DC708A

DC708A demonstration circuit is a complete constant current, constant-voltage battery charger designed to charge one lithium-ion cell used in battery backup applications or applications that require greatly increased cycle life at the expense of battery capacity. The LTC4064EMS-4.0 used on this demo circuit features an internal P-channel power MOSFET with a unique thermal feedback loop that reduces the output current under high ambient temperature and/or high power dissipation conditions. These features allows the charger to provide higher charge currents under normal conditions and still provide safe charging under abnormal conditions such as high ambient temperature, high input voltage or low battery voltage. The IC is available in a 10-pin MSOP thermally enhanced package featuring an exposed bottom-side metal pad for soldering to the PC board.

• Preset float voltage of 4V ±1%
• 1A, 0.5A constant current selected by jumper, 4.25-7V (upper range limited by PC board dissipation)
• Capable of charging directly from USB power
• Charge current monitor output can be used for gas gauging, manual shutdown
• Low battery drain current when input supply is removed
• No isolation diode or current sense resistor required
• Ideal reference circuit for battery-powered, hand-held applications
• Input power OK LED indicator (ACPR), C/10 charge LED indicator (CHRG)
• Current monitor output of 1.5V±5% at full current, battery drain current of <1µA with VIN removed
• 60 to 70°C circuit board temp in thermal feedback mode, 2.457V trickle charge threshold voltage