LM2937ES-15/NOPB [NSC]
IC VREG 15 V FIXED POSITIVE LDO REGULATOR, 1 V DROPOUT, PSSO3, PLASTIC, TO-263, 3 PIN, Fixed Positive Single Output LDO Regulator;
| 型号： | LM2937ES-15/NOPB |
| 厂家： | 
National Semiconductor |
| 描述： | IC VREG 15 V FIXED POSITIVE LDO REGULATOR, 1 V DROPOUT, PSSO3, PLASTIC, TO-263, 3 PIN, Fixed Positive Single Output LDO Regulator 输出元件 调节器 |
| 文件： | 总13页 (文件大小：737K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
August 2005
LM2937
500 mA Low Dropout Regulator
connections, two-battery jumps and up to +60V/−50V load
dump transients. Familiar regulator features such as short
circuit and thermal shutdown protection are also built in.
General Description
The LM2937 is a positive voltage regulator capable of sup-
plying up to 500 mA of load current. The use of a PNP power
transistor provides a low dropout voltage characteristic. With
a load current of 500 mA the minimum input to output voltage
differential required for the output to remain in regulation is
typically 0.5V (1V guaranteed maximum over the full oper-
ating temperature range). Special circuitry has been incor-
porated to minimize the quiescent current to typically only
10 mA with a full 500 mA load current when the input to
output voltage differential is greater than 3V.
Features
n Fully specified for operation over −40˚C to +125˚C
n Output current in excess of 500 mA
n Output trimmed for 5% tolerance under all operating
conditions
n Typical dropout voltage of 0.5V at full rated load current
n Wide output capacitor ESR range, up to 3Ω
n Internal short circuit and thermal overload protection
n Reverse battery protection
n 60V input transient protection
n Mirror image insertion protection
The LM2937 requires an output bypass capacitor for stabil-
ity. As with most low dropout regulators, the ESR of this
capacitor remains a critical design parameter, but the
LM2937 includes special compensation circuitry that relaxes
ESR requirements. The LM2937 is stable for all ESR below
3Ω. This allows the use of low ESR chip capacitors.
Ideally suited for automotive applications, the LM2937 will
protect itself and any load circuitry from reverse battery
Connection Diagrams
TO-220 Plastic Package
SOT-223 Plastic Package
01128002
01128026
Front View
Front View
TO-263 Surface-Mount Package
01128006
Side View
01128005
Top View
© 2005 National Semiconductor Corporation
DS011280
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Ordering Information
Package
Temperature
Range
Part Number
Packaging Marking
LM2937ES-5.0
LM2937ES-8.0
LM2937ES-10
LM2937ES-12
LM2937ES-15
Transport Media
NSC Drawing
TO-263
−40˚C ≤ TJ ≤ 125˚C
LM2937ES-5.0
LM2937ESX-5.0
LM2937ES-8.0
LM2937ESX-8.0
LM2937ES-10
LM2937ESX-10
LM2937ES-12
LM2937ESX-12
LM2937ES-15
LM2937ESX-15
LM2937ET-5.0
LM2937ET-8.0
LM2937ET-10
LM2937ET-12
LM2937ET-15
LM2937IMP-5.0
LM2937IMPX-5.0
LM2937IMP-8.0
LM2937IMPX-8.0
LM2937IMP-10
LM2937IMPX-10
LM2937IMP-12
LM2937IMPX-12
LM2937IMP-15
LM2937IMPX-15
Rail
TS3B
500 Units Tape and Reel
Rail
500 Units Tape and Reel
Rail
500 Units Tape and Reel
Rail
500 Units Tape and Reel
Rail
500 Units Tape and Reel
Rail
TO-220
−40˚C ≤ TJ ≤ 125˚C
LM2937ET-5.0
LM2937ET-8.0
LM2937ET-10
LM2937ET-12
LM2937ET-15
TO3B
Rail
Rail
Rail
Rail
SOT-223
−40˚C ≤ TJ ≤ 85˚C
1k Units Tape and Reel
2k Units Tape and Reel
1k Units Tape and Reel
2k Units Tape and Reel
1k Units Tape and Reel
2k Units Tape and Reel
1k Units Tape and Reel
2k Units Tape and Reel
1k Units Tape and Reel
2k Units Tape and Reel
MP04A
L71B
L72B
L73B
L74B
L75B
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2
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
TO-263 (10 seconds)
230˚C
215˚C
220˚C
2 kV
SOT-223 (Vapor Phase, 60 seconds)
SOT-223 (Infared, 15 seconds)
ESD Susceptibility (Note 3)
Input Voltage
Continuous
26V
60V
Operating Conditions (Note 1)
Temperature Range (Note 2)
Transient (t ≤ 100 ms)
Internal Power Dissipation (Note 2)
Maximum Junction Temperature
Storage Temperature Range
TO-220 (10 seconds)
Internally Limited
150˚C
LM2937ET, LM2937ES
LM2937IMP
−40˚C ≤ TJ ≤125˚C
−40˚C ≤ TJ ≤85˚C
26V
−65˚C to +150˚C
260˚C
Maximum Input Voltage
Electrical Characteristics
VIN = VNOM + 5V, (Note 4) IOUTmax = 500 mA for the TO-220 and TO-263 packages, IOUTmax=400mA for the SOT-223 pack-
age, COUT = 10 µF unless otherwise indicated. Boldface limits apply over the entire operating temperature range of the
indicated device., all other specifications are for TA = TJ = 25˚C.
