|
 |
lowpowerZONE Products for the week of September 1, 2008
Microchip Technology Says…
MCP73871: USB/Ac Load-Sharing Li-Ion/Li-Polymer Battery Charger
Enables Simultaneous Ac-Dc or USB Battery Charging, and Powering of Devices
Microchip Technology Inc., a leading provider of microcontroller and analog semiconductors, announced the MCP73871 charge-management controller—a Li-Ion/Li-Polymer charger with an intelligent charge management feature that enables simultaneous AC-DC-adapter or USB-port charging and powering of devices. The single-chip charger features an integrated pass transistor, and numerous battery and termination-voltage options—making it ideal for complex, space-constrained portable applications.
By enabling electronic devices to be simultaneously powered and charged via either an AC-to-DC adapter or through a USB port, the MCP73871 charge-management controller simplifies the charging and powering of today’s portable electronic devices. With highly accurate voltage regulation of 0.5%, the new charger extends battery life by allowing the battery to be charged closer to its optimal limit. Additionally, with its integrated pass transistor, the charger eliminates the need for an external FET, and only a few small passive components are necessary. This results in smaller, less complex and less expensive designs.
“Our customers have requested a compact, single-chip charger to meet the needs of today’s advanced portable consumer-electronic devices, many of which now offer traditional wall-plug charging, plus USB port charging and connectivity,” said Bryan Liddiard, vice president of marketing with Microchip’s Analog and Interface Products Division. “The MCP73871 charger meets these needs, head on. Microchip’s battery-charger offering now includes products that provide everything from simple, USB-based battery charging, to complex power-path solutions.”
EN-Genius Says…
Dual-source single-chip battery chargers are not unique and we have seen a number of ac/USB versions over the last two years. Microchip, however, comes in with a fresh mindset and offers some feature combinations that I have not seen elsewhere.
The MCP73781 selects the source for load power automatically between Li-Ion/Li-polymer battery, USB or ac-adapter input. With USB, current is limited to that of the standard at 500 mA (a 100 mA setting is also provided). For ac supplies the current would be limited by an external resistor to allow for a maximum current of 1.8 A, with 1 A of that allowed for battery charge. The system load is always the priority load for the external dc source to supply.
A constant current/constant voltage algorithm is employed and the final (constant) voltage can be optioned for 4.10 V, 4.20 V, 4.35 V, or 4.40 V – in line with the increasing battery voltages we are seeing in the industry. The charge termination point can be set. Regulation tolerance is ±0.5%.
A low battery indicator is provided, as is a power-good indicator and two charge status outputs that could be connected to LEDs or to a microcontroller. There is also a battery cell monitor and 0.1C preconditioning for deeply-depleted cells.
The input capacitor on the battery source is suggested at 4.7 µF, as is the output capacitor. That from the ac/USB source is suggested as 10 µF. All can be ceramic.
At some stage Microchip will be asked at extend the product features to include switching between USB and a wall wort, whichever supply is available, but the first product, this MCP73871, will be a no-brainer for existing PIC customers who are designing portable products. The pricing will also attract non-PIC customers if they manage to stumble across it – marketing to the general analog world not being one of Microchip’s strongest activities…
The MCP73871 is in production in thermally-enhanced QFN-20 and is priced at $1.28 in 1000-piece lots. An evaluation board is also available.
Data Sheet
|
|
|
|
|
