Hi!
I'm designing an OMAP3530-system which only requires a simple PMU so I think the TPS65073 would fit well.
However, the design-in Wiki and the TPS6507x documentation is a bit sparse or downright ambigous on a couple of points which I thought I'd ask here:
1) If not using a battery or USB, do you still need to connect any decoupling caps to these pins, as stated in the datasheet?
2) Similarily, how to connect ISET or TS for no-battery/usb operation?
3) The EN_DCDCx inputs, if everything should be per default for the OMAP3530 (1.2v core, 1.2v MPU_IVA, 1.8v IO/MEM), should these be left floating or grounded? The datasheet first says they will be disabled if grounded, then further down it says they should be grounded for default operation...
4) If the led backlight regulator is not needed, do we still need to connect anything to L4, FB_WLED, ISET1/2, ISINK1/2 ?
5) Does the PGOOD output need the fast buffer before connecting to SYS_nRESPWRON or not?
6) Should the I2C-interface be connected to I2C4 on OMAP3530 or to I2C1-3 ? I guess the SmartReflex only works with I2C4, but is this supported in the Linux distribution at all for the TPS65073-OMAP3530 anyway? There is nothing that stops me from programming it manually even if I connect it to I2C4 right?
7) Default is 1.2v output from DCDC2, but the voltage should really be 1.15V on the VCORE. Does this matter? Will it be corrected upon boot by I2C or should the DEF_DCDC2 pin be used to alter this?
8) If I don't need the MMC on the OMAP, are there any drawbacks on using LDO2 for VDAC-voltage 1.8v ?
9) How do I connect the PB_IN and POWER_ON if I just want the system to start upon power-on? I don't have any start-button.
Thanks!
Best regards,
Bjorn W
Sweden
Hi Bjorn,
May be you selected TPS65073 based on specific requirements. Have you looked at TPS65920 as an option?
You can select TPS65920 which is fairly straight forward to use. It is specifically designed for supporting OMAP3 family power sequence. Other connections are easy as it is power companion for OMAP.
If you still want to use TPS65073 then I will forward your query to another person. He will reply to you on this forum.
Regards,
Gandhar.
Regards,Gandhar------------------------------------------------------------------------------------------------------Kindly click the Verify Answer button on this post, if it answers your question.------------------------------------------------------------------------------------------------------
Hello, thanks for the reply,
I just checked the TPS65920 and as far as I see briefly, on the plus side it integrates the USB transceiver which we need, but on the minus side it requires an oscillator as the HFCLK source instead of an xtal and it has a maximum input voltage of 4.5 volts while we have 5.5-6V in right now so that would require some workarounds..
Pricing seems comparable.
I was under the impression that the TPS65073 also is specifically designed for the OMAP3 family with regards to power demands, SmartReflex interface and power sequencing.
If you really don't recommend using the TPS65073 I'll use the TPS65920 instead of course.
Hello Bjorn,
please find answer embedded below
In case you are not using a battery or USB, you can connect both USB and BAT pins to GND.
I would recommend to connect a resistor from ISET to GND and also TS to GND.
Connect a 10kOhm resistor form ISET to GND to program 100mA charge current.
Although the charger is not used do not leave the ISET pin floating.
I would recommend to connect a resitor from TS to GND, that will cuase a temp error ==> disabled the charger.
e.g. connect 1k from TS to GND ==> will cause hig temp error
Do not leave EN_DCDCx pins floating!
The DCDC converters in the TPS65073 are not part of the automatic power up sequence, therfore the the converters need to be enabled by the EN_DCDCx pin.
Have a look at figure 55 in the TPS65073 datasheet.
The reason why the DCDC converters are not part of teh automatic sequence is to support the SYS Off Mode.
If you do no need the SYS OFF mode in your application you can go with the TPS650731 that has the converters part of the automatic power up sequence.
In case the converters are part of the automatic power up sequence the EN_DCDCx pins need to be terminated to GND.
The application schematics figure 55 and figure 57 in the TPS65073 datasheet show the correct connection of the EN_DCDCx pins.
The WLED boost conevrter and current sinks are disabled per default.
You can connect L4, FB_WLED to GND.
I would recommedn to connect a 100kOhm resistor from ISINK1 and ISINK2 to GND.
I can't anwer the question right away, need to double check
The seuqencing is completely different, when you are using LDO2 instead of an exteranl LDO.
Would need to double check if this is fine for the OMAP.
You canleave /PB_IN floating. In case you are using AC as the only supply of the TPS6507x, you can pull- up POWER ON. When AC is detected the TPS6507x starts up.
Bjorn, please refer to the following wiki for information on OMAP35x with TPS65073. http://processors.wiki.ti.com/index.php/OMAP35x_with_TPS65073:_Design_In_Guide
There are certain limitations which are described in the docs. Noteably, you will not be able to take advantage of Class 3 Smart Reflex with the TPS65073. If you are interested in doing detailed power management with Smart Reflex, or taking advantage of the power management built into the Linux distributions from TI, then I would recommend the TPS659xx devices as Gandhar has stated.
If you just want to do basic DVFS then TPS65073 would be adequate.
I've added some comments below.
