SMB135
Advanced Information
Programmable, USB/AC, Switch-Mode Battery Charger
FEATURES & APPLICATIONS
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Programmable USB/AC Li-Ion battery charger
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High-efficiency current-mode PWM controller
•
•
•
•
o
o
750kHz to 1.25MHz switching frequency
0% to 100% duty-cycle
INTRODUCTION
The SMB135 is a programmable single-cell lithium-ion/lithium-polymer
battery charger for a variety of portable applications. The device
provides a simple and efficient way to charge high-capacity Li-Ion
batteries via a USB port or an AC adapter. Unlike conventional
devices, the SMB135’s high-efficiency operation eliminates large
internal temperature rise and localized hot spot in handheld equipment.
Charge control includes qualification, trickle-charge, pre-charge,
constant current/constant voltage, and termination/safety settings that
are fully programmable via a serial I2C/SMBus making the device truly
a flexible solution. Fast charge current level (one or five unit loads)
can be set via I2C or an input pin (USB500/100). An Enable (EN) pin
is also provided for suspending USB charging and allowing the device
to work in parallel with AC charger, which may already be integrated
into a PMIC device. In this case, the SMB135 does not allow current
to flow back to the USB port.
The SMB135 offers a wide variety of features that protect the battery
pack as well as the charger and input circuitry: over-current,
under/over-voltage and thermal protection. Ultra-precise, 1% accurate,
Kelvin-sensed ADOC™ technology allows accurate control of battery
float voltage and improves battery capacity utilization. Status can be
monitored via the serial port for charge state and fault conditions. In
addition, one LED driver output can be used to signal charge status.
As a protection mechanism, when the junction temperature
approaches approximately 145°C, the PWM switcher will start to cut
back on the duty cycle, to reduce current.
The SMB135 is available in a space-saving 1.3mm x 2.1mm uCSP
package with lead-free balls and is rated over the -30°C to +85°C
temperature range.
TM
4.35 to 6.0V input voltage range
TM
Small 1.3 x 2.1 uCSP -15 package (0.4mm pitch)
High-accuracy output voltage regulation: 1%
Low reverse leakage current
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Digital programming of all major parameters via I
2
C
interface (with several addresses) and non-volatile
memory
o
o
o
o
o
Battery voltage set point
Pre-charge, fast charge, termination current
Fast charge voltage threshold
Temperature limits
Automatic restart threshold
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Status indicator
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Stability with ceramic capacitors
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Wide range of protection features
o
o
Thermal monitor
Input/output over-voltage lockout
Applications
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GSM Handsets
UMTS Handsets
Portable Media Players
Digital camcorders/still cameras
Handheld GPS/PDA’s
SIMPLIFIED APPLICATIONS DRAWING
SMB135
IN
4.7uF
6.8uH
OUT
SENSEH
SENSEL
10uF
500-700mA
4.35V-6.0V
GND
D+
D-
VDDCAP
1uF
50-100mΩ
SDA
SCL
USB500/100
EN
ADC+ ADC-
C
comp
R
comp
BATT
Li-Ion
THERM
STAT
GND
USB
Controller
R
LIM
LED
VDC
COMP
Figure 1 – Applications block diagram featuring the SMB135 programmable switch-mode battery charger.
© SUMMIT
Microelectronics, Inc. 2006
• 1717 Fox Drive • San Jose CA 95131 • Phone 408 436-9890 • FAX 408 436-9897
http://www.summitmicro.com/
2106 1.3 2/21/2006
1
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