LM2940N [ETC]
1.25A High Current Low Dropout; 1.25A的高电流低压降
| 型号： | LM2940N |
| 厂家： | 
ETC |
| 描述： | 1.25A High Current Low Dropout |
| 文件： | 总5页 (文件大小：198K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Bay Linear
Inspire the Linear Power
1.25A High Current Low Dropout
LM2940/2941
Voltage Regulator Adjustable
Description
The Bay Linear LM2940 & LM2941 is a 1.25A high accuracy, low
dropout voltage regulator with only 40mV at light loads and
350mV(Typ.)@ 1.0A) and low quiescent current of 240µA typical.
Features
•
•
•
•
•
•
•
•
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High output accuracy of 1%
Output Adjustable from 1.24V to 26V
Output Current of 1.25A
Low Dropout Voltage
Low quiescent current
The LM2940/41 is designed for low voltage a application that
requires lower dropout voltage and faster transient response. This
device is an excellent choice for use in powering low voltage
applications where require a lower dropout, faster transient response
to regulate from +2.5V to 3.8V supplies and as a post regulator for
switching supplies applications.
Extremely Tight Load & Line Regulation
Reverse-battery and “Load Dump” Protection
Zero Current Shutdown Mode (5-pin version)
Offer in TO-263, TO-220, SOT-223, & New Slim
LPDD
•
Similar to industry Standard MIC2940LM2941
The LM2940/41 offers full protection against over-current faults,
reversed input polarity, reversed load insertion, and positive and
negative transient voltage. On-Chip trimming adjusts the reference
voltage to 1%. The LM2940-xx devices are in 3 pin fixed voltage
regulators. The LM2941 include an Enable pin in the 5 pin
Applications
•
•
•
•
•
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Powering VGA & Sound Card
LCD Monitor
packages.
Battery Powered Equipments/Laptop & Notebook
SMPS Post Regulator / DC to DC Modules
High Efficiency Linear Power Supply
Adjustable Power Supply
The LM2940/41 are offered in a 3 & 5-pin SOT-223, TO-220 &
TO-263 package compatible with other 3 terminal regulators. The
LM2940/41 is also offer in a new LPDD (Low Profile TO-263)
package from 4.47 mm (DD) tickness down to only 1.27 mm
Pin Connection
Ordering Information
Devices
Package
TO-220-3
TO-220-5
TO-263-3
TO-263-5
SOT-223-3
SOT-223-5
LPDD-3
Temp.
LM2940T
-40 °C to 125 °C
-40 °C to 125 °C
-40 °C to 125 °C
-40 °C to 125 °C
-40 °C to 125 °C
-40 °C to 125 °C
-40 °C to 125 °C
-40 °C to 125 °C
LM2941T
LM2940S
LM2941S
LM2940N
LM2941N
LM2940J
LM2941J
LPDD-5
TO-220-5 Package
TO-220-3 Package
TO-263-3 Package
TO-263-5 Package
1)
ADJUST
2) ON/OFF
3)
BAY
BAY
B2941
B2940
BAY
BAY
B2940
GND
4) INPUT
5)
B2941
1
2
3
1
2 3 4 5
OUPUT
1
2 3 4 5
V
GND
V
OUT
V
V
OUT
GND
IN
IN
Top View
Top View
Front View
Front View
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556
www.baylinear.com
LM2940/41
ABSOLUTE MAXIMUM RATINGS
Lead Temp. (Soldering, 5 Seconds).................................260°C
Storage Temperature Range.............................. -65° to +150°C
Operating Junction Temperature Range
Input Voltage ........................................................26V
Maximum Output Current....................................3.5A
Input Supply Voltage (Note1) (Survival)-20V to +60V
LM2940/2941 Control Section.................. -45°C +125°C
LM2940/2941 Power Transistor.................-45°C +150°C
ELECTRICAL CHARACTERISTICS (NOTE 1) at IOUT = 5mA, V IN =V OUT + 1V, I l = 1000mA, C L = 10µF. Ta=25°C, unless otherwise
specified. The LM2941 is programmed to output 5V and has V SHUTDOWN ≤ 0.6V
PARAMETER
CONDITIONS
Typ
LM2940
Units
Min
Max
2.5V Version
Output Voltage (Note 2)
IOUT = 5mA
2.5
2.475
2.525
V
V
2.5
2.450
2.550
5mA ≤IOUT≤1.25A, 4.75V≤VIN ≤26V
3.3V Version2.
