LM3670MF-1.2EV National Semiconductor, LM3670MF-1.2EV Datasheet

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LM3670MF-1.2EV

Manufacturer Part Number
LM3670MF-1.2EV
Description
BOARD EVALUATION LM3670MF-1.2
Manufacturer
National Semiconductor
Series
PowerWise®r

Specifications of LM3670MF-1.2EV

Main Purpose
DC/DC, Step Down
Outputs And Type
1, Non-Isolated
Voltage - Output
1.2V
Current - Output
350mA
Voltage - Input
2.5 ~ 5.5V
Regulator Topology
Buck
Frequency - Switching
1MHz
Board Type
Fully Populated
Utilized Ic / Part
LM3670
Lead Free Status / RoHS Status
Not applicable / Not applicable
Power - Output
-
Lead Free Status / Rohs Status
Not Compliant
© 2006 National Semiconductor Corporation
LM3670
Miniature Step-Down DC-DC Converter for Ultra Low
Voltage Circuits
General Description
The LM3670 step-down DC-DC converter is optimized for
powering ultra-low voltage circuits from a single Li-Ion cell or
3 cell NiMH/NiCd batteries. It provides up to 350 mA load
current, over an input voltage range from 2.5V to 5.5V. There
are several different fixed voltage output options available as
well as an adjustable output voltage version (see ordering
information).
The device offers superior features and performance for
mobile phones and similar portable applications with com-
plex power management systems. Automatic intelligent
switching between PWM low-noise and PFM low-current
mode offers improved system control. During full-power op-
eration, a fixed-frequency 1 MHz (typ). PWM mode drives
loads from ∼70 mA to 350 mA max, with up to 95% efficiency.
Hysteretic PFM mode extends the battery life through reduc-
tion of the quiescent current to 15 µA (typ) during light
current loads and system standby. Internal synchronous rec-
tification provides high efficiency (90 to 95% typ. at loads
between 1 mA and 100 mA). In shutdown mode (Enable pin
pulled low) the device turns off and reduces battery con-
sumption to 0.1 µA (typ.).
The LM3670 is available in a SOT23-5 package. A high
switching frequency - 1 MHz (typ) - allows use of tiny
surface-mount components. Only three external surface-
mount components, an inductor and two ceramic capacitors,
are required.
Typical Application
FIGURE 1. Fixed Output Voltage - Typical Application Circuit
DS200758
Features
n V
n 2.5V ≤ V
n 15 µA typical quiescent current
n 350 mA maximum load capability
n 1 MHz PWM fixed switching frequency (typ.)
n Automatic PFM/PWM mode switching
n Available in fixed output voltages as well as an
n SOT23-5 package
n Low drop out operation - 100% duty cycle mode
n Internal synchronous rectification for high efficiency
n Internal soft start
n 0.1 µA typical shutdown current
n Operates from a single Li-Ion cell or 3 cell NiMH/NiCd
n Only three tiny surface-mount external components
n Current overload protection
Applications
n Mobile phones
n HandHeld
n PDAs
n Palm-top PCs
n Portable Instruments
n Battery Powered Devices
3.3V
adjustable version
batteries
required (one inductor, two ceramic capacitors)
OUT
= Adj (0.7V min), 1.2, 1.5, 1.6, 1.8, 1.875, 2.5,
IN
≤ 5.5V
20075801
January 2006
www.national.com

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LM3670MF-1.2EV Summary of contents

Page 1

... Only three external surface- mount components, an inductor and two ceramic capacitors, are required. Typical Application FIGURE 1. Fixed Output Voltage - Typical Application Circuit © 2006 National Semiconductor Corporation Features Adj (0.7V min), 1.2, 1.5, 1.6, 1.8, 1.875, 2.5, OUT 3.3V n 2.5V ≤ ...

Page 2

Typical Application (Continued) FIGURE 2. Adjustable Output Voltage - Typical Application Circuit Connection Diagram and Package Mark Information Note: The actual physical placement of the package marking will vary from part to part. Pin Descriptions Pin # Name 1 V ...

