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  • Automotive Power Supply Reference Design With Three Outputs Using PMIC and LDOs

    • TIDT289 July   2022

       

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  • Automotive Power Supply Reference Design With Three Outputs Using PMIC and LDOs
  1.   Description
  2.   Features
  3.   Applications
  4. 1Test Prerequisites
    1. 1.1 Voltage and Current Requirements
    2. 1.2 Considerations
    3. 1.3 Dimensions
  5. 2Testing and Results
    1. 2.1 Efficiency Graphs
    2. 2.2 Load Regulation
      1. 2.2.1 Output Voltage 1 (1.1 V)
      2. 2.2.2 Output Voltage 2 (3.3 V)
    3. 2.3 Thermal Images
    4. 2.4 Bode Plots
      1. 2.4.1 Output Voltage 1 (1.1 V at 6 A)
      2. 2.4.2 Output Voltage 2 (3.3 V at 1 A)
  6. 3Waveforms
    1. 3.1 Switching
      1. 3.1.1 Output Voltage 1 (1.1 V at 6 A)
        1. 3.1.1.1 Test Point TP3may be TP3 can be linked to the schematic which will be uploaded with the design (Pin SW_B0)
        2. 3.1.1.2 Test Point TP9may be TP9 can be linked to the schematic which will be uploaded with the design (Pin SW_B1)
      2. 3.1.2 Output Voltage 2 (3.3 V at 1 A)
    2. 3.2 Output Voltage Ripple
      1. 3.2.1 VOUT1 (1.1 VD at 6 A) and VOUT2 (3.3 V at 1 A)
      2. 3.2.2 VOUT3 (2.5 V at 0.3 A) and VOUT4 (1.1 V at 0.4 A)
    3. 3.3 Input Voltage Ripple
    4. 3.4 Load Transients
      1. 3.4.1 Switching Load on Output Voltage 1 (1.1 VD)
        1. 3.4.1.1 Output Voltage 1 (VOUT1)
        2. 3.4.1.2 Cross Talking on VOUT2 (3.3 V)
      2. 3.4.2 Switching Load on Output Voltage 2 (3.3 V)
    5. 3.5 Start-Up Sequence
      1. 3.5.1 Hot Plug-In
      2. 3.5.2 Enable with Switch S1
        1. 3.5.2.1 All Traces
        2. 3.5.2.2 Without VOUT1
        3. 3.5.2.3 Without VOUT4
    6. 3.6 Shutdown Sequence
      1. 3.6.1 Hot Plug Off
      2. 3.6.2 Disable With Switch S1
        1. 3.6.2.1 All Traces
        2. 3.6.2.2 Without VOUT1
        3. 3.6.2.3 Without VOUT4
  7. IMPORTANT NOTICE
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TEST REPORT

Automotive Power Supply Reference Design With Three Outputs Using PMIC and LDOs

Description

This multi-output supply powers a custom ASIC out of 5-V input voltage via multichannel IC (PMIC) LP87653-Q1. Despite this PMIC having four rails, phase #3 is unused and 1.1 VA ("A" ⇒ analog; for sensitive loads) is generated via low-dropout regulator (LDO) on customer demand. LDO is used for 2.5 VA and the 1.1 VA is TPS745-Q1. Both LDOs are powered out of 3.3 V. To lower the losses of the LDO 1.1 VA, two power resistors are added to the input.

Features

  • Automotive power supply to energize a custom ASIC out of 5-V input
  • I/O, to enable a LMK00804 level translator, for example
  • Individual sequencing, first 3.3 V, then 2.5 V, and then 1.1 V (buck and LDO), the start-up of the 1.1-V outputs are delayed 11 ms
  • Dual-stage differential input filter to attenuate switching frequency and harmonics as well as RF noise
  • I²C bus for control and monitoring on the fly

Applications

  • Mechanically scanning LIDAR

GUID-20220609-SS0I-QNDD-8DBC-FZZHBSN6CF1W-low.jpgTop Photo
GUID-20220609-SS0I-QNZD-VMMM-71W5KHQJPZ56-low.jpgBottom Photo

1 Test Prerequisites

1.1 Voltage and Current Requirements

Table 1-1 Voltage and Current Requirements
Parameter Specifications
Input Voltage Range 5 V
Output Voltage 1 1.1 V at 6 AMAX
Output Voltage 2 3.3 V
Output Voltage 3 2.5 V at 0.4 AMAX
Output Voltage 4 1.1 V at 0.4 AMAX
Switching Frequency 2 MHz

 
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