Datasheet RC1585 Datasheet (Fairchild Semiconductor)

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RC1585

5A Adjustable/Fixed Low Dropout Linear Regulator

Features

• Fast transient response

• Low dropout voltage at up to 5A

• Load regulation: 0.05% typical

• Trimmed current limit

• On-chip thermal limiting

• Standard TO-220, TO-263, TO-263 center cut and TO-252 packages

Applications

• Pentium® class GTL+ bus supply

• Low voltage logic supply

• Post regulator for switching supply

Typical Applications

RC1585

= 3.3V

10µF

ADJ

Description

The RC1585 and RC1585-1.5 are low dropout three-terminal regulators with 5A output current capability. These devices have been optimized for low voltage applications including

bus termination, where transient response and mini-

mum input voltage are critical. The RC1585 is ideal for low voltage microprocessor applications requiring a regulated output from 1.5V to 3.6V with an input supply of 5V or less. The RC1585-1.5 offers ﬁxed 1.5V with 5A current capabilities for GTL+ bus V

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 and ambient temperature that would create excessive junction temperatures.

The RC1585 series regulators are available in the industrystandard TO-220, TO-263, TO-263 center cut and TO-252 power packages.

OUT

124Ω

22µF

termination.

1.5V at 5A

24.9Ω

RC1585-1.5

= 3.3V

10µF

Pentium is a registered trademark of Intel Corporation. REV. 1.1.4 10/8/02

OUT

GND

22µF

1.5V at 5A

65-1585-01a

Page 2

RC1585 PRODUCT SPECIFICATION

Pin Assignments

RC1585T-1.5RC1585T

FRONT VIEW

RC1585MRC1585M-1.5

FRONT VIEW

12 3

GND

FRONT VIEW

3-Lead Plastic TO-263

θJC = 3°C/W*

12 3

GND

3-Lead Plastic TO-263 Center Cut

θJC = 3°C/W*

12 3

RC1585MCRC1585MC-1.5

FRONT VIEW

12 3

ADJ

Tab is Out.

ADJ

OUT

INADJ

3-Lead Plastic TO-220

θJC = 3°C/W

FRONT VIEW

12 3

GND

3-Lead Plastic TO-252

θJC = 3°C/W*

12 3

GND OUTOUT OUT

RC1585DRC1585D-1.5

FRONT VIEW

12 3

ADJ

Tab is Out.

* θJA can vary from 20°C/W to >40°C/W with various mounting techniques.

65-1585-02

Absolute Maximum Ratings

Parameter Min. Max. Unit

Operating Junction Temperature Range 0 125 °C

Storage Temperature Range -65 150 °C

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

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Page 3

PRODUCT SPECIFICATION RC1585

Electrical Characteristics

Tj = 25°C unless otherwise speciﬁed. The • denotes speciﬁcations which apply over the speciﬁed operating temperature range.

Parameter Conditions Min. Typ. Max Units

Reference Voltage

Output Voltage

Line Regulation

Load Regulation

1, 2

1, 2, 3

Dropout Voltage ∆V

Current Limit (VIN – V

Adjust Pin Current

Adjust Pin Current Change31.5V ≤ (VIN – V

Minimum Load Current 1.5V ≤ (VIN – V

Quiescent Current VIN = 5V • 413mA

Ripple Rejection 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 (% of V

OUT

)

Thermal Resistance, Junction to Case

Thermal Shutdown 150 °C

Notes:

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.

2. Line and load regulation are guaranteed up to the maximum power dissipation (18W). Power dissipation is determined by

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

3. RC1585 only.

4. RC1585-1.5 only.

1.5V ≤ (VIN – V 10mA ≤ I

OUT

3V ≤ VIN ≤ 7V 10mA ≤ I

(V I

OUT

(VIN – V 10mA ≤ I

OUT

+ 1.5V) ≤ VIN ≤ 7V,

OUT

= 10mA

) = 3V,

OUT

= 1%, I

REF

) = 2V • 5.1 5.5 A

OUT

≤ 5A

) ≤ 5.75V,

• 1.225 (-2%)

1.250 1.275 (+2%)

• 1.47 1.5 1.53 V

≤ 5A

• 0.005 0.2 %

• 0.05 0.5 %

≤ 5A

= 5A • 1.150 1.300 V

OUT

• 35 120 µA

10mA ≤ I

(VIN – V

OUT

) ≤ 5.75V,

OUT

≤ 5A

) ≤ 5.75V • 10 mA

OUT

= 22µF Tantalum,

OUT

) = 3V, I

OUT

= 5A

• 0.2 5 µA

60 72 dB

TA = 25°C, 10Hz ≤ f ≤ 10kHz 0.003 %

TO-220 3 °C/W

TO-263, TO-252 3 °C/W

REV. 1.1.4 10/8/02 3

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RC1585 PRODUCT SPECIFICATION

