TPS25750: 电源管理论坛

pengchao wang

Part Number: TPS25750
Other Parts Discussed in Thread: BQ25792,

Hello，

We use a PD induction chip to obtain a voltage of 20V from TYPE-C and input it to the BQ25792 input terminal. A 10.5K Ω resistor is connected to the PROG pin, and the ShipFET in Ship Mode is not connected.The peripheral circuit diagram of BQ25792 is consistent with the circuit diagram at this link(TPS25750: When TPS25750 is used in combination with BQ25792,Part of the time, when the battery is connected first and then the USB PD charger is connected, there is a situation where it cannot be charged - 电源管理论坛 - 电源管理 - E2E 设计支持) ,The circuit at the PD chip can be ignored, and TPS25750 is not used.

Some issues arose during this process, which caused us trouble and we hope to find a solution.

1.When the battery is not present, the input current of BQ25792 seems to be limited to below 1A. Is there any way to lift this restriction?

2.When the battery is not present, we turn off the MOSFET between BAT and SYS.At this point, when the SYS pin is connected to the load, registers 0x3D and 0x3E display that there is a voltage of 9V or more on the SYS pin.But when we use a multimeter to measure, the voltage is only about 6.5V~7V. Is this phenomenon normal?

3.When we add a boost device after the SYS pin to stabilize the voltage at 12V (with a power of approximately 12W), will the voltage at the SYS pin fluctuate and affect the output of the subsequent circuit？

4.When TYPE-C, battery, and rear circuit are present simultaneously, BQ25792 will experience VBUS-OVP and VBAT-OVP faults,but the voltage values read through registers 0x35, 0x36, 0x3B, and 0x3C are all within the normal range.The image captured by the oscilloscope is shown below(The first image shows the voltage at VBUS, and the second image shows the voltage at VBAT).What is the reason for this phenomenon and what are the solutions？

Looking forward to your reply.

21 天前

0 pengchao wang 21 天前

Prodigy 20 points

This post is mainly related to BQ25792 rather than TPS25750

0 Links 21 天前回复 pengchao wang

TI__Mastermind 31160 points

Hello!

We have received your case and will take some time. Thank you for your patience.

0 Links 20 天前

TI__Mastermind 31160 points

Hi Links,

1.When the battery is not present, the input current of BQ25792 seems to be limited to below 1A. Is there any way to lift this restriction?

Is the device reporting a BATOVP here? What is your ILIM_HIZ resistor value? What is your IINDPM register setting?

2.When the battery is not present, we turn off the MOSFET between BAT and SYS.At this point, when the SYS pin is connected to the load, registers 0x3D and 0x3E display that there is a voltage of 9V or more on the SYS pin.But when we use a multimeter to measure, the voltage is only about 6.5V~7V. Is this phenomenon normal?

What is your VSYSMIN? I would not trust the ADC readings to be accurate here.

3.When we add a boost device after the SYS pin to stabilize the voltage at 12V (with a power of approximately 12W), will the voltage at the SYS pin fluctuate and affect the output of the subsequent circuit？

We will current limit. I don't know that 12W output will cause the output to fluctuate. Are you seeing this happen?

4.When TYPE-C, battery, and rear circuit are present simultaneously, BQ25792 will experience VBUS-OVP and VBAT-OVP faults,but the voltage values read through registers 0x35, 0x36, 0x3B, and 0x3C are all within the normal range.The image captured by the oscilloscope is shown below(The first image shows the voltage at VBUS, and the second image shows the voltage at VBAT).What is the reason for this phenomenon and what are the solutions？

VBATOVP normally occurs when there is no battery present. The current will ramp up the battery voltage very quickly and the device will not respond before reaching the OVP threshold. The best way to avoid this is to always have a battery present on the device.