ETC FAN1084MC-1.5

www.fairchildsemi.com
FAN1084
4.5A Adjustable/Fixed Low Dropout Linear Regulator
Features
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.
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
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
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.
Block Diagram
FAN1084
VOUT
VIN
VIN = 5V
+
ADJ
10µF
2.5V at 4.5A
+
124Ω
22µF
124Ω
FAN1084-1.5
VIN
VOUT
VIN = 3.3V
+
10µF
GND
1.5V at 4.5A
+
22µF
REV. 1.0.3 9/24/01
FAN1084
PRODUCT SPECIFICATION
Pin Assignments
FAN1084M-3.3
FAN1084M-1.5
FRONT VIEW
FAN1084M
FAN1084D-3.3
FAN1084D-1.5
FRONT VIEW
FAN1084T
FAN1084T-3.3
FAN1084T-1.5
FRONT VIEW
FRONT VIEW
FAN1084D
FRONT VIEW FRONT VIEW
Tab is out.
1
2
1
3
2
3
Tab is out.
1
2
3
1
2
1 2 3
3
GND
GND
IN
ADJ
IN
1 2 3
ADJ
IN
3-Lead Plastic TO-263
ΘJC=3°C/W*
GND OUT IN
ADJ OUT IN
IN
3-Lead Plastic TO-220
ΘJC=3°C/W*
3-Lead Plastic TO-252
ΘJC=3°C/W*
*With package soldered to 0.5 square inch copper area over backside ground plane or internal power plane, ΘJA can vary from
30°C/W to more than 40°C/W. Other mounting techniques may provide better power dissipation than 30°C/W.
Absolute Maximum Ratings
Parameter
Min.
Max.
Unit
7
V
0
125
°C
–65
150
°C
300
°C
VIN
Operating Junction Temperature Range
Storage Temperature Range
Lead Temperature (Soldering, 10 seconds)
2
REV. 1.0.3 9/24/01
PRODUCT SPECIFICATION
FAN1084
Electrical Characteristics
Operating Conditions: 4.75 ≤ VIN < 5.25V, Tj = 25°C unless otherwise specified.
Parameter
Conditions
Min.
Typ.
Max
Units
Reference Voltage
Adj connected to ground, IOUT = 10mA
1.23
1.250
1.27
V
Output Voltage5
IOUT = 10mA
1.475
1.5
1.525
V
6
Output Voltage
IOUT = 10mA
3.234
3.3
3.366
V
Line Regulation1, 2
IOUT = 10mA
0.5
2
%
10mA ≤ IOUT ≤ 4.5A
0.5
2.5
%
1.5
V
3
Load
Regulation1, 2
Dropout Voltage
∆VREF% = 2%, IOUT = 4.5A
Current Limit
(VIN – VOUT) = 2V
5.5
Adjust Pin Current3
35
A
100
µΑ
1.5V ≤ (VIN – VOUT) ≤ 5.75V
10
mA
Quiescent Current4
VIN = 5V
4
mA
Thermal Resistance,
Junction to Case
TO-220
3
°C/W
TO-263 Center Cut, TO-252
3
°C/W
150
°C
Mimimum Load
Thermal
Current4
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
POWER (W)
20
15
10
5
0
25
45
65
85
105
125
CASE TEMPERATURE
Figure 1. Maximum Power Dissipation
REV. 1.0.3 9/24/01
3
FAN1084
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 150°C. 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+.
PRODUCT SPECIFICATION
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
10µF
OUT
+
ADJ
R1
VOUT
C2
22µF
Stability
The FAN1084 series requires an output capacitor as a part of
the frequency compensation. It is recommended to use a 22µF
solid tantalum or a 100µF 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
<1Ω. It is also recommended to use bypass capacitors such
as a 22µF tantalum or a 100µF 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.
+ CADJ
R2
D1
1N4002
(OPTIONAL)
FAN1084-1.5
VIN
+
IN
C1
10µF
OUT
GND
+
VOUT
C2
22µF
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 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 2. Usually, normal power supply
cycling or system “hot plugging and unplugging” will not
generate current large enough to do any damage.
4
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
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 22µF. At 10kHz, only 0.22µF 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.
REV. 1.0.3 9/24/01
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.
RP
Parasitic
Line Resistance
FAN1084
FAN1084
VIN
+
IN
C1
10µF
VIN
OUT
ADJ
+
VREF
IADJ
35µA
R1
IN
VOUT
C2
22µF
OUT
ADJ
R1*
R2
*Connect R1 to case
Connect R2 to load
RL
R2*
Figure 3. Connection for Best Load Regulation
Figure 5. 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
OUT
GND
RL
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
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.
