LM3679TL-1.8EV National Semiconductor, LM3679TL-1.8EV Datasheet

no-image

LM3679TL-1.8EV

Manufacturer Part Number
LM3679TL-1.8EV
Description
BOARD EVALUATION LM3679TL-1.8
Manufacturer
National Semiconductor
Series
PowerWise®r
Datasheets

Specifications of LM3679TL-1.8EV

Main Purpose
DC/DC, Step Down
Outputs And Type
1, Non-Isolated
Voltage - Output
1.8V
Current - Output
350mA
Voltage - Input
2.5 ~ 5.5V
Regulator Topology
Buck
Frequency - Switching
3MHz
Board Type
Fully Populated
Utilized Ic / Part
LM3679
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Power - Output
-
© 2008 National Semiconductor Corporation
LM3679
3MHz, 350mA Miniature Step-Down DC-DC Converter for
Ultra Low Profile Applications (Height < 0.55mm)
General Description
The LM3679 step-down DC-DC converter is optimized for
powering ultra-low voltage circuits from a single Li-Ion cell
battery and input voltage rails from 2.5V to 5.5V. It provides
up to 350mA load current, over the entire input voltage range.
The LM3679 output voltage can be configured to 1.2V, 1.5V,
or 1.8V.
The device offers superior features and performance for mo-
bile phones and similar portable applications with complex
power management systems. Automatic intelligent switching
between PWM low-noise and PFM low-current mode offers
improved system control. During PWM mode operation, the
device operates at a fixed-frequency of 3 MHz (typ). PWM
mode drives loads from ~ 80mA to 350mA max. Hysteretic
PFM mode extends the battery life by reducing the quiescent
current to 16 µA (typ) during light load and standby operation.
Internal synchronous rectification provides high efficiency. In
shutdown mode (Enable pin pulled low), the device turns off
and reduces battery consumption to 0.01 µA (typ).
The LM3679 is available in a lead-free (No PB) 5-bump micro
SMD package, 0.6mm height, and in an ultra thin 0.3mm
height UR package. Using the UR package along with specific
external components, allows for a low profile solution size with
a max height of 0.55mm. A switching frequency of 3 MHz (typ)
allows use of tiny surface-mount components. Only three ex-
ternal surface-mount components, an inductor and two ce-
ramic capacitors, are required. .
Typical Application Circuit
FIGURE 1. Typical Low Profile Application Circuit
(0.55mm max height using LM3679UR)
300163
30016301
Features
Applications
16 µA typical quiescent current
350 mA maximum load capability
3 MHz PWM fixed switching frequency (typ)
Automatic PFM/PWM mode switching
Available in 5-bump micro SMD package and UR package
Internal synchronous rectification for high efficiency
Internal soft start
0.01 µA typical shutdown current
Operates from a single Li-Ion cell battery
Current overload and Thermal shutdown protection
Three external components required for typical
applications
Low profile solution (0.55mm max height, includes four
external components)
Mobile phones
PDAs
MP3 players
W-LAN
Portable Instruments
Digital still cameras
Portable Hard disk drives
Efficiency vs. Output Current
(V
OUT
= 1.8V)
February 5, 2008
30016387
www.national.com

Related parts for LM3679TL-1.8EV

LM3679TL-1.8EV Summary of contents

Page 1

... Only three ex- ternal surface-mount components, an inductor and two ce- ramic capacitors, are required. . Typical Application Circuit FIGURE 1. Typical Low Profile Application Circuit (0.55mm max height using LM3679UR) © 2008 National Semiconductor Corporation Features ■ 16 µA typical quiescent current ■ 350 mA maximum load capability ■ ...

Page 2

... Name GND Ordering Information Order Number Spec LM3679TL - 1.8 NOPB LM3679TLX - 1.8 NOPB LM3679UR - 1.8 NOPB LM3679UR X -1.8 NOPB LM3679UR - 1.5 NOPB LM3679UR X -1.5 NOPB LM3679UR - 1.2 NOPB LM3679UR X -1.2 NOPB Contact National Semiconductor for future voltage options www.national.com Description Power supply input. Connect to the input filter capacitor (Figure 1). ...

