MTK PE 1
1.1 Principle
Before talking about the text, we look at an example.
For a battery, we assume that its capacity is 6000mAh, and the nominal voltage is 3.7V, in terms of Wh (watt hour) in units of value is 22.3Wh (6000mAh * 3.7V); Common charger output voltage and current is 5V2A (10W), this battery requires full 2.23 hours (22.3Wh / 10W) under ideal conditions. Now we assume that the output voltage of the charger current is adjusted 10V2A (20W), then a full battery requires the same 1.115 hours (22.3Wh / 20W).
We note that, due to the process of charging the battery internal resistance and the temperature will rise, so the actual charging process is not always have such a high power charging.
Lithium-ion battery charging process can be divided into three parts: pre-charge, constant current, constant voltage.
Since the pre-charge the lithium ion battery is to help the over-discharge recovery media activity, require less current, the charging process is time-consuming in the constant current phase, therefore, only be used in a large voltage and current constant current phase.
Based on the above principle, we can come up with a definition of rapidly charging the phone: Mobile charging process dynamically adjusting method request charger output voltage and current of the battery voltage, battery temperature, and other parameters.
The MTK Pump express precisely to reduce the use of constant current charging time proposed a fast charge mode.
Pump express support for fast charging AC adapter as shown in Figure 1-1:
Figure 1-1
We know that the transformer has a feature that, when the secondary coil is connected to the load, cause voltage and current of the primary coil produces a change, this principle is also called "load modulation."
Pump express took advantage of a change in current on VBUS to continuously adjust the charging voltage of the constant current phase.
Works as follows:
when the constant current charging, the battery current is sent to the shrinking, NAUX auxiliary winding voltage and current also fluctuates, gave NAUX output current Vsense pin, Vsense circuit calculates a change in current, by adjusting the switch Q1 adjusting the on-time Npri primary winding voltage, so that large, so that the output voltage of the secondary winding Nsec also increased, the formula P = UI, the power exported to the phone Charger IC is increased according; to ensure that when the battery when the voltage close to 4.2V, performed continuously from P = UI (* 5V current is small) to P = UI (little greater than 5V voltage * current) is adjusted to achieve the purpose of rapid charging of the battery.
Note: Pump express plus maximum output voltage is 12V
1.2 URLs
[power] lianfake mtk-pe + successfully induce rapid charging (MediaTek Pump Express PLUS)
http://bbs.mydigit.cn/read.php?tid=1740978
2 the PE 3.0 ON the VDM the USB the PD -Based
http://blog.sina.com.cn/s/blog_63f7b4540102wbhx.html
Figure 2-1 the PE 3.0 Direct Charge
