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TPS61085
Related Posts

  • Forum Post: TPS61085 - output voltage problem

    pankaj patel
    Hi, I am working with TPS61085, i want to charge the mobile phone using the button cell, i am having the source with 2.3volt 10ma and output load 5V 4W. I have made the design using TPS61085, but it is working properly, the output volt from the circuit is getting down up to 2.8Vdc and it is...
    on Feb 21, 2010

  • Forum Post: Re: Problem with TPS61085

    Brigitte
    Hello Mr. Patel, TPS61085 is a boost converter which generates a higher output voltage than the supplied input voltage. The output power is always lower than the available input power (efficiency is always below 100%). You have a source that delivers 25mW and you want to supply a load of 2.5W which...
    on Feb 22, 2010

  • Forum Post: Re: Problem with TPS61085

    Michael Day
    Please go to www.ti.com and click on the Power Management link. Use the quick search function to enter electrical requirements. The tool will show you all ICs that meet those electrical requirements.
    on Feb 22, 2010

  • Forum Post: Switcher Pro desktop with TPS61085 - resistor divider current

    Dvir
    Hi, I'm using Switcher Pro desktop to design step up converter with TPS61085. Setting Vout is done by an external resistor divider, the min. current in the divider should be 50uA, according to data sheet. Switcher Pro sets a design that doesn't meet that requirement (!) and I can't...
    on Mar 7, 2010

  • Forum Post: Re: Switcher Pro desktop with TPS61085 - resistor divider current

    Michael Day
    Per the datasheet, 50uA of resistor divider current is typical guidance. Less current is more succeptable to noise. More current is a more robust design. Either design should work, but must be verified with your specific layout. If you have noise problems, use smaller values.
    on Mar 8, 2010

  • Forum Post: Re: Switcher Pro desktop with TPS61085 - resistor divider current

    Brigitte
    Hello Dvir, Could you please send me the parameters you used to generate the design with TPS61085. I want to reproduce the problem that you are seeing. In general if the current through the resistive divider is 50uA or more, the accuracy and noise immunity of the part is higher. It is working with...
    on Mar 8, 2010

  • Forum Post: TPS61087 - Loop Response at no load is very low

    Brigitte
    At 0 load in PWM the feedback to output frequency response bandwidth drops to 500Hz or so. Does this mean that the converter reacts very slow?
    on May 21, 2010

  • Forum Post: Re: TPS61087 - Loop Response at no load is very low

    Brigitte
    Let me try to describe the operation of TPS61085, TPS61086 and TPS61087 when no load is attached and they work in PWM mode: Keep in mind that the converter is non-synchronous (using a diode not a second switch). The minimum on-time of the internal switch is in the range of 100ns or so, therefore whenever...
    on May 21, 2010

  • Forum Post: TPS61085 won't go to zero volts

    Patrick DeLuca
    I set up the TPS61085 to have the following parameters: Enable pin controlled by microcontroller (either 0 volts or 5volts) 8V output from a 3V source (power supply at the moment) 650Khz FREQ, 13k/3.3nF COMP circuit My problem is I get 8 Volts when the microcontroller output pin is high...
    on Jul 9, 2010

  • Forum Post: Re: TPS61085 won't go to zero volts

    Brigitte
    Hello Patrick, Have a look in the datasheet on page 15. You will find a load disconnect circuit with a bipolar transistor. The small feature in this diagram is that the Enable pin is connected to Vin. It should be connected to your microcontroller. If now you disable the device, the output voltage...
    on Jul 9, 2010

  • Forum Post: Re: TPS61085 operating temperature

    Brigitte
    Hello Chris, First of all, it is not possible to destroy the part by overlaod. The part has an overtemperature protection which will stop switching if it gets too hot. If this happens, the converter will start again when its temperature reduced by typically 14°C. Your application will have an...
    on Sep 23, 2010

  • Forum Post: Re: TPS61085 doesn't work

    Brigitte
    Hello Tommy, If you have 4.85V on the feedback pin, the IC will not switch, because this voltage shows the IC that the output voltage is a lot too high. The voltage on this pin has to be 1.238V then it is in regulation. Please recheck your feedback resistors, because 4.85V on the FB pin with 5V...
    on Nov 18, 2010

  • Forum Post: Re: TPS61085 - Boost + negative voltage source

    Brigitte
    Hello Denis, Normally the circuit you show above should work. The TPS61085 is tested with charge pumps attached to the switch pin. Please review the datasheet and you will find an application with a positive and negative charge pump connected to the switch pin. With 1uF flying capacitor and...
    on Jun 1, 2011

  • Forum Post: Re: TPS61085's off-time is fixed?How to realize?