REV. 1.0.3 9/24/01
Assumptions
•
•
•
•
•
VIN = 3.4V worst case
VOUT = 1.475V worst case
IOUT = 4.5A continuous
TA = 60°C
θCase-to-Ambient = 5°C/W (assuming both a heatsink and
a thermally conductive material)
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) * (θCase-to-Ambient + θJC)
= 60 + (9.6) * (5 + 3) = 137°C
The junction temperature is below the maximum thermal limit.
5
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
10µF
OUT
R1
124Ω
ADJ
+ C2
100µF
+
VOUT
C3 2.5V
100µF
R2
124Ω
Figure 6. Application Circuit
Table 1. Bill of Materials for Application Circuit for the FAN1084
Item
Quantity
Manufacturer
Part Number
Description
C1
1
Xicon
L10V10
10µF, 10V Aluminum
C2, C3
2
Xicon
L10V100
100µF, 10V Aluminum
FAN1084T
4.5A Regulator
R1, R2
2
Generic
U1
1
Fairchild
124Ω, 1%
U1
RC1084-1.5
VIN = 3.3V
IN
C1
10µF
+
VOUT 1.5V
OUT
+
GND
C3
100µF
Figure 7. Application Circuit (FAN1084-1.5)
Table 2. Bill of Materials for Application Circuit for the FAN1084-1.5
6
Item
Quantity
Manufacturer
Part Number
Description
C1
1
Xicon
L10V10
10µF, 10V Aluminum
C3
1
Xicon
L10V100
100µF, 10V Aluminum
U1
1
Fairchild
FAN1084T-1.5
4.5A Regulator
REV. 1.0.3 9/24/01
FAN1084
PRODUCT SPECIFICATION
Mechanical Dimensions
3-Lead TO-263 Center Cut Package
Symbol
Inches
Millimeters
Notes
Min.
Max.
Min.
Max.
A
b
b2
c2
D
E
e
.160
.020
.190
.036
4.06
0.51
4.83
0.91
L
L1
L2
.575
.090
—
.050
.017
0°
.049
.051
.045
.055
.340
.380
.380
.405
.100 BSC
L3
R
α
.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°
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-.
15.88
2.79
1.40
1.78
0.78
8°
E
@PKG/
@HEATSINK
L2
c2
D
E-PIN
L
R (2 PLCS)
b2
L1
L3
b
e
-B-
-A-
A
-C-
7
REV. 1.0.3 9/24/01
FAN1084
PRODUCT SPECIFICATION
Mechanical Dimensions (continued)
3-Lead TO-220 Package
Inches
Symbol
Min.
A
b
b1
c1
øP
D
E
e
Millimeters
Max.
Min.
.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°
e1
e3
F
H1
J1
L
L1
Q
α
Notes
Max.
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
Q
L
e3
b1
e
e1
E
b
L1
E-PIN
øP
α (5X)
c1
A
J1
D
8
F
REV. 1.0.3 9/24/01
PRODUCT SPECIFICATION
FAN1084
Mechanical Dimensions (continued)
3-Lead TO-252 Package
Symbol
Inches
Millimeters
Notes:
Notes
Min.
Max.
Min.
Max.
A
b
b2
b3
c
c2
.086
.025
.030
.205
.018
.018
.094
.035
2.19
0.64
0.76
5.21
0.46
0.46
2.39
0.89
D
E
e
H
5.33
6.22
6.35
6.73
2.29 BSC
9.40
10.41
1.40
1.78
2.74 REF
1
L
L1
.210
.245
.250
.265
.090 BSC
.370
.410
.055
.070
.108 REF
L3
L4
.035
.025
0.89
0.64
4
.045
.215
.024
.023
.080
.040
1.14
5.46
0.61
0.58
2.03
1.02
E
@PKG/
@HEATSINK
b3
4
1
1.
Dimensions are exclusive of mold flash, metal burrs or interlead
protrusion.
2.
Stand off-height is measured from lead tip with ref. to Datum -B-.
3.
Foot length is measured with ref. to Datum -A- with lead surface.
4.
Thermal pad contour optional within dimension b3 and L3.
5.
Formed leads to be planar with respect to one another at seating
place -C-.
6.
Dimensions and tolerances per ASME Y14.5M-1994.
3
L3
c2
D
E-PIN
H
L4
b2
L1
L
b
e
-B-
α = 0° – 10°
-A-
A
-C-
REV. 1.0.3 9/24/01
9
FAN1084
PRODUCT SPECIFICATION
Ordering Information
Product Number
Package
FAN1084MC
TO-263 Center Cut
FAN1084T
TO-220
FAN1084D
TO-252
FAN1084MC-1.5
TO-263 Center Cut
FAN1084T-1.5
TO-220
FAN1084D-1.5
TO-252
FAN1084MC-3.3
TO-263 Center Cut
FAN1084T-3.3
TO-220
FAN1084D-3.3
TO-252
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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.
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FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES
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CORPORATION. As used herein:
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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.
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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