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Better Driving Solution

A project log for Modular Nixie Display

Modular nixie display board based on the soviet Russian IN-12A cold-cathode tubes.

JohnnyJohnny 11/05/2015 at 03:060 Comments

Came across this component the other day:

It's a 32-bit serial-in parallel-out shift-register with open drain outputs designed for driving high voltage loads, perfect for nixie tubes. The shift-register has typical 'Data In', 'Clock' and 'Data Out' pins. The active-low 'Latch Enable' pin is used to latch/save the data stored in the shift register to the buffer/output register, which in turn, turns on the appropriate output MOSFET. The 'LE' pin should be kept at logic-high in rest state, then send a logic-low pulse to latch. The active-low 'Polarity' pin can be used to invert the outputs on logic-low and the active-low 'Blanking' pin will turn off the outputs on logic-low (this doesn't change the buffer value and note the polarity function has higher priority). The 'BL' pin can be used to change the displays brightness using PWM. The HV5530 shifts data anticlockwise around the IC, where it's brother, the HV5630 shifts clockwise. This is useful for different PCB layouts. But in truth you could just change to shifting order from MSB to LSB or vice-versa in your program. If you plan on using SPI with the HV5530, note that MODE1 or MODE2 should be used with MSB first. MODE1 or MODE2 are used because the HV5530 and HV5630's shift-register latches data on the falling edge of the 'CLK' pin.

The voltage requirements for this device are a bit of a downer, as it's not 5V CMOS compatible (technically). 12V logic is specified by the datasheet, but in practice I've used 5V logic fine. In my case 12V is needed for my SMPS to produce 180V for the nixies; so the 12V here can be used in conjunction with a level shifting circuit to convert 5V signals to 12V signals.

The real positives for this device are:

  1. It's still being manufactured, unlike the SN74141 and K155ID1.
  2. Replaces many components and number of tracks, resulting in a much more compact board.

Cons:

  1. 12V CMOS logic
  2. Costly at about $6USD each

My original driving solution using the K155ID1 with 73HC595 resulted in a design that looked like this:

The new design using the HV5530 looks like this:

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