SNVS511U June   2007  – January 2018 LP3907

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application Circuit
  4. 4 Revision History
  5. 5 Device Comparison Tables
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions (Bucks)
    4. 7.4  Thermal Information
    5. 7.5  General Electrical Characteristics
    6. 7.6  Low Dropout Regulators, LDO1 And LDO2
    7. 7.7  Buck Converters SW1, SW2
    8. 7.8  I/O Electrical Characteristics
    9. 7.9  Power-On Reset (POR) Threshold/Function
    10. 7.10 I2C Interface Timing Requirements
    11. 7.11 Typical Characteristics — LDO
    12. 7.12 Typical Characteristics — Bucks
    13. 7.13 Typical Characteristics — Buck1
    14. 7.14 Typical Characteristics — Buck2
    15. 7.15 Typical Characteristics — Bucks
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 DC-DC Converters
        1. 8.3.1.1 Linear Low Dropout Regulators (LDOs)
        2. 8.3.1.2 No-Load Stability
        3. 8.3.1.3 LDO and LDO2 Control Registers
      2. 8.3.2 SW1, SW2: Synchronous Step-Down Magnetic DC-DC Converters
        1. 8.3.2.1  Functional Description
        2. 8.3.2.2  Circuit Operation Description
        3. 8.3.2.3  PWM Operation
        4. 8.3.2.4  Internal Synchronous Rectification
        5. 8.3.2.5  Current Limiting
        6. 8.3.2.6  PFM Operation
        7. 8.3.2.7  SW1, SW2 Operation
        8. 8.3.2.8  SW1, SW2 Control Registers
        9. 8.3.2.9  Soft Start
        10. 8.3.2.10 Low Dropout Operation
        11. 8.3.2.11 Flexible Power Sequencing of Multiple Power Supplies
        12. 8.3.2.12 Power-Up Sequencing Using the EN_T Function
      3. 8.3.3 Flexible Power-On Reset (Power Good with Delay)
      4. 8.3.4 Undervoltage Lockout
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
    5. 8.5 Programming
      1. 8.5.1 I2C-Compatible Serial Interface
        1. 8.5.1.1 I2C Signals
        2. 8.5.1.2 I2C Data Validity
        3. 8.5.1.3 I2C Start and Stop Conditions
        4. 8.5.1.4 Transferring Data
      2. 8.5.2 Factory Programmable Options
    6. 8.6 Register Maps
      1. 8.6.1 LP3907 Control Registers
        1. 8.6.1.1  Interrupt Status Register (ISRA) 0x02
        2. 8.6.1.2  Control 1 Register (SCR1) 0x07
        3. 8.6.1.3  EN_DLY Preset Delay Sequence After EN_T Assertion
        4. 8.6.1.4  Buck and LDO Output Voltage Enable Register (BKLDOEN) – 0x10
        5. 8.6.1.5  Buck and LDO Status Register (BKLDOSR) – 0x11
        6. 8.6.1.6  Buck Voltage Change Control Register 1 (VCCR) – 0x20
        7. 8.6.1.7  Buck1 Target Voltage 1 Register (B1TV1) – 0x23
        8. 8.6.1.8  Buck1 Target Voltage 2 Register (B1TV2) – 0x24
        9. 8.6.1.9  Buck1 Ramp Control Register (B1RC) - 0x25
        10. 8.6.1.10 Buck2 Target Voltage 1 Register (B2TV1) – 0x29
        11. 8.6.1.11 Buck2 Target Voltage 2 Register (B2TV2) – 0x2A
        12. 8.6.1.12 Buck2 Ramp Control Register (B2RC) - 0x2B
        13. 8.6.1.13 Buck Function Register (BFCR) – 0x38
        14. 8.6.1.14 LDO1 Control Register (LDO1VCR) – 0x39
        15. 8.6.1.15 LDO2 Control Register (LDO2VCR) – 0x3A
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Custom Design With WEBENCH® Tools
        2. 9.2.2.2 Component Selection
          1. 9.2.2.2.1 Inductors for SW1 And SW2
            1. 9.2.2.2.1.1 Method 1:
            2. 9.2.2.2.1.2 Method 2:
          2. 9.2.2.2.2 External Capacitors
        3. 9.2.2.3 LDO Capacitor Selection
          1. 9.2.2.3.1 Input Capacitor
          2. 9.2.2.3.2 Output Capacitor
          3. 9.2.2.3.3 Capacitor Characteristics
          4. 9.2.2.3.4 Input Capacitor Selection for SW1 And SW2
          5. 9.2.2.3.5 Output Capacitor Selection for SW1, SW2
          6. 9.2.2.3.6 I2C Pullup Resistor
        4. 9.2.2.4 Operation Without I2C Interface
          1. 9.2.2.4.1 High VIN High-Load Operation
          2. 9.2.2.4.2 Junction Temperature
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
    1. 10.1 Analog Power Signal Routing
  11. 11Layout
    1. 11.1 DSBGA Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Thermal Considerations of WQFN Package
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
        1. 12.1.1.1 Custom Design With WEBENCH® Tools
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Trademarks
    4. 12.4 Receiving Notification of Documentation Updates
    5. 12.5 Community Resources
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

8.5.1.4 Transferring Data

Every byte put on the SDA line must be eight bits long, with the most significant bit (MSB) being transferred first. Each byte of data has to be followed by an acknowledge bit. The acknowledged related clock pulse is generated by the master. The transmitter releases the SDA line (HIGH) during the acknowledge clock pulse. The receiver must pull down the SDA line during the 9th clock pulse, signifying acknowledgment. A receiver which has been addressed must generate an acknowledgment (“ACK”) after each byte has been received.

After the START condition, the I2C master sends a chip address. This address is seven bits long followed by an eighth bit which is a data direction bit (R/W).

NOTE

According to industry I2C standards for 7-bit addresses, the MSB of an 8-bit address is removed, and communication actually starts with the 7th most significant bit. For the eighth bit (LSB), a “0” indicates a WRITE and a “1” indicates a READ. The second byte selects the register to which the data is written. The third byte contains data to write to the selected register.

The LP3907 has factory-programmed I2C addresses. The WQFN chip has a chip address of 60'h, while the DSBGA chip has a chip address of 61'h.

LP3907 30017818.gifFigure 41. I2C Chip Address (see note above)
LP3907 30017819.gif
w = write (SDA = “0”)
r = read (SDA = “1”)
ack = acknowledge (SDA pulled down by either master or slave)
rs = repeated start
id = LP3907 WQFN chip address: 0x60; DSBGA chip address: 0x61
Figure 42. I2C Write Cycle

When a READ function is to be accomplished, a WRITE function must precede the READ function, as shown in the Read Cycle waveform.

LP3907 30017824.gifFigure 43. I2C Read Cycle