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current limit
Related Posts

  • Forum Post: Re: TPS40131 Over Current Protection

    Peter Miller13277
    Brian, The TPS40131 uses a voltage forced on the ILIM pin to set the current limit in comparison to the peak current sense from the CS+ and CS- pin voltages. The customer could use this pin voltage to generate a current limit which is inversely proportional to the ouptut voltage by sinking a current...
    on Jan 29, 2010

  • Forum Post: Re: TPS40055 Current Limit

    Peter Miller13277
    Saied, There are two components to this, possibly 3, and both are actually working against the current limit over temperature: 1) The temperature dependence of the offset voltage of the SCP. The Offset Voltage (difference between SW and ILIM at current limit) increases (becomes less negative...
    on Jan 29, 2010

  • Forum Post: Re: TPS61026 start up; voltage droop

    Michael Day
    The datasheet is correct. The inductor peak current is equal to the switch peak current. Remember that when the power FET is on, the current flows from through the inductor and into the power FET and then to ground. During the time when the power FET is on, the FET current and inductor current are equal...
    on Apr 12, 2010

  • Forum Post: Re: TPS51315 Peak inductor current calculation.

    Peter Miller13277
    Alek, Vtrip is the voltage drop across the current sense resistor, Rtrip. It is a design value which programs the current limit. It would be R2 in the simplied schematic on page 1 times Itrip specified as 9-11uA in the electrical specifications table on page 4. Rds(on) is the On-State Drain...
    on Jul 22, 2010

  • Forum Post: Re: TPS40180

    Peter Miller13277
    Kurt, Under Voltage Protection is not active until soft-start is declared "complete" This occurs when Soft-start reaches 1V. To ensure regulation, soft-start should not be clamped below 0.8V, but if soft-start is clamped below 1V, the UVP is not active and no shut-down will occur.
    on Aug 17, 2010

  • Forum Post: Re: TPS5450 Current-limit

    JohnTucker
    The EP parts may have different specifications. I don't support those, so I don't keep track of teh exact differences. I can tell you also, that the placement of the input decoupling capacitor is fairly critical for correct operation. Also, the thermal capabilities of teh TPS5450 are at the limit...
    on Sep 14, 2010

  • Wiki Page: TPS62110 low side FET current limit?

    Michael Day
    Q: TPS62110 low side FET current limit? by 9092 Is there any current limiting built into the low side FET on the TPS62110? Thanks! A: Re: TPS62110 low side FET current limit? by 10449 The TPS62110 does not have any low side (synchronous) FET current limiting.
    on Sep 15, 2010

  • Forum Post: Re: TPS40210 boost converter

    Peter Miller13277
    Klaus, Peak Current Mode Control (the style of Pulse Width Modulation used by the TPS40210 controller) compares the control voltage (COMP) to the sensed switch current, terminating the switching pulse when the sensed switching current exceeds the level programmed by the COMP voltage. It is possible...
    on Oct 5, 2010

  • Forum Post: Re: TPS40210 Design Problem for LED Backlight Power Supply

    Peter Miller13277
    Bird, First, I would recommend considering the TPS40211 controller in an LED drive configuration (controller regulates the voltage drop across a series ground resistor rather than the voltage at the top of the LED string) for an LED application. 1. This circuit cannot output 2A if the Rsns is...
    on Oct 5, 2010

  • Forum Post: Re: TPS51116 DDR2

    Peter Miller13277
    Joel, Look at your schematic. On the TPS51116 controller, find the CS pin. What is connected to CS? This pin should either be: Connected to the junction of the source of the low-side FET and a current sense resistor to PGND. In this configuration the current limit is set by the voltage...
    on Oct 26, 2010

  • Forum Post: Re: TPS51116 DDR2

    Peter Miller13277
    Joel, CS is connected to V5IN via 5.1K. The 5.1K value was taken from the TPS51116 datasheet and also from the reference schematic from Freescale. Check the Rdson of your low-side MOSFET. This is being used as the current sense element. The current limit during start-up will me 20-30mV / Rdson...
    on Oct 27, 2010

  • Forum Post: Re: Problems with TPS40200

    Peter Miller13277
    Kyle, The TPS40200 controller current limit function is very fast, but if you programmed the current limit for 5A and you're only able to support resistive loads to 1.65A, it is likely that there is a time-constant mismatch between the IC's VIN pin and the ISNS pin. If you have selected...
    on Dec 8, 2010

  • Forum Post: TPS63020 for constant current LED Driving

    Vladimir Demikh
    Hi, We designed a constant current circuit using the TPS63020. Efficiency is our peimary goal. We used an "active feedback" amplifier. We have two questions: 1) Is the attached design ok? Please see drawing. 2) When voltage goes down from 5v to 3v and then back up to 5v the input current...
    on Dec 26, 2010

