LM26484SQEV National Semiconductor, LM26484SQEV Datasheet

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LM26484SQEV

Manufacturer Part Number
LM26484SQEV
Description
BOARD EVALUATION FOR LM2684
Manufacturer
National Semiconductor
Datasheets

Specifications of LM26484SQEV

Main Purpose
DC/DC, Step Down with LDO
Outputs And Type
3, Non-Isolated
Voltage - Output
1V, 1.8V, 1V
Current - Output
2A, 2A, 1A
Voltage - Input
3 ~ 5.5V
Regulator Topology
Buck
Frequency - Switching
2MHz
Board Type
Fully Populated
Utilized Ic / Part
LM26484
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Power - Output
-
© 2010 National Semiconductor Corporation
Power Management Unit
General Description
The LM26484 is a multi-function, configurable Power Man-
agement Unit. This device integrates two highly efficient 2.0A
Step-Down DC/DC converters, one LDO Controller, a POR
(Power On Reset) circuit, and thermal overload protection
circuitry. All regulator output voltages are externally ad-
justable. The LDO controller is a low-voltage NMOS voltage
regulator. The LM26484 is offered in a 5 x 4 x 0.8 mm LLP-24
pin package.
Key Specifications
STEP-DOWN DC/DC CONVERTER (BUCK)
Typical Application Circuit
3.0–5.5V Input Range
Externally adjustable V
— Bucks 1 & 2: 0.8V–3.5V @ 2A
180° Phase Shift between Bucks Clocks
2 MHz PWM switching frequency
±1% feedback voltage accuracy
Automatic soft start
Current overload protection
PWM/PFM efficiency modes available
OUT
:
300661
LM26484
LINEAR REGULATOR (LDO) CONTROLLER
Applications
3.0V–5.5V Input range
Externally adjustable V
±1.5% feedback voltage accuracy
Regulated to Low V
Output) NFET operation
Input to the LI-LO configuration, can be post regulated
when supply is regulated by Buck2
Up to 1000 mA output current by selection of external FET
Digital Cores and I/Os (FPGAs, ASICs, DSPs)
Automotive infotainment
Set-top-box
Cordless phone base station
Networking router
Printers
IN
- Low V
OUT
OUT
30066101
LI-LO (Low Input Low
December 10, 2010
www.national.com

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LM26484SQEV Summary of contents

Page 1

... Automatic soft start ■ Current overload protection ■ PWM/PFM efficiency modes available Typical Application Circuit © 2010 National Semiconductor Corporation LM26484 LINEAR REGULATOR (LDO) CONTROLLER ■ 3.0V–5.5V Input range ■ Externally adjustable V ■ ±1.5% feedback voltage accuracy ■ ...

Page 2

Connection Diagram and Package Mark Information Note: The physical placement of the package marking will vary from part to part. (*) UZXYTT format: ‘U’ – wafer fab code; ‘Z’ – assembly code; ’XY’ 2 digit date code; ‘TT” – die ...

Page 3

Pin Descriptions Pins Name I/O 1 VIN1 I 2 ENSW1 I 3 FB1 I 4 AVIN I 5 FB2 I 6 ENSW2 I 7 VIN2 I 8 VIN2 I 9 SW2 O 10 SW2 O 11 PGND_SW2 G 12 PGND_SW2 ...

Page 4

... Absolute Maximum Ratings 2) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. VIN1, VIN2, AVDD, AVIN nPOR, ENSW1, FB1, ENSW2, FB2, ENLDO, LDO_FB GND to GND SLUG Junction Temperature (T ) J-MAX Storage Temperature Range ...

Page 5

... Note 6: Junction-to-ambient thermal resistance is highly application and board-layout dependent. In applications where high maximum power dissipation exists, special care must be paid to thermal dissipation issues in board design. More information is available in National Semiconductor Application Note AN1187. Note 7: Min and Max limits are guaranteed by design, test, or statistical analysis. Typical numbers are not guaranteed, but do represent the most likely norm. ...

Page 6

Typical Performance Characteristics — LDO Load Transient V — 1.0V, I OUT Typical Performance Characteristics — Buck Startup of Buck1 1.8V; I OUT Startup of Buck2 1.0V; I OUT www.national.com T = 200 mA-1A Load Transient ...

Page 7

Line Transient 3.0V - 3.6V 250 mA 1.8V OUT OUT Buck1 Load Transient 3.3V 1.8V 250 mA - 1.5A OUT OUT Buck2 Load Transient ...

Page 8

Efficiency of Buck1 1.8V, at Room Temp OUT Efficiency of Buck1 3.5V at Room Temp OUT Flexible Power Sequencing of Multiple Power Supplies The two bucks and the LDO in the LM26484 can be individ- ually ...

Page 9

LDO Functional Description The LDO is a linear regulator which targets analog loads characterized by low noise requirements. The LDO is enabled through the ENLDO pin. The output voltage is determined by the configuration of the external feedback resistors, as ...

Page 10

... At very light loads, the converter enters PFM mode and op- erates with reduced switching frequency and supply current to maintain high efficiency. For the PFM mode to be enabled, please contact National Semiconductor Sales. www.national.com The part will automatically transition into PFM mode when ei- ...

Page 11

SOFT START The soft-start feature allows the power converter to gradually reach the initial steady state operating point, thus reducing start-up stresses and surges. The two LM26484 buck con- verters have a soft-start circuit that limits in-rush current dur- ing ...

Page 12

Component Selection SW1, SW2 OPERATION TABLE 2. Buck1/2 Configuration and Component Selection Guide Target Ideal Resistor Values V (V) R1/3 (KΩ) R2/4 (KΩ) OUT 0.8 120 200 0.9 160 200 1 200 200 1.1 240 200 1.2 280 200 1.3 ...

Page 13

... Over-current ruggedness. The LM26484 has been optimized for use with nominal values 0.5 µH and 22 µF. If other values are needed for the design, please contact National Semiconductor sales with any con- cerns. INDUCTOR SELECTION FOR SW1 AND SW2 A nominal inductor value of 0.5 µH is recommended im- portant to guarantee the inductor core does not saturate during any foreseeable operational situation ...

Page 14

I : Inductor saturation current at operating tempera- SAT ture I : Peak inductor current during worst case conditions LPEAK Inductor Value L1 and L2 0.5 SUGGESTED INDUCTORS AND THEIR SUPPLIERS Output Voltage Range ≥ V 2.0V OUT V < ...

Page 15

Model 10 µF for CIN or COUT; C9, C2, C1, C5, C7, C10 GRM21BR60J106K JMK212BJ106K LMK212C106KG-T C1608X5R0J106K Model 22 µF for COUT; C10, C2, C7 GRM31CR70J226KE23L JMK316B7226ML-T Capacitor Min Value C10, 10.0 C2, 10.0 C7, 10.0 Type Vendor Ceramic, X7R ...

Page 16

Physical Dimensions www.national.com inches (millimeters) unless otherwise noted 0.8 mm 24-Pin LLP Package NSC Package SQA24B 16 ...

Page 17

Notes 17 www.national.com ...

Page 18

... For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Amplifiers www.national.com/amplifiers Audio www.national.com/audio Clock and Timing www.national.com/timing Data Converters www.national.com/adc Interface www.national.com/interface LVDS www.national.com/lvds Power Management www.national.com/power Switching Regulators www.national.com/switchers LDOs www.national.com/ldo LED Lighting www ...

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