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Hello,
I have a doubt regarding the IRPS5401 tracking mode.
Looking at the UltraZED carrrier card PS schematic, the LDO output is NOT connected to LDO_FB with resistor divider feedback:
From what is seems, the IRPS5401's LDO is configured in NON tracking mode. This is what I understand also from the device evaluation kit user guide (https://www.infineon.com/dgdl/Infineon-UG-IRSP5401Demoboard-UM-v01_02-EN.pdf?fileId=5546d4625e37f35a...)
The guide says that:
Sink/Source (Tracking) mode
Set REG 0x1420 bit [8] (ldo_track_config) to 1
In Tracking mode, VO_LDO must be connected directly to FB_L.
But when I look at the programmed register map from IR PowerIRCenter software (Read All Reg and the Save config file), it results that:
REG 1420h = 72FFh
where the 8th bit is set to 0, which would mean that the LDO is in non-tracking mode.
What am I misunderstanding about this configuration ?
Could someone clarify this ?
Thanks,
Simon
Solved! Go to Solution.
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Hi,
The LDO has 2 modes, tracking, and non-tracking (source only)
It is not possible to have the LDO output 1.8V with FB_L open (or tied to GND)
Thanks,
SPCH
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Hi,
Thanks for posting at Infineon community.
I couldn't find the schematic at the UltraZED carrrier card.
As per the schematic snap shot what you shared, it says VO_LDO and FB_L pins are not connected with Resistive
divider as you said correctly.
At the same time VO_LDO and FB_L pins are not short, they are open. Hardware Configuration must be done to
select any of the mode (either short or keep divider).
Mode Selection Guide
1. Populate hardware divider between VO_LDO and FB_L pins for Non tracking mode and also Set REG 0x1420
bit[8] (ldo_track_config) to 0
2. Short between VO_LDO and FB_L pins for tracking mode and also Set REG 0x1420 bit [8] (ldo_track_config)
to 1.
Please let me know if need any help.
Thanks
SPCH
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Hello @Shiva_C ,
The UltraZED IO Carrrier Card schematic can be found here:
https://www.avnet.com/opasdata/d120001/medias/docus/137/AES-ZU-IOCC-G-schematics.PDF
VO_LDO and LDO_FB ARE NOT shorted, sorry I made a typo, mistake and confusion in my first post.
In fact, R135 and R136 from schematics are not placed (DNP)
For what it seems from the configuration, the tracking mode is disabled, but the IRPS5401 datasheet says, at section 9.20:
The reference voltage for the LDO is nominally 0.5V and hence a resistor divider is needed from Vo_LDO to FB_L
to generate output voltages higher than 0.5V
So it's not clear to me how the 1V8 at the LDO output are generated.
The block schematic for the LDO is the following:
Does the switch closed represent non tracking mode ?
With 1.8 V Delta V 15% on the non inverting input I could explain myself the 1V8 at the output (op amp connected as voltage follower).
Thanks
Simon
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Hi,
The LDO has 2 modes, tracking, and non-tracking (source only)
It is not possible to have the LDO output 1.8V with FB_L open (or tied to GND)
Thanks,
SPCH