Datasheet LTM8062, LTM8062A (Analog Devices) - 9

LTM8062/LTM8062A
operaTion
The LTM8062/LTM8062A are complete monolithic, mid- also contain an internal charge cycle control timer, for power, power tracking battery chargers, addressing timer-based termination. When using the internal timer, high input voltage applications with solutions that use a the charge cycle can continue beyond the C/10 level to minimum of external components. The products can be top-off the battery. The charge cycle terminates when programmed for float voltages between 3.3V and 14.4V the programmed time elapses, about three hours for a (LTM8062) or between 3.3V and 18.8V (LTM8062A) with 0.68µF timer capacitor. The CHRG status pin continues just two external resistors, operating under a 1MHz fixed to signal charging at a C/10 or greater rate, regardless of frequency, average current mode step-down architecture. A which termination scheme is used. When the timer-based 2A power Schottky diode is integrated within the μModule scheme is used, the LTM8062/LTM8062A also support bad charger for reverse input voltage protection. A wide input battery detection, which triggers a system fault if a battery range allows the operation to full charge from an input stays in precondition mode for more than one-eighth of voltage up to 32V. A precision threshold on the RUN pin the total programmed charge cycle time. allows the implementation of a UVLO feature by using a simple resistor network. The charger can also be put into Once charging terminates and the LTM8062/LTM8062A are a low current shutdown mode, in which the input supply not actively charging, the charger automatically enters a bias is reduced to only 15μA. low current standby mode in which supply bias currents are reduced to 85μA. If the battery voltage drops 2.5% The LTM8062/LTM8062A employ an input voltage regula- from the full charge float voltage, the LTM8062/LTM8062A tion loop, which reduces charge current if a monitored engage an automatic charge cycle restart. The IC also au- input voltage falls below a programmed level at the VINREG tomatically restarts a new charge cycle after a bad-battery pin. There is a 1% 100k resistor to GND at this pin. When fault once the failed battery is removed and replaced with the LTM8062/LTM8062A are powered by a solar panel, another battery. The LTM8062/LTM8062A contain a bat- the input regulation loop is used to maintain the panel at tery temperature monitoring circuit. This feature, using a peak output power. The LTM8062/LTM8062A automatically thermistor, monitors battery temperature and will not allow enter a battery precondition mode if the sensed battery charging to begin, or will suspend charging, and signal voltage is very low. In this mode, the charge current is a fault condition if the battery temperature is outside a reduced to 300mA. Once the battery voltage climbs above safe charging range. The LTM8062/LTM8062A contain the internally set precondition threshold (2.3V at the ADJ two digital open-collector outputs, CHRG and FAULT, pin), the μModule charger automatically increases the which provide charger status and signal fault conditions. maximum charge current to the full programmed value. These binary coded pins signal battery charging, standby The LTM8062/LTM8062A can use a charge current based or shutdown modes, battery temperature faults and bad C/10 termination scheme, which ends a charge cycle battery faults. For reference, C/10 and TMR based charg- when the battery charge current falls to one-tenth the ing cycles are shown in Figures 1 and 2. programmed charge current. The LTM8062/LTM8062A 8062fd For more information www.linear.com/LTM8062 9 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Applications Information Typical Application Related Parts