Output Voltage (VOUT
)
5V
8V
10V
Units
Parameter
Output Voltage
Conditions
Typ
Limit
4.85
4.75
5.15
5.25
50
Typ
Limit
7.76
7.60
8.24
8.40
80
Typ
Limit
9.70
5 mA ≤ IOUT ≤ IOUTmax
V(Min)
V(Min)
5.00
8.00
10.00
9.50
10.30
10.50
100
V(Max)
V(Max)
mV(Max)
Line Regulation
(VOUT + 2V) ≤ VIN ≤ 26V,
IOUT = 5 mA
15
24
30
Load Regulation
5 mA ≤ IOUT ≤ IOUTmax
(VOUT + 2V) ≤ VIN ≤ 26V,
IOUT = 5 mA
5
2
50
10
8
2
80
10
10
2
100
10
mV(Max)
mA(Max)
Quiescent Current
VIN = (VOUT + 5V),
IOUT = IOUTmax
10
20
10
20
10
20
mA(Max)
µVrms
Output Noise
Voltage
10 Hz–100 kHz
IOUT = 5 mA
150
240
300
Long Term Stability
Dropout Voltage
1000 Hrs.
20
0.5
110
1.0
75
32
0.5
110
1.0
75
40
0.5
110
1.0
75
mV
IOUT = IOUTmax
1.0
250
0.6
60
1.0
250
0.6
60
1.0
250
0.6
60
V(Max)
mV(Max)
A(Min)
V(Min)
IOUT = 50 mA
Short-Circuit Current
Peak Line Transient
Voltage
<
tf 100 ms, RL = 100Ω
Maximum Operational
Input Voltage
26
26
26
V(Min)
V(Min)
V(Min)
Reverse DC
VOUT ≥ −0.6V, RL = 100Ω
−30
−75
−15
−50
−30
−75
−15
−50
−30
−75
−15
−50
Input Voltage
<
tr 1 ms, RL = 100Ω
Reverse Transient
Input Voltage
3
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Electrical Characteristics
VIN = VNOM + 5V, (Note 4) IOUTmax = 500 mA for the TO-220 and TO-263 packages, IOUTmax=400mA for the SOT-223 pack-
age, COUT = 10 µF unless otherwise indicated. Boldface limits apply over the entire operating temperature range of the
indicted device., all other specifications are for TA = TJ = 25˚C.
Output Voltage (VOUT
)
12V
15V
Units
Parameter
Output Voltage
Conditions
Typ
Limit
11.64
11.40
12.36
12.60
120
Typ
Limit
14.55
14.25
15.45
15.75
150
5 mA ≤ IOUT ≤ IOUTmax
V (Min)
V(Min)
12.00
15.00
V(Max)
V(Max)
mV(Max)
Line Regulation
(VOUT + 2V) ≤ VIN ≤ 26V,
IOUT = 5 mA
36
45
Load Regulation
5 mA ≤ IOUT ≤ IOUTmax
(VOUT + 2V) ≤ VIN ≤ 26V,
IOUT = 5 mA
12
2
120
10
15
2
150
10
mV(Max)
mA(Max)
Quiescent Current
VIN = (VOUT + 5V),
IOUT = IOUTmax
10
20
10
20
mA(Max)
µVrms
Output Noise
Voltage
10 Hz–100 kHz,
IOUT = 5 mA
360
450
Long Term Stability
Dropout Voltage
1000 Hrs.
44
0.5
110
1.0
75
56
0.5
110
1.0
75
mV
IOUT = IOUTmax
1.0
250
0.6
60
1.0
250
0.6
60
V(Max)
mV(Max)
A(Min)
V(Min)
IOUT = 50 mA
Short-Circuit Current
Peak Line Transient
Voltage
<
tf 100 ms, RL = 100Ω
Maximum Operational
Input Voltage
26
26
V(Min)
V(Min)
V(Min)
Reverse DC
VOUT ≥ −0.6V, RL = 100Ω
−30
−75
−15
−50
−30
−75
−15
−50
Input Voltage
<
tr 1 ms, RL = 100Ω
Reverse Transient
Input Voltage
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when operating the device
outside of its rated Operating Conditions.
