The ICL3221EM and ICL3221EF devices are 3. 3V powered RS-232 transmitters/receivers that meet ElA/TIA-232 and V. 28/V. 24 specifications. Additionally, they provide ±15kV ESD protection (IEC61000-4-2 Air Gap and Human Body Model) on transmitter outputs and receiver inputs (RS-232 pins). Efficient on-chip charge pumps, coupled with manual and automatic powerdown functions, reduce the standby supply current to a 1µA trickle. Small footprint packaging, and the use of small, low value capacitors ensure board space savings as well. Data rates greater than 250kbps are ensured at worst case load conditions. These devices are fully compatible with 3. 3V-only systems. The ICL3221EM and ICL3221EF feature an automatic power-down function that powers down the on-chip power-supply and driver circuits. Power-down occurs when an attached peripheral device is shut off or the RS-232 cable is removed, and conserves system power automatically without changes to the hardware or operating system. These devices power up again when a valid RS-232 voltage is applied to any receiver input.