The voltage in the use of various batteries will fall, when falling to the lower limit of the system that is lower than the system that is powered by it, this battery can not be used, and people can do with the ability to replace the battery or for Battery charging, otherwise this system is stopped. Can there be a residual electric energy in the battery that can't be used? Usually, the answer to this problem is certain because the threshold for people will always have a certain room, and there are many designs to end the system's work in advance. For example, many system operating voltages are 3.3V, and devices taken from lithium-ion batteries are usually buck or linear regulators, they all can only complete buck, so they can only be high in battery voltage. At 3.3V, it is possible to provide 3.3V output voltage. After the battery voltage is low, the output of 3.3V cannot be guaranteed. At this time, it can only shut down or quickly charge, but at this time, the electric energy in the lithium ion battery is actually actually It is not completely exhausted.
The 3.3V mentioned above is just an example. The actual threshold setting is always different. There are customers who have told me that the voltage required for me a system-level chip must be above 3.6V, and there must be at 3.9V. The above case. It can be seen from the above figure, the higher the shutdown voltage threshold set by the system, the more the remaining electricity in the battery is turned off, and the more severe waste. I will encounter such a situation in life, so I often keep the old battery when changing the battery. Wait until the system needs to allow the operating voltage to make these old batteries to play a role.
If the system designer encounters RT4803A, such a situation can be improved because it can dry the residual power of the battery, so that the battery can be used longer.
Using the most easily understood language, I want to express this: When the battery voltage is relatively high, it uses a switch to directly access the battery voltage; when the battery voltage is relatively low, it puts the battery After the voltage increases, the system is supplied. At this time, the battery is shown is a false battery, which seems to have endless energy, always maintain a constant voltage. Such a RT4803A, its application is very simple:
The working parameters of the RT4803A can be set by the I2C interface, controlling its working state, but you can also use this interface, then let SDA, SCL is grounded.
VSEL can connect high or low, which makes the RT4803A preset output voltage will not be less than 3.4V or 3.15V.
The EN end is enabled, the NBYP terminal is the control terminal of the bypass switch. The high and low level combination has a total of 4 states, which allows the chip to enter the shutdown state, and the power-consuming power is in power, no low power consumption Mandatory Practical Practical Status and Status of Power Conversion and Direct Automatic Switching. When the boost circuit works, its working mode will automatically switch between PFM and PWM as loaded, and maintain high conversion efficiency as much as possible.
GPIO is a universal I / O terminal whose function is a reset input or status output that can be selected by an instruction.
The Package of RT4803A is WL-CSP-16B1.67X1.67 (BSC), and there is very few peripheral components in use, so the demand for space in portable applications is not large, but the improvement effect on battery usage time is It is seen. It lists its main technical features:
Input voltage range: 1.8V ~ 5V
Output voltage adjustable range: 2.85V ~ 4.4V, step in steps with 50mV
Preset Output Voltage: 3.4V or 3.15V
Maximum continuous load capacity: 2.65V input, 3.35V output is 2A
Conversion efficiency is as high as 96%
BOOST operating frequency: 2.5MHz
Direct pattern load capacity: >3a
Start with a linear charging mode of current
With overcurrent protection, undervoltage protection, overvoltage protection, overheating protection, etc.
Static power consumption can be as low as 4μA
Shutdown power consumption below 1μA
Output discharge function
Reprinted from Richtektechnology.
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