Principles, parameters and precautions of vehicle charger
The conventional vehicle charger used in automotive battery (car 12V, truck 24V) power supply is widely used in the field of lithium battery charging in various portable and hand-held devices, such as mobile phone, PDA, GPS and so on. The car charge should not only consider the actual demand of lithium battery charging (constant voltage CV, constant current CC, overvoltage protection OVP), but also take into account the vehicle vehicle. The bad environment of the battery (transient peak voltage, system switch noise interference, EMI and so on); therefore, the power management IC of the car charging scheme must meet the switching power chip of high voltage, high efficiency, high reliability and low frequency (for EMI design).
The principle of vehicle charger
The common introduction of car charging is as follows:
Schematic diagram of low end vehicle charging scheme implemented by [1] single chip 34063
Advantages: low cost;
Such
Vehicle charger
Disadvantages: (1) poor reliability, single function, no temperature protection, short circuit protection and other safety measures.
(2) although the output is DC voltage, the way to control the output constant current is the maximum switching current.
Limit of flow peak and not high precision
(3) since 34063 is 1.5A switch current PWM+PFM mode (without error amplifier inside).
The output voltage and current ripple of the vehicle charging scheme are relatively large and not pure enough, and the output current capability is very strong.
Limit; (commonly used in the low end vehicle charging scheme between 300ma~600ma)
[2] 34063+NPN (NMOS) schematic diagram of vehicle charging scheme for expansion
Advantages: Based on the [1] scheme, expanding the current to meet the growing demand for charging current capability.
Shortcomings: there are similar deficiencies in the [1] scheme
Schematic diagram of [3] with 2576+358+ regulator
Advantages: (1) because of the 2576 safety measures such as overcurrent protection and over temperature protection, combined with 358 (Shuang Yunfang) to realize the function of output constant voltage CV, constant current CC, overvoltage protection OVP and so on, a reliable, safe and perfect lithium battery charging scheme has been realized.
(2) since 2576 is a fixed 52K PWM converter, the EMI design of vehicle charging is relatively easy.
(3) as 2576 and 358 are manufactured by 40V high voltage bipolar process, they are more "solid".
(4) this scheme is commonly used in vehicle charging of 0.8A ~ 1.5A; disadvantages: (1) the system is relatively complex and the cost is high.
(2) the constant current CC and overvoltage protection OVP are achieved by controlling 2576 of the EN by 358 output, so the charging current has a larger ripple, and the response speed of the CC and OVP is not fast enough (by switching 2576 if it works).
[4] XLSEMI design single - chip IC XL4002 schematic
Based on the system requirements of the vehicle filling field, Shanghai Coron Semiconductor Co., Ltd. provides a series of monolithic IC dedicated to the car charging scheme; in addition to conventional overcurrent protection, overtemperature protection, output short circuit protection, and the built-in CV, CC, and OVP for lithium battery charging, the equivalent of 2576+358+ regulator in the [3] scheme, etc. All functional modules are integrated into a IC
Advantages: in addition to the corresponding advantages of the [3] scheme, there are:
(1) a fully integrated scheme dedicated to vehicle charging, with low system cost and high reliability.
(2) IC internal CV, CC, OVP are all achieved by controlling PWM; therefore, the output voltage, the output current, the output overvoltage protection precision is higher, the response speed is very fast.
(3) the core dragon provides a series of cost-effective products with charging current between 0A and 3A.
[5] XLSEMI car filled series of products fast selection table
Product model XL4001 XL4002 XL4101 XL4102
Switching frequency 150KHZ 52KHZ 150KHZ 52KHZ
Output current 2A 2A 3A 3A
Encapsulation of SOP8-EP SOP8-EP TO263-5L TO263-
Vehicle charger application
Vehicle charger is used to facilitate vehicle owners to use electric vehicles to recharge digital products anytime and anywhere. At present, some high-end vehicle charger generally includes 2 USB interfaces, which can charge two digital products at the same time. Such products generally have over load protection, short circuit protection, high voltage input protection, high temperature protection, and four safety protection functions to ensure safe use. Vehicle charger can also be used for vehicle charging, direct charging and USB charging for three to one function.
Features: versatile, portability, fashion and safety.
With the development of the automobile industry, vehicle charger is widely used, showing the characteristics of multi-function, portability and fashion. At present, in the market, more influential car charger has MiLi Universal Charge products. The unique power management scheme of this product has an output current of 1A and is currently the world's fastest charging USB charger.
Versatile: the car charger is equipped with four AC couplings in the United States, Britain, Austria, Austria and Europe; it integrates the vehicle, the direct charge and the USB, and satisfies the charge under different conditions; the dual USB output interface can charge a number of electronic products. And this product is also the world's first charger charged for iPad, which can be completed in about 4 hours for iPad and can take iPad for a ride.
Such
Car charging head
Portability: portability is a major trend in the development of electronic products today. MiLi Universal Charger uses a unique folding car filling design, concentrating the volume of the product to 6.9 * 5.6 x 3.1cm, which is very convenient to carry with you.
Fashion: in view of the high-end consumer group of car owners, the vogue of vehicle charger is also emphasized by manufacturers. In general, the use of ABS material and piano baking process is not only fashionable but also very good.
Security: the product has passed CCC, UL