power consumption still high in power down modes?

[hg-chen]

Posted on May 30, 2007 at 07:10

power consumption still high in power down modes?

[hg-chen]

Posted on May 17, 2007 at 10:19

What to check if power consumption is still too high while entering power down modes?

ex. enter the standby mode with STR711FR2 ,

10 mA is measured ,but the data sheet shown should be 20uA?

[sofiene]

Posted on May 25, 2007 at 05:28

Be sure that you have well configured the PCU_PWRCR register to enter in Standby mode:

PCU->PWRCR |= 0x8000; /* Disable write protect in PCU_PWRCR */

PCU->PWRCR |= 0x0040; /* Enter in Standby mode */

and be sure that you have measured the consumption on V33 pin (the power input of the microcontroller).

[hg-chen]

Posted on May 25, 2007 at 06:51

thank you

however,normally the power consumption requirement is for whole application,especially with battery power!

so I think the major issue is what should we check about the peripheral

component arragement ? ex. resisitor and capacitor values choosed?

or any other firmware action needed to be check for entering power

down mode to ensure low power consumption,

Is there any guideline for checking?

[sofiene]

Posted on May 25, 2007 at 12:27

First, the consumption of STR712 is around 10µA when entering in standby mode(conditions: LP VReg=on, LVD=on, RTC=on) and the measurment is taken on V33 supply input of STR712.

Since you measuring the current consumption of all the board,it may be that there are other components which consume an important current. So if possible, disable or isolate these components from the power to reduce the current consumption.

The resistors values, have an important involevement in the consumption in low power modes, so if possible try to use great resistor values as possible.

[hg-chen]

Posted on May 28, 2007 at 06:06

take IAR STR71X start kit for example, schematic as attached,

the run mode current I measured is around 33mA, while enter in hardware standby mode, the current measured is still 13mA,

what should I do in the circuit to make the current in standby mode

less than 100 uA?

________________

Attachments :

STR-P711_C_Schematic.pdf : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006HtOJ&d=%2Fa%2F0X0000000aPL%2FyjWdH3ZrGoak7hcDstYvQuLSrLp7DBVdQmOgwp0Ouic&asPdf=false

[sofiene]

Posted on May 28, 2007 at 08:29

Ok, please, could you specify where you measure the current in IAR STR71X start kit (on which level)? and which power source do you use: external power or J-Link source?

[hg-chen]

Posted on May 28, 2007 at 08:47

the EXT/J-LINK jumper is the point that I measure the current!

use either external 9V DC supply or J-LINK power source gets the

same result at run mode 33 mA, standby mode 13 mA!

[sofiene]

Posted on May 28, 2007 at 10:43

Measuring the consumption on EXT/J-LINK jumper is not the right procedure to get a current less than 100µA. First, you have after this jumper ''PWR'' LED which consumes a current I = (5v - 2v)/560ohm = 5mA (2v : the LED voltage drop). Do not forget the other components consumption: Regulators, ST3232, STM1001 etc...

However, the STR711FR2 IAR board is not a reference design for low power.

[ This message was edited by: M3allem on 28-05-2007 14:14 ]

[hg-chen]

Posted on May 28, 2007 at 22:28

thanks ,got it!

[sofiene]

Posted on May 30, 2007 at 07:10

Good ;) !