LM2941T - Bay Linear, Inc.

Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com

1.25A High Current Low Dropout LM2940/2941

Voltage Regulator Adjustable

Pin Connection

Ordering Information

Devices Package Temp.

LM2940T TO-220-3

-40 °C to 125 °C

LM2941T TO-220-5

-40 °C to 125 °C

LM2940S TO-263-3

-40 °C to 125 °C

LM2941S TO-263-5

-40 °C to 125 °C

LM2940N SOT-223-3

-40 °C to 125 °C

LM2941N SOT-223-5

-40 °C to 125 °C

LM2940J LPDD-3

-40 °C to 125 °C

LM2941J LPDD-5

-40 °C to 125 °C

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.

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.

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

packages.

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

(LPDD) t t l ti k

Features

• High output accuracy of 1%

• Output Adjustable from 1.24V to 26V

• Output Current of 1.25A

• Low Dropout Voltage

• Low quiescent current

• 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

Applications

• Powering VGA & Sound Card

• LCD Monitor

• Battery Powered Equipments/Laptop & Notebook

• SMPS Post Regulator / DC to DC Modules

• High Efficiency Linear Power Supply

• Adjustable Power Supply

•

Bar Code Scanners

Bay Linear

Inspire the Linear Power

TO-263-3 Package

VOUT

GND

VIN

BAY

B2940

Front View

123

Front View

TO-220-3 Package

BAY

B2940

VIN VOUT

GND

TO-263-5 Package

Top View

BAY

B2941

321

GND

OUPUT

2) ON/OFF

ADJUST

INPUT

TO-220-5 Package

Top View

BAY

B2941

12345

TO-263-3 Package

VOUT

GND

VIN

BAY

B2940

Front View

123

Front View

TO-220-3 Package

BAY

B2940

VIN VOUT

GND

TO-263-3 Package

VOUT

GND

VIN

BAY

B2940

Front View

123

Front View

TO-220-3 Package

BAY

B2940

VIN VOUT

GND

Front View

TO-220-3 Package

BAY

B2940

VIN VOUT

GND

TO-263-5 Package

Top View

BAY

B2941

321

GND

OUPUT

2) ON/OFF

ADJUST

INPUT

TO-220-5 Package

Top View

BAY

B2941

12345

TO-263-5 Package

Top View

BAY

B2941

321

GND

OUPUT

2) ON/OFF

ADJUST

INPUT

GND

OUPUT

2) ON/OFF

ADJUST

INPUT

TO-220-5 Package

Top View

BAY

B2941

12345

TO-220-5 Package

Top View

BAY

B2941

12345

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 Input Voltage ........................................................26V

Storage Temperature Range.............................. -65° to +150°C Maximum Output Current....................................3.5A

Operating Junction Temperature Range 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

Min Max

Units

2.5V Version

Output Voltage (Note 2) IOUT = 5mA

5mA ≤IOUT≤1.25A, 4.75V≤VIN ≤26V

2.5

2.475

2.450

2.525

2.550

3.3V Version2.

Output Voltage (Note 2) IOUT = 5mA

5mA ≤IOUT≤1.25A, 4.75V≤VIN ≤26V

3.3

3.267

3.234

3.330

3.366

5.0V Version

Output Voltage (Note 2) IOUT = 5mA

5mA ≤IOUT≤1.25A, 5.5V≤VIN ≤26V

5.0

4.95

4.90

5.05

5.10

Output Voltage

Accuracy

5mA ≤IOUT≤1.0 A

-1

-2

-2.5

2.5

All Voltage Options

Line Regulation IO = 5mA, (VOUT + 1V) ≤ VIN≤ 26V 0.06 0.5 %

Load Regulation VIN = VOUT + 5V, 5mA ≤ IOUT≤ 1 A

(Note 2, 6)

0.2 1.6 %

∆V° 20 100 ppm/°C

∆T

Output Voltage (Note 6)

Temperature Coef.

IO = 5mA 80 150

IO = 1000mA 350 450

Dropout Voltage

IO = 1.25A 400 600

Ground Current IO = 5mA, VIN = VOUT, +1V

IO = 1000mA, VIN = VOUT, +1V

IO = 1.25A

240

350

µA

IGNDDO Ground Pin Current at

Dropout

VIN = 0.5V less than specified VOUT IOUT = 10mA 0.9 mA

Current Limit VOUT = 0V (Note 4) 1.7 1.5 A

Output Noise Voltage

(10Hz to 100kHz)

IL = 100mA

CL = 10µF

CL = 33µF

400

260

µV RMS

Reference Voltage 1.235 1.223

1.210

1.247

1.260

Vmax

Reference Voltage (Note 8)` 1.204 1.266 V

Adjust Pin

Bias Current

40 80

120

Reference Voltage

Temperature

Coefficient

(Note 7) 20 ppm/°C

Adjust Pin Bias

Current Temperature

Coefficient

0.1

nA/°C

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)

High (ON)

2.4

0.8

VEN = 26V 100 600

750

Enable Pin

Input Current

VEN = 0.8V 2.5

µA

Regulator Output

Current in Shutdown

(Note 10) 10

500

µA

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

Reference

Thermal

Shutdown

IN OUT

ADJ

GND

O.V

LIMIT

28V R1*

R2*

1.180V 1.240V

FLAG

Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com

LM2940/2941

APPLICATION HINTS

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.

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.

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

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.

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.

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.

Minimum Load Current

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:

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.

1BAY

B2941

VOUT

VIN R1

Fig. 2 Adjustable Output Voltage Regulator

VOUT = VREF X [1 + (R

R2)]

For best results, the total series resistance should be small

enough to pass the minimum regulator load current

1BAY

B2941

VOUT

VIN R1

Fig. 2 Adjustable Output Voltage Regulator

VOUT = VREF X [1 + (R

R2)]

For best results, the total series resistance should be small

enough to pass the minimum regulator load current

BAY

B2940

Fig.1 Basic Fixed Output Regulator

VOU

VIN

BAY

B2940

Fig.1 Basic Fixed Output Regulator

VOU

VIN

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.