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SN74LV1T34: Can I connect 4 SN74LV1T34 in parallel?

Sujeesh v
Prodigy 105 points
Part Number: SN74LV1T34
Other Parts Discussed in Thread: SN74LVC244A

Hi TI Team,

I'm trying to control 4 brushless motor using a PWM signal from Raspberry Pi. The motor controller is ATMEGA328P.

I'm using SN74LV1T34 to convert 5V PWM to 3.3V PWM. In my architecture, Raspberry Pi PWM output is split to 4 output and each one is down translated to 3.3V at the motor controller side.

My question is, can I connect 4 SN74LV1T34 in parallel and can be controlled using Raspberry Pi?

Whether the input impedance/current changes in this configuration? I'm not connecting any series resistor between Raspberry Pi GPIO and SN74LV1T34 input pin.

 

Thanks in advance.

  • +1
    TI__Guru* 97066 points

    Hello,

    The SN74LV1T34 can be used to convert a 5V PWM signal to a 3.3V PWM signal, and you can connect the inputs of four SN74LV1T34 devices together to produce the same PWM output, however you should not connect the outputs of four SN74LV1T34 devices directly together.

    I would recommend to look at a hex or octal buffer to reduce the number of devices in your system. For example, SN74LVC244A is an octal buffer that can support 5V inputs with the supply (and thus the output) set to 3.3V.

  • 0 in reply to Emrys Maier
    Prodigy 105 points

    Hi ,

    Output of each SN74LV1T34 is connected to separate motor controller as all are physically placed in separate sub-systems. 

    Can you please let me know about the input impedance of SN74LV1T34 ?

  • 0 in reply to Sujeesh v
    TI__Guru* 97066 points

    CMOS devices have high impedance inputs. The Electrical Characteristics table has what you need to determine the input impedance:

    With the given maximum leakage, you can determine the minimum input resistance -- R = V/I = 5.5 / 1uA = 5.5 MΩ

    The input capacitance is provided directly as 10 pF maximum.