Techniques are disclosed for controlling data transmission in multi-stream digital systems. The techniques disclosed allow an input stream to a conditional access system to be throttled when a FIFO begins to fill up. Each data stream may have its own FIFO, which sends data to a MUX and exports its status to a backpressure rate control module. Multiple seconds worth of data may be stored in a BPRC buffer ahead of the backpressure rate control module prior to being transmitted to a MUX FIFO buffer. The backpressure rate control module may use the cached data to fill available spaces within a MUX FIFO buffer. The determination to forward a data packet may be based on the individual MUX FIFO buffer levels, the sum of all the MUX FIFO buffer levels, and/or one or more configurable threshold values. In some embodiments, individual thresholds may be assigned to each FIFO buffer.