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ISL6292-1CR4Z Datasheet(PDF) 10 Page - Renesas Technology Corp |
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ISL6292-1CR4Z Datasheet(HTML) 10 Page - Renesas Technology Corp |
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10 / 20 page  ISL6292 FN9105 Rev.9.00 Page 10 of 20 December 17, 2007 Theory of Operation The ISL6292 is an integrated charger for single-cell Li-ion or Li-polymer batteries. The ISL6292 functions as a traditional linear charger when powered with a voltage-source adapter. When powered with a current-limited adapter, the charger minimizes the thermal dissipation commonly seen in traditional linear chargers. As a linear charger, the ISL6292 charges a battery in the popular constant current (CC) and constant voltage (CV) profile. The constant charge current IREF is programmable up to 2A (1.5A for the 3x3 DFN package) with an external resistor or a logic input. The charge voltage VCH has 1% accuracy over the entire recommended operating condition range. The charger always preconditions the battery with 10% of the programmed current at the beginning of a charge cycle, until the battery voltage is verified to be above the minimum fast charge voltage, VMIN. This low-current preconditioning charge mode is named trickle mode. The verification takes 15 cycles of an internal oscillator whose period is programmable with the timing capacitor. A thermal-foldback feature removes the thermal concern typically seen in linear chargers. The charger reduces the charge current automatically as the IC internal temperature rises above +100°C to prevent further temperature rise. The thermal-foldback feature guarantees safe operation when the printed circuit board (PCB) is space limited for thermal dissipation. A TEMP pin monitors the battery temperature to ensure a safe charging temperature range. The temperature range is programmable with an external negative temperature coefficient (NTC) thermistor. The TEMP pin is also used to detect the removal of the battery. The charger offers a safety timer for setting the fast charge time (TIMEOUT) limit to prevent charging a dead battery for an extensively long time. The TIMEOUT limit can be disabled as needed by the TOEN pin. The trickle mode is limited to 1/8 of TIMEOUT and cannot be disabled by the TOEN pin. The charger automatically re-charges the battery when the battery voltage drops below a recharge threshold. When the wall adapter is not present, the ISL6292 draws less than 1µA current from the battery. Three indication pins are available from the charger to indicate the charge status. The V2P8 outputs a 2.8VDC voltage when the input voltage is above the power-on reset (POR) level and can be used as the power-present indication. This pin is capable of sourcing a 2mA current, so it can also be used to bias external circuits. The STATUS pin is an open-drain logic output that turns LOW at the beginning of a charge cycle until the end-of-charge (EOC) condition is qualified. The EOC condition is: the battery voltage rises above the recharge threshold and the charge current falls below a user-programmable EOC current threshold. Once the EOC condition is qualified, the STATUS output rises to HIGH and is latched. The latch is released at the beginning of a charge or re-charge cycle. The open-drain FAULT pin turns low when any fault conditions occur. The fault conditions include the external battery temperature fault, a charge time fault, or the battery removal. Figure 17 shows the typical charge curves in a traditional linear charger powered with a constant-voltage adapter. From top to bottom, the curves represent the constant input voltage, the battery voltage, the charge current and the power dissipation in the charger. The power dissipation PCH is given by Equation 1: where ICHARGE is the charge current. The maximum power dissipation occurs during the beginning of the CC mode. The maximum power the IC is capable of dissipating is dependent on the thermal impedance of the printed-circuit board (PCB). Figure 17 shows (with dotted lines) two cases that the charge currents are limited by the maximum power dissipation capability due to the thermal foldback. FIGURE 17. TYPICAL CHARGE CURVES USING A CONSTANT-VOLTAGE ADAPTER V CH V MIN V IN I REF I REF/10 P 1 P 2 P 3 Trickle Mode Constant Current Mode Constant Voltage Mode Inhibit TIMEOUT Input Voltage Battery Voltage Charge Current Power Dissipation PCH VIN-VBAT I CHARGE = (EQ. 1) FIGURE 18. TYPICAL CHARGE CURVES USING A CURRENT- LIMITED ADAPTER V CH V MIN V IN I REF I REF/10 P 1 P 2 I LIM Trickle Mode Constant Current Mode Constant Voltage Mode Inhibit TIMEOUT Input Voltage Battery Voltage Charge Current Power Dissipation |
Similar Part No. - ISL6292-1CR4Z |
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Similar Description - ISL6292-1CR4Z |
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