Output Voltage (Note 2)
IOUT = 5mA
3.3
3.267
3.330
3.3
3.234
3.366
5mA ≤IOUT≤1.25A, 4.75V≤VIN ≤26V
5.0V Version
IOUT = 5mA
5.0
4.95
4.90
-1
5.05
5.10
1
V
Output Voltage (Note 2)
5.0
5mA ≤IOUT≤1.25A, 5.5V≤VIN ≤26V
%
Output Voltage
Accuracy
-2
2
-2.5
2.5
5mA ≤IOUT≤1.0 A
All Voltage Options
Line Regulation
Load Regulation
0.06
0.2
0.5
1.6
%
%
IO = 5mA, (VOUT + 1V) ≤ VIN≤ 26V
VIN = VOUT + 5V, 5mA ≤ IOUT≤ 1 A
(Note 2, 6)
Output Voltage (Note 6)
Temperature Coef.
20
100
ppm/°C
∆V°
∆T
Dropout Voltage
80
150
450
600
mV
IO = 5mA
350
400
IO = 1000mA
IO = 1.25A
240
22
350
35
µA
Ground Current
IO = 5mA, VIN = VOUT, +1V
IO = 1000mA, VIN = VOUT, +1V
IO = 1.25A
mA
35
70
VIN = 0.5V less than specified VOUT IOUT = 10mA
0.9
mA
IGNDDO Ground Pin Current at
Dropout
Current Limit
VOUT = 0V (Note 4)
1.7
1.5
A
400
CL = 10µF
µV RMS
Output Noise Voltage
(10Hz to 100kHz)
IL = 100mA
260
1.235
CL = 33µF
1.223
1.210
1.204
1.247
1.260
1.266
V
Vmax
V
Reference Voltage
(Note 8)`
Reference Voltage
40
20
80
nA
Adjust Pin
120
Bias Current
(Note 7)
ppm/°C
Reference Voltage
Temperature
Coefficient
0.1
nA/°C
Adjust Pin Bias
Current Temperature
Coefficient
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556
www.baylinear.com
LM2940/2941
ENABLE Input LM2941
Input Logic Voltage
Low (OFF)
V
0.8
High (ON)
2.4
VEN = 26V
VEN = 0.8V
(Note 10)
100
10
600
750
2.5
5
V
Enable Pin
Input Current
µA
µA
Regulator Output
500
Current in Shutdown
NOTES:
The Bold specifications apply to the full operating temperature range.
Note 1: Maximum positive supply voltage of 60V must be of limited duration (<100msec) and duty cycle.) The maximum continuous supply voltage is 26V.
Note 2: Full load current (IFL) is defined as 1.25A for the LM2941.
Note 3: Dropout voltage is defined as the input-to output differential when the output voltage drops to 99% of its nominal value with VOUT + 1V applied to VIN.
Note 4: VIN = VOUT (NOMINAL) +1V. For example, use VIN= 4.3V for a 3.3V regulator. Employ pulse-testing procedures to minimize temperature rise.
Note 5: Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load current to the ground current.
Note 6: Output voltage temperature coefficient is defined as the worst case voltage changed divided by the total temperature range.
Note 7: Thermal regulation is defined as the change in the output voltage at a time T after a change in power dissipation is applied, excluding load or line regulation
effects. Specifications are for a 200mA load pulse as VIN = 20V (a 4W pulse) for T = 10ms.
Note 8: VREF ≤ VOUT ≤ (VIN - 1), 2.3V ≤ VIN≤ 26V, 10mA < IL ≤ IFL, TJ ≤ TJMAX
Note 9: Comparator threshold is expressed in terms of a voltage differential at the Adjust terminal below the nominal reference voltage measured 6V input. To express
these thresholds in terms of output voltage change, multiply the error amplifier gain = VOUT/VREF = (R1 + R2)/R2. For example, at a programmable output voltage of
5V, the Error output is guaranteed to go low when the output drops by 95mVx 5V/ 1.240V = 38mV. Threshold remains constant as a percent of VOUT as VOUT is varied,
with the dropout warning occurring at typically 5% below nominal, 7.7% guaranteed.
Note 10: VEN ≤ 0.8V and VIN≤ 26V, VOUT = 0.
