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Q: TPS61026 boot up problem by 1419131
I am using TPS61026, BQ24070 and BQ27501 to build my Battery management circuit. My AC-DC is 5V 2A, the battery is 3.7V Lithium Ion Battery 2250mAH. The input of TPS61026 is 4.4V and output is 5V. My load is an ARM CPU board (around 240mA) and a 3.5 inch LCD touch screen (around 350-400mA). My problem is I can boot up CPU board but can’t boot up CPU board and LCD at same time. The input of TPS61026 is 4.4V but VOUT is only 1.8V when boot up with LCD. If I power up PM circuit first and put resister as a load, I can get 800mA to 1000mA constantly from TPS61026 VOUT with AC-DC or battery. In my circuit FB pin is NC.
A: Re: TPS61026 boot up problem by 8433
I suspect your problem is a known limitation of the TPS6102x family during startup. The short circuit protection and soft-start circuitry are essentially combined in this part. Therefore, during startup, if the load that the IC sees is excessive, the TPS6102x will stop in one of its 4 startup phases. Figure 21 and the paragraph before it gives you some insite into why this happens. Two possible solutions are either to stagger the statup of the load circuitry or place a FET in series with the TPS61026 output voltage to isolate it from the load until the IC has fully started.
Q: Re: TPS61026 boot up problem by 1419131
Thanks Jeff. I will try with a FET and let you know.
A: Re: TPS61026 boot up problem by 10449
Can you confirm that the problem is startup related. Measure the inductor current on an oscilloscope. If the peak current is 40% of the nromal peak current (Isw Switch Current Limit), then it is a simple startup problem.
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