New mobile phone power management chip

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New mobile phone power management chip [Copy link]

A well-functioning power management circuit is the basis for the normal operation of a mobile phone. If the power management circuit can be power-saving, efficient, multifunctional and occupy a small area of the circuit board, it is possible to make the mobile phone small and have a long working time. RICOH's new mobile phone power management chip R5313B is just such a special chip.
R5313B structure R5313B adopts CMOS process, CSP package, has 48 pins, and the size is only 5×5×1.05mm3. It contains almost all the functions of power management required in the mobile phone (see Figure 1): There are nine LDOs, one of which is a DC-DC high-efficiency voltage regulator, which has significant power saving advantages for large currents with output voltages below 1.8V; multi-function lithium battery charging circuit; vibration motor and ringtone driver; SIM card power supply and interface circuit; and perfect protection, power-on reset and voltage monitoring circuits. The following focuses on voltage regulation and charging.
The composition and characteristics of the voltage-stabilized power supply LDO is the main form of mobile phone power supply circuit. According to the different characteristics of the entire circuit of the mobile phone, the LDO in R5313B corresponds to the power supply of the RF, baseband and DSP core circuits respectively. At the same time, each LDO is micro-power and can be managed. See Table 1, it can be seen that the distinctive characteristics of each group of LDO and the corresponding application performance. In view of the continuous enhancement of the functions of the MCU and DSP in the current baseband part, the core voltage is gradually reduced, and the linear voltage-stabilized circuit obviously cannot meet the needs of high-efficiency and large dynamic range power supply. R5313B introduces the DC-DC method in this part of the power supply, which significantly improves the efficiency of low voltage (output voltage below 2.0V) and voltage-stabilized output, and the power saving effect is significant.
Charging circuit The importance of the mobile phone charging circuit is self-evident. R5313B contains a complete lithium battery charging circuit, which can select the corresponding charging method according to the different battery voltages and charge according to the reasonable charging curve, and display the status through an external light-emitting diode. It also contains a battery status monitoring circuit inside to check whether the battery is connected, over-voltage, or under-voltage, and combines the over-current/temperature protection circuit to ensure the normal operation of the charging and even the entire system. The charging circuit of the highly integrated R5313B requires very few external components, see Figure 2. The system controls whether charging is in progress through the CHG pin. A high level turns on charging, and a low level turns off charging. In addition to monitoring the charging status internally, the system can also understand the exact voltage of the battery through the BATMON pin. When the battery voltage is lower than 3.15V and an external power supply is connected, the battery is pre-charged with a charging current of 50mA, and the LED flashes to indicate that the battery voltage reaches 3.15V, and it switches to normal charging. The internal power enable terminal is turned on to power the baseband part, and the entire mobile phone can be used. At the same time, the system can also control the LED through the FLASH-LED terminal to display the current charging status. When the battery voltage is between 3.15V and 4.2V, the charging circuit enters the fast charging state (the charging current can be set) by setting the CHG terminal to a high level. After the battery voltage reaches 4.2V, the system can turn off charging, or it can perform pulse charging through CHG, and the frequency gradually decreases to ensure complete charging.
Power-on reset circuit SIM card interface circuit R5313B has a complete power-on and boot circuit, as well as a protection circuit, see Figure 3. When the battery voltage is higher than 3.15V and the chip temperature is lower than 140℃, the external power supply is connected, and the ON/OFF or UP-ON-OFF pin is set to a high level, the boot action will be executed. R5313B has not only a SIM card power supply circuit with a settable voltage, but also a level conversion interface, see Figure 4. From the above, it can be seen that R5313B has excellent mobile phone power management performance. It is not only powerful, but also does not need to be specially written for this. Through the external control pin, it can be made to work normally by using high and low levels. It is the best way to evolve from traditional discrete components to a single power management chip.