BLOCK DIAGRAM
IN
OUT
O.V
ILIMIT
FLAG
1.180V
1.240V
28V
R1*
Reference
+
-
+
-
ADJ
EN
Thermal
Shutdown
R2*
GND
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556
www.baylinear.com
LM2940/2941
APPLICATION HINTS
Minimum Load Current
The Bay Linear LM2941 incorporates protection against over-current
faults, reversed load insertion, over temperature operation, and
positive and negative transient voltage. However, the use of an output
capacitor is required in order to insure the stability and the
performances.
To ensure a proper behavior of the regulator at light load, a
minimum load of 5mA for LM2941 is required.
Adjustable Regulator Design
B29152/53 are adjustable regulators and maybe programmed for
any value between 1.25V and 26V using two resistors. The relation
between the resistors is given by:
Thermal Consideration
Although the LM2941 offers limiting circuitry for overload
conditions, it is necessary not to exceed the maximum junction
temperature, and therefore to be careful about thermal resistance. The
heat flow will follow the lowest resistance path, which is the Junction-
to-case thermal resistance. In order to insure the best thermal flow of
the component, a proper mounting is required. Note that the case of
the device is electrically connected to the output. The
case has to be electrically isolated, a thermally conductive spacer can
be used. However do not forget to consider its contribution to thermal
resistance.
R1=R2 (VOUT/1.240 –1)
Resistors have a large value up to 1mΩ in order to reduce the
current consumption. This might be interesting in the case of
widely varying load currents.
Enable Input
LM2941 features enable input allowing turning ON & OFF the
device. EN has been designed to be compatible with TTL/CMOS
logic. When the regulator is ON, the current flowing through this
pin is approximately 20µA.
Assuming:
VIN = 10V, VOUT = 5V, IOUT = 1.5A, TA = 90°C, θCASE= 1°C/W (no
external heat sink, no wind)
Power dissipation under these conditions
PD = (VIN – VOUT) * IOUT = 7.5W
V OU
BAY
VIN
T
B2940
Junction Temperature
TJ = TA + PD * (θCASE+ θJC)
For the Control Section
TJ = 90°C + 7.5W*(1°C/W + 0.6°C/W) = 102°C
114°C < TJUNCTION MAX for the control section.
For the Power Section
TJ = 90°C + 7.5W*(1°C/W + 1.6°C/W) = 104.5°C
109.5°C < TJUNCTION MAX for the power transistor.
Fig.1 Basic Fixed Output Regulator
In both case reliable operation is insured by adequate junction
temperature.
Capacitor Requirements
The output capacitor is needed for stability and to minimize the output
noise. The required value of the capacitor varies with the load.
However, a minimum value of 10µF Aluminum will guarantee
stability over load. A tantalum capacitor is recommended for a fast
load transient response.
1
2
4
5
VOUT
BAY
VIN
B2941
3
R1
R2
If the power source has high AC impedance, a 0.1µF capacitor
between input & ground is recommended. This capacitor should have
good characteristics up to 250 kHz.
V
OUT = VREF X [1 + (R /
1
R2)]
For best results, the total series resistance should be small
enough to pass the minimum regulator load current
Fig. 2 Adjustable Output Voltage Regulator
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556
www.baylinear.com
LM2940/2941
Advance Information- These data sheets contain descriptions of products that are in development. The specifications are based on the engineering calculations, computer simulations and/
or initial prototype evaluation.
Preliminary Information- These data sheets contain minimum and maximum specifications that are based on the initial device characterizations. These limits are subject to change upon the
completion of the full characterization over the specified temperature and supply voltage ranges.
The application circuit examples are only to explain the representative applications of the devices and are not intended to guarantee any circuit design or permit any
industrial property right to other rights to execute. Bay Linear takes no responsibility for any problems related to any industrial property right resulting from the use of
the contents shown in the data book. Typical parameters can and do vary in different applications. Customer’s technical experts must validate all operating parameters
including “ Typical” for each customer application.
LIFE SUPPORT AND NUCLEAR POLICY
Bay Linear products are not authorized for and should not be used within life support systems which are intended for surgical implants into the body
to support or sustain life, in aircraft, space equipment, submarine, or nuclear facility applications without the specific written consent of Bay Linear
President.
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556
www.baylinear.com
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