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I would like to drive multiple nixie tubes using shift register. I wonder that can I cascade two different shift registers to control them using arduino or another MCU? My plan is to connect DATA OUT of HV5522 to SER IN of TPIC6B595. enter image description hereenter image description here

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The other answer already covers daisy chaining shift registers, with considerations about potentially needing to add a buffer on the clock and latch line according to the length of the line.

Given the use of HV5522 and TPIC6B595 also need to consider the different supply voltages and digital signal voltage levels.

From the HV5522 datasheet Recommended Operating Conditions:

Parameter Sym. Min. Max. Unit
Logic Supply Voltage VDD 10.8 13.2 V
High-level Input Voltage VIH VDD–2 VDD V
Low-level Input Voltage VIL 0 2 V

And DC Electrical Specifications:

Parameter Sym. Min. Max. Unit Conditions
High-level Output Data Out VOH VDD–1V - V IDOUT = –100 μA
Low-level Output Voltage - Data Out VOL - 1 V IDOUT = 100 μA

Which means the HV5522 logic supply voltage and input/output voltages are not 5 V TTL or CMOS standard compatible, due to operating in the range around 12 V.

Whereas the TPIC6B595 datasheet Recommended Operating Conditions look 5 V CMOS compatible:

Parameter Min. Max. Unit
VCC Logic supply voltage 4.5 5.5 V
VIH High-level input voltage 0.85 VCC V
VIL Low-level input voltage 0.15 VCC V

As a result, it will not be possible to directly daisy chain the HV5522 and TPIC6B595 devices, since logic level translators will also be necessary. If a 5 V MCU is used then depending upon which order the devices are daisy chained will affect the number of level translators needed. E.g.:

  1. 5 V MCU -> level translator -> 12 V HV5522 -> level translator -> 5 V TPIC6B595
  2. 5 V MCU -> 5 V TPIC6B595 -> level translator -> 12 V HV5522

If a 3.3 V MCU is used, it's output levels might be directly compatible with the input thresholds of the TPIC6B595.

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Yes, daisy chaining shift registers that way is commonly done and one of the reasons that they are such popular.

If this device gets bigger, you might have to add a buffer to the clock line and the latch line (because that needs to drive all shift registers, and all the long lines leading to them). At speeds at which you'd want to control Nixie tubes, it's very unlikely this will become necessary (you can basically drive the serial clock as slowly as you want, and latching will happen at most a handful of times per second).

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