SC16IS850LIPW,112 NXP Semiconductors, SC16IS850LIPW,112 Datasheet - Page 12

• Manufacturer Part Number: SC16IS850LIPW,112
• Manufacturer: NXP Semiconductors

Specifications of SC16IS850LIPW,112

• Lead Free Status / Rohs Status: Compliant

NXP Semiconductors
SC16IS850L
Product data sheet
7.8 Programmable baud rate generator
The SC16IS850L UART contains a programmable rational baud rate generator that takes
any clock input and divides it by a divisor in the range between 1 and (2
SC16IS850L offers the capability of dividing the input frequency by rational divisor. The
fractional part of the divisor is controlled by the CLKPRES register in the ‘first extra feature
register set’.
where:
Prescaler = 1 when MCR[7] is set to 0.
Prescaler = 4 when MCR[7] is set to 1.
A single baud rate generator is provided for the transmitter and receiver. The
programmable Baud Rate Generator is capable of operating with a frequency of up to
80 MHz. To obtain maximum data rate, it is necessary to use full rail swing on the clock
input. The SC16IS850L can be configured for internal or external clock operation. For
internal clock operation, an industry standard crystal is connected externally between the
XTAL1 and XTAL2 pins (see
to the XTAL1 pin (see
custom rates (see
The generator divides the input 16 clock by any divisor from 1 to (2
SC16IS850L divides the basic external clock by 16. The baud rate is configured via the
CLKPRES, DLL and DLM internal register functions. Customized baud rates can be
achieved by selecting the proper divisor values for the MSB and LSB sections of the baud
rate generator.
Programming the baud rate generator registers CLKPRES, DLM (MSB) and DLL (LSB)
provides a user capability for selecting the desired final baud rate. The example in
shows the selectable baud rate table available when using a 1.8432 MHz external clock
input when MCR[7] = 0, and CLKPRES = 0x00.
baud rate
Fig 5.
N is the integer part of the divisor in DLL and DLM registers;
M is the fractional part of the divisor in CLKPRES register;
f
XTAL1
XTAL1
XTAL2
is the clock frequency at XTAL1 pin.
Prescalers and baud rate generator block diagram
=
OSCILLATOR
------------------------------------------------------------------ -
MCR 7  
All information provided in this document is subject to legal disclaimers.
Table

Figure
f
XTAL1
Rev. 1 — 22 July 2011
5).
16

DIVIDE-BY-1
DIVIDE-BY-4
Figure
7) to clock the internal baud rate generator for standard or


N
+
----- -
16
M
6). Alternatively, an external clock can be connected


MCR[7] = 0
MCR[7] = 1
Single UART with I
GENERATOR
BAUD RATE
(DLL, DLM)
CLKPRES
SC16IS850L
[3:0]
2
16
C-bus/SPI interface
 1). The
© NXP B.V. 2011. All rights reserved.
16
 1). The
transmitter and
receiver clock
002aac645
Table 5
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