PlayStation Knowledge Center
The maximum amount that a master account wallet can contain - at any one time - is $150 US Dollars for users registered in the United States and $150 Canadian for users registered in Canada. There is no limit on the number of times a master account may fund a wallet as long as the total amount does not exceed $150. You can fund your wallet for the maximum amount at one time from your PS3 or PC.
A master account can place a monthly spending limit on associated sub accounts. The maximum monthly limit on a sub account can be set to "Unlimited" for users registered in the United States and for users registered in Canada. The Sub Account monthly spending limit can be higher than the Master Account wallet limit because there is no limit on the number of times a master account can fund its wallet as long as the wallet limit does not exceed $150 at any one time.
Click here to learn how to check the current amount of funds in your PlayStation Network wallet.