SNAA377 December   2025 LMK05318 , LMK05318B , LMK5B12204 , LMK5B12212 , LMK5B33216 , LMK5B33414 , LMK5C22212A , LMK5C23208A , LMK5C33216 , LMK5C33216A , LMK5C33414A

 

  1.   1
  2.   Trademarks
  3.   Abstract
  4. 1Introduction
  5. 2General Termination Guidelines
    1. 2.1 Identify the Driver and Receiver Requirements
    2. 2.2 Determine the Coupling Type
      1. 2.2.1 DC-Coupled Signal
      2. 2.2.2 AC-Coupled Signal
  6. 3Differential
    1. 3.1 Setting the Common-Mode Voltage (Thevenin Termination)
    2. 3.2 LVPECL
      1. 3.2.1 DC-Coupled LVPECL
      2. 3.2.2 AC-Coupled LVPECL
    3. 3.3 LVDS
      1. 3.3.1 DC-Coupled LVDS
      2. 3.3.2 AC-Coupled LVDS
    4. 3.4 HSDS
      1. 3.4.1 DC-Coupled HSDS
      2. 3.4.2 AC-Coupled HSDS
    5. 3.5 HCSL
      1. 3.5.1 DC-Coupled HCSL
      2. 3.5.2 AC-Coupled HCSL
    6. 3.6 LP-HCSL
      1. 3.6.1 DC-Coupled LP-HCSL
      2. 3.6.2 AC-Coupled LP-HCSL
  7. 4Single-Ended
    1. 4.1 LVCMOS
      1. 4.1.1 DC-Coupled LVCMOS (Series Termination)
      2. 4.1.2 AC-Coupled LVCMOS (Series Termination)
    2. 4.2 Differential P or N
      1. 4.2.1 DC-Coupled Differential P or N
  8. 5Summary
  9. 6References

3.6.1 DC-Coupled LP-HCSL

LP-HCSL is similar to HCSL through the same swing (750mV) and common-mode (350mV) specifications. LP-HCSL is different from HCSL through the type of driver architecture used. LP-HCSL uses a push-pull voltage driver instead of a current-mode. As a result, external termination is not required for LP-HCSL signals and the outputs must drive into capacitve loads. LP-HCSL signals also use newer technology newer technology which have low power consumption (about 4mA).

General guidelines:

  • Series resistors (RS) can be placed close to the the output pins to correct overshoot and reduce the output slew rate. The value of RS is determined by the transmission line impedance and the internal output impedance of the driver. Fulfill the equation to maintain impedance-matched outputs:
    • ZO = RO + RS
  • When RO is unknown, set RS = 0Ω in the initial design. RS can be adjusted for impedance matching after testing the signal integrity of the PCB. The typically used RS values are listed:
    Table 3-3 Typical Series Termination for LP-HCSL
    ZO (SINGLE-ENDED) [Ω] ZO (DIFFERENTIAL) [Ω] RO [Ω] RS [Ω]
    50 100 17 33
    42.5 85 15.5 27

Example termination:

  • DC-Coupled LP-HCSL to LP-HCSL
    DC-Coupled LP-HCSL to LP-HCSL Figure 3-28 DC-Coupled LP-HCSL to LP-HCSL
  • DC-Coupled LP-HCSL to HCSL

    Follow the same guidelines as interfacing with DC-coupled LP-HCSL to LP-HCSL receivers.

    DC-Coupled LP-HCSL to HCSL Figure 3-29 DC-Coupled LP-HCSL to HCSL