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# TPS61020: Enable pin threshold level question

Part Number: TPS61020
Other Parts Discussed in Thread: MSP430G2353

Situation: VBAT = Li+ battery, single cell, 4.2V fully charged. TPS61020 boosts this to a 5V level.

1) Per the data sheet, the EN input requires a minimum of 0.8*Vbat.

How much leeway there is on the EN minimum high voltage, VIH. The reason I ask it that way is that the minimum EN voltage would be 3.36V (0.8*4.2) with a fully charged battery.  The EN circuit is driven by a digital output (P1.7/CAOUT/UCB0SIMO/UCB0SDA/A7/CA7/TDO/TDI) of an MSP430G2353 that's power supply is a 3V.   So, at the best

possible scenario, the EN circuit voltage from the MSP430 is <= 3V. So theoretically, with a fully charged battery, the EN pin would never reach a high enough voltage to EN the chip.

2) If the battery voltage is low (prior to being charged) such that the 0.8*Vbatt EN voltage is met by the MSP430, what happens as the battery voltage rises as the battery is charged. Will the EN circuit shut the TP61026 off once the 0.8*Vbatt requirement is no longer met. Or, once on, does the EN pin require the voltage to drop even more, ie, some hysteresis?  If so, what is the it?

Thanks!

• Hello
we don't know if the logic is high or low when the voltage is between 0.8*VBAT and 0.2*VBAT. so you need make sure the voltage is not within this range. you may need to add a NPN to implement the logic high and low for this device.

or you can change to other better performance boost converter, because the TPS61020 is very old device.
• I agree - just like with any Logic IC, the state of the logic function is unknown/indeterminate when the input(s) are between VIL and VIH.
Applying this logic (no pun intended) to question #2 above - the TPS6102x will enter a disabled state as VBAT rises to a point where the VIH minimum level is no longer satisfied - and that point (below VIH) is not defined/unknown.
And, yes, I plan on implementing a transistor to get around this issue.