Intersil's ISL4241E, ISL4243E devices are 2. 7V to 5. 5V powered RS-232 transmitters/receivers which meet ElA/TIA-232 and V. 28/V. 24 specifications, even at VCC = 3. 0V. Additionally, they provide ±15kV ESD protection (IEC61000-4-2 Air Gap and Human Body Model) on transmitter outputs and receiver inputs (RS-232 pins). Targeted applications are PDAs, Palmtops, and notebook and laptop computers where the low operational, and even lower standby, power consumption is critical. Efficient on-chip charge pumps, coupled with manual and automatic power-down functions, reduce the standby supply current to a 10nA trickle. Tiny 5mmx5mm Quad Flat No-Lead (QFN) packaging and the use of small, low value capacitors ensure board space savings as well. Data rates greater than 250kbps are guaranteed at worst case load conditions. The ISL4241E, ISL4243E's are 3 driver, 5 receiver devices that, coupled with the 5x5 QFN package, provide the industry's smallest, lowest power complete serial port suitable for PDAs, and laptop or notebook computers. The 32 Ld 5X5 QFN requires 60% less board area than a 28 Ld TSSOP, and is nearly 20% thinner. The devices also include a noninverting always-active receiver for wake-up capability. The ISL4243E features an automatic power-down function that powers down the on-chip power-supply and driver circuits. This occurs when an attached peripheral device is shut off or the RS-232 cable is removed, conserving system power automatically without changes to the hardware or operating system. It powers up again when a valid RS-232 voltage is applied to any receiver input. Table 1 summarizes the features of both the ISL4241E and ISL4243E, while Application Note AN9863 summarizes the features of each device comprising the 3V RS-232 family.


  • Pb-Free Available (RoHS compliant)
  • Parameters Fully Specified for 10% Tolerance Supplies and Full Industrial Temp Range
  • Available in Small QFN (5mmx5mm) Package which is 60% Smaller than a 28 Lead TSSOP
  • ESD Protection for RS-232 I/O Pins to ±15kV (IEC61000)
  • Meets EIA/TIA-232 and V.28/V.24 Specifications at 3V
  • RS-232 Compatible with VCC = 2.7V
  • On-Chip Voltage Converters Require Only Four External 0.1µF Capacitors
  • Manual and Automatic Power-down Features
  • Receiver Hysteresis For Improved Noise Immunity
  • Guaranteed Minimum Data Rate: 250kbps
  • Wide Power Supply Range: Single +2.7V to +5.5V
  • Low Supply Current in Power-down State: 10nA




  • Any Space Constrained System Requiring RS-232 Ports Battery Powered, Hand-Held, and Portable Equipment Laptop Computers, Notebooks PDAs and Palmtops, Data Cables Cellular/Mobile Phones, Digital Cameras, GPS


Design & Development