Other Parts Discussed in Thread: TPS5401
Tool/software:
Hi
I have made a power Supply Ckt using this TI Module TLVM365R1. Output voltage is set to 3.0V DC
The earlier design used TPS5401 successfully and this ckts it working fine.
The objective to use TLVM365R1 was to reduce cost, component count and create more space on the PCB to place some other parts.
The new Power Supply Ckt using TLVM365R1 is developing 3.3V dc correctly over a large range in Vin from 10V to 20V dc.
This Vin is derived from the secondary of a Transformer 1.3VA with 230V ac input and 9V secondary output.
This output is rectified by Bridge Rectifier to supply Vin from 10V to 20V dc from a large AL EL Capacitor of 470uF, 35V dc.
3.3 V dc is developed correctly with input to the transformer from 120V to 250V ac.
3.3V dc output is measured by a Fluke DMM.
The DMM shows the correct output voltage of 3.3V upto ac input of upto 160V to the transformer.
However, when the input voltage to the transformer is increased beyond 160V, the dc V on DMM shows OL & -Ve alternatively.
The Analog & Digital boards supplied by the 3.3V output are working fine.
It is this reading on the DMM that worries me.
So, I changed the range of DMM from Dc V to ac V.
When this is done, the voltage seen on the DMM is the same as the ac input voltage to the transformer primary!
I tried to connect a 10uF AL EL capacitor between 3.3V & GND. But it exploded into flames!!
Assuming there is some AC voltage coming at 3.3V dc output due to nearby track carrying this AC voltage, how can I suppress this by using an capacitor in parallel or an inductor is series?
Although all CKT connected to the 3.3V DC output from TLVM365R1 are working, I very worried that this ac signal equal to the AC voltage input to the transformer may damage the ckts in field.
The entire power supply ckt is the convert 230V ac to 3.3V dc. Output is less than 50mA, well below the capacity of TLVN365R1.
Would be grateful for your suggestions to find the root cause and then solve this problem.
GGTR UK
