XR16L788IQ-F Exar Corporation, XR16L788IQ-F Datasheet - Page 16

• Manufacturer Part Number: XR16L788IQ-F
• Description: IC UART 64B 3.3V OCTAL 100QFP
• Manufacturer: Exar Corporation
• Type: IrDA or RS- 485r

Specifications of XR16L788IQ-F

• Number Of Channels: 8
• Package / Case: 100-BQFP
• Features: *
• Fifo's: 64 Byte
• Protocol: RS485
• Voltage - Supply: 2.97 V ~ 5.5 V
• With Auto Flow Control: Yes
• With Irda Encoder/decoder: Yes
• With False Start Bit Detection: Yes
• With Modem Control: Yes
• Mounting Type: Surface Mount
• Data Rate: 6.25 Mbps
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2.97 V
• Supply Current: 5 mA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Operating Supply Voltage: 3.3 V or 5 V
• No. Of Channels: 8
• Uart Features: Tx/Rx FIFO Counters
• Supply Voltage Range: 2.97V To 5.5V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: QFP
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: 1016-1284

XR16L788
HIGH PERFORMANCE 2.97V TO 5.5V OCTAL UART
When software flow control is enabled
characters with the programmed Xon or Xoff-1,2 character value(s). If receive character(s) (RX) match the
programmed values, the 788 will halt transmission (TX) as soon as the current character has completed
transmission. When a match occurs, the Xoff (if enabled via IER bit-5) flag will be set and the interrupt output
pin will be activated. Following a suspension due to a match of the Xoff character, the 788 will monitor the
receive data stream for a match to the Xon-1,2 character. If a match is found, the 788 will resume operation
and clear the flags (ISR bit-4).
Reset initially sets the contents of the Xon/Xoff 8-bit flow control registers to a logic 0. Following reset, any
desired Xon/Xoff value can be used for software flow control. Different conditions can be set to detect Xon/Xoff
characters
selected, the 788 compares two consecutive receive characters with two software flow control 8-bit values
(Xon1, Xon2, Xoff1, Xoff2) and controls TX transmissions accordingly. Under the above described flow control
mechanisms, flow control characters are not placed (stacked) in the user accessible RX data buffer or FIFO.
In the event that the receive buffer is overfilling and flow control needs to be executed, the 788 automatically
sends an Xoff message (when enabled) via the serial TX output to the remote modem. The 788 sends the Xoff-
1,2 characters two character times (= time taken to send two characters at the programmed baud rate) after
the receive FIFO crosses the programmed trigger level (for all trigger tables A-D). To clear this condition, the
788 will transmit the programmed Xon-1,2 characters as soon as receive FIFO is less than one trigger level
below the programmed trigger level (for Trigger Tables A, B, and C) or when receive FIFO is less than the
trigger level minus the hysteresis value (for Trigger Table D). This hysteresis value is the same as the Auto
RTS/DTR Hysteresis value in
selected.
* After the trigger level is reached, an xoff character is sent after a short span of time (= time required to send 2
A special character detect feature is provided to detect an 8-bit character when bit-5 is set in the Enhanced
Feature Register (EFR). When this character (Xoff2) is detected, it will be placed in the FIFO along with normal
incoming RX data.
The 788 compares each incoming receive character with Xoff-2 data. If a match exists, the received data will
be transferred to FIFO and ISR bit-4 will be set to indicate detection of special character. Although the Internal
Register Table shows Xon, Xoff Registers with eight bits of character information, the actual number of bits is
dependent on the programmed word length. Line Control Register (LCR) bits 0-1 defines the number of
character bits, i.e., either 5 bits, 6 bits, 7 bits, or 8 bits. The word length selected by LCR bits 0-1 also
determines the number of bits that will be used for the special character comparison. Bit-0 in the Xon, Xoff
Registers corresponds with the LSB bit for the receive character.
The auto RS485 half-duplex direction control changes the behavior of the transmitter when enabled by FCTR
bit-5. It asserts RTS# or DTR# (LOW) after a specified delay indicated in MSR[7:4] following the last stop bit of
the last character that has been transmitted. This helps in turning around the transceiver to receive the remote
station’s response. The delay optimizes the time needed for the last transmission to reach the farthest station
on a long cable network before switching off the line driver. This delay prevents undesirable line signal
characters); for example, after 2.083ms has elapsed for 9600 baud and 10-bit word length setting.
2.11
2.12
2.13
RX T
Auto Xon/Xoff (Software) Flow Control
RIGGER
Special Character Detect
Auto RS485 Half-duplex Control
16
24
28
(See Table
8
L
EVEL
18) and suspend/resume transmissions. When double 8-bit Xon/Xoff characters are
INT P
T
ABLE
IN
Table
A
16
24
28
8
CTIVATION
6: A
17.
UTO
(See Table
Table 6
X
ON
X
/X
(
OFF
CHARACTERS IN RX FIFO
OFF
below explains this when Trigger Table-B (See
18), the 788 compares one or two sequential receive data
C
16
(S
HARACTER
OFTWARE
16*
24*
28*
8*
(
S
) S
) F
ENT
LOW
)
C
ONTROL
X
(
CHARACTERS IN RX FIFO
ON
C
HARACTER
16
24
0
8
(
S
) S
Table
ENT
REV. 1.2.3
)
14) is