SC16C650BIBS PHILIPS [NXP Semiconductors], SC16C650BIBS Datasheet - Page 14

• Manufacturer Part Number: SC16C650BIBS
• Description: 5 V, 3.3 V and 2.5 V UART with 32-byte FIFOs and infrared (IrDA) encoder/decoder
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
9397 750 14451
Product data
6.7 Programmable baud rate generator
The SC16C650B supports high speed modem technologies that have increased
input data rates by employing data compression schemes. For example, a 33.6 kbit/s
modem that employs data compression may require a 115.2 kbit/s input data rate.
A 128.0 kbit/s ISDN modem that supports data compression may need an input
data rate of 460.8 kbit/s.
A single baud rate generator is provided for the transmitter and receiver, allowing
independent TX/RX channel control. The programmable Baud Rate Generator is
capable of accepting an input clock up to 48 MHz, as required for supporting a
3 Mbit/s data rate. The SC16C650B can be configured for internal or external clock
operation. For internal clock oscillator operation, an industry standard microprocessor
crystal (parallel resonant/22-33 pF load) is connected externally between the XTAL1
and XTAL2 pins (see
the XTAL1 pin to clock the internal baud rate generator for standard or custom rates
(see
The generator divides the input 16 clock by any divisor from 1 to 2
SC16C650B divides the basic crystal or external clock by 16. The frequency of the
BAUDOUT output pin is exactly 16 (16 times) of the selected baud rate
(BAUDOUT = 16 Baud Rate). Customized baud rates can be achieved by selecting
the proper divisor values for the MSB and LSB sections of baud rate generator.
Setting MCR[7] to a logic 1 provides an additional divide-by-4, whereas setting
MCR[7] to a logic 0 only divides by 1 (see
Programming the Baud Rate Generator registers DLM (MSB) and DLL (LSB)
provides a user capability for selecting the desired final baud rate. The example in
Table 5
MCR[7] to a logic 0.
For custom baud rates, the divisor value can be calculated using the following
equation:
Divisor (in decimal)
Fig 6. Crystal oscillator connection.
Table
shows selectable baud rates when using a 1.8432 MHz crystal and setting
5).
Rev. 03 — 10 December 2004
=
C1
22 pF
1.8432 MHz
Figure
XTAL1 clock frequency
---------------------------------------------------------- -
X1
serial data rate 16
6). Alternatively, an external clock can be connected to
UART with 32-byte FIFOs and IrDA encoder/decoder
C2
33 pF
Table 5
and
1.8432 MHz
C1
22 pF
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
Figure
X1
SC16C650B
7).
1.5 k
C2
47 pF
002aaa586
16
1. The
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