Capacitor before or after DC-DC mini360, how to protect against drawdown?

Question

Electronics

I bought a step-down dc-dc to MP2307DN from the Chinese and powered the DVR through it from the backlight (in the car). Thus got rid of hanging wires and freed the cigarette lighter socket.
But there was a problem. When the ignition is turned on, the DVR turns on, and when you start the car, the voltage drops and the DVR perceives this as a shutdown signal. There is no such problem on the native block.
Can you tell me how to solve this problem with capacitors? Bet before or after and what denomination?

Answer 1

According to the passport, the coefficient of suppression of input ripples for this thing == 400, so, apparently, the starter squanders the on-board network below 5 volts. This is weird. Try to power the converter through a diode and hang a 1000..4700μ conduit on the input

Answer 2

Both before and after, the electrolyte is microfarad at 100, 25 volts.

Answer 3

connect the input not directly but through a diode.
to eliminate drawdowns for buck converters, capacitance is needed at the input.