Datasheet

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MIC2954

250mA Low-Dropout Regulator

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (

408

) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

September 2007

M9999-090607

General Description

The MIC2954 is a “bulletproof” efficient voltage regulator

with very low dropout voltage (typically 40mV @ light loads

and 375mV @ 250mA), and low quiescent current (120µA

typical). The quiescent current of the MIC2954 increases

only slightly in dropout, thus prolonging battery life. Key

MIC2954 features include protection against reversed

battery, fold-back current limiting, and automotive load

dump protection (60V positive transient).

The MIC2954-07/08BM is an adjustable version that

includes an error flag output that warns of a low output

voltage, which is often due to failing batteries on the input.

This may also be used as a power-on reset. A logic-

compatible shutdown input is provided which enables the

regulator to be switched on and off. This part may be pin-

strapped for 5V output, or programmed from 1.24V to 29V

with the use of two external resistors.

The MIC2954 is available in two voltage tolerances, ±0.5%

maximum and ±1% maximum. Both are guaranteed for

junction temperatures from –40°C to +125°C.

Data sheets and support documentation can be found on

Micrel’s web site at www.micrel.com.

Features

• High-accuracy 5V, guaranteed 250mA output

• Low quiescent current

• Low dropout voltage

• Extremely tight load and line regulation

• Very low temperature coefficient

• Current and thermal limiting

• Input can withstand –20V reverse battery and+60V

positive transients

• Error flag warns of low output voltage

• Logic-controlled electronic shutdown

• Output programmable from 1.24V to 29V

(MIC2954-07/08)

• Available in TO-220, TO-92, and surface-mount SOT-

223 and SOIC-8 packages

Applications

• Battery powered equipment

• Cellular telephones

• Laptop, notebook, and palmtop computers

• PCMCIA V

and V

regulation/switching

• Bar code scanners

• Automotive electronics

• SMPS post-regulator/dc-to-dc modules

• Voltage reference

• High-efficiency linear power supplies

___________________________________________________________________________________________________________

Ordering Information

Part Number

Standard

Pb-Free /

RoHS Compliant

Accuracy

Junction

Temp. Range Package

MIC2954-02BT MIC2954-02WT* 0.5% –40° to +125°C TO-220-3

MIC2954-03BT MIC2954-03WT* 1.0% –40° to +125°C TO-220-3

MIC2954-02BS MIC2954-02WS* 0.5% –40° to +125°C SOT-223-3

MIC2954-03BS MIC2954-03WS* 1.0% –40° to +125°C SOT-223-3

MIC2954-02BZ MIC2954-02YZ 0.5% –40° to +125°C TO-92-3**

MIC2954-03BZ MIC2954-03YZ 1.0% –40° to +125°C TO-92-3**

MIC2954-07BM MIC2954-07YM 0.5% –40° to +125°C 8-Pin SOIC

MIC2954-08BM MIC2954-08YM 1.0% –40° to +125°C 8-Pin SOIC

* RoHS compliant with ‘high-melting solder’ exemption.

** TO-92 package discontinuance notification issued September 2007. End-of-life-buy offered thru December 31, 2007.

Contact factory for additional information.

Summary of content (15 pages)

