SBC chip 35584 data manual pre regulator translation

SBC chip 35584 Data book translation

Chapter VI pre regulator
6.1 Introduce
The pre regulator must maintain a stable intermediate circuit voltage , To provide the following rear regulators . It consists of two independent regulators ： A step-down frequency converter , There is an external power stage ahead , To maintain the minimum input voltage of the following step-down converter .
By placing the pin STU Connect to ground , The l-converter can be deactivated （ If you don't need to ）. Let pin STU open , Activate the boost regulator .
The frequency of the step-down regulator can be preset to FRE High switching frequency range with pin open , Or connect to... In the low switching frequency range GND To preset the frequency of the step-down regulator .
The step-down frequency converter is on continuously , Provide a stable intermediate circuit voltage VPREREG, To provide monitoring voltage . The boost converter is directly connected to the input voltage VBat. It only works at low input voltage , When the input voltage drops to the threshold VPRE_REG,boost,UV, Following time , Keep the input voltage high enough , To meet the following steps of the step-down regulator . The low input voltage condition is referred to at pin VSx The input voltage at is too low , The intermediate circuit voltage cannot be supplied within the specified range VPREREG. Threshold value when the internal comparator connected to the input voltage path detects when the boost converter is turned on . If the input voltage is higher than the output voltage of the boost converter （ Threshold for switching on the boost converter ）, The regulator is deactivated by the internal comparator ,
The internal logic can open the uplink converter at any time （ Or close it again ）.

Main pre regulator

6.2 Boost regulator
6.2.1 Function description
The asynchronous boost pre regulator provides a higher output voltage than the input voltage . When the supply voltage is too low to allow the nominal value of the rear regulator output , This will happen . The output voltage of the boost pre regulator will be much lower than the nominal power supply （ The battery ） voltage , To ensure that it only works at low input voltage .
If you do not need to apply this function , You can skip the external power supply components (Mosfet, diode ), Filter elements can be adjusted to the requirements of the application .
Boost regulator

6.2.2 Electrical characteristics
VVS=6.0V to 40V,Tj=-40°C to +150°C, All voltages relative to earth , Positive current entering the pin （ Unless otherwise specified ）.

6.3 Depressurization regulator
6.3.1 Function description
The Synchronous Step-Down pre regulator operates continuously , Provide stable intermediate circuit voltage . The internal power stage is synchronized by P passageway （ High side ） and N passageway （ Low side ）Mosfets form . For start-up procedures , We implemented a soft start function .
The regulating circuit operates in voltage mode .
Under normal load conditions , The regulator can perform pulse width modulation (PWM) operation . Under light load , It will be modulated at pulse frequency (PFM) Work in China , To minimize internal current consumption ( Only in sleep , Not normal 、WAKE or INIT state ).
The output filter of the step-down regulator must be sized so that the maximum output voltage pulse value is 100mV, To meet the requirements of the rear regulator PSRR.

Depressurization regulator

6.3.2 Electrical characteristics

6.4 Frequency setting
6.4.1 Introduce
The frequency source provides a boost pre regulator and a step-down pre regulator at a constant frequency . The synchronous power switch of the step-down pre regulator will switch directly with the frequency fosc.
The frequency range of the step-down pre regulator can be adjusted by setting the pin FRE The open frequency range is set to the high switching frequency range , Or by placing the pin FRE Connect to GND To set the low switching frequency range . The switching frequency will be set to the default value for the selected frequency range . It can also pass through SPI command (BCK_FREQ_CHANGE) Fine tuning , You can also activate the spread spectrum option (BCK_FRE_SPREAD). The switching frequency range of the boost pre regulator is lower than that of the step-down pre regulator .
The switching frequency of the step-down pre regulator is foot if SEC The pins remain open , Then for µC The core power supply has an optional external switching mode after the regulator's foot SYN.
This synchronization function is available in PFM Not available in mode .TLF35584 Unable to synchronize to an external frequency source .
6.4.2 Electrical characteristic frequency setting