FAIRCHILD RC1584

www.fairchildsemi.com
RC1584
7A Adjustable/Fixed Low Dropout Linear Regulator
Features
Description
•
•
•
•
•
•
The RC1584 and RC1584-1.5 are low dropout three-terminal
regulators with 7A 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 RC1584 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 RC1584-1.5 offers fixed 1.5V with 7A current capability for GTL+ bus VTT termination.
Fast transient response
Low dropout voltage at up to 7A
Load regulation: 0.05% typical
Trimmed current limit
On-chip thermal limiting
Standard TO-220, TO-263 and TO-263 center cut
packages
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 RC1584 and RC1584-1.5 are available in the industrystandard TO-220, TO-263 and TO-263 center cut power
packages.
Typical Applications
VIN
VIN = 3.3V
10µF
+
RC1584
VOUT
1.5V at 7A
+
ADJ
124Ω
22µF
24.9Ω
RC1584-1.5
VIN
VOUT
VIN = 3.3V
+
10µF
GND
1.5V at 7A
+
22µF
65-1584-16
Pentium is a registered trademark of Intel Corporation.
REV. 1.0.5 7/13/00
RC1584
PRODUCT SPECIFICATION
Pin Assignments
RC1584M-1.5
RC1584M
FRONT VIEW
FRONT VIEW
RC1584T
RC1584T-1.5
FRONT VIEW
FRONT VIEW
1
1
2
3
GND OUT IN
1
2
2
3
1
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
RC1584MC-1.5
RC1584MC
FRONT VIEW
FRONT VIEW
Tab is Out.
1
GND
2
3
1
IN
ADJ
2
3
IN
3-Lead Plastic TO-263 Center Cut
θJC = 3°C/W*
65-1584-02
* θJA can vary from 20°C/W to >40°C/W with various mounting techniques.
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 sec.)
2
REV. 1.0.5 7/13/00
PRODUCT SPECIFICATION
RC1584
Electrical Characteristics
Tj = 25°C unless otherwise specified.
The • denotes specifications which apply over the specified operating temperature range.
Parameter
Conditions
Min.
Typ.
Max
Units
Reference Voltage
1.5V ≤ (VIN – VOUT) ≤ 5.75V,
10mA ≤ IOUT ≤ 7A
•
1.225
(-2%)
1.250
1.275
(+2%)
V
Output Voltage4
3.3V ≤ VIN ≤ 7V
10mA ≤ IOUT ≤ 7A
•
1.47
1.5
1.53
V
Line Regulation1, 2
(VOUT + 1.5V) ≤ VIN ≤ 7V,
IOUT = 10mA
•
0.005
0.2
%
Load Regulation1, 2
(VIN – VOUT) = 3V
10mA ≤ IOUT ≤ 7A
•
0.05
0.5
%
Dropout Voltage
∆VREF = 1%, IOUT = 7A
•
1.150
1.300
V
Current Limit
(VIN – VOUT) = 2V
•
3
7.1
8
A
Adjust Pin Current3
•
35
120
µA
Adjust Pin Current Change3 1.5V ≤ (VIN – VOUT) ≤ 5.75V,
10mA ≤ IOUT ≤ 7A
•
0.2
5
µA
Minimum Load Current
1.5V ≤ (VIN – VOUT) ≤ 5.75V
•
Quiescent Current
VIN = 5V
•
Ripple Rejection
f = 120Hz, COUT = 22µF Tantalum,
(VIN – VOUT) = 3V, IOUT = 7A
Thermal Regulation
TA = 25°C, 30ms pulse
mA
4
60
13
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
TO-263
3
°C/W
150
°C
Thermal Shutdown
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. RC1584 only.