Typical Performance Characteristics

1.5

1.4

1.3

1.2

1.1

1.0

0.9

0.8

DROPOUT VOLTAGE (V)

0.7

T=0°C

T=25°C

T=125°C

0.6

0.5 123

450

65-1585-03

OUTPUT CURRENT (A)

Figure 1. Dropout Voltage vs. Output Current Figure 2. Load Regulation vs. Temperature

0.10 ∆I = 5A

0.05

-0.05

-0.10

-0.15

OUTPUT VOLTAGE DEVIATION (%)

-0.20

-75 -50 -25 0 25 50 75 100 125 150 175

JUNCTION TEMPERATURE (°C)

65-1585-04

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

-75 -50 -25 0 25 50 75 100 125 150 175

65-1585-05

JUNCTION TEMPERATURE (°C)

3.70 V

SET WITH 1% RESISTORS

OUT

3.65

3.60

3.55

3.50

3.45

3.40

3.35

REFERENCE VOLTAGE (V)

3.30

3.25

3.20

-75 -50 -25 0 25 50 75 100 125 150 175

JUNCTION TEMPERATURE (°C)

OUT

= 3.3V

= 3.6V

Note:

1. RC1585 Only

65-1585-06

Figure 3. Reference Voltage vs. Temperature Figure 4. Output Voltage vs. Temperature

MINIMUM LOAD CURRENT (mA)

-75 -50 -25 0 25 50 75 100 125 150 175

JUNCTION TEMPERATURE (°C)

65-1585-07

100

ADJUST PIN CURRENT (µA)

-75 -50 -25 0 25 50 75 100 125 150 175

JUNCTION TEMPERATURE (°C)

Note:

1. RC1585 Only

65-1585-08

Figure 5. Minimum Load Current vs. Temperature Figure 6. Adjust Pin Current vs. Temperature

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Page 5

PRODUCT SPECIFICATION RC1585

Typical Performance Characteristics (continued)

8.0

7.0

6.0

5.0

SHORT-CIRCUIT CURRENT (A)

4.0

-75 -50 -25 0 25 50 75 100 125 150 175

JUNCTION TEMPERATURE (°C)

65-1585-09

(VIN – V

RIPPLE REJECTIONS (dB)

0.5V ≤ V I

OUT

10 100 1K 10K 100K

≤ 3V

OUT)

RIPPLE

= 5A

FREQUENCY (Hz)

≤ 2V

Figure 7. Short-Circuit Current vs. Temperature Figure 8. Ripple Rejection vs. Frequency

65-1585-10

POWER (W)

50 60 70 80 90 100 110 120 130 140 150

CASE TEMPERATURE (°C)

Figure 9. Maximum Power Dissipation

65-1585-11

REV. 1.1.4 10/8/02 5

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RC1585 PRODUCT SPECIFICATION

Applications Information

General

The RC1585 and RC1585-1.5 are three-terminal regulators optimized for GTL+ VTT termination and logic applications. These devices are short-circuit protected and offer thermal shutdown to turn off the regulator when the junction temperature exceeds about 150°C. The RC1585 series provides low dropout voltage and fast transient response. Frequency compensation uses capacitors with low ESR while still maintaining stability. This is critical in addressing the needs of low voltage high speed microprocessor buses like GTL+.

Stability

The RC1585 series requires an output capacitor as a part of the frequency compensation. It is recommended to use a 22µF solid tantalum or a 100 µF aluminum electrolytic on the output to ensure stability. The frequency compensation of these devices optimizes the frequency response with low ESR capacitors. In general, it is suggested to use capacitors with an ESR of <300mΩ. It is also recommended to use bypass capacitors such as a 22µF tantalum or a 100µF aluminum on the adjust pin of the RC1585 for low ripple and fast transient response. When these bypassing capacitors are not used at the adjust pin, larger values of output capacitors provide equally good results.

10µF

+ +

Figure 10. Optional Protection

1N4002

(OPTIONAL)

RC1585

IN OUT

ADJ

1N4002

(OPTIONAL)

RC1585-1.5

IN OUT

GND

C2 22µF

OUT

65-1585-12

C2 22µF

OUT

Protection Diodes

In normal operation, the RC1585 series does not require any protection diodes. For the RC1585, 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.

A protection diode between the input and output pins is usually not needed. An internal diode between the input and the output pins on the RC1585 series 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 can generate those levels of current; a diode from output to input is then recommended, as shown in Figure 10. 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.

Ripple Rejection

In applications that require improved ripple rejection, a bypass capacitor from the adjust pin of the RC1585 to ground reduces the output ripple by the ratio of V

OUT

/1.25V. The 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 10. 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 22µF. At 10kHz, only 0.22µF is needed.

