mps mp3388 & mp3389 wled back light solution

1、Monolithic Power Systems®,MPS WLED Back Light Solution,MP3388 Monitor Back Light Solution,MP3388 50V 8 Strings White LED Driver,Application: Monitor WLED back light solution FEATURES:? High Efficiency and Small

2、Size ? 4.5V to 28V Input Voltage Range? 50V Maximum Step-up Voltage? Balanced Driver for 8 Strings of WLED? ± 3% Current Matching Accuracy Between Strings? Selectable Switching Frequency: 1.25MHz or 625kHz? PW

3、M or DC Input Burst PWM Dimming? Programmable Over-voltage Protection Threshold? Under Voltage Lockout? Open and Short LED protection? Thermal Shutdown (150℃),MP3388 50V 8 Strings White LED Driver,Package,Function Bl

4、ock,MP3388 50V 8 Strings White LED Driver,Pin Description,MP3388 50V 8 Strings White LED Driver,Pin Description,MP3388 50V 8 Strings White LED Driver,LED Current Sources,The MP3388 support 8-channel current sources tore

5、gulate their LED string currents. The LED currents are determined by the external current setting resister Rset.,,,Tie OSC pin to GND the IC work to600kHz frequency.Tie OSC pin to VCC or floating the IC work to 1.2MHz

6、.,Setting the frequency,,MP3388 50V 8 Strings White LED Driver,PWM Dimming Method,The MP3388 provides two different PWM dimming methods:1. External PWM signal fromPWMI pin.2. DC input PWM Dimming Both of these meth

7、ods results in PWM chopping of the each string LEDs current.,DC Input Dimming,,,,MP3388 50V 8 Strings White LED Driver,Protection Function,? Condition: Open all LED strings OVP Voltage will hit to 1.23V ? IC shut

8、down ? Condition: Open a string of LEDs OVP Voltage will hit to 1.23V?Disable the open string, the other string works normally ? Condition: Vout short to LEDX. LEDX voltage >5.5V?The

9、 shorten string LED is disabled and other strings works normally. ? Condition: Vout short to GND. OVP UVLO Threshold 150℃,MP3388 EVB Test,Application Circuit,MP3388 EVB Test,Efficiency test result:,

10、The efficiency is up to about 88% @Vin=15V.,MP3388 EVB Test,Current matching test result:,MP3388 EVB Test,PWM Dimming Test:,The PWM dimming signal is connected to PWMO pin directly. The performance is OK. It is a negati

11、ve logic.,,,Tie to Vcc pin,MP3388 EVB Test,PWM Dimming Test:,The PWM dimming signal is connected to PWMI pin directly.The performance is OK. It is a positive logic.,,,Bias the FSET pin to about 1V via resistor divider f

12、rom Vcc,MP3388 EVB Test,PWM Dimming Test:,LED current linearly increase with PWM dimming duty.,MP3389 Monitor Back Light Solution,FEATURESHigh Efficiency and Small Size8V to 28V Input Voltage RangeMaximum 60mA for Eac

13、h StringBalanced Driver for 12 Strings of WLED±3% Current Matching Accuracy Between StringsProgrammable Switching FrequencyPWM & DC Input Burst PWM PWM DimmingProgrammable Over-voltage Protection Threshold

14、Under Voltage LockoutOpen and Short LED protectionThermal Shutdown,MP3389 12 String For Monitor Back Light Solution,,,,,Package,Function Block,MP3389 12 String For Monitor Back Light Solution,,,MP3389 12 String For Mon

15、itor Back Light Solution,Pin Description,,,MP3389 12 String For Monitor Back Light Solution,Pin Description,MP3389 12 String For Monitor Back Light Solution,LED Current Sources,The MP3389 support 12-channel current sourc

16、es toregulate their LED string currents. The LED currents are determined by the external current setting resister Rset.,,,A oscillator resistor on OSC pin sets the internal frequency from 150KHz to 500KHz.,Setting the

17、frequency,,MP3389 12 String For Monitor Back Light Solution,PWM Dimming Method,The MP3389 provides two different PWM dimming methods:1. External PWM signal fromPWMI pin.2. DC input PWM Dimming Both of these methods

18、 results in PWM chopping of the each string LEDs current.,MP3389 12 String For Monitor Back Light Solution,Protection Function,? Condition: Open all LED strings OVP Voltage will hit to 1.23V ? IC shut down ?

19、 Condition: Open a string of LEDs OVP Voltage will hit to 1.23V?Disable the open string, the other string works normally ? Condition: Vout short to LEDX. LEDX voltage >5.5V?The shorten str

20、ing LED is disabled and other strings works normally. ? Condition: Vout short to GND. OVP UVLO Threshold 150℃,MP3389 EVB circuit,Application Circuit,MP3389 EVB Test,Efficiency test result:,The effic

21、iency is up to about 90% @Vin=12V.,MP3388 EVB Test,PWM Dimming Test:,DC Burst Dimming.,External PWM Dimming.,MP3388 EVB Test,Start up Test:,Vin start up,Ven start up,,,MP3389 12 String For Monitor Back Light Solution,LED

22、 Protection Test:,Open LED Protection,Short LED Protection,MP3389 Layout Guide,MP3389 Layout Guide,? Connect the positive and negative terminals of the load panel (14 white LEDs in series, 12 strings paralleled) to the L

23、ED+ and LED 1~12 pins on the EV board, respectively.? Connect the positive and negative terminals of the power supply (8V~28V) to the VIN and GND pins on the EV board, respectively.? Drive EN pin high (2.5V < Ven

24、< 5V) to enable the MP3389.? For PWM dimming, apply a PWM rectangular waveform with a minimum voltage less than 0.5V and a maximum greater than 2.5V on PWM DIM pin. The frequency of the PWM signal is recommended be