www.fairchildsemi.com
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 V
TT
bus termination, where transient
response and minimum input voltage are critical. The
FAN1084 is ideal for low voltage microprocessor applica-
tions 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 V
TT
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 industry-
standard 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 V
CC
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
V
IN = 5V
+
10µF
FAN1084
V
IN
V
OUT
ADJ
124Ω
+
2.5V at 4.5A
22µF
124Ω
V
IN = 3.3V
+
10µF
FAN1084-1.5
V
IN
V
OUT
GND
+
1.5V at 4.5A
22µF
REV. 1.0.8 11/10/03
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.
1 2 3
1 2 3
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
Θ
JC
=3°C/W*
3-Lead Plastic TO-252
Θ
JC=3°C/W*
3-Lead Plastic TO-220
Θ
JC
=3°C/W*
*With package soldered to 0.5 square inch copper area over backside ground plane or internal power plane,
Θ
JA
can vary from
30°C/W to more than 40°C/W. Other mounting techniques may provide better power dissipation than 30°C/W.
†
FAN1084M-3.3 also available with uncut center lead.
Absolute Maximum Ratings
Parameter
V
IN
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
REV. 1.0.8 11/10/03
PRODUCT SPECIFICATION
FAN1084
Electrical Characteristics
Operating Conditions: 4.75
≤
V
IN
< 5.25V, T
j
= 25°C unless otherwise specified.
Parameter
Reference Voltage
3
Output Voltage
5
Output Voltage
6
Line Regulation
1, 2
Load Regulation
1, 2
Dropout Voltage
Current Limit
Adjust Pin Current
3
Mimimum Load Current
4
Quiescent Current
4
Thermal Resistance,
Junction to Case
Thermal Shutdown
4
1.5V
≤
(V
IN
– V
OUT
)
≤
5.75V
V
IN
= 5V
TO-220
TO-263 Center Cut, TO-252
Conditions
Adj connected to ground, I
OUT
= 10mA
I
OUT
= 10mA
I
OUT
= 10mA
I
OUT
= 10mA
10mA
≤
I
OUT
≤
4.5A
∆V
REF%
= 2%, I
OUT
= 4.5A
(V
IN
– V
OUT
) = 2V
5.5
35
10
4
3
3
150
100
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
µΑ
mA
mA
°C/W
°C/W
°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. 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
REV. 1.0.8 11/10/03
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=25°C
0.8
0.7
0.6
0.5
0
1
2
3
4
5
6
OUTPUT CURRENT (A)
T=0°C
T=125°C
∆I
= 4.5A
Figure 2. Dropout Voltage vs. Output Current
Figure 3. Load Regulation vs. Temperature
1.275
1.270
1
OUT
V
OUT
= 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
V
OUT
= 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
REV. 1.0.8 11/10/03
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
(V
IN
– V
OUT
)
≤
3V
0.5V
≤
V
RIPPLE
≤
2V
I
OUT
= 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, (Ω)
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 V
IN
/V
OUT
= 5V/1.5V
REV. 1.0.8 11/10/03
5
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