Preheat oven to 350 degrees. Grease 2- 8 1/2 x 4 1/2 inch loaf pans. Sift flour, baking powder, baking soda, and salt into large bowl: set aside. Beat peanut butter, butter, sugar, and brown sugar in large bowl with electric mixer at medium speed until light and fluffy. Beat eggs, one at a time, scraping down side of bowl after each addition. Beat in buttermilk and vanilla. Gradually add flour to mixture, beat at low speed. Stir in chips with wooden spoon. Spoon into prepared pans. Bake 45 minutes or until wooden toothpick inserted in center comes out clean. Cool in pans or on wire racks 10 minutes. Remove from pans: cool completely on rack.