Monday, April 13, 2009

Switch-Mode Battery Charger ICs

Switch-Mode 1-Cell Li+ Chargers

The MAX1925/MAX1926 single-cell lithium-ion (Li+)
switch-mode battery chargers use an external PMOS
pass element step-down configuration. Charge current
is programmable, and an external capacitor sets the
maximum charge time.

Additional features include automatic input power
detection (ACON output), logic-controlled enable, and
temperature monitoring with an external thermistor. The
MAX1925 disables charging for inputs greater than
6.1V, while the MAX1926 charges for inputs between
4.25V and 12V.

The MAX1925/MAX1926 feature two precondition levels
to restore near-dead cells. The devices source 4mA to
a cell that is below 2V while sourcing C/10 to a cell
between 2V and 3V. Full charge current is then applied
above 3V. A CHG output drives an LED to indicate
charging (LED on) and fault conditions (LED blinking).
The MAX1925/MAX1926 are available in a 12-pin
4mm * 4mm thin QFN package and are specified over
the extended temperature range (-40°C to +85°C). An
evaluation kit is available to speed design.
_ Small (4mm * 4mm) Package
_ 4.25V to 12V Input Range (MAX1926)
_ Overvoltage Lockout at 6.1V (MAX1925)
_ ±0.75% Battery Regulation Voltage
_ Set Charge Current with One Resistor
_ Automatic Input Power Sense
_ LED (or Logic-Out) Charge Status and Fault
_ Programmable Safety Timer
_ Autorestart at Cell = 4V
_ Thermistor Monitor Input

Switch-Mode Lithium-Ion

The MAX745 provides all functions necessary for
charging lithium-ion (Li+) battery packs. It provides a
regulated charging current of up to 4A without getting
hot, and a regulated voltage with only ±0.75% total
error at the battery terminals. It uses low-cost, 1% resistors
to set the output voltage, and a low-cost N-channel
MOSFET as the power switch.

The MAX745 regulates the voltage set point and charging
current using two loops that work together to transition
smoothly between voltage and current regulation.
The per-cell battery voltage regulation limit is set
between 4V and 4.4V using standard 1% resistors, and
then the number of cells is set from 1 to 4 by pin-strapping.
Total output voltage error is less than ±0.75%.
For a similar device with an SMBus™ microcontroller
interface and the ability to charge NiCd and NiMH cells,
refer to the MAX1647 and MAX1648. For a low-cost Li+
charger using a linear-regulator control scheme, refer
to the MAX846A.
_ Charges 1 to 4 Li+ Battery Cells
_ ±0.75% Voltage-Regulation Accuracy
Using 1% Resistors
_ Provides up to 4A without Excessive Heating
_ 90% Efficient
_ Uses Low-Cost Set Resistors and
N-Channel Switch
_ Up to 24V Input
_ Up to 18V Maximum Battery Voltage
_ 300kHz Pulse-Width Modulated (PWM) Operation
Low-Noise, Small Components
_ Stand-Alone Operation—No Microcontroller

MAX745 Datasheet pdf

LTC4009 - High Efficiency, Multi-Chemistry
Battery Charger

The LTC4009 is a constant-current/constant-
voltage battery charger controller. It uses
a synchronous quasi-constant frequency
PWM control architecture that will not
generate audible noise with ceramic bulk
capacitors. Charge current is set by the
combination of external sense, input and
programming resistors. With no built-in
termination, the LTC4009 family charges a
wide range of batteries under external
1.Click Here For LTC4009 Evaluation Kits
2.General Purpose Battery Charger Controller
3.Efficient 550kHz Synchronous Buck PWM Topology
4.±0.5% Output Float Voltage Accuracy
5.Programmable Charge Current: 4% Accuracy
6.Programmable AC Adapter Current Limit: 3% Accuracy
7.No Audible Noise with Ceramic Capacitors
8.Wide Input Voltage Range: 6V to 28V
9.Wide Output Voltage Range: 2V to 28V
10.Indicator Outputs for AC Adapter Present, Charging,
C/10 Current Detection and Input Current Limiting
11.Analog Charge Current Monitor
12.Micropower Shutdown
13.Thermally Enhanced 20-Pin 4mm × 4mm × 0.75mm QFN Package

LTC4009 Datasheet pdf

LTC4062 - Standalone Linear Li-Ion Battery Charger with
Micropower Comparator

The LTC4062 is a full-featured, flexible, standalone linear
charger for single-cell Lithium-Ion batteries. It is capable of
operating within USB power specifications.

Both programmable time and programmable current based
termination schemes are available. Furthermore, the CHRG
open-drain status pin can be programmed to indicate the
battery charge state according to the needs of the application.
A precise low power comparator is available even with no
power applied as long as battery voltage is higher than 2.5V.
Additional safety features designed to maximize battery
lifetime and reliability include the SmartStart charging algorithm.

1.Charge Current Programmable up to 1A
2.Charges Single Cell Li-Ion Batteries Directly from USB Port
3.Preset Float Voltage with ±0.35% Accuracy
4.Micropower Comparator for Battery Monitoring
5.Thermal Regulation Maximizes Charge Rate Without Risk
of Overheating*
6.Programmable Charge Current Detection/Termination
7. Charge Termination Timer
8.Smart Pulsing Error Feature
9.SmartStartTM Prolongs Battery Life
10.20µA Charger Quiescent Current in Shutdown
11.Available in a Low Profile (0.75mm) 10-Lead12.
(3mm × 3mm) DFN Package

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