Output Voltage

The RC1585 regulator develops a 1.25V reference voltage between the output pin and the adjust pin (see Figure 11). 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 35µA. Its output voltage contribution is small and only needs consideration when a very precise output voltage setting is required.

6 REV. 1.1.4 10/8/02

Page 7

PRODUCT SPECIFICATION RC1585

PARASITIC

R1*

R2*

65-1585-15

OUT

= V

C1 10µF

(1 + R2/R1) + I

REF

ADJ

35µA

Figure 11. Basic Regulator Circuit

Load Regulation

RC1585

ADJ

OUT

ADJ

(R2)

REF

C2 22µF

65-1585-13

OUT

CONNECT R1 TO CASE

CONNECT R2 TO LOAD

RC1585

IN OUT

ADJ

LINE RESISTANCE

It is not possible to provide true remote load sensing because the RC1585 series are three-terminal devices. Load regula-

Figure 13. Connection for Best Load Regulation

tion 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.

Thermal Considerations

The RC1585 series protect themselves under overload conditions with internal power and thermal limiting circuitry.

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 12.

PARASITIC

LINE RESISTANCE

RC1585-1.5

IN OUT

GND

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 case-to-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.

For example, look at using an RC1585T to generate 5A @

1.5V ± 2% from a 3.3V source (3.2V to 3.6V).

65-1585-14

Figure 12. Connection for Best Load Regulation

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 load regulation is obtained when the top of the resistor divider R1 connects directly to the regulator output and not to the load. Figure 13 illustrates this point.

If R1 connects to the load, then the effective resistance between the regulator and the load would be:

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

The connection shown in Figure 13 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.

Assumptions:

•VIN = 3.6V worst case

•V

•I

= 1.46V worst case

OUT

= 5A continuous

OUT

•TA = 60°C

• θ

Case-to-Ambient

= 3°C/W (assuming both a heatsink and

a thermally conductive material)

The power dissipation in this application is:

PD = (VIN – V

OUT

) * (I

) = (3.6 – 1.46) * (5) = 10.7W

OUT

From the speciﬁcation table:

TJ = TA + (PD) * (θ

Case-to-Ambient

+ θJC)

= 60 + (10.7) * (3 + 3) = 120°C

The junction temperature is below the maximum rating.

REV. 1.1.4 10/8/02 7

Page 8

RC1585 PRODUCT SPECIFICATION

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. Use of a thermally conductive material at the

3.3V

10µF

100µF

RC1585

ADJ

case-to-heat sink interface is recommended. Use a thermally conductive spacer if the case of the device must be electrically isolated and include its contribution to the total thermal resistance. The cases of the RC1585 series are directly connected to the output of the device.

OUT

R1 124Ω

24.9Ω

OUT

1.5V

C3 100µF

65-1586-16

Figure 14. Application Circuit (RC1585)

Table 1. Bill of Materials for Application Circuit for the RC1585

Item Quantity Manufacturer Part Number Description

C1 1 Xicon L10V10 10µF, 10V Aluminum

C2, C3 2 Xicon L10V100 100µF, 10V Aluminum

R1 1 Generic 124Ω, 1%

R2 1 Generic 24.9Ω, 1%

U1 1 Fairchild RC1585T 5A Regulator

RC1585-1.5

GND

OUT

1.5V

C3 100µF

65-1585-17

3.3V

10µF

Figure 15. Application Circuit (RC1585-1.5)

Table 2. Bill of Materials for Application Circuit for the RC1585-1.5

Item Quantity Manufacturer Part Number Description

C1 1 Xicon L10V10 10µF, 10V Aluminum

C3 1 Xicon L10V100 100µF, 10V Aluminum

U1 1 Fairchild RC1585T-1.5 5A Regulator

8 REV. 1.1.4 10/8/02

Page 9

PRODUCT SPECIFICATION RC1585

Mechanical Dimensions

3-Lead TO-263 Package

Symbol

A .160 .190 4.06 4.83

b .020 .036 0.51 0.91 b2 c2

D E e

L .575 .625 14.61 15.88 L1 L2 R

Inches

Min. Max. Min. Max.

