LM3686TL-AADWEV National Semiconductor, LM3686TL-AADWEV Datasheet

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LM3686TL-AADWEV

Manufacturer Part Number
LM3686TL-AADWEV
Description
BOARD EVAL FOR LM3686
Manufacturer
National Semiconductor

Specifications of LM3686TL-AADWEV

Main Purpose
DC/DC, Step Down with LDO
Outputs And Type
3, Non-Isolated
Voltage - Output
1.2V, 2.8V, 1.8V
Current - Output
350mA, 300mA, 250mA
Voltage - Input
2.7 ~ 5.5V
Regulator Topology
Buck
Frequency - Switching
3MHz
Board Type
Fully Populated
Utilized Ic / Part
LM3686
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Power - Output
-
© 2011 National Semiconductor Corporation
Step-Down DC-DC Converter with Integrated Post Linear
Regulators System and Low-Noise Linear Regulator
General Description
The LM3686 is a step-down DC-DC converter with one inte-
grated very low dropout linear regulator and a low noise linear
regulator optimized for powering ultra-low voltage circuits
from a single Li-Ion cell or 3 cell NiMH/NiCd batteries. It pro-
vides three outputs with combined load current up to 900 mA
over an input voltage range from 2.7V to 5.5V.
The device offers superior features and performance for
many applications. Automatic intelligent switching between
PWM low-noise and PFM low-current mode offers improved
system control. During full-power operation, a fixed-frequency
3 MHz (typ.), PWM mode drives loads from ~70 mA to 600
mA max. Hysteretic PFM mode extends the battery life
through reduction of the quiescent current to 28 μA (typ.) at
light load and system standby. Internal synchronous rectifi-
cation provides high efficiency.
Three enable pins allow the separate operation of either the
DC-DC, post-regulation linear regulator or the linear regulator
alone. If the DC-DC is not enabled during startup of the post-
regulation linear regulator, a parallel small pass transistor
supplies the linear regulator from V
In the combined operation where both enables are raised to-
gether, the small pass transistor is deactivated and the big
pass transistor provides 350 mA output current. In shutdown
mode (Enable pins pulled low), the device turns off and re-
duces battery consumption to 2.5 μA (typ.).
The LM3686 is available in a 12-bump micro SMD package.
A high-switching frequency of 3 MHz (typ.) allows the use of
a few tiny surface-mount components. Only six external sur-
face-mount components, an inductor and five ceramic capac-
itors, are required to establish a 15.66 mm
BATT
with maximal 50 mA.
300255
2
total solution size.
LM3686
Features
DC-DC REGULATOR
DUAL RAIL LINEAR REGULATOR: LILO
LINEAR REGULATOR: LDO
COMBINED GLOBAL FEATURES
Applications
V
programmed )
600 mA maximum load capability (LILO = OFF)
3 MHz PWM fixed switching frequency (typ.)
Automatic PFM/PWM mode switching
Internal synchronous rectification for high efficiency
Internal soft start
Load transients < 50 mV peak typ.
Line transients < 1 mV peak typ.
V
programmed )
70 µA typical I
350 mA Maximum Load Capability (Large FET)
Load transients < 80 mV peak typ.
Line transients < 1 mV peak typ.
V
programmed )
50 µA typical I
300 mA Maximum Load Capability
V
900 mA maximum combined load capability
Operates from a single Li-Ion cell or 3 cell NiMH/NiCd
batteries
Only six tiny surface-mount external components required
(one inductor, five ceramic capacitors)
12–bump micro SMD
100 µA Iq from V
15.66 mm
Moblie TV
Hand-Held Radios
Personal Digital Assistants
Palm-top PCs
Portable Instruments
Battery-Powered Devices
Portable Personal Clients
OUT_DCDC
OUT_LILO
OUT_LDO
BATT
V
= 1.5V to 3.3V ( in 100 mV steps - factory
= 0.7V to 2.0V ( in 50 mV steps - factory
OUT_LILO
2
= 1.2V to 2.5V ( in 100 mV steps - factory
total solution size
Q
Q
from V
BATT
+ 1.5V or 2.7V, whichever is higher
IN_LILO
March 4, 2011
www.national.com

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LM3686TL-AADWEV Summary of contents

Page 1

... The LM3686 is available in a 12-bump micro SMD package. A high-switching frequency of 3 MHz (typ.) allows the use of a few tiny surface-mount components. Only six external sur- face-mount components, an inductor and five ceramic capac- itors, are required to establish a 15.66 mm © 2011 National Semiconductor Corporation LM3686 Features DC-DC REGULATOR ■ ...

