Serial interfaces shrink for handheld applications

The ISL4221E and ISL4223E are the latest additions to the Intersil Linearlink high-performance RS232 interface portfolio.

The ISL4221E and ISL4223E are the latest additions to the Intersil Linearlink high-performance RS232 interface portfolio.

Targeted for portables, handhelds and data cables, these new ICs join Intersil's ISL4270E, ISL4260E, ISL424XE and ISL4238E RS232 family of the world's smallest transceivers all available in the near-chip-scale 5 x 5 x 0.9mm quad flat no-lead (QFN) package.

The ISL4221E contains one transmitter and one receiver.

The ISL4223E has two transmitters and two receivers.

Both ICs operate from a single 2.7 to 5.5V supply range and are fully compatible with 3V, mixed 3/5V and 5V-only systems.

The ICs' transmitters and receivers meet EIA/TIA232 and V.28/V.24 specifications, even at 3V.

At 2.7V the devices are still RS232 compatible.

Each IC features a low 300uA supply current and a very low 150nA power-down current.

All exposed transmitter and receiver pins are ESD protected to +/-15kV in compliance with the IEC61000-4-2 airgap and human body model standard.

Each of these transceivers 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 RS232 cable is removed, conserving system power automatically without changes to the hardware or operating system.

It powers up again when a valid RS232 voltage is applied to any receiver input.

"Force-on" and "force-off" pins are provided to override these automatic functions.

The 20-pad 5 x 5mm QFN package occupies 40% less board space and is 20% thinner than a 20-lead TSSOP used by competing products.

Small lands on the underside perimeter of the QFN package provide circuit contact so there are no leads to become bent during handling or assembly.

Unlike chip-scale packages that use an array of solder bumps, the perimeter lands of the QFN package allow post-assembly inspection of solder joints.

Special manufacturing equipment is not needed.

These ICs are intended for use in PDAs and other handheld devices requiring an RS232 link to a PC.

Intersil's ISL424X series ICs complete the serial communications interface on the PC end of the link.

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