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
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