Page 3

... Continuous Power Dissipation (Note 3) Junction Temperature (T ) J-MAX Storage Temperature Range Maximum Lead Temperature (Soldering, 10 sec.) Electrical Characteristics Limits in boldface type apply over the operating ambient temperature range (−30°C specifications apply to the LM3679TL/UR with V Symbol Parameter V Input Voltage IN V Feedback Voltage FB V ...

Page 4

Dissipation Rating Table θ JA 85°C/W (4-layer board) Block Diagram www.national.com ≤ 60°C T 25° Power Rating Power Rating 1176 mW 765 mW FIGURE 3. Simplified Functional Diagram 85°C A Power Rating 470 ...

Page 5

... Typical Performance Characteristics LM3679TL/UR, Circuit of Figure 3.6V Quiescent Supply Current vs. Supply Voltage (Switching) Switching Frequency vs. Temperature Open/Closed Loop Current Limit vs. Temperature = 1.8V 25°C, unless otherwise noted. OUT A Shutdown Current vs. Temperature 30016381 R DS(ON) 30016383 Output Voltage vs. Supply Voltage 30016349 5 30016382 vs. Temperature 30016351 ( ...

Page 6

Output Voltage vs. Temperature (V = 1.8V) OUT Output Current vs. Input Voltage at Mode Change Point (V = 1.8V) OUT Line Transient Response V = 1.8V (PWM Mode) OUT www.national.com Output Voltage vs. Output Current 30016385 Line Transient Response ...

Page 7

Load Transient Response (V = 1.8V) OUT (PFM Mode 50mA to 1mA) Mode Change by Load Transients V = 1.8V (PWM to PFM) OUT Start Up into PWM Mode V = 1.8V (Output Current = 300mA) OUT Mode Change by ...

Page 8

Operation Description DEVICE INFORMATION The LM3679, a high efficiency step down DC-DC switching buck converter, delivers a constant voltage from a single Li- Ion battery and input voltage rails from 2.5V to 5.5V such as cell phones and PDAs. Using ...

Page 9

FIGURE 5. Typical PFM Operation During PFM operation, the converter positions the output volt- age slightly higher than the nominal output voltage during PWM operation allowing additional headroom for voltage drop during a load transient from light to heavy load. ...

Page 10

Application Information INDUCTOR SELECTION There are two main considerations when choosing an induc- tor; the inductor should not saturate, and the inductor current ...

Page 11

Model LQM21PN1R0M * MIPSA2520D 1R0 LQM2HP 1R0 BRL2518T1R0M Note : *For Low Profile Solution OUTPUT CAPACITOR SELECTION A ceramic output capacitor of 10 µF, 6.3V is sufficient for most applications. Use X7R or X5R types; do not use Y5V. DC ...

Page 12

... Micro SMD PACKAGE ASSEMBLY AND USE Use of the Micro SMD package requires specialized board layout, precision mounting and careful re-flow techniques, as detailed in National Semiconductor Application Note 1112. Refer to the section "Surface Mount Technology (SMD) As- sembly Considerations". For best results in assembly, align- ment ordinals on the PC board should be used to facilitate placement of the device ...

Page 13

LM3679 and inductor to the output filter capacitor and back through ground, forming a current loop. In the second half of each cycle, current is pulled up from ground, through the LM3679 by the inductor, to the output ...

Page 14

Physical Dimensions www.national.com inches (millimeters) unless otherwise noted 5-Bump (Large) Micro SMD Package, 0.5mm Pitch NS Package Number TLA05FEA The dimensions for X1, X2, and X3 are as given 1.107 mm +/- 0.030mm X2 = 1.488 mm +/- ...

Page 15

15 www.national.com ...

Page 16

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

Related keywords