SLLS881G December   2007  – October 2014 SN65LVDS315

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 Handling Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Device Electrical Characteristics
    6. 6.6 Output Electrical Characteristics
    7. 6.7 Input Electrical Characteristics
    8. 6.8 Switching Characteristics
    9. 6.9 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1 Typical Blanking Power Consumption Test Pattern
    2. 7.2 Maximum Power Consumption Test Pattern
    3. 7.3 Jitter Performance
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Frame Counter Size
      2. 8.3.2 Data Formats
      3. 8.3.3 Parallel Input Port Timing Information
      4. 8.3.4 MIPI CSI-1 / CCP2-Class 0 Interface
      5. 8.3.5 Frame Structure and Synchronization Codes
      6. 8.3.6 Preventing Wrong Synchronization
      7. 8.3.7 Frame Structure
      8. 8.3.8 VS and HS Timing to Generate the Correct Control Signals
    4. 8.4 Device Functional Modes
      1. 8.4.1 Powerdown Modes
        1. 8.4.1.1 Shutdown Mode
        2. 8.4.1.2 Standby Mode
      2. 8.4.2 Active Modes
        1. 8.4.2.1 Acquire Mode (PLL Approaches Lock)
        2. 8.4.2.2 Transmit Mode
      3. 8.4.3 Status Detect and Operating Modes Flow Diagram
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Receiver Termination Requirement
      2. 9.1.2 Preventing Control Inputs From Increased Leakage Currents
    2. 9.2 Typical Application
      1. 9.2.1 VGA Camera Application
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Calculation Example: VGA Camera Sensor
          2. 9.2.1.2.2 Typical Application Frequencies
            1. 9.2.1.2.2.1 8-Bit Camera Application
        3. 9.2.1.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Trademarks
    2. 12.2 Electrostatic Discharge Caution
    3. 12.3 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9 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.

9.1 Application Information

The typical application for the SN65LVDS315 is the video streaming, where the device communicates the image sensor and the video processor, the SN65LVDS315 takes the video data from the image sensor in parallel format, then it serializes and sends this information in MIPI CSI-1.

9.1.1 Receiver Termination Requirement

The SN65LVDS315 outputs two differential lanes that must be specially terminated near the CSI-1 receiver device. As shown in Figure 25, place two resistors and one capacitor in each lane (within ±20% to the values shown). There are two possible implementations, based on whether the termination inside the receiver device can be disabled. If it can be disabled, place the components as close to the receiver as possible. This RC filter is a requirement that adds stability to the common mode voltage.

solutions_slls881.pngFigure 25. CSI-1 Receiver Device Termination

9.1.2 Preventing Control Inputs From Increased Leakage Currents

To ensure the lowest possible leakage current during standby or power down, all inputs must be held static. Any kind of input switching will cause increased leakage current. Hold inputs TXEN and MODE either at VIH or VIL. The LVDS315 incorporates a bus-hold feature on the D[0:7] inputs, DCLK, VS, and HS. This feature ensures that the input-stage leakage current is minimized during times when the camera output is in a high impedance state. Inputs with the bus-hold feature can be left open without the need of an external pullup or pulldown. This feature minimizes the power consumption of standby and power down modes in particular.

pcurr_lk_lls881.gifFigure 26. Bus-Hold Circuit

9.2 Typical Application

9.2.1 VGA Camera Application

Figure 27 shows a possible implementation of a 10-Mpixel camera transfer with 30Hz frame refresh rate. The SN65LVDS315 interfaces to the OMAP2420, a TI application processor with integrated CSI receiver. The pixel clock rate is 11 MHz, assuming ≈20% blanking overhead. The application assumes 8-bit color resolution.

vga_display_lls881.gifFigure 27. Typical VGA Display Application

9.2.1.1 Design Requirements

PARAMETERS VALUE
VDD supply voltage 1.8 V to 3.3 V
VDDPLLD, VDDPLLA & VDDLVDS supply voltage 1.8 V
Input frequency 3.5 to 27 MHz (fixed to 11 MHz)
8-bit parallel input data YUV422, YUV420, RGB888, RGB565 & RAW8
Input clock period jitter 5 ps-rms

9.2.1.2 Detailed Design Procedure

9.2.1.2.1 Calculation Example: VGA Camera Sensor

The following calculation shows an example for a VGA camera with following parameter:

display resolution: 640 x 480
frame refresh rate: 30 fps
vertical visible pixel: 480 lines
vertical blanking: 10 lines
horizontal visible pixel: 640 columns
horizontal blanking: 5 columns
camra_sen_lls881.gifFigure 28. VGA - Full Frame Composition
Calculation of the total number of pixel and Blanking overhead:
visible area pixel count: 640 x 480 = 307,200 pixel
total frame pixel count: (640+5) x (480+10) = 316,050 pixel
blanking overhead: (316,050–307,200) div 307,200 = 2.8%
The application requires following serial link parameters:
pixel clk frequency: fDCLK = 316.050 x 30 Hz = 9.5 MHz
DOUT serial data rate: dR = fDCLK x8 = 76 Mbps
CLK output clock rate: fCLK = f(dR) = 76 MHz

9.2.1.2.2 Typical Application Frequencies

The SN65LVDS315 in display mode supports pixel clock frequencies from 7 MHz to 27 MHz (which translates to DCLK frequencies of 56 MHz to 208 MHz). Table 7 provides a few typical display resolution examples. Table 7 also shows the assumed blanking overhead, which often times is smaller in the final application, resulting in a lower data rate.

9.2.1.2.2.1 8-Bit Camera Application

Table 7. Typical Application Data Rates And Serial Lane Usage

DISPLAY SCREEN RESOLUTION VISIBLE PIXEL COUNT CONTROL OVERHEAD FRAME REFRESH RATE DCLK PIXEL CLOCK FREQUENCY [MHz] DATA RATE ON D0 WITH LS=0 f(CLK)
640x480 (VGA) 307,200 14% 10 Hz 3.5 MHz 28 Mbps 28 MHz
640x480 (VGA) 307,200 2% 15 Hz 4.7 MHz 38 Mbps 38 MHz
640x480 (VGA) 307,200 10% 30 Hz 10.1 MHz 81 Mbps 81 MHz
3 Mpixel 3,000,000 10% 7 Hz 23.1 MHz 185 Mbps 185 MHz
4 Mpixel 4,000,000 10% 5 Hz 22.0 MHz 176 Mbps 176 MHz
5 Mpixel 5,000,000 10% 4 Hz 22.0 MHz 176 Mbps 176 MHz
6 Mpixel 6,000,000 10% 3 Hz 19.8 MHz 158 Mbps 158 MHz
8 Mpixel 8,000,000 10% 2 Hz 17.6 MHz 141 Mbps 141 MHz
10 Mpixel 10,000,000 10% 2 Hz 22.0 MHz 176 Mbps 176 MHz
12 Mpixel 12,000,000 10% 2 Hz 25.1 MHz 201 Mbps 201 MHz

9.2.1.3 Application Curve

idd_ta_lls881.gif
Figure 29. Supply Current IDD Overtemperature
idd_f_lls881.gif
Figure 30. Supply Current IDD Over PCLK Frequency