Stream analytics job with iot hub data

Hi Team

I have the following query in azure database, this query retrieves two sensors data namely; temp and illuminance. I am struggling to get a field 'date' to retrieve current date time stamp. I need help as to how to go about using this syntax in my below query?

DO i need to use DATEDIFF() function? Any ideas to improve my query below please show me and guide me, thanks.

SELECT
illuminance as illuminance,
temperature as temperature,
MAX(CAST([timeStamp] AS datetime)) AS Date
INTO
[PowerBIVisualizationOutput]
FROM
[PowerBIVisualizationInput]

GROUP BY
illuminance,
temperature,
TumblingWindow(minute,5)