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FAN1084
4.5A Adjustable/Fixed Low Dropout Linear Regulator
Features
* * * * * Fast transient response Low dropout voltage at up to 4.5A Load regulation: 0.5% typical On-chip thermal limiting Standard TO-220, TO-263 center cut, and TO-252 packages
Description
The FAN1084, FAN1084-1.5, and FAN1084-3.3 are low dropout three-terminal regulators with 4.5A output current capability. These devices have been optimized for low voltage applications including VTT bus termination, where transient response and minimum input voltage are critical. The FAN1084 is ideal for low voltage microprocessor applications requiring a regulated output from 1.5V to 3.6A with an input supply of 5V or less. The FAN1084-1.5 offers fixed 1.5V with 4.5A current capabilities for GTL+ bus VTT termination. The FAN1084-3.3 offers a fixed 3.3V output at 4.5A. On-chip thermal limiting provides protection against any combination of overload and ambient temperature that would create excessive junction temperatures. The FAN1084 series regulators are available in the industrystandard TO-220, TO-263 center cut, and TO-252 (DPAK) power packages.
Applications
* * * * * * * Desktop PCs, RISC and embedded processors' supply GTL, SSTL logic Reference bus supply Low voltage VCC logic supply Battery-powered circuitry Post regulator for switching supply Cable and ADSL modems' DSP core supply Set Top Boxes and Web Boxes modules' supply
Application Diagrams
VIN = 5V + 10F VIN FAN1084 VOUT ADJ 124 + 2.5V at 4.5A 22F
124
VIN = 3.3V + 10F
FAN1084-1.5 VIN VOUT GND +
1.5V at 4.5A 22F
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FAN1084
PRODUCT SPECIFICATION
Pin Assignments
FAN1084T FRONT VIEW FAN1084T-3.3 FAN1084T-1.5 FRONT VIEW
FAN1084M-3.3 FAN1084M-1.5 FRONT VIEW
FAN1084M FRONT VIEW Tab is out.
FAN1084D-3.3 FAN1084D-1.5
FAN1084D
FRONT VIEW FRONT VIEW 1 Tab is out. 123 123 2 3 1 2 3
1
2
3
1
2
3
GND GND IN ADJ IN
IN
ADJ
IN ADJ OUT IN GND OUT IN
3-Lead Plastic TO-263 JC=3C/W*
3-Lead Plastic TO-252 JC=3C/W*
3-Lead Plastic TO-220 JC=3C/W*
*With package soldered to 0.5 square inch copper area over backside ground plane or internal power plane, JA can vary from 30C/W to more than 40C/W. Other mounting techniques may provide better power dissipation than 30C/W. FAN1084M-3.3 also available with uncut center lead.
Absolute Maximum Ratings
Parameter VIN Operating Junction Temperature Range Storage Temperature Range Lead Temperature (Soldering, 10 seconds) 0 -65 Min. Max. 7 125 150 300 Unit V C C C
2
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PRODUCT SPECIFICATION
FAN1084
Electrical Characteristics
Operating Conditions: 4.75 VIN < 5.25V, Tj = 25C unless otherwise specified. Parameter Reference Voltage Output Voltage5 Output Voltage
6 3
Conditions Adj connected to ground, IOUT = 10mA IOUT = 10mA IOUT = 10mA IOUT = 10mA 10mA IOUT 4.5A VREF% = 2%, IOUT = 4.5A (VIN - VOUT) = 2V
Min. 1.23 1.475 3.234
Typ. 1.250 1.5 3.3 0.5 0.5
Max 1.27 1.525 3.366 2 2.5 1.5
Units V V V % % V A
Line Regulation1, 2 Load Regulation1, 2
Dropout Voltage Current Limit Adjust Pin Current3 Mimimum Load Current4
5.5 35 100
mA mA C/W C/W C
1.5V (VIN - VOUT) 5.75V VIN = 5V TO-220 TO-263 Center Cut, TO-252
10 4 3 3 150
Quiescent Current4 Thermal Resistance, Junction to Case Thermal Shutdown4
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. 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. FAN1084 only. 4. Guaranteed by design. 5. FAN1084-1.5 only. 6. FAN1084-3.3 only.