PAGE 1
MIC2954 250mA Low-Dropout Regulator General Description Features The MIC2954 is a “bulletproof” efficient voltage regulator with very low dropout voltage (typically 40mV @ light loads and 375mV @ 250mA), and low quiescent current (120µA typical). The quiescent current of the MIC2954 increases only slightly in dropout, thus prolonging battery life. Key MIC2954 features include protection against reversed battery, fold-back current limiting, and automotive load dump protection (60V positive transient).
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Micrel, Inc. MIC2954 Typical Application 100k VIN VOUT 1.
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Micrel, Inc. MIC2954 Pin Configuration OUT 1 8 IN SNS 2 7 FB SHDN 3 6 TAP GND 4 5 ERR 1 IN 3 3-Pin SOT-223 (S) TO-92 3 OUT 2 GND 1 IN TAB 8-Pin SOIC (M) 2 GND OUT 3-Pin TO-92 (Z) 3 OUT 2 GND 1 IN 3-Pin TO-220 (T) Pin Description Pin No. SOIC-8 Pin No. SOT-223 Pin No. TO-92 Pin No. TO-220 Pin Name 8 1 1 1 IN 4 2, TAB 2 2 GND Ground. 1 3 3 3 OUT Regulator Output. 2 SNS Sense (Input): Output-sense-voltage end of internal resistive divider.
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Micrel, Inc. MIC2954 Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VIN) ....................................... –20V to +60V Feedback Voltage (VFB) (14, 15)........................ –1.5V to +26V Shutdown Input Voltage (VSHDN).................... –0.3V to +30V Error Output Voltage (VERR) .......................... –0.3V to +30V Power Dissipation (PD) (4) ..........................Internally Limited Lead Temperature (soldering, 5 sec.)........................
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Micrel, Inc. MIC2954 Symbol Parameter Condition ILIMIT Current Limit, Note 11 VOUT = 0V ∆VOUT/∆PD Thermal Regulation, Note 12 en Output Noise Voltage (10Hz to 100kHz) IL = 100mA, CL = 2.2µF Reference Voltage MIC2954-02/-07 (±0.5%) 1.220 1.200 1.235 1.250 1.260 V V MIC2954-03/-08 (±1%) 1.210 1.200 1.235 1.260 1.270 V V MIC2954-02/-07 (±0.5%), Note 13 1.190 1.270 V MIC2954-03/-08 (±1%), Note 13 1.185 Reference Voltage Min 0.05 Max Units 750 800 mA mA 0.
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Micrel, Inc. MIC2954 Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. Devices are ESD sensitive. Handling precautions recommended. 4. PD(max) = (TJ(max) – TA) ÷ θJC. Exceeding TJ(max) will cause thermal shutdown. 5. Thermal resistance (θJC) of the TO-220 package is 2.5°C/W, and 15°C/W for the SOT-223. Thermal resistance (θJC) of the TO-92 package is 180°C/W with 0.4" leads and 160°C/W with 0.25" leads.
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Micrel, Inc.
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Micrel, Inc.
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Micrel, Inc. MIC2954 Functional Diagrams Unregulated DC Supply IN OUT 5V/250mA Output Error Amp. 182k 62k 2.2µF 1.23V REF.
PAGE 10
Micrel, Inc. MIC2954 The error comparator has an open-collector output which requires an external pull-up resistor. Depending on system requirements, this resistor may be returned to the 5V output or some other supply voltage. In determining a value for this resistor, note that while the output is rated to sink 400µA, this sink current adds to battery drain in a low battery condition. Suggested values range from 100k to 1MΩ. The resistor is not required if this output is unused.
PAGE 11
Micrel, Inc. MIC2954 Thermal Calculations Layout Considerations The MIC2954-07BM/-08BM (8-pin surface-mount package) has the following thermal characteristics when mounted on a single layer copper-clad printed circuit board. PC Board Dielectric Material θJA FR4 160°C/W Ceramic 120°C/W Multilayer boards having a ground plane, wide traces near the pads, and large supply bus lines provide better thermal conductivity.
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Micrel, Inc.
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Micrel, Inc. MIC2954 Package Information 8-Pin SOIC (M) 0.090 (2.286) Radius, t yp. 2 3 1 0.145 (3.683) 0.135 (3.429) 0.055 (1.397) 0.045 (1.143) 10° typ. BOTTOM VIEW 0.085 (2.159) Diam. 0.185 (4.699) 0.175 (4.445) 5° typ. 0.185 (4.699) 0.175 (4.445) 0.090 (2.286) typ. 5° typ. Seat ing Plane 0.025 (0.635) Max Uncont rolled Lead Diamet er 0.500 (12.70) Min. 0.016 (0.406) 0.014 (0.356) 0.0155 (0.3937) 0.0145 (0.3683) 0.055 (1.397) 0.045 (1.143) 0.105 (2.667) 0.095 (2.
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Micrel, Inc.
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Micrel, Inc. MIC2954 MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.