LP8733: About LP873347RHDT

Hiroyuki Kanematu

Part Number: LP8733
Other Parts Discussed in Thread: AWR1843

Immediately, I have two questions.

1. Default values of SW_B0 and SW_B1 of LP873347RHDT
When using this IC as a switching regulator, what voltage will come out if no program is written?
By the way, how to connect the circuit is as shown in the attached file.

Please tell me the values of VOUT1 and VOUT2 respectively.
(Input voltage is direct current of 3.3 V)

2. Pin for writing the program
Is it correct to write the LP873347RHDT program (output voltage setting, etc.) on pins 17 and 18?

(As I said in another thread, I heard that there is no problem connecting to the I2C pins (G14, F13) of AWR1843.)

over 2 years ago

0 Hiroyuki Kanematu over 2 years ago

Expert 2975 points

If I want to run LP873347RHDT before mounting, do I have to write a program in advance?
(Do I have to write a program to get the desired output voltage (SW_B0 and SW_B1) before mounting?)

0 Tomi Koskela over 2 years ago

TI__Genius 11020 points

Hello Hiroyuki,

You can see the default settings in this TRM:

/cfs-file/__key/communityserver-discussions-components-files/196/LP873347_5F00_TRM_5F00_snvu679.pdf

Yes pins 17 and 18 are the I2C bus for the device.

You would get the default output voltages when you set the EN pin high. Note it is not possible to reprogram the non-volatile memory settings. You can only change the registers which are volatile (means when you power it down the settings are lost).

In your schematic it seems LDOs are missing the output capacitors. You would get PGOOD fault for these rails if you try to turn on the LDOs without output caps.

Thanks.

Regards,

Tomi Koskela

0 Hiroyuki Kanematu over 2 years ago in reply to Tomi Koskela

Expert 2975 points

Thank you for answering the question.

If you set the EN pin to HIGH, the default voltage will be output, right?
What is that value?

I will not use an LDO this time, but does the LDO still need an output capacitor?

0 Tomi Koskela over 2 years ago in reply to Hiroyuki Kanematu

TI__Genius 11020 points

Hello Hiroyuki,

Did you manage to open the TRM? Default output voltages are listed there.

If you don't populate LDO output capacitors you need to make sure the LDOs are not turned on.

Thanks.

Regards,

Tomi Koskela

0 Hiroyuki Kanematu over 2 years ago in reply to Tomi Koskela

Expert 2975 points

Hello , Thank you for your answer!

>Default output voltages are listed there.
I understood it. I confirm TRM!

>If you don't populate LDO output capacitors you need to >make sure the LDOs are not turned on.
OK, I'll confirm it.

0 Hiroyuki Kanematu over 2 years ago in reply to Hiroyuki Kanematu

Expert 2975 points

If the only way to disable LDO operation is to set it in a register?

Is it impossible to control by connecting the circuit?

0 Hiroyuki Kanematu over 2 years ago in reply to Tomi Koskela

Expert 2975 points

The operation flow of LP873347RHDT is described below.

1. When voltage is input to VANA pin, reading of OTP memory starts.

2. When the reading of the OTP memory is completed, the register bit transmission / reception starts in STANDBY mode. (Output voltage setting, etc.)

3. The desired operation starts after the writing of the register bit is completed.

Is it all right with the above recognition?

By the way, since OTP memory is non-volatile memory, is it okay to recognize that we cannot write here?

0 Tomi Koskela over 2 years ago in reply to Hiroyuki Kanematu

TI__Genius 11020 points

Hello Hiroyuki,

Yes the only way to disable LDOs is with register write.

The sequence you mentioned is correct. And once the OTP is loaded you can keep the EN low and rewrite the settings to the registers (=volatile memory).

The OTP memory content cannot be changed, that is correct.

Thanks.

Regards,

Tomi Koskela

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LP8733: About LP873347RHDT