Typical Performance Characteristics
20
POWER (W)
15 10 5 0 25 45 65 85 105 125
CASE TEMPERATURE
Figure 1. Maximum Power Dissipation
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3
FAN1084
PRODUCT SPECIFICATION
Typical Performance Characteristics (Continued)
1.5 1.4 DROPOUT VOLTAGE (V) 1.3 1.2 1.1 1.0 0.9 T=25C 0.8 0.7 0.6 0.5 0 1 2 3 4 5 6 OUTPUT CURRENT (A) T=0C T=125C
I = 4.5A
Figure 2. Dropout Voltage vs. Output Current
Figure 3. Load Regulation vs. Temperature
1.275 1.270
1
OUT
VOUT = 3.6V
1
REFERENCE VOLTAGE (V)
1.265 1.260 1.255 1.250 1.245 1.240 1.235 1.230 1.225 -75 -50 -25 0 25 50 75 100 125 150 175
VOUT = 3.3V
1
JUNCTION TEMPERATURE (C)
Figure 4. Reference Voltage vs. Temperature
Figure 5. Output Voltage vs. Temperature
5 MINIMUM LOAD CURRENT (mA)
4
3
2
1
0 -75 -50 -25
0
25 50 75 100 125 150 175
JUNCTION TEMPERATURE (C)
Figure 6. Minimum Load Current vs. Temperature
Figure 7. Adjust Pin Current vs. Temperature
4
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PRODUCT SPECIFICATION
FAN1084
Typical Performance Characteristics (continued)
8.0 SHORT-CIRCUIT CURRENT (A)
90 80 RIPPLE REJECTIONS (dB)
7.0
70 60 50 40 30 20 10 (VIN - VOUT) 3V 0.5V VRIPPLE 2V IOUT = 5A 100 1K FREQUENCY (Hz) 10K 100K
6.0
5.0
4.0 -75 -50 -25
0
25 50 75 100 125 150 175
0 10
JUNCTION TEMPERATURE (C)
Figure 8. Short-Circuit Current vs. Temperature
2.5 OUTPUT CAPACITANCE ESR, ()
Figure 9. Ripple Rejection vs. Frequency
2
1.5 Area of Instability 1
0.5 Stable Area 0 0 1000 2000 3000 4000 LOAD CURRENT (mA)
Figure 10. Stability Region VIN/VOUT = 5V/1.5V
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FAN1084
PRODUCT SPECIFICATION
Applications Information
General
The FAN1084, FAN1084-1.5, and FAN1084-3.3 are threeterminal 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 150C. The FAN1084 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+.
The adjust pin can be driven on a transient basis 7V with respect to the ouput, without any device degradation. As with any IC regulator, exceeding the maximum input-to-output voltage differential causes the internal transistors to break down and none of the protection circuitry is then functional.
D1 1N4002 (OPTIONAL)
FAN1084 VIN + IN C1 10F ADJ + CADJ OUT R1 + VOUT C2 22F
Stability
The FAN1084 series requires an output capacitor as a part of the frequency compensation. It is recommended to use a 22F solid tantalum or a 100F 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 <0.2. It is also recommended to use bypass capacitors such as a 22F tantalum or a 100F aluminum on the adjust pin of the FAN1084 for low ripple and fast transient response. When these bypassing capacitors are not used at the adjust pin, smaller values of output capacitors provide equally good results. Refer to Typical Performance Characteristics for graph of stability of output capacitance ESR vs load current.
R2
D1 1N4002 (OPTIONAL)
FAN1084-1.5 VIN + IN C1 10F GND OUT + VOUT C2 22F
Protection Diodes
In normal operation, the FAN1084 series does not require any protection diodes. For the FAN1084, 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 FAN1084 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 1000F to 5000F, 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 2. Usually, normal power supply cycling or system "hot plugging and unplugging" will not generate current large enough to do any damage.
