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LM3658SD-A 数据表(PDF) 8 Page - Texas Instruments |
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LM3658SD-A 数据表(HTML) 8 Page - Texas Instruments |
8 / 20 page ICHG = KISET RISET 120°C - T A TJA(VCC - VBATT) ] or USB_sel or ICHG = min [ KISET RISET LM3658 SNVS328E – MAY 2005 – REVISED MARCH 2007 www.ti.com LM3658 OPERATION DESCRIPTION POWER-DOWN MODE The LM3658 will power down automatically when the voltage on the USBpwr or CHG_IN pin drops below the battery voltage with an amount that is equal to VOK_CHG (VBATT > VCC - VOK_CHG). Power-Down mode shuts off the internal power FETs as well as the open-drain pull-down transistors on the status pins STAT1 and STAT2. The only current consumed by the LM3658 is an ultra-low quiescent current of 1 µA typical. POWER-ON RESET As soon as the voltage of one of the power sources rises above VBATT + VOK_CHG, the charger will wake up. However, charging will not be initiated unless the supply voltage source exceeds the VPOR. AUTOMATIC POWER SOURCE DETECTION When the voltage of one of the power sources exceeds the VPOR threshold, the LM3658 detects which power source is a valid charge supply. When both supply voltages are valid and present, CHG_IN will automatically be selected over USBpwr. The USBpwr will be the designated power source only if no CHG_IN is present or when the voltage on the CHG_IN pin is less than the battery voltage. THERMAL POWER FET REGULATION The internal power FETs are thermally regulated to the junction temperature of 120ºC to specify optimal charging of the battery. At all times is the charge current limited by the ISET resistor setting, the USB 100 mA/500 mA selection, or the 100ºC junction temperature of the LM3658. The charge current is therefore a function of the charge current settings, the thermal conductivity of the package and the ambient temperature as described in the following equation: Where TA is the ambient temperature and θJA is the thermal resistance of the package. Thermal regulation specifies maximum charge current and superior charge rate without exceeding the power dissipation limits of the LM3658. PRE-QUALIFICATION MODE During pre-qualification, STAT1 is on and STAT2 is off, and the charger supplies a constant current of 50 mA to the battery. When the battery voltage reaches VFULL_RATE, the charger transitions from pre-qualification to full-rate charging. The pre-qualification mode aborts when the battery doesn’t reach VFULL_RATE within the time allowed in TPREQUAL timer. In this event, charging stops and STAT1 and STAT2 will both be on, indicating a bad battery condition. CHG_IN FULL-RATE CHARGING MODE The full-rate charge cycle is initiated following the successful completion of the pre-qualification mode. Timer TCHG starts to count when the charger enters full-rate charging, with STAT1 on and STAT2 off. When charging with an AC wall adapter, the full-rate charge current is proportional to the value of the resistor that is connected to the ISET pin as described in the following equation: It is recommended to charge Li-Ion batteries at 1C rate, where “C” is the capacity of the battery. As an example, it is recommended to charge a 750 mAh battery at 750 mA, or 1C. Charging at a higher rate can cause damage to the battery. 8 Submit Documentation Feedback Copyright © 2005–2007, Texas Instruments Incorporated Product Folder Links: LM3658 |
类似零件编号 - LM3658SD-A |
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类似说明 - LM3658SD-A |
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