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Smart Battery System (sbs) the emergence of an independent battery laptop battery system greatly simplifies the design, so its application has gone beyond the laptop computer field, out now a variety of other applications, such as backup power systems, high-reliability military and aerospace applications, the other Key applications include automotive, security / surveillance / security systems, medical devices, blade servers, telecommunications and portable electronics products

Smart battery using the internal electronic circuits to measure, calculate and store the battery data, it makes the use of power is more predictable and, smart battery there is a significant advantage, and that is to prevent unexpected system downtime

Smart Battery System

Sbs a basic system consists of the following components: System Management Bus (smbus), Smart Battery Charger and Smart Battery

sbs's modular design features make the closed-loop battery ThinkPad X60 charging system become very easy, such a system allows the use of independent battery charger (smart charger), minimizing hardware and software, non-recurring engineering (nre) of the cost of and contributed to a solid system, which is highly reliable battery backup applications is particularly important and integrated into the battery pack in the high accuracy could have been an accurate barometer to monitor the battery, even when the battery is not in the same system, in accordance with the Barometer Battery The actual capacity value of the calibration, thus removing the bias, ensuring accuracy

Smart battery charging and protection of the

Smart battery charger main function is to provide smart battery charging voltage source and current source of intelligent battery chargers by smbus interface and smart communication, and can select the host communication in order to prevent loss of function rather than due to smbus charge watchdog timer continues to run Smart battery and charger to monitor FRU 92P1167 the frequency of the call action, if the battery no longer than 3 minutes, then pause and wait for the battery charger to recharge again requested In addition, the battery can also force a shutdown feature to control the charger, so you can bypass the smbus, to provide redundancy level and let the Chargers know that the battery does indeed exist

Figure 1 ltc1760 for Dual-Battery Systems

In short, when compared with the fixed independent chargers, smart battery charger has the following advantages

① truly plug and play, free from battery chemistry and battery configuration can affect any smart battery pack with any smart battery charger with different chemical characteristics, configuration, and even different battery charging algorithms can be used ThinkPad Z60t without modification for charging circuit
② built-in security features sbs standards watchdog timer and a battery and charger in particular between the "safety signal" interface
③ reliable battery detection system
④ automatic charge management, not the host
⑤ without host intervention, the closed-loop charging system host power measurements in accordance with the need to collect information on

ltc1760 Dual Smart Battery System Manager

ltc1760 is a highly integrated battery charger and selector 3, for the use of dual smart battery products that it is a buck topology switching battery chargers, smart battery standard definitions were consistent with a variety of functions and other new features, such as the input current limit and security restrictions, and so on 3 smbus interface allows ltc1760 to ThinkPad Z61t achieve, such as track two battery's internal voltage and current of the servo-like features, and allows a smbus host either a battery status monitor this servo technology so that the accuracy of the charger with the battery internal voltage and current measurement error of only ± 0.2%

Traditionally, dual-battery system is the order of discharge system, allowing the order of the battery (first consumption of the battery 1, and then consume the battery 2) to simply extend the overall battery ltc1760 analog control using proprietary technology that allows secure two batteries in parallel for charging or discharging Figure 1 is a dual-battery system using ltc1760 a simplified schematic diagram of this structure allows a 50% faster recharge the battery to extend the working hours by 10% In addition, the parallel discharge not only enhance the current capacity, but also reduces the i2r loss and improved conditions at very high load capacity of the voltage regulator to reduce losses 40Y6793 and improve voltage regulation i2r have extended timing solutions, the total discharge time (see Figure 2)

Figure 2 dual battery sequence comparison of the battery charge time

Figure 3 ltc1760 dual battery charger / selector system architecture

● ltc1760 the main features of

① three independent polling battery charger charging requirements and monitor the internal battery power measurements to determine the actual current and voltage (error ± 0.2%), fast, safe and thorough charge
② fast-charge mode can be used to further reduce the recharge time
③ support the battery identified in order to achieve the barometer calibration
④ 3 power supply channel fet diode to allow safe and low-loss and two batteries from the same time discharge dcin
⑤ two fet diode to achieve two batteries at the same time safe, low loss to discharge
⑥ hardware programmable current and voltage security constraints, as well as many other security features to supplement the battery's internal protection circuitry
ltc1760 Although it is sophisticated, but very easy to use in any given design, only identified four key parameters: input current limit sense resistor ricl, current-limiting FRU 92P1125 resistors and matching rilim charge current sense resistor rsense, limited pressure resistance rvlim, short-circuit protection resistor rsc
ltc1760 plus some smart battery, and an ac adapter, you can set up a simple system architecture as shown in Figure 3

● Input Current Limiting sense resistor rcl

As shown in Figure 4, this circuit limits the charge current to prevent the system increases when the AC adapter power overload to set the input current limit, the most important thing is to minimize the wall fitting device rated current limiting resistor can be the next 2-type to calculate the
ilim = Adapter Min Current Value - (Adapter Min Current value × 5%) (1)
rcl = 100mv/ilim (2)
However, the AC adapter can be at least +10% of the current limit margin, so often simply set the adapter current limit value of the actual adapter Rating

Figure 4 input resistance of the circuit should be limited to influenza -

● current-limiting resistor rilim

rilim resistor has two effects First, it tells ltc1760 the smbus interface, the battery charger will be available to the maximum allowable current, any more than this limit value will be replaced by limit values of second role is to make the charger pwm full-scale degree of current and smbus FRU 92P1121 interface, full-scale current-limiting value of synchronization

● limited pressure resistance rvlim

vlim pin to gnd connection between the external resistor value can determine the 5 charger output voltage limiting value of either one (see Table 3) This limit pressure value with the hardware implementation of the method is a kind of safety measures, it can not be replaced by the software means

● Short-Circuit Protection Resistance rsc

Each power supply channel formed by two back to back pfet, these two pfet with the short-circuit detection resistor rsc series battery power path (powerpathtm) switch driver equivalent circuit shown in Figure 5

Figure 5 ltc1760 power path circuit

Short-circuit protection feature is available in current mode and voltage mode short-circuit if the output current exceeds the
Compaq Laptop Battery comparator threshold is longer than 15ms, then disconnect all power path pfet switch, and power_not_good bit similar, if the voltage drops below the 3v time for more than 15ms, it will also disconnect all power path switches, power_not_good bit also be set to remove all power bit can be reset if power_not_good bit power_not_good bit is set, then the charge is also prohibited

● no software

Without the software-based ltc1760 charger at the beginning of the hardware prototype of the system into the integrated circuit will allow access to the battery charge and discharge but in some cases, you can write some software in order to be able to complete the following actions on the host
① directly from the smart battery (that is, as a barometer) to collect "charger status" information;
② Support Battery inspection

Conclusion

Smart Battery System to provide advanced features, with a minimum of design work ltc1760 is a very comprehensive, single-chip dual smart battery system representatives, easy to use, only need to determine the four parameters can be done a complete design, but does not require software code of the device requires only a minimum of nre work, you can form a complete independent Armada M700 battery charger system and work