Page 2

Typical Application Circuit www.national.com FIGURE 1. Typical Application 2 30025501 ...

Page 3

FIGURE 2. Functional Diagram (Always Connenct VIN_LDO to VBATT) 3 30025502 www.national.com ...

Page 4

... Order Information Part Number LM3686TL-AADW LM3686TLX-AADW LM3686TLE-AAED LM3686TLX-AAED LM3686TLE-AAEF LM3686TLX-AAEF *Voltage options are read as follow: 1.81.22.8 = 1.8V for VOUT_DC-DC, 1.2V for VOUT_LILO, and 2.8V for VOUT_LDO; Contact National Semiconductor for other factory VOUT programmed options. www.national.com 12-pin micro SMD package at all times ) BATT connects to output of DCDC or standalone) ...

Page 5

Enable Combinations EN_DCDC EN_LILO Note A: The LILO is turned on via a small NMOS device supplied by V NMOS is ON. If higher current > ...

Page 6

... Absolute Maximum Ratings 2) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. V pin to GND and QGND BATT Enable pins, Feedback pins, SW pin Junction Temperature (T ) J-MAX Storage Temperature Range Continuous Power Dissipation (Note ...

Page 7

Symbol Parameter e N_LILO Output Noise voltage (Note 12) ΔV Dynamic load transient OUT_LILO response ΔV Dynamic line transient IN_LILO response on V BATT Linear Regulator — LDO Symbol Parameter V LDO input voltage range IN_LDO Output voltage ΔV / ...

Page 8

DC-DC Converter Symbol Parameter V Feedback Voltage PWM Mode FB_DCDC Accuracy V Internal reference REF voltage R Pin-Pin Resistance for V DSON(P) PFET Pin-Pin Resistance for V DSON(N) NFET Quiescent current for No load, ...

Page 9

... Note 3: Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages 130°C (typ.). Note 4: For detailed soldering specifications and information, please refer to National Semiconductor Application Note 1112: Micro SMD Wafer Level Chip Scale Package (AN-1112) Note 5: In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may have to be derated ...

Page 10

Typical Performance Characteristics V = 3.6V 25°C, enable pins tied to V BATT A V vs. I OUT_DCDC Efficiency DC-DC vs. Output Current LILO and LDO disabled PSRR vs. Frequency (LDO - VIN_LDO = 3.6V) www.national.com Unless otherwise ...

Page 11

Switching Frequency vs. Temperature 30025537 R vs. Temperature DSON 30025539 V Line Transient Response BATT Current Limit vs. Temperature (Open Loop) Startup (all three enables tied together) Line Transient Response 30025525 11 30025538 30025524 30025518 www.national.com ...

Page 12

Load Transient Response DC-DC (PWM Mode: 100mA to 350mA) Load Transient Response LILO 50mA to 250mA www.national.com Load Transient Response DC-DC (PFM Mode: 1mA to 150mA) 30025519 Load Transient Response LDO 100mA to 250mA 30025521 12 30025520 30025522 ...

Page 13

Operation Description DEVICE INFORMATION The LM3686 incorporates a high efficiency synchronous switching step-down DC-DC converter, a very low dropout linear regulator (LILO), and ultra low noise linear regulator. The DC-DC converter delivers a constant voltage from a sin- gle Li- ...

Page 14

Current Limiting A current limit feature allows the LM3686 to protect itself and external components during overload conditions. PWM mode implements current limiting using an internal comparator that trips at 1220mA (typ). If the output is shorted to ground the ...

Page 15

Soft Start The DC-DC converter has a soft-start circuit that limits in-rush current during start-up. During start-up the switch current limit is increased in steps. Soft start is activated only if EN_DCDC goes from logic low to logic high after ...

Page 16

Application Selection It is strongly recommended to select the required components of LM3686 as described within the datasheet. If other com- ponents are selected, the device will not perform up to stan- dard and electrical characteristics are not guaranteed. Inductor ...

Page 17

V input pin and returned to QGND. C IN_LDO An input capacitor is required for stability recommended to use a 1 µF ceramic capacitor and connected between ...

Page 18

... 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 19

Physical Dimensions inches (millimeters) unless otherwise noted 12–Bump (large) micro SMD, 0.5mm Pitch NS Package Number TLA12HTA Physical dimensions are as given 1.692 2.428 0 www.national.com ...

Page 20

... 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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