SOT23 IC IS INDUSTRY'S SMALLEST LITHIUM-ION BATTERY CHARGER
SUNNYVALE, CA—June 5, 2000—Maxim Integrated Products introduces the MAX1736 SOT23 stand-alone charger for single-cell lithium-ion (Li+) batteries. In conjunction with an inexpensive current-limited wall cube, an external P-FET switch is used in a gated control scheme, which does not generate heat like a linear-mode regulator. This allows the entire charging circuit to run very cool and fit in cellular/PCS phone handsets and low-power hand-held equipment, such as PDAs and portable digital-audio players.
The MAX1736 features better than 0.5% battery-regulation voltage accuracy and a complete state machine to safely control the charging sequence. An on-board precharge circuit charges near-dead cells prior to fast charge to prevent damage. Once the battery-regulation voltage is reached, a hysteretic algorithm is used to top off the cell. This algorithm provides full charging of the cell, while eliminating errors due to series resistance.
To accommodate a variety of wall cubes and other input supplies, the MAX1736 operates with a wide input-voltage range of 4.7V to 22V. The device automatically detects the presence of an input supply and, if the input power is removed, will automatically power down to minimize battery current drain. A single ENABLE pin permits simple charge control by an optional microcontroller.
The MAX1736 comes in a tiny 6-pin SOT23 package and is specified for the extended-industrial temperature range (-40° C to +85°C). Prices start from $1.50 (1000-up, FOB USA). To help reduce design time, a preassembled evaluation kit (MAX1736EVKIT) is available with recommended external components. For a similar Li+ charger with added internal time-out counters, LED drive, and thermistor temperature monitoring, consider the MAX1679, which comes in an 8-pin µMAX package.
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