This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Some questions about TPS61201

Other Parts Discussed in Thread: TPS61201, TPS610981

I is using  TPS61201 to make a power  of 3.3V.But I have a problem. I wonder that if the TPS61201 requires  a larger input current when I set the output voltage?

If  I want the output of TPS61201 to be 3.3V. how much current I should the input should provide at least ? 

  • What is the input voltage and output current?
  • you mean startup input current or something else? and what's the input/output condition?

  •        Hi,John Tucker. Thank you for your answer. Let me introduce my circuit. As shown is the figure one. The battery n (n is 1, 2 ….) is microbial fuel cell. The max output voltage is 0.6V. And the current the microbial fuel cell can output is low. So I use four microbial fuel cells to change four super capacitors individually. The capacitor is 1F/5V, as shown in the fiture. When voltage of the capacitor is changed to 0.5 V. I control the switches to connect the four super capacitors .So I use the voltage of the connected capacitors as the input voltage of TPS61201. The beginning input voltage of TPS61201 is about 2V. I set the output voltage of TPS61201 to 3.3V. And the output of TPS61201 is open. But as soon as I change the switch I measure the output voltage of TPS61201 by voltmeter. It show 0V.I do not know why? Can you give me some suggestions? By the way when I test the same circuit by connecting a 1.5V battery to the input pin of TPS61201 directly, The output voltage is just right. So I think the circuit is right.

              Figure one :the circuit

  •   Hi,Charles Wong1. Thank you for your answer. Let me introduce my circuit. As shown is the figure one. The battery n (n is 1, 2 ….) is microbial fuel cell. The max output voltage is 0.6V. And the current the microbial fuel cell can output is low. So I use four microbial fuel cells to change four super capacitors individually. The capacitor is 1F/5V, as shown in the fiture. When voltage of the capacitor is changed to 0.5 V. I control the switches to connect the four super capacitors .So I use the voltage of the connected capacitors as the input voltage of TPS61201. The beginning input voltage of TPS61201 is about 2V. I set the output voltage of TPS61201 to 3.3V. And the output of TPS61201 is open. But as soon as I change the switch I measure the output voltage of TPS61201 by voltmeter. It show 0V.I do not know why? Can you give me some suggestions? By the way when I test the same circuit by connecting a 1.5V battery to the input pin of TPS61201 directly, The output voltage is just right. So I think the circuit is right.

                                                                

                                                                                                                                  Figure One 

  • this is caused by the statup current, as the fuel battery has high output impedence, very little current will make it crash.Do umean when the input voltage of tps61201 is 0.5V or each cap is charged to 0.5V when switchesare on? the startup voltage is 0.5V and you'd better switch on when the voltage is much higher than 0.5V for the input current.
    Ps:
    what's the application? where will the output of tps61201 will power?
  • Iam very glad to see your reply. I mean that each cap is chaeged to 0.5V, then the switch are on , the four caps are in series .So the input voltage of TPS61201 is 2V at the beginning . Do you mean the statup current is too low?
    By the way, I want to design a power management circuit for fuel battery. The output of TPS61201 will power a low-power MCU and the MCU can work intermittently. But the output voltage of fuel battery is too low ( about 0.4V ) and the enable output current of fuel battery is too low (1mA). So I design this circuit. Is it suitable that I use TPS61201 in this case? Can you give me some suggestions ? can you recommend some chips I can use?
  • hi

    if each cap is charged to 0.5V, i don'y think the circuit will crash. can you capture the vin vout and IL waveform for analysis? we have tps610981 which is suitable for low power application. but we need to know why the circuit crash, the supercap have stored enough energy for tps61021 to startup.

  • Hi,Charles Wong1 I have mesured the Vin and Vout. I do as follows:

    First, I let the four batterys charge the four caps. when the voltage of the cap is 0.9V , and the S2 is open.I change the switches to let the four caps in series. So the Vin of TPS61201 is 3.6V(the same as I measured ). Then the S2 is closed. But The Vin becomes 0.65V, and the Vout of TPS61201 is almost 0V. When I open S2 ,the Vin get back to 3.3V. So it is very strange. The circuit as follows:

                                                                                                                

  • hi

    I need the waveform because I need to see when tps61021 startup and when it crash. what's the capability of the battery. if the input energy is very limited and there is load at output side at the same time, maybe, this system can't work.

  • Hi , I have  mesured the waveforms of  Vin and Vout.  The results are as follows :the Figure 1 is the input voltage of TPS61201(the output voltage of caps), and the Figure 2 is the output voltage of TPS61201. For the Figure 1 .when the S2 is closed ,the Vin  drops to 760mV.When S2 is open, the Vin is back to 2.36V. For Figure 2 the Vout doesnot change when S2 changes. By the way ,when I measure the Vout ,the output of TPS61201 is open.

                                                                                                     

                                                                                                                                                                                              Figure 1: the input voltage of TPS61201.

                                                                                                     

                                                                                                                                                           Figure 2: the output voltage of TPS61201

                  

                                                     

  • when startup, there will be hundred mA current flow through the inductor for some mS.from the data you provide, I think the on-resistance of the switch is too high, that's why you can measure 0.76V(the minimum startup voltage is 0.5V). the voltage drop across S2 is higher than 0.76-0.5=0.26V. this is one possible reason why it crash. if possible ,can you capture the VIN/VOUT in a single waveform?