TPSM365R6FEVM: ok

Hi,

Datasheet Page 10 mentions the test condition for 4uA current: VIN = 24 V, VBIAS = 3.3-V VOUT, IOUT = 0 A, FPWM mode (fixed output voltage). The IC on EVM is TPSM365R6FRDNR and this is the variant of adjustable Vo. (details on Page3 device comparison table)

Regards,

Hongjia

Hello,
I have the same problem. At no load condition I mesure consomption about 12mA. I also mesure 3.32V at the VCC capacitor, which is out of the specification, and the noise of the switching is visible on the VCC

I have played with the capacitors ESR but no changes exept if the value is inappropriable high.

So, what is the Iq current at no load for the ajustable vertion of the regulator and is it normal to have 3.32V at VCC pin?

Please advise.

Regards,
Emil

Hi Emil,

1. Datasheet section 8.5 lists the Iq for adjustable option. 

2. VCC is in the range of 3.125 to 3.22V and it's probably the noise when you measure the signal that makes VCC high. 

Regards,

Hongjia

Hello Hongjia-Wu,

Thank you for the quick answer!

I am reading once again the DS and do not see what the ISUPPLY current will be while there is no load and the regulator is running. The only parameter avaliable for ajustable version is IQ_24p0_Adj given as a Non-switching input current. 

So, when the EN is high and there is no load what current consumtion is expected ? Is the 12mA normal ?

Regarding the VCC the nois is  about 90mVpp for the spikes. The RMS contribution of the nois is less then 6mV. What I say is that the RMS valule of VCC is higher then the specified. 

Just to mention that there is heat rise about 15°C at 24V with no load!

Regards,
Emil

Hi Emil,

Is the device running with FPWM mode? If so, the no load input current can be mA level. Regarding the thermal issue you observed under no load, can you make the device run at full load and capture the thermal image? 

Regards,

Hongjia

Hello again,

@ T°amb = 25.6°C
Vin=24.000V
Vout=7.182V
Iout=0.599A

After 5 min T°pkg = 58.7°C

at no load the 12mA are invariable in regard of the Vin changes in the range 12-42V


Else, seems that we get the wrong part number i.e. TPSM365R6FRDNR
We will try with TPSM365R6RDNR but anyway I am concerned that VCC is out of limit.


So what Isupply at no load to expect for TPSM365R6RDNR ?
Is IQ_24p0_Adj = 24 µAmax  applicble ?

Thanx in advance!

Regards,
Emil

Hi Emil,

Datasheet Page40 shows the thermal performance of the device with 1MHz and 2.2MHz. What is your frequency setting? The temperature you tested at full load looks reasonable.  

I tested on TPSM365R6EVM (IC: TPSM365R6RDNR) with the default setup and when Vin=24V, Vo=5V, no load, Iin=170uA. 

Please note the test condition for the 24 µAmax current, FB is pulled high so there is no switching. 

Regards,

Hongjia

Hello Hongjia,

As I mentioned I use TPSM365R6FRDNR. I can test the TPSM365R6RDNR next week when I get the part.

The frequency setting is 2.2 MHz (RT INPUT to GND).

Regarding the themperature:
I see T°pkg = 58.7°C at full load, which is with about 10°C more in regard of the datasheet - the difference I mesure at no load condition. 

in=170uA is pretty ok, but I see 12mA instead (yes, in FPWM mode) and higrer VCC. I am wandering if this is a problem in the cirquit as the initial question on the topic.

So, if I understand correctly  can expect at no load; Vin=24; Fsw=2,2MHz; for

TPSM365R6FRDNR Iin= abput 6-13mA
TPSM365R6  RDNR Iin= abput 170uA

Is it correct ?

Regards,
Emil

Hi Emil,

I don't have TPSM365R6FEVM in hand so I cannot tell the exact Iq for FPWM variant. I need to apply an EVM to test and it will take around 1-2 week for the EVM to arrive. But definitely PFM will have much lower Iq at no load. Do you have to get an exact number? Please let me know if you need it. 

Regards,

Hongjia

Hi Emil,

As there is no response for quite a few days, I will close the thread. Let me know if you have further questions.

Regards,

Hongjia