[SOLVED] Power consumption of TDA8029 USIM controller with 3V/5V cards

we are using TDA8029 in one of our application board. Just a summary of the circuit.

TDA8029 in our board connects a USIM card and reads the data and sends on UART.

In our board, 2 supply inputs of TDA8029 VDD, VDCIN are connected to 3.3V and we have support for 3V and 5V cards.

We need to find the TDA8029 current consumption for below 2 cases

VDD=VDCIN=3.3V and 3V card
VDD=VDCIN=3.3V and 5V card
Below picture shows current consumption for other cases.



There is no support from manufacturer currently. How to interpolate/approximate the current for the above 2 cases.

One more thing, as Card power is driven from controller after detecting the card, for table shared above in picture.

for VDD=2.7V 5V card Idd = 250mA but card current is 65mA --> Actual TDA8029 current consumption is 250-65= 185mA

For VDD=2.7, 3V card TDA8029 alone current 125-50 = 75mA (excluding card current)

For VDD=5V, 3V card TDA8029 alone current 65-50 = 15mA

All these 3 situations are giving 3 different values of current consumption for TDA8029, which i couldn't able to interpret correctly. What could be wrong. please help.

There are similar controllers from other manufacturers with 80C51 core like SEC1120/SEC1100 or 73S1209F - These controllers have very less current consumption in 10-30mA.

Is there any issue with datasheet or my interpretation.?

Hi,

Did you measure these values?

I don't understand where the values come from.

Klaus

that's snap from TDA8029 datasheet, i want current consumption for different scenario as mentioned in my question.

Hi,

the datasheet values are "max" only values. You shouldn´t treat them as typical continous values.
I have to agree, that the datasheet isn´t very informative in regard of power consumption.

But you say "we are using TDA8029"... so why don´t you simply measure it?

Klaus

We don't have that board(old version of board designed few years back we are modifying that board) with us currently. No measured data even. As i said in 1st msg, TDA8029 current consumption varied from 15mA to 75mA to max 185mA for different cases. It's very unusual. When there is no correlation between values, it's hard to arrive for current consumption for other conditions. If somebody has any EVB or used this board can give more accurate values.

The simple problem behind your question is that you apparently don't understand TDA8029 DC/DC converter operation. Respectively your current "calculations" Idd - card current can't give the internal device power consumption and are meaningless.

The calculation could make more sense if you calculate in power rather than current units, but you still need to consider DC/DC converter efficiency to estimate the controller net power consumption.

As a matter of fact, card power is the dominant share of the total power requirement and also can't be reduced at will, that's apparently why NXP focussed on maximum input current for different configurations. It should be almost easy to estimate the maximum and typical current consumption for different input supply voltage levels, presumed you know the actual card current.

" It should be almost easy to estimate the maximum and typical current consumption for different input supply voltage levels, presumed you know the actual card current."
I want to confirm board means our application where we used TDA8029 USIM controller to access USIM card/Smart card. Card power is very clear from datasheet (Icc) or from standard ISO7816-3. Max Card current for 5V USIM card is 65mA (this is mentioned in datasheet as well the snap i attached in mail) - So, from this, i feel i know card current exactly..

"The simple problem behind your question is that you apparently don't understand TDA8029 DC/DC converter operation." --> Yes, I need your help in understanding TDA8029 DC/DC converter operation (it is a switched capacitor converter) Section 8.11 of page 41 of TDA8029(datasheet attached) has details regarding modes and operation of DC-DC converter. for my cases Either doubler/tripler this operates. In which case output voltage of DC-DC is 2*3.3=6.6V (doubler)/ 3*3.3 = 9.9V (trippler) - these both values are not looking like correct as i have VCC =3V/5V (cards suppoorted).

Please note Idd is total controller current including USIM card current. Icc/Vcc are card voltages/currents which are generated from controller.

I would consider linear voltage regulation after the switched capacitor doubler/trippler. Respectively the converter input current will be minimum double/threefold the card current.

Expect a surcharge for the clock driver which is also supplied by the DC/DC. Plus the controller supply current at Vdd.

In my view, the simple scheme would be sufficient for a rough estimation of input current in different configurations. Particularly there won't be a big Vdd current variation between 2.7 and 3.3V Vdd.

I got current measured from counter parts. max current for 5V card <30mA ( it is similar to other equalent manufacturer parts like SEC1120).