Solid state disks (SSDs) employ internal parallelism for high throughput, but concurrent flash operations can draw a high instantaneous current. Due to power budgeting or powersource changing, SSDs could be forced into a new operation mode with a lower current supply limit. This study presents a flash scheduling algorithm to optimize the SSD internal parallelism subject to the current limit. Based on realistic flash current models, our scheduler decides the actual starting times of every flash operation, and it efficiently examines the peak current only at a few time points. Our experiments show that our approach outperformed existing methods, and its feasibility had been verified on the OpenSSD platform.