SPRAC31 February   2019 TMS320C5505 , TMS320C5515 , TMS320C5535

 

  1.   TMS320C5505/15/35/45 schematic checklist
    1.     Trademarks
    2. 1 Introduction
      1. 1.1 Device Applicability
      2. 1.2 Links to TI Hardware Designs Based on C5505/15/35/45
        1. 1.2.1 C5505 eZdsp
        2. 1.2.2 C5515 eZdsp
        3. 1.2.3 C5515 EVM
        4. 1.2.4 C5535 eZdsp
        5. 1.2.5 C5535 Audio Capacitive Touch BoosterPack
        6. 1.2.6 C5545 BoosterPack (BOOST5545ULP)
      3. 1.3 EVM vs Data Sheet
    3. 2 Complimentary Resources
    4. 3 Recommendations Specific to C5504/05/14/15/32/33/34/35/45
      1. 3.1  Before You Begin
        1. 3.1.1 Documentation
        2. 3.1.2 Pin Out
      2. 3.2  Unused Pins
      3. 3.3  Unused Power Rails
        1. 3.3.1 If USB is not Used
        2. 3.3.2 If RTC is not Used
        3. 3.3.3 If EMIF is not Used (not applicable to C5532/33/34/35 or C5545)
        4. 3.3.4 If an On-Chip LDO Output is not Used
      4. 3.4  Clocking
      5. 3.5  OSC Internal Oscillator Clock Source
      6. 3.6  Power
        1. 3.6.1 CVDDRTC Must be Always Supplied - [0.998 V - 1.43 V]
        2. 3.6.2 LDOI Must be Always Supplied
        3. 3.6.3 On-Chip LDOs
        4. 3.6.4 Recommended PMIC
        5. 3.6.5 DVDDIO Supply ON While CVDD OFF
        6. 3.6.6 Power Sequencing
        7. 3.6.7 Voltage Rails of IO Pins
      7. 3.7  Decoupling Capacitors
      8. 3.8  LDO Output Decoupling Capacitors
      9. 3.9  Digital GND, Analog GND, Local GND
        1. 3.9.1 Recommended USB Supplies
      10. 3.10 Reset
      11. 3.11 USB
      12. 3.12 I2C
      13. 3.13 I2S
      14. 3.14 RTC
      15. 3.15 SAR ADC
      16. 3.16 Pin Muxing
      17. 3.17 Signal Visibility
      18. 3.18 EMIF (not applicable to C5532/33/34/35 or C5545)
      19. 3.19 JTAG
      20. 3.20 Bootloader
    5. 4 References

3.5 OSC Internal Oscillator Clock Source

Figure 1 shows the recommended crystal circuit. It is recommended that pre-production printed circuit board (PCB) designs include the two optional resistors: Rbias and Rs. They may be required for proper oscillator operation when combined with production crystal circuit components

sprac31_clockckt_v2.gifFigure 1. OSC Crystal Circuit Schematics

In general, adding Rbais and Rs resistors improves circuit performance by reducing the long start-up time, crystal overdrive and voltage and temperature related issues. Specifically, they provide the following functionality:

Rs helps reduce the drive level on the crystal and decreases the slew rate, which adds additional phase shift Recommended value: 50 Ω Rbais (the feedback resistor) is used to bias the input of the inverting amplifier and improve the loop gain Recommended value: 1M Ω. However, in most cases Rbias is not required and Rs is a 0-Ω resistor. These resistors may be removed from production PCB designs after evaluating oscillator performance with production crystal circuit components installed on pre-production PCBs.

For the calculation of Rs and RBais values, see the Crystek Application notes. Oscillator components (Crystal, C1, C2, optional Rbias and Rd) must be located close to the device package. Parasitic capacitance to the printed circuit board (PCB) ground and other signals should be minimized to reduce noise coupled into the oscillator.