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SN74ACT244-Q1: Driver Led

Juan Jacinto Montenegro
Prodigy 160 points

Part Number: SN74ACT244-Q1
Other Parts Discussed in Thread: SN74LXC1T45-Q1, SN74LXC2T45-Q1, TXU0104-Q1, SN74LXC8T245-Q1, SN74LVC07A-Q1, SN74LVC06A-Q1, SN74LVC1G07-Q1, SN74LVC2G06-Q1, SN74LVC3G07-Q1, TLC6C598-Q1, TLC69621-Q1

Hello, I am Juan Jacinto Montenegro, from Rother.

We are currently defining the LED control architecture for our custom PCB based on the CQS290 module.

The application is intended for automotive use, and we need to control several status indicators from the CQS290 GPIOs.

For the MCU, whose GPIOs operate at 3.3V, we have used the SN74ACT244-Q1 to control the status of the LEDs

However, for the CQS290 module, the main requirements are:

  • The CQS290 GPIOs operate at 1.8 V.
  • The LEDs would be powered from a 5 V rail.
  • Some LEDs may also require blinking or PWM control depending on the application.
  • Since the product is intended for use inside a vehicle, an automotive-qualified device, preferably AEC-Q100, would be strongly preferred.

Therefore, we could not use that component (SN74ACT244-Q1), as its VHI is not sufficient for 1.8V

One of the possible architectures to use is, a multi-channel constant-current LED sink driver, rather than a conventional logic buffer. The general architecture would be:

CQS290 GPIO → LED driver control input→LED driver current-sink output→Cathode(LED)Anode→+5 V

  1. Could you recommend any TI devices that would fit this architecture?
    In particular, we are looking for a device with multiple independent current-sink outputs that can be controlled directly from GPIO/PWM signals.
  2. If there is no device that exactly matches these requirements, we would also appreciate any recommended TI architecture or alternative component that you consider appropriate for this application.

Thank you in advance for your support.

Best regards,

Juan

  • 0
    TI__Genius 10060 points

    Hi Juan,

    If you're looking for a non-inverting buffer that operates at 5V and accepts 1.8V logic, there are not many single-chip options. You could look at TPLD801-Q1 or TPLD1201-Q1 which can be configured in this way.

    Are you able to have the device use VCC = 1.8V? If you need to output 5V and input 1.8V, take a look at SN74AC7541-Q1 which is open-drain output and can operate at VCC = 1.8V and can be used to produce a 5V output using an external pull-up.

    If you would like recommendations for a voltage translator, I can move this post to the voltage translator forum. This is the Logic forum.

    Regards,

    Nikki

  • 0
    Guru 325840 points

    You were using the SN74ACT244-Q1 as a level shifter. With a larger voltage difference, you need an actual level shifter with two supplies, i.e., SN74LXC1T45-Q1/SN74LXC2T45-Q1/SN74LXC8T245-Q1 or TXU0104-Q1.

    When driving the LED from the cathode, you can use any buffer with open-drain output. The logic family with the highest drive strength at 1.8 V is LVC; consider the SN74LVC1G07-Q1/SN74LVC3G07-Q1/SN74LVC07A-Q1 buffers or SN74LVC2G06-Q1/SN74LVC06A-Q1 inverters. (The specified drive strength is 4 mA, but you can use higher currents if you take the output resistance into account.)

    There are automotive LED drivers like the TLC6C598-Q1 or TLC69621-Q1, but they must be programmed over SPI.