Page 3

... LM3670MFX-2.5 LM3670MF-2.5 LM3670MFX-2.5 1.875 LM3670MF-1.875 LM3670MFX-1.875 LM3670MF-1.875 LM3670MFX-1.875 1.8 LM3670MF-1.8 LM3670MFX-1.8 LM3670MF-1.8 LM3670MFX-1.8 1.6 LM3670MF-1.6 LM3670MFX-1.6 LM3670MF-1.6 LM3670MFX-1.6 1.5 LM3670MF-1.5 LM3670MFX-1.5 LM3670MF-1.5 LM3670MFX-1.5 1.2 LM3670MF-1.2 LM3670MFX-1.2 LM3670MF-1.2 LM3670MFX-1.2 Adjustable LM3670MF-ADJ LM3670MFX-ADJ LM3670MF-ADJ LM3670MFX-ADJ SPEC Package Marking NOPB SDEB NOPB NOPB SDDB ...

Page 4

... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. V Pin: Voltage to GND IN EN Pin: Voltage to GND FB, SW Pin: Junction Temperature (T ) J-MAX Storage Temperature Range Maximum Lead Temperature (Soldering, 10 sec.) Electrical Characteristics the full operating junction temperature range (− ...

Page 5

Electrical Characteristics the full operating junction temperature range (−40˚C ≤ T 150mA (Continued) IN Symbol Parameter I DC Bias Current into Minimum V below which V UVLO IN will be disabled R Pin-Pin ...

Page 6

FIGURE 4. Simplified Functional Diagram 6 20075832 ...

Page 7

Typical Performance Characteristics I (Non-switching) vs vs. V OUT IN Efficiency vs. I OUT (unless otherwise stated 20075804 20075806 20075808 7 = 3.6V 1.8V) IN OUT I vs. Temp Q 20075805 V vs. ...

Page 8

Typical Performance Characteristics Frequency vs. Temperature Line Transient (V = 2.6V to 3.6V LOAD Load Transient I = 3mA to 280mA LOAD www.national.com (unless otherwise stated: V 20075810 = 100 mA) (V 20075812 20075816 8 = 3.6V, V ...

Page 9

Typical Performance Characteristics Load Transient I = 0mA to 280mA LOAD Load Transient I = 50mA to 350mA LOAD PFM Mode vs. Time SW OUT INDUCTOR (unless otherwise stated LOAD 20075818 I LOAD ...

Page 10

Typical Performance Characteristics Soft Start OUT INDUCTOR (I = 350mA) LOAD Operation Description DEVICE INFORMATION The LM3670, a high efficiency step down DC-DC switching buck converter, delivers a constant voltage from either a single ...

Page 11

Operation Description The part automatically transition into PFM mode when either of two conditions occurs for a duration more clock cycles: A. The inductor current becomes discontinuous B. The peak PMOS switch current drops below the I ...

Page 12

Operation Description LDO - Low Drop Out Operation The LM3670 can operate at 100% duty cycle (no switching, PMOS switch is completely on) for low drop out support of the output voltage. In this way the output voltage is con- ...

Page 13

Application Information noise filtering of the input voltage spikes due to this rapidly changing current. Select an input filter capacitor with a surge current rating sufficient for the power-up surge from the input power source. The power-up surge current is ...

Page 14

Application Information TABLE 3. Adjustable LM3670 Configurations for Various V VOUT (V) R1 (KΩ) R2 (KΩ) 1.1 240 1.2 280 1.24 300 1.24 221 1.5 402 1.6 442 1.7 487 1.875 549 2.5 806 www.national.com (Continued) C1 (pF) C2 (pF) ...

Page 15

Application Information BOARD LAYOUT CONSIDERATIONS PC board layout is an important part of DC-DC converter design. Poor board layout can disrupt the performance of a FIGURE 6. Board Layout Design Rules for the LM3670 Good layout for the LM3670 can ...

Page 16

Application Information arrange the CMOS digital circuitry around it (since this also generates noise), and then place sensitive preamplifiers and www.national.com IF stages on the diagonally opposing corner. Often, the (Continued) sensitive circuitry is shielded with a metal pan and ...

Page 17

... BANNED SUBSTANCE COMPLIANCE National Semiconductor manufactures products and uses packing materials that meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. ...

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