SNVSBK2 September   2019 LP8733

PRODUCTION DATA.  

  1. Features
    1.     Simplified Schematic
  2. Applications
  3. Description
    1.     DC/DC Efficiency vs Output Current
  4. Revision History
  5. Pin Configuration and Functions
    1.     Pin Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 I2C Serial Bus Timing Parameters
    7. 6.7 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  DC/DC Converters
        1. 7.3.1.1 Overview
        2. 7.3.1.2 Dual-Phase Operation and Phase-Adding/Shedding
        3. 7.3.1.3 Transition Between PWM and PFM Modes
        4. 7.3.1.4 Dual-Phase Switcher Configurations
        5. 7.3.1.5 Buck Converter Load Current Measurement
        6. 7.3.1.6 Spread-Spectrum Mode
      2. 7.3.2  Sync Clock Functionality
      3. 7.3.3  Low-Dropout Linear Regulators (LDOs)
      4. 7.3.4  Power-Up
      5. 7.3.5  Regulator Control
        1. 7.3.5.1 Enabling and Disabling Regulators
        2. 7.3.5.2 Changing Output Voltage
      6. 7.3.6  Enable and Disable Sequences
      7. 7.3.7  Device Reset Scenarios
      8. 7.3.8  Diagnosis and Protection Features
        1. 7.3.8.1 Power-Good Information (PGOOD pin)
          1. 7.3.8.1.1 PGOOD Pin Gated Mode
          2. 7.3.8.1.2 PGOOD Pin Continuous Mode
        2. 7.3.8.2 Warnings for Diagnosis (Interrupt)
          1. 7.3.8.2.1 Output Power Limit
          2. 7.3.8.2.2 Thermal Warning
        3. 7.3.8.3 Protection (Regulator Disable)
          1. 7.3.8.3.1 Short-Circuit and Overload Protection
          2. 7.3.8.3.2 Overvoltage Protection
          3. 7.3.8.3.3 Thermal Shutdown
        4. 7.3.8.4 Fault (Power Down)
          1. 7.3.8.4.1 Undervoltage Lockout
      9. 7.3.9  Operation of the GPO Signals
      10. 7.3.10 Digital Signal Filtering
    4. 7.4 Device Functional Modes
      1. 7.4.1 Modes of Operation
    5. 7.5 Programming
      1. 7.5.1 I2C-Compatible Interface
        1. 7.5.1.1 Data Validity
        2. 7.5.1.2 Start and Stop Conditions
        3. 7.5.1.3 Transferring Data
        4. 7.5.1.4 I2C-Compatible Chip Address
        5. 7.5.1.5 Auto-Increment Feature
    6. 7.6 Register Maps
      1. 7.6.1 Register Descriptions
        1. 7.6.1.1  DEV_REV
          1. Table 8. DEV_REV Register Field Descriptions
        2. 7.6.1.2  OTP_REV
          1. Table 9. OTP_REV Register Field Descriptions
        3. 7.6.1.3  BUCK0_CTRL_1
          1. Table 10. BUCK0_CTRL_1 Register Field Descriptions
        4. 7.6.1.4  BUCK0_CTRL_2
          1. Table 11. BUCK0_CTRL_2 Register Field Descriptions
        5. 7.6.1.5  BUCK1_CTRL_1
          1. Table 12. BUCK1_CTRL_1 Register Field Descriptions
        6. 7.6.1.6  BUCK1_CTRL_2
          1. Table 13. BUCK1_CTRL_2 Register Field Descriptions
        7. 7.6.1.7  BUCK0_VOUT
          1. Table 14. BUCK0_VOUT Register Field Descriptions
        8. 7.6.1.8  BUCK1_VOUT
          1. Table 15. BUCK1_VOUT Register Field Descriptions
        9. 7.6.1.9  LDO0_CTRL
          1. Table 16. LDO0_CTRL Register Field Descriptions
        10. 7.6.1.10 LDO1_CTRL
          1. Table 17. LDO1_CTRL Register Field Descriptions
        11. 7.6.1.11 LDO0_VOUT
          1. Table 18. LDO0_VOUT Register Field Descriptions
        12. 7.6.1.12 LDO1_VOUT
          1. Table 19. LDO1_VOUT Register Field Descriptions
        13. 7.6.1.13 BUCK0_DELAY
          1. Table 20. BUCK0_DELAY Register Field Descriptions
        14. 7.6.1.14 BUCK1_DELAY
          1. Table 21. BUCK1_DELAY Register Field Descriptions
        15. 7.6.1.15 LDO0_DELAY
          1. Table 22. LDO0_DELAY Register Field Descriptions
        16. 7.6.1.16 LDO1_DELAY
          1. Table 23. LDO1_DELAY Register Field Descriptions
        17. 7.6.1.17 GPO_DELAY
          1. Table 24. GPO_DELAY Register Field Descriptions
        18. 7.6.1.18 GPO2_DELAY
          1. Table 25. GPO2_DELAY Register Field Descriptions
        19. 7.6.1.19 GPO_CTRL
          1. Table 26. GPO_CTRL Register Field Descriptions
        20. 7.6.1.20 CONFIG
          1. Table 27. CONFIG Register Field Descriptions
        21. 7.6.1.21 PLL_CTRL
          1. Table 28. PLL_CTRL Register Field Descriptions
        22. 7.6.1.22 PGOOD_CTRL_1
          1. Table 29. PGOOD_CTRL_1 Register Field Descriptions
        23. 7.6.1.23 PGOOD_CTRL_2
          1. Table 30. PGOOD_CTRL_2 Register Field Descriptions
        24. 7.6.1.24 PG_FAULT
          1. Table 31. PG_FAULT Register Field Descriptions
        25. 7.6.1.25 RESET
          1. Table 32. RESET Register Field Descriptions
        26. 7.6.1.26 INT_TOP_1
          1. Table 33. INT_TOP_1 Register Field Descriptions
        27. 7.6.1.27 INT_TOP_2
          1. Table 34. INT_TOP_2 Register Field Descriptions
        28. 7.6.1.28 INT_BUCK
          1. Table 35. INT_BUCK Register Field Descriptions
        29. 7.6.1.29 INT_LDO
          1. Table 36. INT_LDO Register Field Descriptions
        30. 7.6.1.30 TOP_STAT
          1. Table 37. TOP_STAT Register Field Descriptions
        31. 7.6.1.31 BUCK_STAT
          1. Table 38. BUCK_STAT Register Field Descriptions
        32. 7.6.1.32 LDO_STAT
          1. Table 39. LDO_STAT Register Field Descriptions
        33. 7.6.1.33 TOP_MASK_1
          1. Table 40. TOP_MASK_1 Register Field Descriptions
        34. 7.6.1.34 TOP_MASK_2
          1. Table 41. TOP_MASK_2 Register Field Descriptions
        35. 7.6.1.35 BUCK_MASK
          1. Table 42. BUCK_MASK Register Field Descriptions
        36. 7.6.1.36 LDO_MASK
          1. Table 43. LDO_MASK Register Field Descriptions
        37. 7.6.1.37 SEL_I_LOAD
          1. Table 44. SEL_I_LOAD Register Field Descriptions
        38. 7.6.1.38 I_LOAD_2
          1. Table 45. I_LOAD_2 Register Field Descriptions
        39. 7.6.1.39 I_LOAD_1
          1. Table 46. I_LOAD_1 Register Field Descriptions
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Design Requirements
        1. 8.2.1.1 Inductor Selection
        2. 8.2.1.2 Buck Input Capacitor Selection
        3. 8.2.1.3 Buck Output Capacitor Selection
        4. 8.2.1.4 LDO Input Capacitor Selection
        5. 8.2.1.5 LDO Output Capacitor Selection
        6. 8.2.1.6 Current Limit vs. Maximum Output Current
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

