ETC RC1585MC

www.fairchildsemi.com
RC1585
5A Adjustable/Fixed Low Dropout Linear Regulator
Features
Description
•
•
•
•
•
•
The RC1585 and RC1585-1.5 are low dropout three-terminal
regulators with 5A 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 RC1585 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 RC1585-1.5 offers fixed 1.5V with 5A current capabilities for GTL+ bus VTT termination.
Fast transient response
Low dropout voltage at up to 5A
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
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 RC1585 series regulators are available in the industrystandard TO-220, TO-263, TO-263 center cut and TO-252
power packages.
Typical Applications
VIN
VIN = 3.3V
10µF
+
RC1585
VOUT
1.5V at 5A
+
ADJ
124Ω
22µF
24.9Ω
RC1585-1.5
VIN
VOUT
VIN = 3.3V
+
10µF
GND
1.5V at 5A
+
22µF
65-1585-01a
Pentium is a registered trademark of Intel Corporation.
REV. 1.1.2 1/12/01
RC1585
PRODUCT SPECIFICATION
Pin Assignments
RC1585M-1.5
RC1585M
FRONT VIEW
FRONT VIEW
RC1585T
RC1585T-1.5
FRONT VIEW
FRONT VIEW
1
1
2
3
1
GND OUT IN
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
RC1585MC-1.5
RC1585MC
FRONT VIEW
FRONT VIEW
RC1585D-1.5
RC1585D
FRONT VIEW
FRONT VIEW
Tab is Out.
1
2
GND
3
1
IN
ADJ
2
3
IN
Tab is Out.
1
GND
3-Lead Plastic TO-263 Center Cut
θJC = 3°C/W*
2
3
1
IN
ADJ
2
3
IN
3-Lead Plastic TO-252
θJC = 3°C/W*
* θJA can vary from 20°C/W to >40°C/W with various mounting techniques.
65-1585-02
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. 1.1.2
PRODUCT SPECIFICATION
RC1585
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 ≤ 5A
•
1.225
(-2%)
1.250
1.275
(+2%)
V
Output Voltage4
3V ≤ VIN ≤ 7V
10mA ≤ IOUT ≤ 5A
•
1.47
1.5
1.53
V
Line Regulation1, 2
(VOUT + 1.5V) ≤ VIN ≤ 7V,
IOUT = 10mA
•
0.005
0.2
%
Load Regulation1, 2, 3
(VIN – VOUT) = 3V,
10mA ≤ IOUT ≤ 5A
•
0.05
0.5
%
Dropout Voltage
∆VREF = 1%, IOUT = 5A
•
1.150
1.300
V
Current Limit
(VIN – VOUT) = 2V
•
3
5.1
5.5
A
Adjust Pin Current3
•
35
120
µA
Adjust Pin Current Change3 1.5V ≤ (VIN – VOUT) ≤ 5.75V,
10mA ≤ IOUT ≤ 5A
•
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 = 5A
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, TO-252
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. RC1585 only.
4. RC1585-1.5 only.
REV. 1.1.2
3
RC1585
PRODUCT SPECIFICATION
Typical Performance Characteristics
0.10
1.5
OUTPUT VOLTAGE DEVIATION (%)
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
1
2
3
4
∆I = 5A
0.05
0
-0.05
-0.10
65-1585-04
1.3
65-1585-03
DROPOUT VOLTAGE (V)
1.4
-0.15
-0.20
-75 -50 -25
5
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
3.65
1.265
3.60
REFERENCE VOLTAGE (V)
1.255
1.250
1.245
1.240
1.235
1.230
1.225
-75 -50 -25
0
3.55
3.50
3.45
3.40
3.35
3.30
Note:
1. RC1585 Only
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. RC1585 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
65-1585-08
4
ADJUST PIN CURRENT (µA)
90
65-1585-07
MINIMUM LOAD CURRENT (mA)
1
VOUT = 3.3V
3.25
25 50 75 100 125 150 175
Figure 3. Reference Voltage vs. Temperature
4
1
VOUT = 3.6V
65-1585-06
1.260
65-1585-05
REFERENCE VOLTAGE (V)
VOUT SET WITH 1% RESISTORS
10
0
-75 -50 -25
0
25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
Figure 6. Adjust Pin Current vs. Temperature
REV. 1.1.2
PRODUCT SPECIFICATION
RC1585
Typical Performance Characteristics (continued)
90
8.0
6.0
5.0
4.0
-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 = 5A
0
10
100
1K
65-1585-10
RIPPLE REJECTIONS (dB)
7.0
65-1585-09
SHORT-CIRCUIT CURRENT (A)
80
10K
100K
FREQUENCY (Hz)
JUNCTION TEMPERATURE (°C)
Figure 7. Short-Circuit Current vs. Temperature
Figure 8. Ripple Rejection vs. Frequency
15
10
65-1585-11
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. 1.1.2
5
RC1585
PRODUCT SPECIFICATION
Applications Information
General
The RC1585 and RC1585-1.5 are three-terminal regulators
optimized for GTL+ VTT termination and logic 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 RC1585 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)
RC1585
VIN
+
C1
10µF
IN
OUT
+
R1
ADJ
VOUT
C2
22µF
+
CADJ
R2
Stability
The RC1585 series requires an output capacitor as a part of
the frequency compensation. It is recommended to use a
22µF solid tantalum or a 100 µF 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 <300mΩ. It is also recommended to use
bypass capacitors such as a 22µF tantalum or a 100µF aluminum on the adjust pin of the RC1585 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)
RC1585-1.5
VIN
C1
10µF
IN
+
OUT
GND
+
VOUT
C2
22µF
65-1585-12
Figure 10. Optional Protection
Protection Diodes
Ripple Rejection
In normal operation, the RC1585 series does not require any
protection diodes. For the RC1585, 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 short-circuit conditions.
