Why in the TLD7002-16ES the outputs PWM waveform differs from the PWMI applied to the GPINx pins?
GPINx pins are not intended for PWM transfer to the LED, but only as activators of the outputs, and the output will generate pre-defined duty cycle, which is stored on the OTP configuration
GPIN0_MAP and GPIN1_MAP OTP registers store which LEDs are turned ON when a GPINx is “logic high”. DC0_OUTi and DC1_OUTi registers store the information about the duty cycle generated at the outputs (mapped to that GPIN) when the GPINx “HIGH” is applied.
GPINx pins have 2 options for control
- PWM decoding: an Input PWM Signal can be used to either Enable or Disable LED output.
- Interpreting an input PWM Duty Cycle < 25% as OFF, Disabling GPINx Mapped Output
- Interpreting an input PWM Duty Cycle > 75% as ON, Enabling GPINx Mapped Output
- Not PWM decoding
- HIGH => Disabling GPINx Mapped Output
- LOW =>Enabling GPINx Mapped Output
If the decoding options are not selected and a duty cycle is applied at GPIN0 a flicker could appear at output because the device will sample the GPIN0 and try to have randomly the output ON (with duty stated on DC0_OUTi ) and then outputs off
The GPINs pin usage is explained in the TLD7002-16 User Manual (UM), and a little also in the datasheet (see screenshot below)