Note 2: The maximum allowable power dissipation at any ambient temperature is P
= (125 − T )/θ , where 125 is the maximum junction temperature for
A JA
MAX
operation, T is the ambient temperature, and θ is the junction-to-ambient thermal resistance. If this dissipation is exceeded, the die temperature will rise above
A
JA
125˚C and the electrical specifications do not apply. If the die temperature rises above 150˚C, the LM2937 will go into thermal shutdown. For the LM2937, the
junction-to-ambient thermal resistance θ is 65˚C/W, for the TO-220 package, 73˚C/W for the TO-263 package, and 174˚C/W for the SOT-223 package. When used
JA
with a heatsink, θ is the sum of the LM2937 junction-to-case thermal resistance θ of 3˚C/W and the heatsink case-to-ambient thermal resistance. If the TO-263
JA
JC
or SOT-223 packages are used, the thermal resistance can be reduced by increasing the P.C. board copper area thermally connected to the package (see
Application Hints for more information on heatsinking).
Note 3: ESD rating is based on the human body model, 100 pF discharged through 1.5 kΩ.
Note 4: Typicals are at T = 25˚C and represent the most likely parametric norm.
J
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4
Typical Performance Characteristics
Dropout Voltage vs. Output Current
Dropout Voltage vs. Temperature
01128007
01128008
Output Voltage vs. Temperature
Quiescent Current vs. Temperature
01128009
01128010
Quiescent Current vs. Input Voltage
Quiescent Current vs. Output Current
01128011
01128012
5
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Typical Performance Characteristics (Continued)
Line Transient Response
Load Transient Response
01128014
01128013
Ripple Rejection
Output Impedance
01128015
01128016
Maximum Power Dissipation (TO-220)
Maximum Power Dissipation (TO-263)(Note 2)
01128017
01128018
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Typical Performance Characteristics (Continued)
Low Voltage Behavior
Low Voltage Behavior
Output at Voltage Extremes
Output Capacitor ESR
01128019
01128020
01128022
01128024
Low Voltage Behavior
01128021
Output at Voltage Extremes
01128023
7
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Typical Performance Characteristics (Continued)
Peak Output Current
01128025
Typical Application
01128001
* Required if the regulator is located more than 3 inches from the power supply filter capacitors.
** Required for stability. C must be at least 10 µF (over the full expected operating temperature range) and located as close as possible to the regulator. The
out
equivalent series resistance, ESR, of this capacitor may be as high as 3Ω.
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8
The figure below shows the voltages and currents which are
present in the circuit, as well as the formula for calculating
the power dissipated in the regulator:
Application Hints
EXTERNAL CAPACITORS
The output capacitor is critical to maintaining regulator sta-
bility, and must meet the required conditions for both ESR
(Equivalent Series Resistance) and minimum amount of ca-
pacitance.
MINIMUM CAPACITANCE:
The minimum output capacitance required to maintain sta-
bility is 10 µF (this value may be increased without limit).
Larger values of output capacitance will give improved tran-
sient response.
ESR LIMITS:
01128027
The ESR of the output capacitor will cause loop instability if
it is too high or too low. The acceptable range of ESR plotted
versus load current is shown in the graph below. It is essen-
tial that the output capacitor meet these requirements,
or oscillations can result.
I
= I + I
L G
IN
P
= (V − V
) I + (V ) I
OUT L IN G
D
IN
FIGURE 2. Power Dissipation Diagram
The next parameter which must be calculated is the maxi-
mum allowable temperature rise, TR (max). This is calcu-
lated by using the formula:
Output Capacitor ESR
TR (max) = TJ(max) − TA (max)
where: TJ (max) is the maximum allowable junction tem-
perature, which is 125˚C for commercial
grade parts.
TA (max) is the maximum ambient temperature
which will be encountered in the
application.
Using the calculated values for TR(max) and PD, the maxi-
mum allowable value for the junction-to-ambient thermal
resistance, θ(J−A), can now be found:
01128024
θ(J−A) = TR (max)/PD
IMPORTANT: If the maximum allowable value for θ(J−A) is
found to be ≥ 53˚C/W for the TO-220 package, ≥ 80˚C/W for
the TO-263 package, or ≥174˚C/W for the SOT-223 pack-
age, no heatsink is needed since the package alone will
dissipate enough heat to satisfy these requirements.
FIGURE 1. ESR Limits
It is important to note that for most capacitors, ESR is
specified only at room temperature. However, the designer
must ensure that the ESR will stay inside the limits shown
over the entire operating temperature range for the design.
If the calculated value for θ(J−A)falls below these limits, a
heatsink is required.
For aluminum electrolytic capacitors, ESR will increase by
about 30X as the temperature is reduced from 25˚C to
−40˚C. This type of capacitor is not well-suited for low tem-
perature operation.
