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Original question:

AWR1843AOP: AWR1843AOP

AWR1843AOP: AWR1843AOP - DCDC and PMIC

hk shin
Prodigy 110 points
Part Number: AWR1843AOP
Other Parts Discussed in Thread: AWR2944EVM, LM76003, LM63635-Q1

Tool/software:

When I use the AWR1843AOP considering truck/bus radar, the power supply must be configured to a maximum input of 29V typical and 60V transient.

Therefore, looking at the AWR2944EVM material, I understand that the PMIC uses a switching frequency outside the IF band, so there is no need to use multiple external LDO.

There is no suitable DCDC IC for the first input stage, but according to TI data, the DCDC (LM76003) IC for 60V switches at 400~500KHz due to heat generation.

(Q1) If I use LM76003(1st regulator) at switching frequency 500KHz, please be sure there is no effect on the ripple voltage(AWR1843AOP) required by the radar 1.0V or 1.8V power supply.

(Q2) When I use LP877451A1RXVRQ1 same as AWR2944EVM,  the default setting value(1.0V/1.2V/1.8V/3.3VIO/5V)  is not any problem?(I want to use SPI bus off state) 

        

Addressing 3 power design challenges for corner radar.pdf

tidm946_schematic.pdf

  • 0
    TI__Guru 73196 points

    Hi hk shin,

    For Q2, the LP877451A1RXVRQ1 OTP detailed settings are included in the Technical Reference Manual SNVU806B found in the secure folder here (fill in the form if you do not yet have access): https://www.ti.com/drr/opn/LP8774X-Q1DOCUMENTS From there you can see the rails included and other OTP settings for the part. Note that this TRM covers both LP877451A1-Q1 and LP87745101-Q1, which differ only on the watchdog setting. Then from the AWR1843AOP datasheet, section 6.5 Power Supply Specifications the power rails are listed:

    Note that the default OTP for LP877451A1RXVRQ1 you mentioned does not have 1.3V but it does have 1V so consider this with the mode you would use on the AWR device. 

    Regards,

    Katie

  • 0 in reply to Katie Pier
    TI__Genius 13110 points

    Hi,

    hk shin said:
    (Q1) If I use LM76003(1st regulator) at switching frequency 500KHz, please be sure there is no effect on the ripple voltage(AWR1843AOP) required by the radar 1.0V or 1.8V power supply.

    What is your input voltage? If it is 12 V from Battery system then LM76003 may not be related. 

    In radar reference design (https://www.ti.com/tool/TIDEP-01030 ), LM63635-Q1 is used and input voltage range is 3.5V to 36V and for 12V input is better.  And it is better for so many reasons. Few are quoting below. 

    1. Functional safety-capable device

    2. Good EMI performance

    3.  Large package size and pins. 

    4.  Main application use for Automotive ADAS

    5. And many you can compare. 

    Regarding low Fsw like 500kHz as opposed to 2.2MHz, solution size would be larger with large external components. 

    Regards,

    Ishtiaque