www.fairchildsemi.com
RC1587
3A Adjustable/Fixed Low Dropout Linear Regulator
Description
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
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 applications including VTT bus termination, where transient response
and minimum input voltage are critical. The RC1587 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 RC1587-1.5 offers fixed 1.5V with 3A current
capability for GTL+ bus VTT termination. The RC1587-3.3
offers fixed 3.3V current capability for logic IC operation.
Applications
• Pentium® Class GTL+ bus supply
• Low voltage logic supply
• Post regulator for switching supply
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 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.
Typical Applications
VIN
VIN = 3.3V
10µF
+
RC1587
VOUT
ADJ
1.5V at 3A
+
R1
124Ω
22µF
R2
24.9Ω
VOUT = VREF (1 + R2/R1) + IADJ * R2
RC1587-1.5
VOUT
VIN
VIN = 3.3V
+
GND
1.5V at 3A
+
10µF
22µF
RC1587-3.3
VIN
VIN = 5V
+
10µF
VOUT
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
RC1587M-1.5, 3.3
RC1587M
FRONT VIEW
FRONT VIEW
RC1587T
RC1587T-1.5, -3.3V
FRONT VIEW
FRONT VIEW
1
1
2
3
1
GND OUT IN
2
2
1
3
2
3
3
ADJ OUT IN
ADJ OUT IN
3-Lead Plastic TO-263
θJC = 3°C/W*
GND OUT IN
3-Lead Plastic TO-220
θJC = 3°C/W
RC1587MC-1.5, 3.3
RC1587MC
RC1587D-1.5, 3.3
RC1587D
FRONT VIEW
FRONT VIEW
FRONT VIEW
FRONT VIEW
Tab is Out.
Tab is Out.
1
2
3
1
2
1
IN
ADJ
3
1
IN
ADJ
2
3
3
GND
GND
2
IN
IN
3-Lead Plastic TO-252
θJC = 3°C/W*
3-Lead Plastic TO-263 Center Cut
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°CW to more than 40°C/W. Other mounting techniques can provide a thermal resistance
lower than 30°C/W.
Absolute Maximum Ratings
Parameter
Min.
Max.
7
V
0
125
°C
-65
150
°C
300
°C
VIN
Operating Junction Temperature Range
Storage Temperature Range
Lead Temperature (Soldering, 10 sec.)
2
Unit
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
Conditions
3
Min.
Typ.
Max
Units
Reference Voltage
1.5V ≤ (VIN – VOUT) ≤ 5.75V,
10mA ≤ IOUT ≤ 3A
•
1.225
(-2%)
1.250
1.275
(+2%)
V
Output Voltage4
3.3V ≤ VIN ≤ 7V
10mA ≤ IOUT ≤ 3A
•
1.47
1.5
1.53
V
Output Voltage5
5.1V ≤ VIN ≤ 7V
10mA ≤ IOUT ≤ 3A
•
3.234
3.3
3.366
V
Line Regulation1, 2
(VOUT + 1.5V) ≤ VIN ≤ 7V,
IOUT = 10mA
•
0.005
0.2
%
Load Regulation1, 2
(VIN – VOUT) = 3V
10mA ≤ IOUT ≤ 3A
•
0.05
0.5
%
Dropout Voltage
∆VREF = 1%, IOUT = 3A
•
1.150
1.300
Current Limit
(VIN – VOUT) = 2V
•
Adjust Pin Current3
3.1
4
V
A
•
35
120
µA
1.5V ≤ (VIN – VOUT) ≤ 5.75V,
10mA ≤ IOUT ≤ 3A
•
0.2
5
µA
Minimum Load Current
1.5V ≤ (VIN – VOUT) ≤ 5.75V
•
Quiescent Current
VIN = 5V
•
4
13
Ripple Rejection
f = 120Hz, COUT = 22µF Tantalum,
(VIN – VOUT) = 3V, IOUT = 3A
Thermal Regulation
TA = 25°C, 30ms pulse
Adjust Pin Current
Change3
60
mA
72
0.004
•
Temperature Stability
10
mA
dB
0.02
0.5
%/W
%
Long-Term Stability
TA = 125°C, 1000 hrs.
0.03
RMS Output Noise
(% of VOUT)
TA = 25°C, 10Hz ≤ f ≤ 10kHz
0.003
%
Thermal Resistance,
Junction to Case
TO-220
3
°C/W
3
°C/W
150
°C
Thermal Shutdown
TO-263, TO-252
1.0
%
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
0.10
1.2
1.1
1.0
T=0°C
0.9
T=125°C
T=25°C
0.8
0.7
0.6
0.5
0
0.5
1
1.5
2
2.5
∆I = 3A
0.05
0
-0.05
-0.10
65-1587-04
1.3
65-1587-03
DROPOUT VOLTAGE (V)
1.4
OUTPUT VOLTAGE DEVIATION (%)
1.5
-0.15
-0.20
-75 -50 -25
3.0
0
25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
OUTPUT CURRENT (A)
Figure 1. Dropout Voltage vs. Output Current
Figure 2. Load Regulation vs. Temperature
1.275
3.70
1.270
1.255
1.250
1.245
1.240
1.235
1.230
1.225
-75 -50 -25
3.55
3.50
3.45
3.40
0
3.30
3.20
-75 -50 -25
0
25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
JUNCTION TEMPERATURE (°C)
Figure 4. Output Voltage vs. Temperature
5
100
Note:
1. RC1587 Only
3
2
1
0
-75 -50 -25
0
25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
Figure 5. Minimum Load Current vs. Temperature
80
70
60
50
40
30
20
65-1587-08
4
ADJUST PIN CURRENT (µA)
90
65-1587-07
MINIMUM LOAD CURRENT (mA)
Note:
1. RC1587 Only
2. RC1587, -3.3
3.25
25 50 75 100 125 150 175
Figure 3. Reference Voltage vs. Temperature
4
VOUT = 3.3V2
3.35
65-1587-06
1.260
VOUT SET WITH 1% RESISTORS
VOUT = 3.6V1
3.60
REFERENCE VOLTAGE (V)
1.265
65-1585-05
REFERENCE VOLTAGE (V)
3.65
10
0
-75 -50 -25
0
25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
Figure 6. Adjust Pin Current vs. Temperature
REV. 1.5.4 3/25/02
PRODUCT SPECIFICATION
RC1587
Typical Performance Characteristics (continued)
90
5.0
4.0
3.5
3.0
-75 -50 -25
0
25 50 75 100 125 150 175
70
60
50
40
30
20
10
(VIN – VOUT) ≤ 3V
0.5V ≤ VRIPPLE ≤ 2V
IOUT = 3A
0
10
JUNCTION TEMPERATURE (°C)
100
1K
65-1587-10
RIPPLE REJECTIONS (dB)
4.5
65-1587-09
SHORT-CIRCUIT CURRENT (A)
80
10K
100K
FREQUENCY (Hz)
Figure 7. Short-Circuit Current vs. Temperature
Figure 8. Ripple Rejection vs. Frequency
15
10
65-1587-11
POWER (W)
20
5
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
RC1587
PRODUCT SPECIFICATION
Applications Information
General
The RC1587, RC1587-1.5, and RC1587-3.3 are three-terminal
regulators optimized for GTL+ VTT termination 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 RC1587 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+.
D1
1N4002
(OPTIONAL)
RC1587
VIN
IN
+
C1
10µF
OUT
ADJ
+
R1
VOUT
C2
22µF
+
CADJ
R2
Stability
The RC1587 series require 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
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