SLLSF57A August 2022 – April 2024 TMDS1204
PRODUCTION DATA
HDMI 2.0 standards require a source termination impedance approximately 100Ω for data rates > 3.4Gbps. HDMI 1.4b requires no source termination but has a provision for termination for higher data rates greater than 1.65Gbps. Enabling this termination is optional. Table 7-13 lists how the TMDS1204 terminations are controlled automatically when in pin strap mode. Depending on the MODE pin, the CFG0 pin can be used to select the HDMI 1.4 termination between open and 300Ω.
The TMDS1204 supports automatic selection between open and 300Ω termination when operating in HDMI 1.4. In pin-strap mode with CTL0 low, the TMDS1204 will enable open termination when HDMI clock frequency is less than fHDMI14_open and will enable 300Ω termination when HDMI clock frequency is greater than fHDMI14_300. TXTERM_AUTO_HDMI14 register controls this feature in I2C mode.
In I2C mode, termination is controlled through the registers as provided in Table 7-12.
TX_AC_EN Register | TERM Register | TXTERM_AUTO_HDMI14 Register | Source Termination |
---|---|---|---|
0 | 00 | X | None |
0 | 01 | X | Parallel ≅ 300Ω across P and N |
0 | 10 | X | Automatic. HDMI 2.0 or HDM 2.1. parallel ≅ 100Ω across P and N |
0 | 10 | 1 | Automatic. HDMI 1.4. parallel ≅ 300Ω across P and N |
0 | 10 | 0 | Automatic. HDMI 1.4. No termination if HDMI clock frequency is ≤ fHDMI14_open. |
0 | 10 | 0 | Automatic. HDMI 1.4. Parallel ≅ 300Ω across P and N termination if HDMI clock frequency is ≥ fHDMI14_300. |
0 | 11 | X | Parallel ≅ 100Ω across P and N |
1 | 00 | X | ≅ 150Ω to supply (VCC) on both P and N |
1 | 01 | X | ≅ 150Ω to supply (VCC) on both P and N |
1 | 10 | X | Automatic. ≅ 150Ω to supply (VCC) on both P and N for HDMI 1.4. Otherwise ≅ 50Ω to supply (VCC) on both P and N. |
1 | 11 | X | ≅ 50Ω to supply (VCC) on both P and N |
HDMI Mode | AC_EN pin | Source Termination |
---|---|---|
HDMI 1.4 | 0 | None or parallel ≅ 300Ω across P and N depending on state of SCL/CFG0 pin |
HDMI 2.0 | 0 | Parallel ≅ 100Ω across P and N |
HDMI 1.4 | 1 | ≅ 150Ω to supply (VCC) on both P and N |
HDMI 2.0 | 1 | ≅ 50Ω to supply (VCC) on both P and N |