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Original question:

TPS92520-Q1: How much current needed for TPS92520-Q1 V5A pin under normal work/ switching mode

TPS92520-Q1: TPS929520 design questions (Heat calculation/ V5A current / Interleave output)

Kami Huang60
Genius 3830 points
Part Number: TPS92520-Q1

Dear Sir/Ms.

My customer wants to design a car light product and intends to use TPS92520. There are some questions in the design. Would you please teach me.
Q1: Can TPS92520 be configured as parallel(Interleave / 2-Phase) output ?
Q2: The customer wants to calculate the power consumption at full load and high temperature. Please tell me the Rds(on) of High side and Low Side when the junction temperature is 125°C.
Q3: The customer's board needs to connect 5~6 TPS92520, need to design the current provided to V5D and V5A. Among them, V5D mentions how much current is needed in the data sheet, but V5A does not. Can you let me know how much current V5A needs? The customer is worried that if the total demand exceeds 150mA, he will design another LDO.
Q4: The data manual states that TPS9250 can output 1.6A, but the current limit of Low side mosfet is 1A. What is the current output of this TPS92520? 0.8A per Chanel?

Best Regards,

Kami Huang

  • 0
    TI__Mastermind 23326 points

    Hello Kami,

    (Q1)Yes the 520 can be configured in parallel, but they are not interleaved.  They are two independent current sources that just add together when connected together.  There are some special precautions that you need to take when using it in this way.  We have an application note that is coming out soon that covers that, but I can send you a preliminary app note if you add me as a friend (place your email address in the friendship request).  (Each channel can support up to 1.6A, thus a total of 3.2A if placed in parallel. 

    (Q2)The resistance varies with temperature.  The thermal analysis is dependent on the power dissipation of the application, heatsinking, and temperature range of the environment (ie thermal analysis).  I have a power calculations spreadsheet I can share with you offline and if you input the application information such as VIN, VLED, IOUT, fSW, etc. it will give you an estimate of the total power dissipation (and it includes more than just Rdson of fets).  Note that this is a starting point and it will have to be amended based on your real application and thermal analysis. 

    (Q3)  The current should be ~30mA for the worst case, which is operating two channels at 2.1MHz.  150mA linear should work, but that depends on input voltage of the linear and the power dissipation it can handle. 

    (Q4)  That is the negative current limit of the low side fet.  Remember this is a synchronous buck and the ripple current can go negative at low output currents.  Each channel can support up to 1.6A and is limited based on power dissipation and not exceeding max junction temperature of the TPS92520.  

    -Francis Houde