电源管理芯片BL8025

1、FEATURESHigh Efficiency: Up to 96%Capable of Delivering 1A (Vin 3.3V) 1.5MHz Switching FrequencyNo External Schottky Diode Needed Low dropout 100% Duty operation Internal Compensation and Soft-Start Current Mode control0.6V Reference for Low Output voltages Logic Control Shutdown (Iq2000VNote: Excee

2、d these limits to damage to the device. Exposure to absolute maximum rating conditions may affect device reliability.RECOMMENDED WORK CONDITIONSParameterValueInput Voltage RangeMax. 6VOperating Junction Temperature(Tj)-20 C T25 CELECTRICAL CHARACTERISTICS(VDD=5V, TA=25 C)SymbolParameterConditionsMin

3、TypMaxUnitVDDInput Voltage Range2.66.0VVrefFeedback VoltageVin=5V0.5850.60.615VIfbFeedback Leakage current0.10.4uAIqQuiescent CurrentActive, Vfb=0.65, No Switching40uAShutdown1uALnRegLine RegulationVin=2.7V to 5.5V0.040.2%/VLdRegLoad RegulationIout=0.01 to 1A0.10.2%/AFsocSwitching Frequency1.31.51.7

4、MHzRdsonPPMOS Rdson280350mohmRdsonNNMOS Rdson190250mohmIlimitPeak Current LimitVin3.3V1.21.52AIswlkSW Leakage CurrentVout=5.5V, VSW=0 or 5.5V, EN=0V10uAIenlkEN Leakage Current1uAVh_enEN Input High Voltage1.5VVl_enEN Input Low Voltage0.4Vtang- Call:0257153998 111BL8025PIN DESCRIPTIONPIN #NAMEDESCRIPT

5、ION1VINSupply voltage.2GNDGround3ENEnable pin for the IC. Drive the pin to high to enable the part, and low to disable4FBFeedback input. Connect an external resistor divider from the output to FB and GND to set the output to a voltage between 0.6V and Vin5SWInductor connection. Connect an inductor b

6、etween SW and the regulator output.ELECTRICAL PERFORMANCETested under TA=25 C, unless otherwise specifiedEfficiency / Vout=3.3VVfb Vs. Temperature10.0010.010.1Iout (A)Efficacy / Vout=l.BV / Vin=3JVlUUn rr-t1tI0MO600Mil的匾Efttang- Call:0257153998 111os0.70.60 -SO 050100150Temperature口Load Regulation /

7、 Vin=3.7VEffieiencv / Vout=1.2V / Virt=3,7V在师疆产黑目总JCK匕/tiEt牌网0El融利M0hut eAM 1000O.i0.4U.b 口上grE间BL8025Load Capability at Low VinVout=L2VL22L打1JL191481 17 lift i-iiPower upIIfJ01妣 5肝比际 Tf 30寄上 “2皿 i nrvr17 m/山5皿5江口 aijsj 存此Ch1: Vin, Ch2: Vout, Ch3 ENOutput Ripple and SW at 1A load Vin=6V / Vout=3.3VD

8、OOKXWk W51SE7 WMip 1B43ME2 ?31 如5脑/ : ?3W i 531HUtk 5DnraiCh1: Vin, Ch2: Vout, Ch3 SW, Ch4: I_inductorBLOCK DIAGRAMtang- Call:0257153998 111BL8025DETAILED DESCRIPTIONThe BL8025 high-efficiency switching regulator is a small, simple, DC-to-DC step-down converter capable of delivering up to 1A of outp

9、ut current. The device operates in pulse-width modulation (PWM) at 1.5MHz from a 2.6V to 5.5V input voltage and provides an output voltage from 0.6V to VIN, making the BL8025 ideal for on-board postregulation applications. An internal synchronous rectifier improves efficiency and eliminates the typi

10、cal Schottky free-wheeling diode. Using the on resistance of the internal high-side MOSFET to sense switching currents eliminates current-sense resistors, further improving efficiency and cost.Loop OperationBL8025 uses a PWM current-mode control scheme. An open-loop comparator compares the integrate

11、d voltage-feedback signal against the sum of the amplified current-sense signal and the slope compensation ramp. At each rising edge of the internal clock, the internal high-side MOSFET turns on until the PWM comparator terminates the on cycle. During this on-time, current ramps up through the induc

12、tor, sourcing current to the output and storing energy in the inductor. The current mode feedback system regulates the peak inductor current as a function of the output voltage error signal. During the off cycle, the internal high- side P-channel MOSFET turns off, and the internal low-side N-channel

13、 MOSFET turns on. The inductor releases the stored energy as its current ramps down while still providing current to the output.Current SenseAn internal current-sense amplifier senses the current through the high-side MOSFET during on time and produces a proportional current signal, which is used to

14、 sum with the slope compensation signal. The summed signal then is compared with the error amplifier output by the PWM comparator to terminate the on cycle.Current LimitThere is a cycle-by-cycle current limit on the high- side MOSFET of 1.5A(typ). When the current flowing out of SW exceeds this limi

15、t, the high-side MOSFET turns off and the synchronous rectifier turns on. BL8025 utilizes a frequency fold-back mode to prevent overheating during short-circuit output conditions. The device enters frequency fold-back mode when the FB voltage drops below 200mV, limiting the current to 1.5A (typ) and

16、 reducing power dissipation. Normal operation resumes upon removal of the short-circuit condition.Soft-startBL8025 has a internal soft-start circuitry to reduce supply inrush current during startup conditions. When the device exits under-voltage lockout (UVLO), shutdown mode, or restarts following a

17、 thermal-overload event, the l soft-start circuitry slowly ramps up current available at SW.UVLO and Thermal ShutdownIf VIN drops below 2.5 V, the UVLO circuit inhibits switching. Once VIN rises above 2.6V, the UVLO clears, and the soft-start sequence activates. Thermal-overload protection limits to

18、tal power dissipation in the device. When the junction temperature exceeds TJ= +160 C, a th ermal sensor forces the device into shutdown, allowing the die to cool. The thermal sensor turns the device on again after the junction temperature cools by 15 C, resulting in a pulsed output during continuou

19、s overload conditions. Following a thermal-shutdown condition, the soft-start sequence begins.Design ProcedureSetting Output VoltagesOutput voltages are set by external resistors. The FB_ threshold is 0.6V.RTOP = RBOTTOM(VOUT / 0.6) - 1Input Capacitor SelectionThe input capacitor in a DC-to-DC conve

20、rter reduces current peaks drawn from the battery or other input power source and reduces switching noise in the controller. The impedance of the input capacitor at the switching frequency should be less than that of the input source so high-frequency switching currents do not pass through the input

21、tang- Call:0257153998 111BL8025source. The output capacitor keeps output ripple small and ensures control-loop stability. The output capacitor must also have low impedance at the switching frequency. Ceramic, polymer, and tantalum capacitors are suitable, with ceramicexhibiting the lowest ESR and hi

22、gh-frequency impedance. Output ripple with a ceramic output capacitor is approximately as follows:VRIPPLE = IL(PEAK)1 / (2x fOSC x COUT)If the capacitor has significant ESR, the output ripple component due to capacitor ESR is as follows: VRIPPLE(ESR) = IL(PEAK) x ESRApplication InformationLayout is critical to achieve clean and stable operation. The switching power stage requires particular attention. Follow these guidelines for good PC board layout:Place decoupling capacito