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.