TPS61240-Q1: Loop response measurement at fixed output device

Hi Kazuki,

No, as long as a high input is detected from FB pin, the external voltage divider is disabled and signals from FB pin is disconnected from the internal divider. If you need to confirm the loop response, use the external FB version to verify and apply fix output version for real application. The loop is the same for external FB and internal divider under the same working condition.

Best Regards,

Travis

Hi Travis,

Based on datasheet's block diagram, TPS61240-Q1 has internal resistor divided and top of this divider is located at FB pin as below.

Therefore, we can measure loop response  by just inserting injection resister betweenFB pin and Vout and we don't need to use external FB resistor type device?

is there any missing point in the block diagram?

Best regards,
Kazuki Kuramochi

Hi Kazuki,

I've checked the device with the design team. Unlike new devices, TPS61240 will not disconnect the internal divider. So you can insert injection resistor between FB pin and output.

Best Regards,

Travis

Hi Travis,

I understand that we can measure loop response with TPS61240-Q1 by injection resistor.

By the way, this is from my curiosity, would you tell me the specific part# of new devices which is disconnected the internal divider?

Best regards,
Kazuki Kuramochi

Hi Kazuki,

For TPS61033, the internal comparator compares FB with a threshold . If FB is pulled to Vout and the FB pin detects a high voltage close to Vout power rail. The device will disconnect the FB pin with external divider and apply the internal fix 5V divider.

Best Regards,

Travis