The XR16M554/564/654 series spans six different devices, all sharing a similar core feature set, and all available in a variety of package types. Key features common to all include the following, according to the company:
- Pin-to-pin compatiblity with ST16C454 and ST16C554
- Intel or Motorola Data Bus interface select
- 4 independent UART channels
- Register set compatible with 16C550
- 4 selectable RX FIFO trigger levels
- Full modem interface
- 1.62V to 3.63V supply operation
- Crystal oscillator or external clock input
A block diagram of the XR16M554 and XR16M554D
(Click to enlarge)The XR16M554 and XR16554D, a block diagram of which is shown above, offer data rates up to 4Mbps at 3.3V, 3.125Mbps at 2.5V, and 2Mbps at 1.8V. They have a 16 byte transmit FIFO, and a 16 byte receive FIFO with error tags. Apparently, the difference between the XR16M554 and the XR16M554D is that the former offers three-state interrupt output, while the latter has continuous interrupt output.
A block diagram of the XR16M564 and XR16M564D
(Click to enlarge)The XR16M564 and XR16M564D (block diagram above) add pin-to-pin compatibility with TI's TL16C754B and NXP's SC16C754B. They offer data rates of up to 16Mbps, stepping up to a 32-byte transmit FIFO and a 32-byte receive FIFO with error tags. They also add automatic hardware (RTS/CTS) and software (Xon/Xoff) flow control, an IrDA 1.0 encoder decoder, and sleep mode with automatic wake-up. Again, the "D" suffix connotes continuous interrupt output.
A block diagram of the XR16M654 and XR16M654D
(Click to enlarge)The XR16M654 and XR16M654D (block diagram above) are pin-compatible with TI's TL16C754B and NXP's SC16C654B, in addition to the ST parts listed earlier. They offer all the features of the XR16M564 and XR16M564D, but transmit and receive FIFOs are both 64 bytes. An available 100-pin package provides additional FIFO status outputs, separate infrared transmit data outputs, and a channel C external clock input.
Exar says the XR16M554 and XR16M564 are available in 68-pin PLCC (plastic leaded chip carrier), 64-pin LQFP (low profile quad flat package), 48-pin QFN (quad flat no leads), and 80-pin LQFP packages. The XR16M654 is available in the same packages, but adds a 100-pin QFP (quad flat package) offering. The XR16M554D, XR16M564D, and XR16M654D are all 64-pin LQFP packages. Prices are under $7 for the XR16M554s, under $8 for the XR16M564s, and under $9 for the XR16M654s.
The XR16M554/564/654 are supported by standard serial port drivers, and are compatible with Windows CE 4.2 and 5.0, Windows XP, Windows 2000, and Linux, says Exar.
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