The Intersil ISL4238E, ISL4244E and ISL4245E 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 enhanced
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 (ISL4238E/ISL4244E)/1Mbps (ISL4245E) are
guaranteed at worst case load conditions.
The ISL424xE are 3 driver, 5 receiver (DTE) devices that,
coupled with the 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 lead TSSOP,
and is nearly 20% thinner. The devices also include a
noninverting always-active receiver for “wake-up” capability.
The ISL4238E is a 5 driver, 3 receiver device optimized for
DCE applications with full hardware handshaking. It also
includes a noninverting always-active receiver for RING
INDICATOR monitoring. Transmitter and logic inputs include
active feedback resistors that retain the input state once
driven to a valid logic level.
These devices feature an enhanced automatic power-down
function which powers down the on-chip power-supply and
driver circuits. This occurs when all receiver and transmitter
inputs detect no signal transitions for a period of 30s. These
devices power back-up, automatically, whenever they sense
a transition on any transmitter or receiver input.
Table 1 summarizes the features of the ISL4238E,
ISL4244E, ISL4245, while Application Note AN9863
summarizes the features of each device comprising the 3V
RS-232 family.

Features
• Parameters Fully Specified for 10% Tolerance Supplies
and Full Industrial Temp Range
• Available in Small QFN (5mm x 5mm) Package which is
60% Smaller than a 28 Lead TSSOP
• ESD Protection for RS-232 I/O Pins to ±15kV (IEC61000)
• DTE (ISL4244E/45E) and DCE (ISL4238E) Versions
• Lowest Supply Current in Power-down . . . . . . . . . . .10nA
• Active Feedback Resistors on TX and Logic Inputs
(ISL4238E)
• Flow Through Pinouts
• Manual and Enhanced Automatic Power-down Features
• Guaranteed Minimum Data Rate
250kbps (ISL4238E/ISL4244E) / 1Mbps (ISL4245E)
• Latch-Up Free
• On-Chip Charge Pumps Require Only Four External
0.1µF Capacitors
• Wide Power Supply Range . . . . . . Single +2.7V to +5.5V
• Meets EIA/TIA-232 and V.28/V.24 Specifications at 3V
• RS-232 Compatible with VCC = 2.7V
• Pb-Free Available (RoHS Compliant)

Applications
• 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
Receivers