SMB135
Advanced Information
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
Programmable, USB/AC, Switch-Mode Battery Charger
INTRODUCTION
Programmable USB/AC Li-Ion battery charger
High-efficiency current-mode PWM controller
o 750kHz to 1.25MHz switching frequency
o 0% to 100% duty-cycle
4.35 to 6.0V input voltage range
Small 1.3 x 2.1 uCSP
TM
-15 package (0.4mm pitch)
High-accuracy output voltage regulation: 1%
Low reverse leakage current
Digital programming of all major parameters via I
2
C
interface (with several addresses) and non-volatile
memory
o Battery voltage set point
o Pre-charge, fast charge, termination current
o Fast charge voltage threshold
o Temperature limits
o Automatic restart threshold
Status indicator
Stability with ceramic capacitors
Wide range of protection features
o Thermal monitor
o Input/output over-voltage lockout
Applications
GSM Handsets
UMTS Handsets
Portable Media Players
Digital camcorders/still cameras
Handheld GPS/PDA's
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 ADOCTM 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
TM
package with lead-free balls and is rated over the -30
C to +85C
temperature range.
Figure 1 Applications block diagram featuring the SMB135 programmable switch-mode battery charger.
SIMPLIFIED APPLICATIONS DRAWING
FEATURES & APPLICATIONS
USB
Controller
D+
D-
VDC
GND
ADC+ ADC-
IN
GND
STAT
R
LIM
LED
6.8uH
SMB135
SENSEH
SENSEL
50-100m
10uF
Li-Ion
THERM
EN
OUT
USB500/100
SDA
BATT
COMP
C
comp
R
comp
VDDCAP
1uF
4.7uF
SCL
500-700mA
4.35V-6.0V
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