www.fairchildsemi.com
RC1587
3A Adjustable/Fixed Low Dropout Linear Regulator
Features
• Fast transient response
• Low dropout voltage at up to 3A
• 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
Description
The RC1587, RC1587-1.5, and RC1587-3.3 are low dropout
three-terminal regulators with 3A output current capability.
These devices have been optimized for low voltage applica-
tions including V
TT
bus termination, where transient response
and minimum input voltage are critical. The RC1587 is ideal
for low voltage microprocessor applications requiring a reg-
ulated output from 1.5V to 3.6V with an input supply of 5V
or less. The RC1587-1.5 offers fixed 1.5V with 3A current
capability for GTL+ bus V
TT
termination. The RC1587-3.3
offers fixed 3.3V current capability for logic IC operation.
Current limit is trimmed to ensure specified output current and
controlled short-circuit current. On-chip thermal limiting pro-
vides protection against any combination of overload and
ambient temperature that would create excessive junction
temperatures.
The RC1587, RC1587-1.5, and RC1587-3.3 are available in
the industry-standard TO-220, TO-263, TO-263 center cut,
and TO-252 (DPAK) power packages.
Applications
• Pentium
®
Class GTL+ bus supply
• Low voltage logic supply
• Post regulator for switching supply
Typical Applications
V
IN = 3.3V
10µF
+
RC1587
V
IN
V
OUT
ADJ
R1
124Ω
R2
24.9Ω
V
OUT =
V
REF
(1 + R2/R1) + I
ADJ
*
R2
RC1587-1.5
V
OUT
V
IN
+
10µF
GND
+
+
1.5V at 3A
22µF
V
IN = 3.3V
1.5V at 3A
22µF
V
IN = 5V
+
10µF
RC1587-3.3
V
IN
V
OUT
GND
+
3.3V at 3A
22µF
65-1587-16
Pentium is a registered trademark of Intel Corporation.
REV. 1.5.4 3/25/02
RC1587
PRODUCT SPECIFICATION
Pin Assignments
RC1587T
FRONT VIEW
RC1587T-1.5, -3.3V
FRONT VIEW
RC1587M-1.5, 3.3
FRONT VIEW
RC1587M
FRONT VIEW
1
2
3
1
2
3
1
2
3
1
2
3
GND OUT IN
ADJ OUT IN
ADJ OUT IN
GND OUT IN
3-Lead Plastic TO-263
θ
JC
= 3°C/W*
3-Lead Plastic TO-220
θ
JC
= 3°C/W
RC1587MC-1.5, 3.3
FRONT VIEW
RC1587MC
FRONT VIEW
RC1587D-1.5, 3.3
FRONT VIEW
RC1587D
FRONT VIEW
Tab is Out.
Tab is Out.
1
2
3
1
2
3
1
2
3
1
2
3
GND
GND
IN
ADJ
IN
IN
ADJ
IN
3-Lead Plastic TO-263 Center Cut
θ
JC
= 3°C/W*
3-Lead Plastic TO-252
θ
JC
= 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°CW to more than 40°C/W. Other mounting techniques can provide a thermal resistance
lower than 30°C/W.
Absolute Maximum Ratings
Parameter
V
IN
Operating Junction Temperature Range
Storage Temperature Range
Lead Temperature (Soldering, 10 sec.)
0
-65
Min.
Max.
7
125
150
300
Unit
V
°C
°C
°C
2
REV. 1.5.4 3/25/02
PRODUCT SPECIFICATION
RC1587
Electrical Characteristics
Tj = 25°C unless otherwise specified.
The
•
denotes specifications which apply over the specified operating temperature range.
Parameter
Reference Voltage
Output Voltage
4
Output Voltage
5
Line Regulation
1, 2
Load Regulation
1, 2
Dropout Voltage
Current Limit
Adjust Pin Current
3
Adjust Pin Current Change
3
1.5V
≤
(V
IN
– V
OUT
)
≤
5.75V,
10mA
≤
I
OUT
≤
3A
Minimum Load Current
Quiescent Current
Ripple Rejection
Thermal Regulation
Temperature Stability
Long-Term Stability
RMS Output Noise
(% of V
OUT
)
Thermal Resistance,
Junction to Case
Thermal Shutdown
T
A
= 125°C, 1000 hrs.