Figure 2. Optional Protection
Ripple Rejection
In applications that require improved ripple rejection, a bypass capacitor from the adjust pin of the FAN1084 to ground reduces the output ripple by the ratio of VOUT/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 100 to 120) 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 100 and the ripple frequency equals 120Hz, the adjust pin capacitor should be 22F. At 10kHz, only 0.22F is needed.
Output Voltage
The FAN1084 regulator develops a 1.25V reference voltage between the ouput 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.
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PRODUCT SPECIFICATION
FAN1084
The current out of the adjust pin adds to the current from R1. Its output voltage contribution is small and only needs consideration when a very precise output voltage setting is required.
FAN1084
FAN1084 VIN + IN C1 10F IADJ 35A ADJ OUT VREF R1 + VOUT C2 22F
RP Parasitic Line Resistance VIN IN ADJ R1* *Connect R1 to case Connect R2 to load RL R2* OUT
R2
Figure 3. Connection for Best Load Regulation
Load Regulation
It is not possible to provide true remote load sensing because the FAN1084 series are three-terminal devices. Load regulation is limited by the resistance of the wire connecting the regulator 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.
RP Parasitic Line Resistance FAN1084-1.5 VIN IN GND RL OUT
Figure 5. Connection for Best Load Regulation
Thermal Conditions
The FAN1084 series protect themselves 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 case-to-heatsink 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. Calculate the maximum junction temperature for both sections to ensure that both thermal limits are met. For example, look at using a FAN1084T to generate 4.5A @ 1.5V from a 3.3V source (3.2V to 3.6V).
Figure 4. Connection for Best Load Regulation
Assumptions
* * * * * VIN = 3.4V worst case VOUT = 1.475V worst case IOUT = 4.5A continuous TA = 60C Case-to-Ambient = 5C/W (assuming both a heatsink and a thermally conductive material)
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 5 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 5 does not multiply RP by the divider ration. 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.
The power dissipation in this application is: PD = (VIN - VOUT) * (IOUT) = (3.6 - 1.475) * (4.5) = 9.6W From the specification table: TJ = TA + (PD) * (Case-to-Ambient + JC) = 60 + (9.6) * (5 + 3) = 137C The junction temperature is below the maximum thermal limit.
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7
FAN1084
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
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 FAN1084 series are directly connected to the output of the device.
U1 FAN1084 VIN + IN C1 10F ADJ + C2 100F OUT R1 124 R2 124 + VOUT C3 2.5V 100F
Figure 6. Application Circuit
Table 1. Bill of Materials for Application Circuit for the FAN1084
Item C1 C2, C3 R1, R2 U1
Quantity 1 2 2 1
Manufacturer Xicon Xicon Generic Fairchild
Part Number L10V10 L10V100 FAN1084T
Description 10F, 10V Aluminum 100F, 10V Aluminum 124, 1% 4.5A Regulator
U1 RC1084-1.5 VIN = 3.3V C1 10F + IN GND OUT + VOUT 1.5V C3 100F
Figure 7. Application Circuit (FAN1084-1.5)
Table 2. Bill of Materials for Application Circuit for the FAN1084-1.5
Item C1 C3 U1
Quantity 1 1 1
Manufacturer Xicon Xicon Fairchild
Part Number L10V10 L10V100 FAN1084T-1.5
Description 10F, 10V Aluminum 100F, 10V Aluminum 4.5A Regulator
8
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PRODUCT SPECIFICATION
FAN1084
Mechanical Dimensions
3-Lead TO-263 Center Cut Package
Symbol A b b2 c2 D E e L L1 L2 L3 R Inches Min. .160 .020 Max. .190 .036 Millimeters Min. 4.06 0.51 Max. 4.83 0.91 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-.
