A display driver device including a driver circuit and a control circuit is provided. The driver circuit is configured to drive a display panel to display an animated image for a display period under an always on display mode according to display information of the animated image stored in a storage circuit. The display period includes a writing period and a non-writing period after the writing period. The control circuit is configured to write the display information of the animated image received from an external device into the storage circuit during the writing period of the display period. The control circuit is configured to stop receiving the display information from the external device and writing any display information into the storage circuit during the non-writing period of the display period. A display device including the display driver device and an operating method for the display driver device are also provided.