SLVSB25C August   2011  – June 2015 DRV201

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 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 Data Transmission Timing
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 VCM Driver Output Stage Operation
      2. 7.3.2 Ringing Compensation
    4. 7.4 Device Functional Modes
      1. 7.4.1 Modes of Operation
    5. 7.5 Programming
      1. 7.5.1 I2C Bus Operation
        1. 7.5.1.1 Single Write to a Defined Location
        2. 7.5.1.2 Single Read from a Defined Location and Current Location
        3. 7.5.1.3 Sequential Read and Write
      2. 7.5.2 I2C Device Address, Start and Stop Condition
    6. 7.6 Register Maps
      1. 7.6.1 Register Address Map
      2. 7.6.2 Control Register (Control) Address - 0x02h
      3. 7.6.3 VCM MSB Current Control Register (VCM_Current_MSB) Address - 0x03h
      4. 7.6.4 VCM LSB Current Control Register (VCM_Current_LSB) Address - 0x04h
      5. 7.6.5 Status Register (Status) Address - 0x05h
      6. 7.6.6 Mode Register (Mode) Address - 0x06h
      7. 7.6.7 VCM Resonance Frequency Register (VCM_FREQ) Address - 0x07h
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 VCM Mechanical Ringing Frequency
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 User Example 1
        2. 8.2.2.2 User Example 2
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Community Resources
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

8.1 Application Information

The DRV201 device is a voice coil motor driver designed for camera auto focus control. The device allows for a highly efficient PWM current control for VCM, while reducing lens ringing in order to significantly lower the time needed for the lens to auto focus. The following design is a common application of the DRV201 device.

8.1.1 VCM Mechanical Ringing Frequency

Ringing compensation is dependent on the VCM resonance frequency, and this can be controlled through the VCM_FREQ register (07h) from 50 Hz up to 150 Hz. VCM mechanical ringing frequency for the ringing compensation can be selected using Equation 3. The formula gives the VCM_FREQ[7:0] register value in decimal which should be rounded to the nearest integer.

Equation 3. DRV201 eq1_lvsb25.gif

Default VCM mechanical ringing frequency is 76.4 Hz.

Equation 4. DRV201 eq2_lvsb25.gif

8.2 Typical Application

DRV201 typ_app_slvsb25.gifFigure 20. Typical Application Schematic

8.2.1 Design Requirements

Table 8. Design Parameters

DESIGN PARAMETER REFERENCE EXAMPLE VALUE
Supply voltage Vin 3.7
Motor Winding Resistance RL 15 Ω
Motor Winding Inductance IL 100 µH
Actuator Size 8.5 x 8.5 x 3.4 (mm)
Lens in the VCM M6 (Pitch: 0.35)
Weight of VCM 75 mg
TTL 4.2 mm
FB 1.1 mm

8.2.2 Detailed Design Procedure

8.2.2.1 User Example 1

In Figure 21, lens settling time and settling window shows how lens control is defined. Below is an example case how the lens is controlled and what settling time is achieved:

Measured VCM resonance frequency = 100 Hz

  • According to Table 1, VCM_FREQ[7:0] = ‘10111111’ (reg 0x07h)

VCM resonance frequency, fVCM, variation is within ±10% (minimum 90 Hz, maximum 110 Hz)

  • 1/fVCM ringing compensation is used : RING_MODE = ‘1’ (reg 0x06h)

Stepping the lens by 50 µm

  • The lens is settled into a ±5-µm window within 10 ms (1/fVCM)

8.2.2.2 User Example 2

If the case is otherwise exactly the same, but VCM resonance frequency cannot be guaranteed to stay at more than ±30% variation, slower ringing compensation should be used:

Measured VCM resonance frequency = 100 Hz

  • According to Table 1, VCM_FREQ[7:0] = ‘10111111’ (reg 0x07h)

VCM resonance frequency, fVCM, variation is within ±30% (minimum 70 Hz, maximum 130 Hz)

  • 2/fVCM ringing compensation is used : RING_MODE = ‘0’ (reg 0x06h)

Stepping the lens by 50 µm

  • The lens is settled into a ±5-µm window within 20 ms (2/fVCM)

DRV201 lens_settling_lvsb25.gifFigure 21. Lens Settling Time and Settling Window

8.2.3 Application Curves

DRV201 lens100a_lvsb25.gif
Figure 22. Lens Positions With and Without Ringing Compensation With 100-µm Step on the Lens Position
DRV201 lens30a_lvsb25.gif
Figure 24. Lens Positions With and Without Ringing Compensation With 30-µm Step on the Lens Position
DRV201 lens100b_lvsb25.gif
Figure 23. Lens Positions With and Without Ringing Compensation With 100-µm Step on the Lens Position, Zoomed In
DRV201 lens30b_lvsb25.gif
Figure 25. Lens Positions With and Without Ringing Compensation With 30-µm Step on the Lens Position, Zoomed In