James
ChristianHoefling Hello Bjorn, please find answer embedded below 1) If not using a battery or USB, do you still need to connect any decoupling caps to these pins, as stated in the datasheet? In case you are not using a battery or USB, you can connect both USB and BAT pins to GND. 2) Similarily, how to connect ISET or TS for no-battery/usb operation? I would recommend to connect a resistor from ISET to GND and also TS to GND. Connect a 10kOhm resistor form ISET to GND to program 100mA charge current. Although the charger is not used do not leave the ISET pin floating. I would recommend to connect a resitor from TS to GND, that will cuase a temp error ==> disabled the charger. e.g. connect 1k from TS to GND ==> will cause hig temp error 3) The EN_DCDCx inputs, if everything should be per default for the OMAP3530 (1.2v core, 1.2v MPU_IVA, 1.8v IO/MEM), should these be left floating or grounded? The datasheet first says they will be disabled if grounded, then further down it says they should be grounded for default operation... Do not leave EN_DCDCx pins floating! The DCDC converters in the TPS65073 are not part of the automatic power up sequence, therfore the the converters need to be enabled by the EN_DCDCx pin. Have a look at figure 55 in the TPS65073 datasheet. The reason why the DCDC converters are not part of teh automatic sequence is to support the SYS Off Mode. If you do no need the SYS OFF mode in your application you can go with the TPS650731 that has the converters part of the automatic power up sequence. In case the converters are part of the automatic power up sequence the EN_DCDCx pins need to be terminated to GND. The application schematics figure 55 and figure 57 in the TPS65073 datasheet show the correct connection of the EN_DCDCx pins. 4) If the led backlight regulator is not needed, do we still need to connect anything to L4, FB_WLED, ISET1/2, ISINK1/2 ? The WLED boost conevrter and current sinks are disabled per default. You can connect L4, FB_WLED to GND. I would recommedn to connect a 100kOhm resistor from ISINK1 and ISINK2 to GND. 5) Does the PGOOD output need the fast buffer before connecting to SYS_nRESPWRON or not? I can't anwer the question right away, need to double check [James] SYS_nRESPWRON has some pretty strict rise time requirements, so adding the buffer just sharpens the edge. I can't remember if PGOOD itself satisfies the requirement. 6) Should the I2C-interface be connected to I2C4 on OMAP3530 or to I2C1-3 ? I guess the SmartReflex only works with I2C4, but is this supported in the Linux distribution at all for the TPS65073-OMAP3530 anyway? There is nothing that stops me from programming it manually even if I connect it to I2C4 right? I can't anwer the question right away, need to double check [James] I2C4 on OMAP3530 is a write only port. It is not a traditional I2C port (like I2C1-3). It was intended to connect only to TPS659xx devices for Smart Reflex functionality. If you use TPS65073, you should connect it to I2C1-3. This is the reason why the Linux power management support as is written today would not support the TPS65073. You would have to write that from scratch if you wanted to do any DVFS or power management. 7) Default is 1.2v output from DCDC2, but the voltage should really be 1.15V on the VCORE. Does this matter? Will it be corrected upon boot by I2C or should the DEF_DCDC2 pin be used to alter this? [James] This is fine, it is typically just adjusted down to 1.15 during initialization 8) If I don't need the MMC on the OMAP, are there any drawbacks on using LDO2 for VDAC-voltage 1.8v ? The seuqencing is completely different, when you are using LDO2 instead of an exteranl LDO. Would need to double check if this is fine for the OMAP. [James] This is fine for OMAP. VDAC voltage really doesn't get involved in the sequencing. It can be turned on/off as the application needs it. 9) How do I connect the PB_IN and POWER_ON if I just want the system to start upon power-on? I don't have any start-button. You canleave /PB_IN floating. In case you are using AC as the only supply of the TPS6507x, you can pull- up POWER ON. When AC is detected the TPS6507x starts up.
[James] SYS_nRESPWRON has some pretty strict rise time requirements, so adding the buffer just sharpens the edge. I can't remember if PGOOD itself satisfies the requirement.
[James] I2C4 on OMAP3530 is a write only port. It is not a traditional I2C port (like I2C1-3). It was intended to connect only to TPS659xx devices for Smart Reflex functionality. If you use TPS65073, you should connect it to I2C1-3. This is the reason why the Linux power management support as is written today would not support the TPS65073. You would have to write that from scratch if you wanted to do any DVFS or power management.
[James] This is fine, it is typically just adjusted down to 1.15 during initialization
[James] This is fine for OMAP. VDAC voltage really doesn't get involved in the sequencing. It can be turned on/off as the application needs it.
Hi and thanks for the information, all of you! I think that answers my specific questions about the TPS65073.
However I would suggest you change the document you point to, the design-in guide for TPS65073 and OMAP35xx because in that it says explicitely that the chip fulfills all requisites for SmartReflex class-3, and also that the Linux driver for the chip is in the TI kernel git-tree, implying at least some support for the power management. Perhaps clarify what is included in the driver and what is not. Also, in the power-management selection guide the TPS65073 is listed as being useable for OMAP35x. If it's not recommended, the drawbacks should be more clearly stated (for example that it is OK for non-SmartReflex use but is not recommended for power-saving designs).
The main problem with the TPS65920 for me was the low maximum voltage input of 4.5V. Also our use-case is not battery-operated, so I don't really need the dynamic scaling actually. But the TPS65920 includes the USB transceiver so it might incur a lower cost overall anyway. I'll have to do some more thinking..
Thanks again,
/Bjorn
JJD Bjorn, please refer to the following wiki for information on OMAP35x with TPS65073. http://processors.wiki.ti.com/index.php/OMAP35x_with_TPS65073:_Design_In_Guide There are certain limitations which are described in the docs. Noteably, you will not be able to take advantage of Class 3 Smart Reflex with the TPS65073. If you are interested in doing detailed power management with Smart Reflex, or taking advantage of the power management built into the Linux distributions from TI, then I would recommend the TPS659xx devices as Gandhar has stated. If you just want to do basic DVFS then TPS65073 would be adequate. I've added some comments below. Regards, James