The whole range of RL78 devices utilize a single successive approximation design A/D converter block with a variety of channel counts from device to device; for example 20-, 24- and 25-pin devices include 6 A/D converter channels, 40 pin devices have 9 channels and the 128-pin device features up to 26 channels. Note that any unused A/D converter channels can be used as I/O ports instead. For example, if only 6 out of the 9 channels on the 40-pin device are used as analog inputs, the rest can be used as digital ports.