4. RC1584-1.5 only.
REV. 1.0.5 7/13/00
3
RC1584
PRODUCT SPECIFICATION
Typical Performance Characteristics
0.10
1.2
1.1
T=0°C
0.9
T=125°C
T=25°C
0.8
0.7
0.6
0.5
0
1
2
3
4
5
6
0.05
0
-0.05
-0.10
-0.15
-0.20
-75 -50 -25
7
3.65
1.265
3.60
1.260
1.255
1.250
1.245
1.240
1.235
1.230
25 50 75 100 125 150 175
REFERENCE VOLTAGE (V)
3.70
1.270
0
3.50
3.45
3.40
3.35
3.30
Note:
1. RC1584 Only
3.25
3.20
-75 -50 -25
0
25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
Figure 3. Reference Voltage vs. Temperature
Figure 4. Output Voltage vs. Temperature
5
100
Note:
1. RC1584 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
65-1584-08
4
ADJUST PIN CURRENT (µA)
90
65-1584-07
MINIMUM LOAD CURRENT (mA)
VOUT SET WITH 1% RESISTORS
VOUT = 3.6V1
3.55
JUNCTION TEMPERATURE (°C)
4
25 50 75 100 125 150 175
Figure 2. Load Regulation vs. Temperature
1.275
65-1584-05
REFERENCE VOLTAGE (V)
Figure 1. Dropout Voltage vs. Output Current
1.225
-75 -50 -25
0
JUNCTION TEMPERATURE (°C)
OUTPUT CURRENT (A)
65-1584-06
1.0
∆I = 7A
65-1584-04
1.3
65-1584-03
DROPOUT VOLTAGE (V)
1.4
OUTPUT VOLTAGE DEVIATION (%)
1.5
10
0
-75 -50 -25
0
25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
Figure 6. Adjust Pin Current vs. Temperature
REV. 1.0.5 7/13/00
PRODUCT SPECIFICATION
RC1584
Typical Performance Characteristics (continued)
10
90
8
7
6
-75 -50 -25
0
25 50 75 100 125 150 175
70
60
50
40
30
20
10
0
10
(VIN – VOUT) ≤ 3V
0.5V ≤ VRIPPLE ≤ 2V
IOUT = 7A
100
JUNCTION TEMPERATURE (°C)
1K
65-1584-10
RIPPLE REJECTIONS (dB)
9
65-1584-09
SHORT-CIRCUIT CURRENT (A)
80
10K
100K
FREQUENCY (Hz)
Figure 7. Short-Circuit Current vs. Temperature
Figure 8. Ripple Rejection vs. Frequency
15
10
65-1584-11
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. 1.0.5 7/13/00
5
RC1584
PRODUCT SPECIFICATION
Applications Information
General
The RC1584 and RC1584-1.5 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 RC1584 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)
RC1584
RC1587
VIN
IN
+
C1
10µF
OUT
ADJ
+
R1
VOUT
C2
22µF
+
CADJ
R2
Stability
The RC1584 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 <1Ω. It is also recommended to use bypass
capacitors such as a 22µF tantalum or a 100µF aluminum on
the adjust pin of the RC1584 for low ripple and fast transient
response. When these bypassing capacitors are not used at
the adjust pin, larger values of output capacitors provide
equally good results.
D1
1N4002
(OPTIONAL)
RC1587-1.5,
RC1584-1.5
-3.3
VIN
C1
10µF
IN
+
OUT
GND
+
VOUT
C2
22µF
65-1584-13
65-1587-13
Figure 10. Optional Protection
Protection Diodes
In normal operation, the RC1584 series does not require any
protection diodes. For the RC1584, 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 shortcircuit conditions.
A protection diode between the input and output pins is usually not needed. An internal diode between the input and output pins on the RC1584 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 10. Usually, normal power supply cycling or
system “hot plugging and unplugging” will not generate current large enough to do any damage.
The adjust pin can be driven on a transient basis ±7V with
respect to the output, without any device degradation. As
with any IC regulator, exceeding the maximum input-tooutput voltage differential causes the internal transistors to
break down and none of the protection circuitry is then
functional.
6
Ripple Rejection
In applications that require improved ripple rejection, a
bypass capacitor from the adjust pin of the RC1584 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 10. 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 RC1584 regulator develops a 1.25V reference voltage
between the output pin and the adjust pin (see Figure 11).
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.
The current out of the adjust pin adds to the current from R1
and is typically 35µA. Its output voltage contribution is
small and only needs consideration when very precise output
voltage setting is required.
REV. 1.0.5 7/13/00
PRODUCT SPECIFICATION
RC1584
RC1584
VIN
OUT
IN
+
C1
10µF
ADJ
+
VREF
IADJ
35µA
R1
RC1584
VOUT
C2
22µF
VIN
IN
OUT
ADJ
R1*
R2
VOUT = VREF (1 + R2/R1) + IADJ (R2)
RL
65-1584-14
Figure 11. Basic Regulator Circuit
* CONNECT R1 TO CASE
CONNECT R2 TO LOAD
Load Regulation
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 12.
