ST16C1450CJ28 EXAR [Exar Corporation], ST16C1450CJ28 Datasheet - Page 11

• Manufacturer Part Number: ST16C1450CJ28
• Description: 2.97V TO 5.5V UART
• Manufacturer: EXAR [Exar Corporation]

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REV. 4.2.0
The 145X supports the standard features of the ST16C450. In addition the 145X supports some enhanced
features not available for the ST16C450. These features are enabled by IER bit-5 and include a software
controllable (SOFT) reset, power down feature and FIFO monitoring bits.
Soft resets are useful when the user desires the capability of resetting an externally connected device only.
MCR bit-2 can be used to initiate a SOFT reset at the RST output pin. This does not reset the 145X (only the
RESET input pin can reset the 145X). Soft resets from MCR bit-2 are “ORed” with the RESET input pin.
Therefore both reset types will be seen at the RST output pin.
The power down feature (controlled by MCR bit-7) provides the user with the capability to conserve power
when the package is not in actual use without destroying internal register configuration data. This allows quick
turnarounds from power down to normal operation.
The 145X UART provides an internal loopback capability for system diagnostic purposes. The internal
loopback mode is enabled by setting MCR register bit-4 to logic 1. All regular UART functions operate normally.
Figure 7
output is internally routed to the receive shift register input allowing the system to receive the same data that it
was sending. The TX pin is held at logic 1 or mark condition while RTS# and DTR# are de-asserted, and
CTS#, DSR# CD# and RI# inputs are ignored. Caution: the RX input must be held to a logic 1 during loopback
test else upon exiting the loopback test the UART may detect and report a false “break” signal.
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2.6
2.7
2.6.1
2.6.2
F
IGURE
Special (Enhanced Feature) Mode
Internal Loopback
shows how the modem port signals are re-configured. Transmit data from the transmit shift register
16X Clock
Soft Reset
Power Down Mode
6. R
and Errors
Data Byte
Receive
ECEIVER
O
PERATION IN NON
LSR bits
Tags in
Error
4:2
Receive Data Shift
Register (RSR)
-FIFO M
Holding Register
Receive Data
(RHR)
ODE
11
Validation
Data Bit
RHR Interrupt (ISR bit-2)
Receive Data Characters
2.97V TO 5.5V UART
RXFIFO1
ST16C1450/51