The Intersil ISL324xE devices are 2. 7V to 3. 6V 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 POS systems, 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 0. 5µA 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. ISL324xE are 3 driver, 5 receiver devices that, coupled with the 5x5 QFN package, provide the industry's smallest, lowest power complete serial port. The 5x5 QFN requires 60% less board area than a 28 Ld TSSOP, and is nearly 20% thinner. These devices also include a noninverting always-active receiver for wake-up capability. The ISL3243E features an automatic powerdown 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. The ISL324xE feature a VL pin that adjusts the logic pin (see Pin Descriptions on page 2) output levels and input thresholds to values compatible with the VCC powering the external logic (e. g. , a UART). Table 1 summarizes the features of the ISL324xE.


  • VL Pin for Compatibility in Mixed Voltage Systems Adjusts Logic Output Levels and Input Thresholds for Compatibility with Lower Supply Voltage Logic
  • Parameters Specified for 10% Tolerance Supplies and Full Industrial Temp Range
  • Pb-free Small QFN (5mmx5mm) Package 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
  • Low Supply Current in Power-down State: 0.5µA
  • Pb-Free (RoHS compliant)




  • Any Space Constrained System Requiring RS-232 Ports Battery Powered, Hand-Held, and Portable Equipment POS Systems and Scanners Laptop Computers, Notebooks GPS Receivers
  • Mixed Voltage Serial Ports


Design & Development