HEATSINKING TO-220 PACKAGE PARTS
The TO-220 can be attached to a typical heatsink, or se-
cured to a copper plane on a PC board. If a copper plane is
to be used, the values of θ(J−A) will be the same as shown in
the next section for the TO-263.
Solid tantalum capacitors have a more stable ESR over
temperature, but are more expensive than aluminum elec-
trolytics. A cost-effective approach sometimes used is to
parallel an aluminum electrolytic with a solid Tantalum, with
the total capacitance split about 75/25% with the Aluminum
being the larger value.
If a manufactured heatsink is to be selected, the value of
heatsink-to-ambient thermal resistance, θ(H−A), must first be
calculated:
θ(H−A) = θ(J−A) − θ(C−H) − θ(J−C)
If two capacitors are paralleled, the effective ESR is the
parallel of the two individual values. The “flatter” ESR of the
Tantalum will keep the effective ESR from rising as quickly at
low temperatures.
Where: θ(J−C) is defined as the thermal resistance from the
junction to the surface of the case. A value of
3˚C/W can be assumed for θ(J−C) for this
calculation.
HEATSINKING
θ(C−H) is defined as the thermal resistance between
the case and the surface of the heatsink. The
value of θ(C−H) will vary from about 1.5˚C/W to
about 2.5˚C/W (depending on method of at-
tachment, insulator, etc.). If the exact value is
unknown, 2˚C/W should be assumed for
A heatsink may be required depending on the maximum
power dissipation and maximum ambient temperature of the
application. Under all possible operating conditions, the junc-
tion temperature must be within the range specified under
Absolute Maximum Ratings.
θ(C−H)
.
To determine if a heatsink is required, the power dissipated
by the regulator, PD, must be calculated.
9
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Application Hints (Continued)
When a value for θ(H−A) is found using the equation shown,
a heatsink must be selected that has a value that is less than
or equal to this number.
θ(H−A) is specified numerically by the heatsink manufacturer
in the catalog, or shown in a curve that plots temperature rise
vs power dissipation for the heatsink.
HEATSINKING TO-263 AND SOT-223 PACKAGE PARTS
Both the TO-263 (“S”) and SOT-223 (“MP”) packages use a
copper plane on the PCB and the PCB itself as a heatsink.
To optimize the heat sinking ability of the plane and PCB,
solder the tab of the package to the plane.
Figure 3 shows for the TO-263 the measured values of θ(J−A)
for different copper area sizes using a typical PCB with 1
ounce copper and no solder mask over the copper area used
for heatsinking.
01128029
FIGURE 4. Maximum Power Dissipation vs. TAMB for
the TO-263 Package
Figure 5 and Figure 6 show the information for the SOT-223
package. Figure 6 assumes a θ(J−A) of 74˚C/W for 1 ounce
copper and 51˚C/W for 2 ounce copper and a maximum
junction temperature of +85˚C.
01128028
FIGURE 3. θ(J−A) vs. Copper (1 ounce) Area for the
TO-263 Package
As shown in the figure, increasing the copper area beyond 1
square inch produces very little improvement. It should also
be observed that the minimum value of θ(J−A) for the TO-263
package mounted to a PCB is 32˚C/W.
01128030
FIGURE 5. θ(J−A) vs Copper (2 ounce) Area for the
As a design aid, Figure 4 shows the maximum allowable
power dissipation compared to ambient temperature for the
TO-263 device (assuming θ(J−A) is 35˚C/W and the maxi-
mum junction temperature is 125˚C).
SOT-223 Package
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10
Application Hints (Continued)
SOT-223 SOLDERING RECOMMENDATIONS
It is not recommended to use hand soldering or wave sol-
dering to attach the small SOT-223 package to a printed
circuit board. The excessive temperatures involved may
cause package cracking.
Either vapor phase or infrared reflow techniques are pre-
ferred soldering attachment methods for the SOT-223
package.
01128031
FIGURE 6. Maximum Power Dissipation vs TAMB for
the SOT-223 Package
11
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Physical Dimensions inches (millimeters) unless otherwise noted
Plastic Package
Order Number LM2937ET-5.0,
LM2937ET-8.0, LM2937ET-10, LM2937ET-12,
or LM2937ET-15
NS Package Number T03B
TO-263 3-Lead Plastic Surface Mount Package
Order Number LM2937ES-5.0, LM2937ES-8.0, LM2937ES-10, LM2937ES-12 or LM2937ES-15
NS Package Number TS3B
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12
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
SOT-223 3-Lead Plastic Surface Mount Package
Order Number LM2937IMP-5.0, LM2937IMP-8.0, LM2937IMP-10, LM2937IMP-12 or LM2937IMP-15
NS Package Number MP04A
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
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