Buck Output Capacitor Selection

The output capacitor COUT_BUCK0 and COUT_BUCK1 are shown in Typical Applications. A ceramic local output capacitor of 22 μF is required per phase. Use ceramic capacitors, X7R type; do not use Y5V or F. DC bias voltage characteristics of ceramic capacitors must be considered. The output filter capacitor smooths out current flow from the inductor to the load, which helps maintain a steady output voltage during transient load changes and reduces output voltage ripple. These capacitors must be selected with sufficient capacitance and sufficiently low ESR and ESL to perform these functions. The minimum effective output capacitance to ensure good performance is 10 μF per phase, including the DC voltage rolloff, tolerances, aging, and temperature effects.

The output voltage ripple is caused by the charging and discharging of the output capacitor and due to its RESR. The RESR is frequency dependent (and temperature dependent); ensure the value used for selection process is at the switching frequency of the part. See Table 49.

POL capacitors CPOL_BUCKxcan be used to improve load transient performance and to decrease the ripple voltage. A higher output capacitance improves the load step behavior, reduces the output voltage ripple, and decreases the PFM switching frequency. However, output capacitance higher than 150 μF per phase is not necessarily of any benefit. The output capacitor may be the limiting factor in the output voltage ramp, see Specifications for maximum output capacitance for different slew-rate settings. For large output capacitors, the output voltage might be slower than the programmed ramp rate at voltage transitions, because of the higher energy stored on the output capacitance. Also at start-up, the time required to charge the output capacitor to target value might be longer. At shutdown, the output voltage is discharged to a 0.6 V level using forced-PWM operation. This can increase the input voltage if the load current is small and the output capacitor is large compared to input capacitor. Below the 0.6 V level, the output capacitor is discharged by the internal discharge resistor, and with large capacitor more time is required to settle VOUT down as a consequence of the increased time constant.

Table 49. Recommended Buck Output Capacitors (X7R Dielectric)

MANUFACTURER PART NUMBER VALUE CASE SIZE DIMENSIONS L × W × H (mm) VOLTAGE RATING
Murata GCM31CR71A226KE02 22 µF (10%) 1206 3.2 × 1.6 × 1.6 10 V