    Brigitte
    Hello Li, TPS61085 is a regulator that operates with fixed off-time instead of fixed frequency. You just need to connect the input voltage and the necessary external parts as given in the datasheet and the part will regulate to the required output voltage as long as it is above the input voltage....
    on Jun 27, 2011

  • Forum Post: Re: TPS61085's off-time is fixed?How to realize?

    Brigitte
    Hello Li, The frequency is given in the typical characteristics Figure 9 and Figure 10 on page 7 of the datasheet. The duty cycle depends on the ratio of the output voltage to the input voltage. The IC measures the output voltage on the SW pin and the input voltage on the IN pin and sets the off...
    on Jun 27, 2011

  • Forum Post: Re: TPS61085 Choice of Inductor

    Brigitte
    Hello Joe, I expect that the IC was not able to deliver the requested output voltage and current with the saturated inductor. Nevertheless, measuring the input and output voltages and if possible the inductor current with an oscilloscope is always recommended with a power supply. The power dissipation...
    on Jul 20, 2011

  • Forum Post: Re: TPS61085 oscillations at SWitch pin

    Chris Glaser
    At lighter loads, your circuit is simply going into DCM or discontinuous operation. The inductor current is reaching zero during each switching cycle. This is ok and unavoidable at lower loads for any non-synchronous converter.
    on Jul 20, 2011

  • Forum Post: Re: TPS61085 oscillations at SWitch pin

    Brigitte
    Hello Joe, A change in the output capacitance will not change the point where the IC reaches power save mode. Just the current in the inductor decides if the IC is in continuous conduction mode or in discontinuous conduction mode. So you are reducing the output current value reaching this point if...
    on Jul 21, 2011

  • Forum Post: Re: TPS61085 - Boost + negative voltage source

    Brigitte
    Hello Laurent, During startup, the voltage on the SS pin limits the peak current of the internal switch. The faster the voltage on SS pin rises, the faster is the full peak current available. So if you have a very small capacitor on the SS pin, the full current limit will be reached immediately and...
    on Oct 27, 2011

  • Forum Post: Re: TPS61085 - Boost + negative voltage source

    Brigitte
    Hello Laurent, The voltage on the softstart pin ramps relatively fast to the 0.3V where the softstart starts. Then the slope is defined by the internal current source connected to the SS pin until the output voltage reaches the nominal value (above you can observe this on the SW pin which switches...
    on Oct 28, 2011

  • Forum Post: Re: TPS61085 - Boost + negative voltage source

    Brigitte
    Hello Laurent, In the above measurement, I interpret waveform 1 being SS pin, waveform 2 being the SW pin and waveform 3 being the output voltage of the negative charge pump. Pleaes correct me if I am wrong. For me this looks as if the input voltage crashes because of the current TPS61085 and the...
    on Oct 31, 2011

  • Forum Post: TPS61085 Voltage Drop on Load

    Kshitij Kumar
    Hello I am using TPS61085 for LCD Backlight glowing. I want to generate 12V @ 600mA on output, from 3.8V,3A lithium-ion battery. I am using the application circuit given in the datasheet of TPS61085, with a 6.8uH inductor. I am getting perfect 12V in NO LOAD condition, But as soon as i...
    on Jan 9, 2012

  • Forum Post: Re: TPS61085 Voltage Drop on Load

    Brigitte
    Hello Kshitij, For a boost converter, the output current is not the same as the switch current. Please check the application note "Basic Calculations of a Boost Converter's Power Stage" SLVA372 for the switch current you have to consider. With the above voltages and currents given...
    on Jan 10, 2012

  • Forum Post: RE: TPS63700 - +/- 12V output

    Chris Glaser
    I would recommend a boost converter with the same circuit instead, such as the TPS61085.
    on Sep 27, 2012

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