DAN-164 Datasheet, PDF (1/3 Pages) Exar Corporation – MIGRATING FROM THE ST16C2550 TO THE XR16L2750

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DATA COMMUNICATIONS APPLICATION NOTE
DAN164
January 2005
MIGRATING FROM THE ST16C2550 TO THE XR16L2750
Author: PY
1.0 INTRODUCTION
This application note describes the changes necessary and what to consider when migrating from the
ST16C2550 to the XR16L2750.
1.1 HARDWARE DIFFERENCES
Table 1 below summarizes the differences between the ST16C2550 and XR16L2750.
TABLE 1: SUMMARY OF DIFFERENCES BETWEEN THE ST16C2550 AND XR16L2750
HARDWARE DIFFERENCES
Available Packages
Operating Voltage Range
5V Tolerant Inputs
Maximum data rate at 5V
Maximum data rate at 3.3V
ST16C2550
48-pin TQFP, 44-pin PLCC and 40-pin PDIP
2.97V - 5.5V
No
4 Mbps
1.875 Mbps
XR16L2750
48-pin TQFP and 44-pin PLCC
2.25V - 5.5V
Yes
6.25 Mbps
4 Mbps
• The ST16C2550 and XR16L2750 are both available in the 44-pin PLCC and 48-pin TQFP packages. The
ST16C2550 is also available in the 40-pin PDIP package but the XR16L2750 is not.
• The ST16C2550 can operate from 2.97 V to 5.5V only. The XR16L2750 can operate from 2.25 V up to 5.5 V.
• The maximum data rate for the ST16C2550 is 4 Mbps at 5V using a 64 MHz external clock and 1.875 Mbps
at 3.3V using a 30MHz external clock. The ST16C2550 uses a data sampling rate of 16X. The maximum
data rate for the XR16L2750 is 6.25 Mbps at 5V using a 50 MHz external clock and 4 Mbps at 3.3V using a
33MHz external clock. These maximum data rates can be achieved for the XR16L2750 by enabling the 8X
sampling rate via EMSR bit-7.
• In the 44-pin PLCC and 48-pin TQFP packages, the ST16C2550 and XR16L2750 have identical pinouts so
they are fully pin-to-pin compatible. The XR16L2750 is not available in the 40-pin PDIP package.
1.2 FIRMWARE DIFFERENCES
The internal register set of the XR16L2750 is based on the internal register set of the ST16C2550, except that
some unused bits in the ST16C2550 register set are used in the XR16L2750. Also, the XR16L2750 has an
Enhanced Register Set not found in the ST16C2550. Table 2 on the following page lists the firmware differenc-
es between the ST16C2550 and XR16L2750.
EXAR Corporation 48720 Kato Road, Fremont CA, 94538 • [phone] • FAX [phone] • www.exar.com • [e-mail]