In applications that require improved ripple rejection, a
bypass capacitor from the adjust pin of the RC1585 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.
A protection diode between the input and output pins is
usually not needed. An internal diode between the input and
the output pins on the RC1585 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
Output Voltage
The RC1585 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 a very precise output voltage setting is required.
REV. 1.1.2
PRODUCT SPECIFICATION
RC1585
RC1585
VIN
OUT
IN
+
C1
10µF
ADJ
+
VREF
IADJ
35µA
R1
RC1585
VOUT
C2
22µF
VIN
IN
OUT
ADJ
R1*
R2
VOUT = VREF (1 + R2/R1) + IADJ (R2)
RL
65-1585-13
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.
RC1585-1.5
IN
R2*
65-1585-15
It is not possible to provide true remote load sensing because
the RC1585 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
RP
PARASITIC
LINE RESISTANCE
OUT
GND
RL
65-1585-14
Figure 13. Connection for Best Load Regulation
Thermal Considerations
The RC1585 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 RC1585T to generate 5A @
1.5V ± 2% from a 3.3V source (3.2V to 3.6V).
Assumptions:
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 the resistor divider R1 connects directly to the regulator output and not to the load.
Figure 13 illustrates this point.
•
•
•
•
•
VIN = 3.6V worst case
VOUT = 1.46V worst case
IOUT = 5A continuous
TA = 60°C
θCase-to-Ambient = 3°C/W (assuming both a heatsink and
a thermally conductive material)
The power dissipation in this application is:
If R1 connects to the load, then the effective resistance
between the regulator and the load would be:
PD = (VIN – VOUT) * (IOUT) = (3.6 – 1.46) * (5) = 10.7W
RP x (1 + R2/R1), RP = Parasitic Line Resistance
From the specification table:
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.
TJ = TA + (PD) * (θCase-to-Ambient + θJC)
= 60 + (10.7) * (3 + 3) = 120°C
REV. 1.1.2
The junction temperature is below the maximum rating.
7
RC1585
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 RC1585 series are directly connected to the output of the device.
U1
RC1585
VIN
3.3V
VIN
C1
10µF
VOUT
1.5V
VOUT
+
R1
124Ω
ADJ
+
+
C3
100µF
R2
24.9Ω
C2
100µF
65-1586-16
Figure 14. Application Circuit (RC1585)
Table 1. Bill of Materials for Application Circuit for the RC1585
Item
Quantity
Manufacturer
Part Number
C1
1
Xicon
L10V10
10µF, 10V Aluminum
C2, C3
2
Xicon
L10V100
100µF, 10V Aluminum
R1
1
Generic
124Ω, 1%
R2
1
Generic
24.9Ω, 1%
U1
1
Fairchild
RC1585T
U1
RC1585-1.5
VIN
3.3V
VIN
C1
10µF
+
Description
VOUT
1.5V
VOUT
GND
+
5A Regulator
C3
100µF
65-1585-17
Figure 15. Application Circuit (RC1585-1.5)
Table 2. Bill of Materials for Application Circuit for the RC1585-1.5
Item
Quantity
Manufacturer
Part Number
C1
1
Xicon
L10V10
10µF, 10V Aluminum
C3
1
Xicon
L10V100
100µF, 10V Aluminum
U1
1
Fairchild
RC1585T-1.5
8
Description
5A Regulator
REV. 1.1.2
PRODUCT SPECIFICATION
RC1585
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. 1.1.2
9
RC1585
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. 1.1.2
PRODUCT SPECIFICATION
RC1585
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
.060
.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. 1.1.2
F
11
RC1585
PRODUCT SPECIFICATION
Mechanical Dimensions (continued)
3-Lead TO-252 Package
Symbol
Inches
Min.
A
b
b2
c2
D
E
e
L
Max.
.086
.094
.025
.035
.030
.045
.018
.023
.210
.231
.250
.265
.090 BSC
.370
.410
.020
—
.055
.080
.018
.023
0°
8°
L1
L2
R
α
Millimeters
Min.
Max.
2.19
2.38
0.64
0.88
0.76
1.14
0.46
0.58
5.33
5.88
6.35
6.73
2.285 BSC
9.40
10.42
0.51
—
1.40
2.03
0.46
0.58
0°
8°
E
@PKG/
@HEATSINK
Notes:
Notes
1.
Dimensions are exclusive of mold flash and metal burrs.
2.
Stand off-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.
Dimension exclusive of dambar protrusion or intrusion.
5.
Formed leads to be planar with respect to one another at seating
place -C-.
L2
c2
D
E-PIN
L
R (2 PLCS)
b2
L1
b
e
-B-
-A-
A
-C-
12
REV. 1.1.2
RC1585
PRODUCT SPECIFICATION
Ordering Information
Product Number
Package
RC1585M
TO-263
RC1585MC
TO-263 Center Cut
RC1585T
TO-220
RC1585D
TO-252
RC1585M-1.5
TO-263
RC1585MC-1.5
TO-263 Center Cut
RC1585T-1.5
TO-220
RC1585D-1.5
TO-252
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PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY
LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER
DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
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when properly used in accordance with instructions for use
provided in the labeling, can be reasonably expected to
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device or system whose failure to perform can be
reasonably expected to cause the failure of the life support
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