  • Forum Post: Re: update about last tps40055 post

    Peter Miller13277
    Massimo, Without looking at what the converter is doing, it's hard to say for certain why this would be occuring, but I can propose a hypothisis that you can verify if you have an oscilloscope: The TPS4005x family of controllers uses a pulse - pulse current limit scheme that both detects the...
    on Jan 7, 2011

  • Forum Post: Re: TPS40055 switching waveforms

    Peter Miller13277
    Massimo, The waveforms you describe are consistant with the pulse-by-pulse current limit issue I described before. 400ns is the minimum pulse width tha an over-current condition can detect while 2.24us is likely the maximum duty cycle at 24V input given the UVLO programming. While I appreciate...
    on Jan 10, 2011

  • Forum Post: Re: TPS61241 overloading behave

    Michael Day
    The TPS61240 and TPS61241 have identical behavior except for maximum output current. When the TPS61240 or TPS61241 opreate into a short circuit, the IC delivers a constant current to the short circuit. This behavior is identical to startup where the IC delivers a constant current with no switching...
    on Jan 12, 2011

  • Forum Post: Re: TPS40195 Overcurrent protection

    Peter Miller13277
    akircan, I understand your concern, however it is not necessary to select a 40A inductor. 1) Under heavy load, the sensing FET will heat up quickly, increasing its Rdson. The Rdson can increase upto 40%, providing a significant increase in available sense voltage and reducing the current...
    on Feb 2, 2011

  • Wiki Page: TPS61240 Overload Current / Maximum Output Current

    Michael Day
    Q: TPS61240 Overload Current / Maximum Output Current by 4339 Hi Experters, We are trying to increase TPS6124x output load and find they will limit output current and no switch anymore. But we can't confirm this operation is normal or abnormal, need your confimation. BTW, we have two...
    on Feb 10, 2011

  • Forum Post: Low duty cycle - high pulse current application

    Darren Carpenter
    I am designing a device that I would like to operate off a USB port as one of the options. That gives me 2.5 watts of power (5 volts @ 500mA) My application has a low impedance device (2.5 ohms or there about) and requires 9 to 12 Volts of supply. This is very high current for a short time (5% duty cycle...
    on Feb 14, 2011

  • Wiki Page: TPS61251 Current Limit

    Michael Day
    Q: TPS61251 Current Limit by 1594102 The TPS61251 EVM was modified to set a maximum input current of 160mA and a 3F supercap was added. During startup, the input current has two different values and changes from one value to another value as the supercap charges. Any ideas on what causes this to occur...
    on Feb 23, 2011

  • Wiki Page: TPS62065 current limit

    Chris Glaser
    Q: TPS62065 current limit by 1589050 How long is it from exceeding current limit to FET doing OFF? A: Re: TPS62065 current limit by 1090425 The current limit is defined and tested as the peak inductor current, which is the peak current in the high side FET. The spec for current limit already...
    on Feb 28, 2011

  • Wiki Page: TPS61251 Current Limit in LDO mode

    Michael Day
    Q: TPS61251 Current Limit in LDO mode by 1594102 When the TPS61251 is operating in the LDO mode (Vout < Vin), how is the current limit determined? A: Re: TPS61251 Current Limit in LDO mode by 10449 There is not a defined spec for the “LDO” mode current so I can't point to...
    on Mar 11, 2011

  • Forum Post: Re: TPS40195 Overcurrent protection

    Peter Miller13277
    If the ILIM pin bias current range of 7 uA for min and 11uA for max is not related to the temperature compension Per page 4 of the electrical specification table, the 7-11uA current source is specifically at Tj = 25C and does not include temperature compensation. The temperature compensation and offset...
    on Mar 21, 2011

  • Forum Post: Supercap on TPS54260 Output - Best Efficiency

    Chris R
    I'm trying to build as energy efficient a system as possible--for 12 to ~30V source voltage operation. I'd like to be able to use a supercap to provide a voltage for a time after power is lost... Is it reasonable to use a supercap (say, for example, .25F) directly on the output rail of the...
    on Apr 27, 2011

  • Wiki Page: TPS62065/7 minimum operating voltage

    Chris Glaser
    Q: TPS62065/7 minimum operating voltage by 21634 Ih TPS62065/7 datasheet, it spec the minimum operating voltage is from 2.9V to 6V. However, the UVLO voltage for this part is 1.95V typical. Can this part be used with input voltage down to 2V? What will be the impact on the performance (in term of...
    on Jul 11, 2011
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