RC1584-1.5
IN
RP
PARASITIC
LINE RESISTANCE
OUT
GND
RL
65-1584-17
Figure 12. 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 resistor divider R1 connects directly to the regulator output and not to the load.
Figure 13 illustrates this point.
If R1 connects to the load, then the effective resistance
between the regulator and the load would be:
RP × (1 + R2/R1), RP = Parasitic Line Resistance
The connection shown in Figure 13 does not multiply RP by
the divider ratio. 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. 1.0.5 7/13/00
R2*
65-1584-15
It is not possible to provide true remote load sensing because
the RC1584 series are three-terminal devices. Load regulation is limited by the resistance of the wire connecting the
regulators to the load. Load regulation per the data sheet
specification is measured at the bottom of the package.
VIN
RP
PARASITIC
LINE RESISTANCE
Figure 13. Connection for Best Load Regulation
Thermal Considerations
The RC1584 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-heat sink interface resistance, and the
heat sink resistance. Thermal resistance specifications have
been developed to more accurately reflect device temperature and ensure safe operating temperatures.
For example, look at using an RC1584T to generate 7A @
1.5V ± 2% from a 3.3V source (3.135V to 3.465V).
Assumptions:
•
•
•
•
•
VIN = 3.465V worst case
VOUT = 1.47V worst case
IOUT = 7A continuous
TA = 40°C
θCase-to-Ambient = 3°C/W (assuming both a heatsink and
a thermally conductive material)
The power dissipation in this application is:
PD = (VIN – VOUT) * (IOUT) = (3.465 – 1.47) * (7) = 13.97W
From the specification table:
TJ = TA + (PD) * (θCase-to-Ambient + θJC)
= 40 + (13.97) * (3 + 3) = 124°C
The junction temperature is below the maximum rating.
7
RC1584
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 RC1584 series are directly connected to the output of the device.
U1
RC1584
VIN
3.3V
+
C1
10µF
VOUT
1.5V
VOUT
VIN
R1
124Ω
ADJ
+
+
C3
100µF
R2
24.9Ω
C2
100µF
65-1584-18
Figure 14. Application Circuit (RC1584)
Table 1. Bill of Materials for Application Circuit for the RC1584
Item
C1
Quantity
Manufacturer
Part Number
1
Xicon
L10V10
L10V100
Description
10µF, 10V Aluminum
C2, C3
2
Xicon
R1
1
Generic
124Ω, 1%
100µF, 10V Aluminum
R2
1
Generic
24.9Ω, 1%
U1
1
Fairchild
RC1584T
7A Regulator
U1
RC1584-1.5
VIN
3.3V
VIN
C1
10µF
+
VOUT
1.5V
VOUT
GND
+
C3
100µF
65-1584-19
Figure 15. Application Circuit (RC1584-1.5)
Table 2. Bill of Materials for Application Circuit for the RC1584-1.5
Item
Quantity
Manufacturer
Part Number
C1
1
Xicon
L10V10
10µF, 10V Aluminum
C3
1
Xicon
L10V100
100µF, 10V Aluminum
U1
1
Fairchild
RC1584T-1.5
8
Description
7A Regulator
REV. 1.0.5 7/13/00
PRODUCT SPECIFICATION
RC1584
Mechanical Dimensions
3-Lead TO-263 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
R
α
.575
.090
—
.017
0°
.049
.051
.045
.055
.340
.380
.380
.405
.100 BSC
.625
.110
.055
.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
—
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
0.78
8°
E
@PKG/
@HEATSINK
L2
c2
D
E-PIN
L
R (2 PLCS)
b2
L1
b
e
-B-
-A-
A
-C-
REV. 1.0.5 7/13/00
9
RC1584
PRODUCT SPECIFICATION
Mechanical Dimensions (continued)
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-
10
REV. 1.0.5 7/13/00
PRODUCT SPECIFICATION
RC1584
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
REV. 1.0.5 7/13/00
F
11
RC1584
PRODUCT SPECIFICATION
Ordering Information
Product Number
Package
RC1584M
TO-263
RC1584MC
TO-263 center cut
RC1584T
TO-220
RC1584M-1.5
TO-263
RC1584MC-1.5
TO-263 center cut
RC1584T-1.5
TO-220
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FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES
OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
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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 1998 Fairchild Semiconductor Corporation