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JWChang
Level 1
Level 1
5 sign-ins First question asked Welcome!

Hello All.

I'm using IR38064 in Tracking Mode. (TRACK_EN# pin is tied to GND.)
Vp is controlled from a external DAC.

For example, set the value of VOUT_OV_FAULT_LIMIT to 4.0V and set the external DAC in tracking mode to adjust the voltage of Vp.
(Because SCALE LOOP is set to 0.125, Vp is Vout / 8 is set.)

Experiment1. If both Vp and VOUT_COMMAND values are increased to 0V to 5V, I checked OVP operates at 4.0V.

Experiment2. If VOUT_COMMAND is set to a fixed value of 3.3V and only the Vp value is increased to 0V to 5V, I checked OVP not works.

1. In Datasheet, OVP is specified as Vp*1.2 in tracking mode.
Is OVP always set to Vp*(SCALE LOOP=8)*1.2 to operate?

2. Is it not releated to the setting value of VOUT_COMMAND(21h) and VOUT_OV_FAULT_LIMIT(40h) set to PMBUS in tracking mode?
(I checked the OVP works by adjusting VOUT_COMMAND and VOUT_OV_FAULT_LIMIT even though it is in tracking mode.)

3. In the case of Experiment2, is there any way to operate OVP at 4.0V?

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1 Solution
Nishanth
Moderator
Moderator
Moderator
100 solutions authored 10 likes given 100 replies posted

Hello @JWChang ,

Thank you for contributing to the Infineon community.

Kindly confirm if output voltage tracking (variation of Vout when Vp is varied)is happening in both experiment 1 and Experiment 2.
If yes, until what voltage of Vp output voltage is getting tracked?

Nishanth_0-1668577105757.png

The error amplifier (E/A) has two non-inverting inputs. Ideally, the input with the lowest voltage is used for regulating the output voltage and the other input is ignored. In practice, the voltage of the other input should be about 200mV greater than the low-voltage input so that its effects can completely be ignored.
When you set the output voltage to a particular value there is an internal reference set at one of the non-inverting inputs of the error amplifier. The Vfb pin follows Vp pin till it reaches the reference once this value is reached the internal reference dictates the regulation of output voltage.

Regards,

Nishanth

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1 Reply
Nishanth
Moderator
Moderator
Moderator
100 solutions authored 10 likes given 100 replies posted

Hello @JWChang ,

Thank you for contributing to the Infineon community.

Kindly confirm if output voltage tracking (variation of Vout when Vp is varied)is happening in both experiment 1 and Experiment 2.
If yes, until what voltage of Vp output voltage is getting tracked?

Nishanth_0-1668577105757.png

The error amplifier (E/A) has two non-inverting inputs. Ideally, the input with the lowest voltage is used for regulating the output voltage and the other input is ignored. In practice, the voltage of the other input should be about 200mV greater than the low-voltage input so that its effects can completely be ignored.
When you set the output voltage to a particular value there is an internal reference set at one of the non-inverting inputs of the error amplifier. The Vfb pin follows Vp pin till it reaches the reference once this value is reached the internal reference dictates the regulation of output voltage.

Regards,

Nishanth

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