SC68C752BIBS NXP Semiconductors, SC68C752BIBS Datasheet - Page 17

• Manufacturer Part Number: SC68C752BIBS
• Manufacturer: NXP Semiconductors

Specifications of SC68C752BIBS

• Number Of Channels: 2
• Transmit Fifo: 64Byte
• Receive Fifo: 64Byte
• Transmitter And Receiver Fifo Counter: Yes
• Data Rate: 5Mbps
• Operating Supply Voltage (max): 5.5V
• Mounting: Surface Mount
• Pin Count: 32
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Lead Free Status / Rohs Status: Compliant

NXP Semiconductors
SC68C752B_4
Product data sheet
6.8 Break and time-out conditions
6.9 Programmable baud rate generator
An RX idle condition is detected when the receiver line, RXn, has been HIGH for
4 character time. The receiver line is sampled midway through each bit.
When a break condition occurs, the TXn line is pulled LOW. A break condition is activated
by setting LCR[6].
The SC68C752B UART contains a programmable baud generator that takes any clock
input and divides it by a divisor in the range between 1 and (2
divide-by-4 prescaler is also available and can be selected by MCR[7], as shown in
Figure
formula for the divisor is:
Where:
Remark: The default value of prescaler after reset is divide-by-1.
Figure 12
DLL and DLM must be written to in order to program the baud rate. DLL and DLM are the
least significant and most significant byte of the baud rate divisor. If DLL and DLM are
both zero, the UART is effectively disabled, as no baud clock will be generated.
Remark: The programmable baud rate generator is provided to select both the transmit
and receive clock rates.
Table 8
1.8432 MHz and 3.072 MHz, respectively.
Figure 13
divisor
Fig 12. Prescaler and baud rate generator block diagram
prescaler = 1, when MCR[7] is set to 0 after reset (divide-by-1 clock selected)
prescaler = 4, when MCR[7] is set to 1 after reset (divide-by-4 clock selected).
XTAL1
XTAL2
12. The output frequency of the baud rate generator is 16 times the baud rate. The
and
=
shows the internal prescaler and baud rate generator circuitry.
shows the crystal clock circuit reference.
⎛
⎝
---------------------------------------------------------------------------------------- -
XTAL1 crystal input frequency
-----------------------------------------------------------------------------------
Table 9
OSCILLATOR
INTERNAL
desired baud rate
LOGIC
5 V, 3.3 V and 2.5 V dual UART, 5 Mbit/s (max.), with 64-byte FIFOs
show the baud rate and divisor correlation for crystal with frequency
Rev. 04 — 20 January 2010
prescaler
input clock
(DIVIDE-BY-1)
(DIVIDE-BY-4)
×
PRESCALER
PRESCALER
16
LOGIC
LOGIC
⎞
⎠
MCR[7] = 0
MCR[7] = 1
reference
clock
16
GENERATOR
BAUD RATE
LOGIC
SC68C752B
− 1). An additional
© NXP B.V. 2010. All rights reserved.
002aaa233
internal
baud rate
clock for
transmitter
and receiver
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