I'm suspecting a hold-time violation on the serial-data input pin. Some questions: 1. Are you running all supply (12V +/- 10%) and signal voltages (Vih > 10 volts, Vil < 2 volts) within datasheet specs. Some people have reported using the HV5530 outside these requirements. Since you are using the CD4504 I believe you have the correct voltage levels.
2. Input-data hold-time (10 nsec), which means the input data must not change until at least 10nsec after the falling-edge of clk. If you are cascading devices, there is a good chance the first device is propagating the data-out signal faster than the 10nsec hold-time requirement. The datasheet specs does not specify a min prop-delay, so assume it's zero. 3. Are clock and data signals routed in opposite directions ? This is a common practice with board layout to improve hold-time margin. With 12 inches of separation between devices, routing the clock signal in the opposite direction will have a huge impact on hold-time margin. 4. I actually have a separate ground-trace for the HV5530 that is not directly tied to the same digital grounds of the other ICs. The GND signal for the HV5530 routes back to the HV power-supply ground first, and then that gets tied to the digital GND. I never saw any measurable noise, so I cant conclude whether noise is not a potential problem, or if I eliminated it with the separate GND trace. For my design, which has 2 HV5530's per board, and 3 boards, I did not serialize the data thru all 6 devices. Instead, I serialized thru the 2 devices on each board, and had separate clock signals. So, each board had a dedicated serial data input and the boards shared the clock-lines in-parallel. I built a SPICE model of the clock transmission lines (which have stubs) and experimented with termination resistors to minimize ringing, and the design has worked flawlessly for several years now. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/e650fb00-2d8d-4650-92c5-8d48ebaac4c8%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
