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TPS62162-Q1: What is the maximum rated current of TPS62162-Q1?

Vishnu
Prodigy 180 points
Part Number: TPS62162-Q1
Other Parts Discussed in Thread: TPS62162, , TPS62172-Q1

Hi Ti Team,

This is the part we are using for step down converter: TPS62162-Q1

Input voltage = 5 V

Output voltage = 3.3 V

Maximum required load current = 400 mA.


Maximum current in datasheet description = 1 A

High-side MOSFET forward current limit maximum (Static current limit) I_LIMF from datasheet = 2.45 A

Voltage across the inductor is taken as V_L = 5 - 3.3  = 1.7 V

Output inductor L = 1 uH

Propagation delay = 30 nS  (There is no information in the electrical characteristics for the propagation delay, this 30 nS is the value taken from the calculation side in the datasheet, page-11, Eqn-5, So please let me know if there is a standard value for TPS62162 propagation delay )

Dynamic current limit due to propagation delay = 

I_LIMF + ( V_L / L ) * t_PD   

= 2.45  +  ( 1.7 / 1 * 10 ^(-6) ) * 30 * 10 ^ (-9)   

= 2.501 A

My output current is only 400 mA. But I just need to make sure that my required load current is less than the rated current. Following are my questions,

1. What is the maximum rated output current, 1A or 2.45 A or 2.501 A ? 

2. Is there an over current shut down feature for TPS62162-Q1? I understood that there is a thermal shut down for this device, but I could not find anything as over current shut down?

My intention is to find the maximum shut down time during over current?

3. How much time it will take to shut down the output voltage when EN pin is pulled low? I could not find this information in the datasheet. 

Regards,

VT

 

  • 0
    TI__Expert 5415 points
    The TPS62162-Q1 is designed to reliably provide 1A output current. It cannot be used for higher output currents. So it is not clear to me what you are trying to calculate here.

    Anyway, for a maximum of 400mA load current I would suggest to use TPS62172-Q1.

    I also do not understand your questions about shutdown time. It may be helpful if you provide a more detailed explanation on how you want to use this parameter.
  • 0 in reply to Juergen
    Prodigy 180 points

    Please note, there is no maximum rated current information in the electrical characteristics other than in the first page under " Features ", And there is dynamic current limit information in ( Eqn - 4, Page 10 ). So I am bit confused about the maximum rated current?

    I also do not understand your questions about shutdown time. It may be helpful if you provide a more detailed explanation on how you want to use this parameter:

    From the datasheet: "The current-limit comparator also turns off the switch in case the current-limit of the high-side MOSFET switch is exceeded. After a dead time preventing shoot-through current, the low-side MOSFET rectifier is turned on and the inductor current ramps down. The current flows now from the inductor to the output capacitor and to the load. The current returns back to the inductor through the low-side MOSFET rectifier. The next cycle is initiated by the clock signal again turning off the low-side MOSFET rectifier and turning on the high-side MOSFET switch."

    This sounds like a cycle to cycle limiter, Kindly confirm my understanding.
    I am interested to know at what frequency module will check the over current condition

     

  • 0 in reply to Vishnu
    TI__Expert 5415 points

    You can find minimum, typical and maximum parameters for the current limit in the electrical characteristics table in the datasheet (section 8.5.). This is a switch current limit, not an output current limit. You can find basic information about how buck converters work and how to understand those parameters in the literature, e.g. in this application note.

    As you already found in the datasheet "the current-limit comparator turns off the switch in case the current-limit of the high-side MOSFET switch is exceeded". I am not aware of any exemption.