lm8850urx National Semiconductor Corporation, lm8850urx Datasheet

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lm8850urx

Manufacturer Part Number
lm8850urx
Description
High-performance, Step-up Dc-dc Converter For High- Power Applications In Mobile Devices
Manufacturer
National Semiconductor Corporation
Datasheet
© 2010 National Semiconductor Corporation
High-Performance, Step-Up DC-DC Converter for High-
Power Applications in Mobile Devices
General Description
LM8850 is a step-up DC-DC converter optimized for use with
a supercapacitor to protect a battery from power surges and
enable new high power applications in mobile device archi-
tectures. The device creates an ideal rail from 3.6V to 5.7V
boosting from a single Li-Ion cell with an input voltage range
of 2.3V to 5.5V; Target V
V
An I
input current limits, and load currents up to 1A provides su-
perior user flexibility. The LM8850 operates in Auto mode,
where the converter is in PFM mode at light loads and switch-
es to PWM mode at heavy loads. Hysteretic PFM extends the
battery life by reduction of the quiescent current to 6µA (typ.)
during light load and standby conditions. Synchronous oper-
ation provides true shutdown isolation and improves its effi-
ciency at medium-to-full load conditions.
High-switching frequency enables smaller passive compo-
nents. Internal compensation is used for a broader range of
inductor and output capacitor values to meet system demand
and achieve small system solution size.
LM8850 is available in a 9-bump ultra-thin micro SMD pack-
age. Only four external surface-mount components, a 1.0 µH
inductor, a 4.7 µF for input capacitor, 4.7 µF for output ca-
pacitor and 0.05F-1.0F supercapacitor for energy storage are
required.
Typical Application Circuit
IN
.
2
C interface controlling multiple output voltage settings,
OUT
must be at least 10% higher than
301132
LM8850
Features
Applications
6µA typ. quiescent current
V
Operates from a single lithium ion cell (2.3V to 5.5V)
8 user-selectable output voltages via I
High-speed 3.4 MHz I
Up to 1.0A maximum load current capability
4 levels of current limiting
Auto-mode operation and Forced PWM
2.5 MHz switching frequency (typ.)
±2.5% DC output voltage precision
1.0 µH inductor (2520 case size)
4.7 µF input and output capacitors (0603 case size)
PGOOD signal
True shutdown isolation
Output over-voltage protection
Internal active voltage balancing for supercapacitors
micro SMD 9-bump package
(1.58 mm x 1.62 mm x 0.35 mm)(0.5 mm pitch)
Flash LED
Mobile Phones
WiMAX
USB
Audio Amplifier
OUT
= 3.6V to 5.7V (max V
2
C-compatible interface
O
= 5.7V)
30113220
December 14, 2010
2
C
www.national.com

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lm8850urx Summary of contents

Page 1

... LM8850 is available in a 9-bump ultra-thin micro SMD pack- age. Only four external surface-mount components, a 1.0 µH inductor, a 4.7 µF for input capacitor, 4.7 µF for output ca- pacitor and 0.05F-1.0F supercapacitor for energy storage are required. Typical Application Circuit © 2010 National Semiconductor Corporation LM8850 Features ■ 6µA typ. quiescent current ■ ...

Page 2

Connection Diagram and Package Mark Information Note: The package marking “X” denotes the date code, “V” National Semiconductor internal code of die traceability. Pin Descriptions Pin # Name A1 VIN GND B1 SDA B2 PG ...

Page 3

Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. VIN Pin to GND EN, PG, SDA, SCLK pins to GND VOUT to GND SW pin to GND BAL ...

Page 4

Symbol Parameter T Turn on Time ON I Pin Input current EN F Internal Oscillator OSC Frequency V Logic High Input IH V Logic Low Input IL V Logic Output High OH V Logic Output Low OL Note 1: Absolute ...

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Block Diagram 5 30113226 www.national.com ...

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Typical Performance Characteristics = TDK EDLC272020–501–2F-50). I Shutdown q 1,000 800 600 -40°C 400 25°C 85°C 200 0 -200 2.0 2.5 3.0 3.5 4.0 4.5 5 PWM q 420 400 380 360 -40°C 340 ...

Page 7

Line Regulation OUT V = 3.6V, 100 mV Ripple, Auto Mode IN Line Regulation, V 5V, OUT 250 mA Load, 100 mV Ripple, Auto Mode Startup V 2.7V, V 5.3V, IN OUT 5sec Delay, Room Temp Load Regulation, ...

Page 8

Input Current and V , 1.5A Current Limit OUT Line Transient V 2.7V - 3.6V LOAD Load Transient V = 2.7V, V 5.0V OUT www.national.com Input Current and V 30113203 = 600 mA 30113205 0-1000 mA ...

Page 9

Load Transient V = 3.6V, V 5.0V, I 200-800 mA IN OUT LOAD Load Transient V = 4.2V, V 5.0V, I 0-200 mA IN OUT LOAD Load Transient V = 3.6V, V 5.0V OUT 30113221 Load Transient V ...

Page 10

Operation Description LM8850 FUNCTIONALITY The LM8850, a high-efficiency, step-up DC-DC switching boost converter, delivers a constant voltage from a stable DC input voltage source. Using a voltage mode architecture with synchronous rectification, the LM8850 has the ability to de- liver ...

Page 11

START AND STOP CONDITIONS START and STOP bits classify the beginning and the end of the session. START condition is defined as SDA signal transitioning from HIGH to LOW while SCL line is HIGH. ...

Page 12

When a READ function accomplished, a WRITE func- tion must precede the READ function as shown in the Read Cycle waveform. HIGH-SPEED, 3.4 MHZ MODE High-speed mode is entered by: 1. Start condition; 2. Chip Address: 0000 ...

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13 30113212 www.national.com ...

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www.national.com 14 30113217 ...

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... Physical Dimensions inches (millimeters) unless otherwise noted Order National Semiconductor LM8850URE/LM8850URX 9-bump ultra-thin micro SMD, 0.5 mm pitch NS Package Number URA09EGA X1 = 1.58 mm ± 0.030 1.62 mm ± 0.030 0.35 mm ± 0.075 mm 15 www.national.com ...

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... National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other brand or product names may be trademarks or registered trademarks of their respective holders. ...

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