.049 .051 .045 .055 .340 .380 .380 .405 .100 BSC .575 .090 -- .050 .017 0 .625 .110 .055 .070 .019 8
1.25 1.30 1.14 1.40 8.64 9.65 9.65 10.29 2.54 BSC 14.61 2.29 -- 1.27 0.43 0 15.88 2.79 1.40 1.78 0.78 8
E @PKG/ @HEATSINK
L2 c2
D L b2 E-PIN R (2 PLCS) L1 L3 b e
-B-
-A-
A -C-
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9
FAN1084
PRODUCT SPECIFICATION
Mechanical Dimensions
3-Lead TO-263 Package
Symbol A b b2 c2 D E e L L1 L2 R Inches Min. .160 .020 Max. .190 .036 Millimeters Min. 4.06 0.51 Max. 4.83 0.91 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-.
.049 .051 .045 .055 .340 .380 .380 .405 .100 BSC .575 .090 -- .017 0 .625 .110 .055 .019 8
1.25 1.30 1.14 1.40 8.64 9.65 9.65 10.29 2.54 BSC 14.61 2.29 -- 0.43 0 15.88 2.79 1.40 0.78 8
E @PKG/ @HEATSINK
L2 c2
D L b2 E-PIN R (2 PLCS) L1 b e
-B-
-A-
A -C-
10
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PRODUCT SPECIFICATION
FAN1084
Mechanical Dimensions (continued)
3-Lead TO-220 Package
Symbol A b b1 c1 oP D E e e1 e3 F H1 J1 L L1 Q Inches Min. Max. Millimeters Min. Max. Notes
.140 .190 .015 .040 .045 .070 .014 .022 .139 .161 .560 .650 .380 .420 .090 .110 .190 .210 .045 -- .020 .055 .230 .270 .080 .115 .500 .580 .250 BSC .100 .135 3 7
3.56 4.83 .38 1.02 1.14 1.78 .36 .56 3.53 4.09 14.22 16.51 9.65 10.67 2.29 2.79 4.83 5.33 1.14 -- .51 1.40 5.94 6.87 2.04 2.92 12.70 14.73 6.35 BSC 2.54 3.43 3 7
Notes: 1. Dimension c1 apply for lead finish.
H1 L e3 e e1 E b1 Q
b L1 E-PIN oP
(5X) c1 J1 D A F
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11
FAN1084
PRODUCT SPECIFICATION
Mechanical Dimensions (continued)
3-Lead TO-252 Package
A 6.00 MIN
6.73 6.35 5.46 5.21
L3
4 6.50 MIN
D 1.02 0.84 C 1 2 3 1 1.14 0.78 2.29 4.57 3 6.25
3.00 MIN
(0.59) 0.89 0.54 0.25 M A M C
1.40 MIN 4.80
2.30
LAND PATTERN RECOMMENDATION
B 2.38 2.18
SEE NOTE D
E1
4
0.58 0.48
D1 10.41 9.40
SEE DETAIL A
2 3
1
0.10 B
GAGE PLANE 0.61 0.48 10 0
0.51
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. (1.54) C) D) DIMENSIONING AND TOLERANCING PER ASME Y14.5-1994. HEAT SINK TOP EDGE COULD BE IN CHAMFERED CORNERS OR EDGE PROTRUSION. DIMENSIONS L3, D, E1 & D1 TABLE: OPTION AA OPTION AB L3 0.89 - 1.27 1.52 - 2.03 D 5.97 - 6.22 5.33 - 5.59 E1 4.32 MIN 3.81 MIN D1 5.21 MIN 4.57 MIN
1.78 1.40 2.90
0.127 MAX SEATING PLANE
E)
DETAIL A
(ROTATED -90 SCALE 12X
12
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FAN1084
PRODUCT SPECIFICATION
Ordering Information
Product Number FAN1084MC FAN1084T FAN1084D FAN1084MC15 FAN1084T15 FAN1084D15 FAN1084MC33 FAN1084M33 FAN1084T33 FAN1084D33 Package TO-263 Center Cut TO-220 TO-252 TO-263 Center Cut TO-220 TO-252 TO-263 Center Cut TO-263 TO-220 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, and (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 a significant injury of the user.
www.fairchildsemi.com 11/10/03 0.0m 003 Stock#DS30001084 2001 Fairchild Semiconductor Corporation
2. A critical component in 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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