.049 .051 1.25 1.30 .045 .055 1.14 1.40

.340 .380 8.64 9.65 .380 .405 9.65 10.29

.100 BSC

.090

.017 .019 0.43 0.78

.110

— .055 — 1.40

0° 8° 0° 8°

@PKG/

@HEATSINK

Millimeters

2.54 BSC

2.29 2.79

E-PIN

Notes

Notes:

1. Dimensions are exclusive of mold flash and metal burrs.

2. Standoff-height is measured from lead tip with ref. to Datum -B-.

3. Foot length is measured with ref. to Datum -A- with lead surface (at inner R).

4. Dimensiuon exclusive of dambar protrusion or intrusion.

5. Formed leads to be planar with respect to one another at seating place -C-.

-C-

R (2 PLCS)

-A--B-

REV. 1.1.4 10/8/02 9

Page 10

RC1585 PRODUCT SPECIFICATION

Mechanical Dimensions (continued)

3-Lead TO-263 Center Cut Package

Symbol

A .160 .190 4.06 4.83

b .020 .036 0.51 0.91 b2 c2

D E e

L .575 .625 14.61 15.88 L1 L2

L3 R

Inches

Min. Max. Min. Max.

.049 .051 1.25 1.30 .045 .055 1.14 1.40

.340 .380 8.64 9.65 .380 .405 9.65 10.29

.100 BSC

.090

.050 .017 .019 0.43 0.78

.110

— .055 — 1.40

.070

0° 8° 0° 8°

@PKG/

@HEATSINK

Millimeters

2.54 BSC

2.29 2.79

1.27 1.78

Notes

Notes:

1. Dimensions are exclusive of mold flash and metal burrs.

2. Standoff-height is measured from lead tip with ref. to Datum -B-.

3. Foot length is measured with ref. to Datum -A- with lead surface (at inner R).

4. Dimensiuon exclusive of dambar protrusion or intrusion.

5. Formed leads to be planar with respect to one another at seating place -C-.

E-PIN

-C-

R (2 PLCS)

-A--B-

10 REV. 1.1.4 10/8/02

Page 11

PRODUCT SPECIFICATION RC1585

Mechanical Dimensions (continued)

3-Lead TO-220 Package

Symbol

A .140 .190 3.56 4.83

b .015 .040 .38 1.02

b1 .045 1.14 c1 .014 .022 .36 .56 øP .139 .161 3.53 4.09

D .560 .650 14.22 16.51 E e

e1 .190 .210 4.83 5.33

F H1 .230 .270 5.94 6.87 J1

L L1

Inches

Min. Max. Min. Max.

.070 1.78

.380 .420 9.65 10.67 .090 .110 2.29 2.79

.045 — 1.14 —

.020 .055 .51 1.40

.060 .115 2.04 2.92

.500 .580 12.70 14.73

.100 .135 2.54 3.43

3° 7° 3° 7°

Millimeters

6.35 BSC.250 BSC

Notes

Notes:

1. Dimension c1 apply for lead finish.

E-PIN øP

(5X)

REV. 1.1.4 10/8/02 11

Page 12

RC1585 PRODUCT SPECIFICATION

Mechanical Dimensions (continued)

3-Lead TO-252 Package

6.73

6.35

5.46

5.21

(0.59)

0.89

0.54

0.25 A C

SEE

NOTE D

4.57

6.00 MIN

1.02

0.84

1.14

0.78

2.29

6.25

1.40 MIN

6.50 MIN

3.00 MIN

2.30

4.80

LAND PATTERN RECOMMENDATION

2.38

2.18

0.58

0.48

10°

0°

GAGE PLANE

0.61

0.48

1.78

1.40

2.90

DETAIL A

(ROTATED –90°

SCALE 12X

0.127 MAX

SEATING PLANE

0.51

(1.54)

10.41

DETAIL A

0.10 B

NOTES: UNLESS OTHERWISE SPECIFIED

A) ALL DIMENSIONS ARE IN MILLIMETERS. B) THIS PACKAGE CONFORMS TO JEDEC, TO-252,

ISSUE C. VARIATION AA & AB, DATED NOV. 1999.

C) DIMENSIONING AND TOLERANCING PER

ASME Y14.5–1994.

D) HEAT SINK TOP EDGE COULD BE IN CHAMFERED

CORNERS OR EDGE PROTRUSION.

E) DIMENSIONS L3, D, E1 & D1 TABLE:

OPTION AA OPTION AB

0.89 – 1.27 1.52 – 2.03

5.97 – 6.22 5.33 – 5.59

4.32 MIN 3.81 MIN

5.21 MIN

D1 4.57 MIN

9.40SEE

12 REV. 1.1.4 10/8/02

Page 13

RC1585 PRODUCT SPECIFICATION

Ordering Information

Product Number Package

RC1585M TO-263

RC1585MC TO-263 Center Cut

RC1585T TO-220

RC1585D TO-252

RC1585M-1.5 TO-263

RC1585MC-1.5 TO-263 Center Cut

RC1585T-1.5 TO-220

RC1585D-1.5 TO-252

DISCLAIMER

FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.

LIFE SUPPORT POLICY

FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein:

1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, or (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in significant injury to the user.

2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.

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