRALLY
LOCATING THE LT1585A-1.5 TO MINIMIZE

DISTRIBUTION DROPS AND USING

V

TT

SEPARATE V
BUS END

V

IN

OUT

GND

GENERATORS AT EACH

REF

+

V
5A

TT

= 1.5V

C3 TO C6
100µF
10V

Intel Processor GTL+ Supply

C7 TO
C12
1µF

RX

TX

RX

R1
75Ω

V

REF

R2
150Ω

TX

C13

0.1µF

Q1

Q3

R5
100ΩR7100ΩR8100ΩR6100Ω

•

•

•

142 TOTAL SIGNAL LINES

R3

V

75Ω

REF

R4
150Ω

Q2

Q4

C14

0.1µF

RX

TX

RX

TX

1585-1.5 • TA01

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LT1585-1.5/LT1585A-1.5

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ABSOLUTE MAXIMUM RATINGS

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(Note 1)

VIN............................................................................ 7V

Operating Junction Temperature Range

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

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

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PACKAGE/ORDER INFORMATION

FRONT VIEW

TAB

IS

OUTPUT

Consult factory for Industrial and Military grade parts.

3

2

1

M PACKAGE

3-LEAD PLASTIC DD

θJA = 30°C/W*

*WITH PACKAGE
SOLDERED TO 0.5

V

IN

SQUARE INCH COPPER
AREA OVER BACKSIDE

V

OUT

GROUND PLANE OR
INTERNAL POWER PLANE.

GND

CAN VARY FROM

θ

JA

20°C/W TO >40°C/W
WITH OTHER MOUNTING
TECHNIQUES

ORDER PART

NUMBER

LT1585CM-1.5
LT1585ACM-1.5

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

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

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PRECONDITIONI G

100% Thermal Limit Functional Test

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ORDER PART

IN

OUT

LT1585CT-1.5
LT1585ACT-1.5

TAB IS

OUTPUT

FRONT VIEW

3

2

1

T PACKAGE

3-LEAD PLASTIC TO-220

θJA = 50°C/W

V

V

GND

NUMBER

ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the specified operating

temperature range, otherwise specifications are at TA = 25°C.

PARAMETER CONDITIONS MIN TYP MAX UNITS

Output Voltage (Note 4) VIN = 5V, TJ = 25°C, I

Line Regulation (Notes 2, 3) 3V ≤ VIN ≤ 7V, I
Load Regulation VIN = 5V, TJ = 25°C, 0mA ≤ I

(Notes 2, 3, 4) ● 0.05 0.5 %
Dropout Voltage (Note 4) ∆V
Current Limit LT1585-1.5, (V

Quiescent Current V
Ripple Rejection (Note 4) f = 120Hz, C
Thermal Regulation TA = 25°C, 30ms Pulse 0.004 0.02 %/W
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
Thermal Resistance T Package: Control Circuitry/Power Transistor 0.7/3.0 °C/W

Junction to Case M Package: Control Circuitry/Power Transistor 0.7/3.0 °C/W

Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.

Note 2: 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 3: Line and load regulation are guaranteed up to the maximum
power dissipation (25W for the LT1585-1.5 in T package and 27.5W for

OUT

)

≤ 7V, 0mA ≤ I

3V ≤ V

IN

= 1%, I

OUT

LT1585A-1.5, (V

= 5V ● 713 mA

IN

OUT

IN

OUT

= 0mA 1.485 (–1%) 1.5 1.515 (+1%) V

OUT

≤ I

OUT

FULL LOAD

= 0mA 0.005 0.2 %

OUT

≤ I

OUT

FULL LOAD

= I

FULL LOAD

– V

) = 5.5V ● 4.60 5.25 A

OUT

– V

IN

= 25µF Tant., VIN = 4.5V, I

) = 5.5V ● 5.00 6.00 A

OUT

= I

OUT

FULL LOAD

the LT1585A-1.5). 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 4: I

FULL LOAD

as a function of input-to-output voltage. I
LT1585-1.5 and 5A for the LT1585A-1.5. The LT1585-1.5/LT1585A-1.5
have constant current limit with changes in input-to-output voltage.

● 1.470 (–2%) 1.5 1.530 (+2%) V

0.05 0.3 %

● 1.200 1.400 V

● 60 72 dB

is defined as the maximum value of output load current

FULL LOAD

is equal to 4.6A for the

2

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TEMPERATURE (°C)

–0.20

OUTPUT VOLTAGE DEVIATION (%)

–0.10

0

0.10

–0.15

–0.05

0.05

–25 25 75 125

1585-1.5 G03

175–50–75 0 50 100 150

∆I = I

FULL LOAD

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TYPICAL PERFORMANCE CHARACTERISTICS

LT1585-1.5/LT1585A-1.5

LT1585A-1.5 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

0

T = 25°C

1

2

OUTPUT CURRENT (A)

3

Output Voltage vs Temperature

1.53

1.52

1.51

1.50

1.49

OUTPUT VOLTAGE (V)

1.48

1.47
–25 25 75 125

T = –5°C

T = 125°C

4

5

1585-1.5 G01

TEMPERATURE (°C)

LT1585A-1.5 Short-Circuit Current
vs Temperature

6.0

5.5

5.0

4.5

SHORT-CIRCUIT CURRENT (A)

4.0
–50

–75

1585-1.5 G04

–25

175–50–75 0 50 100 150

50

75

0

25

TEMPERATURE (°C)

100

Load Regulation vs Temperature

125

175

150

1585-1.5 G02

Quiescent Current vs Temperature

13
12
11
10

9
8
7
6

QUIESCENT CURRENT (mA)

5
4
3

–25

0

–50 150

–75

25

50

TEMPERATURE (°C)

75

100

125

175

1585-1.5 G05

Ripple Rejection vs Frequency

90

80

70

60

50

40

30

RIPPLE REJECTION (dB)

20

(VIN – V

0.5V ≤ V

10

I

OUT

0

10 1k 10k 100k

OUT

= I

FULL LOAD

100

RIPPLE

) ≤ 3V

≤ 2V

FREQUENCY (Hz)

1585-1.5 G06

Maximum Power Dissipation*

30

25

20

15

POWER (W)

10

5

0

*AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE

50

LT1585A-1.5

LT1585-1.5

90 110 120 130 140 150

80 100

60 70

CASE TEMPERATURE (˚C)

1585-1.5 G07

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