LM3671 2MHz, 600mA Step-Down DC-DC Converter
October 28, 2008
LM3671
2MHz, 600mA Step-Down DC-DC Converter
General Description
The LM3671 step-down DC-DC converter is optimized for
powering low voltage circuits from a single Li-Ion cell battery
and input voltage rails from 2.7V to 5.5V. It provides up to
600mA load current, over the entire input voltage range.
There are several different fixed voltage output options avail-
able as well as an adjustable output voltage version range
from 1.1V to 3.3V.
The device offers superior features and performance for mo-
bile phones and similar portable systems. Automatic intelli-
gent switching between PWM low-noise and PFM low-current
mode offers improved system control. During PWM mode, the
device operates at a fixed-frequency of 2 MHz (typ.). Hys-
teretic 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 ef-
ficiency during PWM mode operation. In shutdown mode, the
device turns off and reduces battery consumption to 0.01 µA
(typ.).
The LM3671 is available in SOT23-5, tiny 5-bump micro SMD
and a 6-pin LLP packages in leaded (PB) and lead-free (NO
PB) versions. A high switching frequency of 2 MHz (typ.) al-
lows use of tiny surface-mount components. Only three ex-
ternal surface-mount components, an inductor and two
ceramic capacitors, are required.
Features
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■
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16 µA typical quiescent current
600 mA maximum load capability
2 MHz PWM fixed switching frequency (typ.)
Automatic PFM/PWM mode switching
Internal synchronous rectification for high efficiency
Internal soft start
0.01 µA typical shutdown current
Operates from a single Li-Ion cell battery
Only three tiny surface-mount external components
required (one inductor, two ceramic capacitors)
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Current overload and Thermal shutdown protection
■
Available in fixed output voltages and adjustable version
■
SOT23-5, 5-bump micro SMD and 6-pin LLP packages
Applications
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Mobile phones
PDAs
MP3 players
W-LAN
Portable instruments
Digital still cameras
Portable Hard disk drives
Typical Application Circuits
20108401
FIGURE 1. Typical Application Circuit
© 2008 National Semiconductor Corporation
201084
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LM3671
20108431
FIGURE 2. Typical Application Circuit for ADJ version
Connection Diagram and Package Mark Information
20108402
FIGURE 3. Top View
SOT23-5 Package NS Package Number MF05A (2.92mm x 2.84mm x 1.2mm)
20108444
FIGURE 4. 5-Bump Micro SMD Package NS Package Number TLA05CBA (1.05mm x 1.38mm x 0.6mm)
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LM3671
20108462
FIGURE 5. 6-Pin LLP Package Number LCA06B (2mm x 2mm x 0.6mm)
Pin Descriptions (SOT23-5)
Pin #
1
2
3
4
Name
V
IN
GND
EN
FB
Description
Power supply input. Connect to the input filter capacitor (Figure
1).
Ground pin.
Enable pin. The device is in shutdown mode when voltage to this pin is <0.4V and enabled
when >1.0V. Do not leave this pin floating.
Feedback analog input. Connect directly to the output filter capacitor for fixed voltage
versions. For adjustable version external resistor dividers are required (Figure
2).
The
internal resistor dividers are disabled for the adjustable version.
Switching node connection to the internal PFET switch and NFET synchronous rectifier.
5
SW
Pin Descriptions (5-Bump Micro SMD)
Pin #
A1
A3
C1
C3
Name
V
IN
GND
EN
FB
Description
Power supply input. Connect to the input filter capacitor (Figure
1).
Ground pin.
Enable pin. The device is in shutdown mode when voltage to this pin is <0.4V and enabled
when >1.0V. Do not leave this pin floating.
Feedback analog input. Connect directly to the output filter capacitor for fixed voltage
versions. For adjustable version external resistor dividers are required (Figure
2).
The
internal resistor dividers are disabled for the adjustable version.
Switching node connection to the internal PFET switch and NFET synchronous rectifier.
B2
SW
Pin Descriptions (6-Pin LLP)
Pin #
1
2
3
4
5
6
Name
EN
Pgnd
V
IN
SW
Sgnd
FB
Description
Enable pin. The device is in shutdown mode when voltage to this pin is <0.4V and enabled
when >1.0V. Do not leave this pin floating.
Ground pin.
Power supply input. Connect to the input filter capacitor ().
Switching node connection to the internal PFET switch and NFET synchronous rectifier.
Singnal ground (feedback ground).