T
A
= 25°C, 10Hz
≤
f
≤
10kHz
TO-220
TO-263, TO-252
1.5V
≤
(V
IN
– V
OUT
)
≤
5.75V
V
IN
= 5V
f = 120Hz, C
OUT
= 22µF Tantalum,
(V
IN
– V
OUT
) = 3V, I
OUT
= 3A
T
A
= 25°C, 30ms pulse
•
3
Conditions
1.5V
≤
(V
IN
– V
OUT
)
≤
5.75V,
10mA
≤
I
OUT
≤
3A
3.3V
≤
V
IN
≤
7V
10mA
≤
I
OUT
≤
3A
5.1V
≤
V
IN
≤
7V
10mA
≤
I
OUT
≤
3A
(V
OUT
+ 1.5V)
≤
V
IN
≤
7V,
I
OUT
=
10mA
(V
IN
– V
OUT
) = 3V
10mA
≤
I
OUT
≤
3A
∆V
REF
= 1%, I
OUT
= 3A
(V
IN
– V
OUT
) = 2V
•
•
•
•
•
•
•
•
•
•
•
Min.
1.225
(-2%)
1.47
3.234
Typ.
1.250
1.5
3.3
0.005
0.05
1.150
Max
1.275
(+2%)
1.53
3.366
0.2
0.5
1.300
120
5
Units
V
V
V
%
%
V
A
µA
µA
mA
3.1
4
35
0.2
10
4
60
72
0.004
0.5
0.03
0.003
3
3
150
1.0
0.02
13
mA
dB
%/W
%
%
%
°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 (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. RC1587 only.
4. RC1587-1.5 only.
5. RC1587-3.3 only.
REV. 1.5.4 3/25/02
3
RC1587
PRODUCT SPECIFICATION
Typical Performance Characteristics
1.5
OUTPUT VOLTAGE DEVIATION (%)
0.10
∆I
= 3A
1.4
DROPOUT VOLTAGE (V)
1.3
1.2
1.1
1.0
0.9
T=25°C
0.8
65-1587-03
0.05
0
T=0°C
T=125°C
-0.05
-0.10
65-1587-04
0.7
0.6
0.5
0
0.5
1
1.5
2
2.5
OUTPUT CURRENT (A)
-0.15
3.0
-0.20
-75 -50 -25
0
25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
Figure 1. Dropout Voltage vs. Output Current
Figure 2. Load Regulation vs. Temperature
1.275
3.70
1.270
3.65
REFERENCE VOLTAGE (V)
1.260
1.255
1.250
1.245
1.240
65-1585-05
REFERENCE VOLTAGE (V)
1.265
V
OUT
SET WITH 1% RESISTORS
V
OUT
= 3.6V
1
3.60
3.55
3.50
3.45
3.40
3.35
3.30
3.25
3.20
-75 -50 -25
0
Note:
1. RC1587 Only
2. RC1587, -3.3
V
OUT
= 3.3V
2
1.230
1.225
-75 -50 -25
0
25 50 75 100 125 150 175
25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
JUNCTION TEMPERATURE (°C)
Figure 3. Reference Voltage vs. Temperature
Figure 4. Output Voltage vs. Temperature
5
MINIMUM LOAD CURRENT (mA)
100
90
Note:
1. RC1587 Only
4
ADJUST PIN CURRENT (µA)
80
70
60
50
40
30
65-1587-08
3
2
65-1587-07
1
20
10
0
-75 -50 -25
0
0
-75 -50 -25
0
25 50 75 100 125 150 175
25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
JUNCTION TEMPERATURE (°C)
Figure 5. Minimum Load Current vs. Temperature
Figure 6. Adjust Pin Current vs. Temperature
4
REV. 1.5.4 3/25/02
65-1587-06
1.235
PRODUCT SPECIFICATION
RC1587
Typical Performance Characteristics
(continued)
5.0
90
80
SHORT-CIRCUIT CURRENT (A)
RIPPLE REJECTIONS (dB)
4.5
70
60
50
40
30
20
10
0
10
65-1587-10
4.0
3.5
65-1587-09
(V
IN
– V
OUT
)
≤
3V
0.5V
≤
V
RIPPLE
≤
2V
I
OUT
= 3A
100
1K
FREQUENCY (Hz)
10K
3.0
-75 -50 -25
0
25 50 75 100 125 150 175
100K
JUNCTION TEMPERATURE (°C)
Figure 7. Short-Circuit Current vs. Temperature
Figure 8. Ripple Rejection vs. Frequency
20
15
POWER (W)
10
5
65-1587-11
0
50 60 70 80 90 100 110 120 130 140 150
CASE TEMPERATURE (°C)
Figure 9. Maximum Power Dissipation
REV. 1.5.4 3/25/02
5
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