1. Henry is such a good friend. You can always count on him to help you when the chips are down.
2. Laura’s a pleasant person, but she always seems to disappear when we need to get a project finished. When the chips are down , she’s never around.

The expression probably originates from a game like poker in which the players use ‘chips’ to represent money they are betting. To be ‘down on chips’ would be to not have many, or much money, left.