Feedback analog input. Connect directly to the output filter capacitor for fixed voltage
versions. For adjustable version external resistor dividers are required (Figure
2).
The
internal resistor dividers are disabled for the adjustable version.
3
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LM3671
Ordering Information (SOT23-5)
Voltage Option
ADJ
Order Number
LM3671MF-ADJ
LM3671MFX-ADJ
LM3671MF-ADJ
LM3671MFX-ADJ
1.2
LM3671MF-1.2
LM3671MFX-1.2
LM3671MF-1.2
LM3671MFX-1.2
1.25
LM3671MF-1.25
LM3671MFX-1.25
LM3671MF-1.25
LM3671MFX-1.25
1.375
LM3671MF-1.375
LM3671MFX-1.375
LM3671MF-1.375
LM3671MFX-1.375
1.5
LM3671MF-1.5
LM3671MFX-1.5
LM3671MF-1.5
LM3671MFX-1.5
1.6
LM3671MF-1.6
LM3671MFX-1.6
LM3671MF-1.6
LM3671MFX-1.6
1.8
LM3671MF-1.8
LM3671MFX-1.8
LM3671MF-1.8
LM3671MFX-1.8
1.875
LM3671MF-1.875
LM3671MFX-1.875
LM3671MF-1.875
LM3671MFX-1.875
2.5
LM3671MF-2.5
LM3671MFX-2.5
LM3671MF-2.5
LM3671MFX-2.5
2.8
LM3671MF-2.8
LM3671MFX-2.8
LM3671MF-2.8
LM3671MFX-2.8
3.3
LM3671MF-3.3
LM3671MFX-3.3
LM3671MF-3.3
LM3671MFX-3.3
NOPB
NOPB
SJEB
NOPB
NOPB
SJSB
NOPB
NOPB
SJRB
NOPB
NOPB
SDVB
NOPB
NOPB
SBSB
NOPB
NOPB
SDUB
NOPB
NOPB
SBRB
NOPB
NOPB
SEDB
NOPB
NOPB
SDRB
NOPB
NOPB
SBPB
Spec
NOPB
NOPB
SBTB
Package Marking
Supplied As
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
1000 units, Tape-and-Reel
3000 units, Tape-and-Reel
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LM3671
Ordering Information (5-bump Micro SMD)
Voltage Option
ADJ
Order Number
LM3671TL-ADJ
LM3671TLX-ADJ
LM3671TL-ADJ
LM3671TLX-ADJ
1.2
LM3671TL-1.2
LM3671TLX-1.2
LM3671TL-1.2
LM3671TLX-1.2
1.5
LM3671TL-1.5
LM3671TLX-1.5
LM3671TL-1.5
LM3671TLX-1.5
1.8
LM3671TL-1.8
LM3671TLX-1.8
LM3671TL-1.8
LM3671TLX-1.8
1.875
LM3671TL-1.875
LM3671TLX-1.875
LM3671TL-1.875
LM3671TLX-1.875
2.5
LM3671TL-2.5
LM3671TLX-2.5
LM3671TL-2.5
LM3671TLX-2.5
2.8
LM3671TL-2.8
LM3671TLX-2.8
LM3671TL-2.8
LM3671TLX-2.8
3.3
LM3671TL-3.3
LM3671TLX-3.3
LM3671TL-3.3
LM3671TLX-3.3
NOPB
NOPB
J
NOPB
NOPB
K
NOPB
NOPB
L
NOPB
NOPB
S
NOPB
NOPB
B
NOPB
NOPB
D
NOPB
NOPB
C
Spec
NOPB
NOPB
E
Package Marking
Supplied As
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
Ordering Information (6-Pin LLP)
Voltage Option
1.2
1.3
1.6
1.8
Order Number
LM3671LC-1.2
LM3671LCX-1.2
LM3671LC-1.3
LM3671LCX-1.3
LM3671LC-1.6
LM3671LCX-1.6
LM3671LC-1.8
LM3671LCX-1.8
Spec
NOPB
NOPB
NOPB
NOPB
NOPB
NOPB
NOPB
NOPB
Package Marking
S39
S40
S41
S42
Supplied As
1000 units, Tape-and-Reel
4500 units, Tape-and-Reel
1000 units, Tape-and-Reel
4500 units, Tape-and-Reel
1000 units, Tape-and-Reel
4500 units, Tape-and-Reel
1000 units, Tape-and-Reel
4500 units, Tape-and-Reel
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