JAJSDJ8A April 2017 – October 2021 ADC12D1620QML-SP
PRODUCTION DATA
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The DCLK reset feature is available through ECM, but it is disabled by default. DCLKI and DCLKQ are always synchronized, by design, and do not require a pulse from DCLK_RST to become synchronized.
The DCLK_RST signal must observe certain timing requirements, which are shown in Figure 6-7 of Section 6.16. The DCLK_RST pulse must be of a minimum width, and its deassertion edge must observe setup and hold times with respect to the CLK input rising edge. These timing specifications are listed as tPWR, tSR and tHR and may be found in Section 6.13.
The DCLK_RST signal can be asserted asynchronously to the input clock. If DCLK_RST is asserted, the DCLK output is held in a designated state (logic-high) in demux mode; in non-demux mode, the DCLK continues to function normally. Depending upon when the DCLK_RST signal is asserted, there may be a narrow pulse on the DCLK line during this reset event. When the DCLK_RST signal is de-asserted, there are tSYNC_DLY CLK cycles of systematic delay and the next CLK rising edge synchronizes the DCLK output with those of other ADC12D1620 devices in the system. For 90° mode (DDRPh = logic-high), the synchronizing edge occurs on the rising edge of CLK, 4 cycles after the first rising edge of CLK after DCLK_RST is released. For 0° mode (DDRPh = logic-low), this is 5 cycles instead. The DCLK output is enabled again after a constant delay of tOD.
For both demux and non-demux modes, there is some uncertainty about how DCLK comes out of the reset state for the first DCLK_RST pulse. For the second (and subsequent) DCLK_RST pulses, the DCLK comes out of the reset state in a known way. Therefore, if using the DCLK reset feature, TI recommends applying one dummy DCLK_RST pulse before using the second DCLK_RST pulse to synchronize the outputs. This recommendation applies each time the device or channel is powered-on.
When using DCLK_RST to synchronize multiple ADC12D1620 devices, the select-phase bits in the Control Register (Addr: Eh, Bits: 4:3) must be the same for each primary ADC12D1620.