Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
IBM PC/AT is a trademark of International Business Machines Corporation.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
Copyright 1999, Texas Instruments Incorporated
1
TL16C552A, TL16C552AM
DUAL ASYNCHRONOUS COMMUNICATIONS ELEMENT
WITH FIFO
The TL16C552A is an enhanced dual-channel version of the popular TL16C550B asynchronous
communications element (ACE). The device serves two serial input/output interfaces simultaneously in
microcomputer or microprocessor-based systems. Each channel performs serial-to-parallel conversion on data
characters received from peripheral devices or modems and parallel-to-serial conversion on data characters
transmitted by the CPU. The complete status of each channel of the dual ACE can be read at any time during
functional operation by the CPU. The information obtained includes the type and condition of the transfer
operations being performed and the error conditions encountered.
In addition to its dual communications interface capabilities, the TL16C552A provides the user with a
bidirectional parallel data port that fully supports the parallel Centronics-type printer interface. The parallel port
and the two serial ports provide IBM PC/A T-compatible computers with a single device to serve the three system
ports. A programmable baud rate generator that can divide the timing reference clock input by a divisor between
1 and (2
The TL16C552A is available in a 68-pin plastic-leaded chip-carrier (FN) package, a 48-pin TQFP (PN) package,
and the 80-pin TQFP (PN) package. The TL16C552AM is available in a 68-pin ceramic quad flat (HV) package.
16
– 1) is included.
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
functional block diagram
TL16C552A, TL16C552AM
DUAL ASYNCHRONOUS COMMUNICATIONS ELEMENT
WITH FIFO
SLLS189D – NOVEMBER 1994 – REVISED JANUARY 1999
A0–A2
IOW
IOR
RESET
CLK
35–33
36
37
39
4
CTS0
DSR0
DCD0
RI0
SIN0
CS0
DB0–DB7
CTS1
DSR1
DCD1
RI1
SIN1
CS1
3
ERR
SLCT
BUSY
PE
ACK
PEMD
CS2
ENIRQ
28
31
29
30
41
32
14–21
13
5
8
6
62
3
Select
and
Control
Logic
63
65
66
67
68
1
38
43
24
RTS0
25
DTR0
26
ACE
#1
8
8
ACE
#2
8
8
53–46
Parallel
Port
45
9
22
12
11
10
60
61
42
44
57
56
55
58
59
SOUT0
INT0
RXRDY0
TXRDY0
RTS1
DTR1
SOUT1
INT1
RXRDY1
TXRDY1
BDO
PD0–PD7
INIT
AFD
STB
SLIN
INT2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
3
TL16C552A, TL16C552AM
NAME
DUAL ASYNCHRONOUS COMMUNICATIONS ELEMENT
WITH FIFO
SLLS189D – NOVEMBER 1994 – REVISED JANUARY 1999
Terminal Functions
TERMINAL
DESCRIPTION
has an internal pullup resistor to VDD of
terminal has changed states
. When ENIRQ is tied high, the PS-2 mode of interrupt
bit in the line printer status register.
. INT2 is held until the status register is read, which then
has an internal pullup resistor to VDD of
73
I/O
generates a printer port interrupt during its positive transition.
Line printer autofeed. AFD is an open-drain line that provides the printer with an active-low signal when
continuous form paper is to be autofed to the printer. AFD
approximately 10 kΩ.
2 for the decode of the serial channels and Table 13 for the decode of the parallel printer port.
port is read. BDO controls the system bus driver (74LS245 or 54LS245).
to accept data.
Chip select. Each CSx input acts as an enable for the write and read signals for serial channels 1 (CS0)
and 2 (CS1
register (CTS is bit 4 of the modem status register, written as MSR4) of each ACE. A change of state
in either CTS
(MSR0) of each modem status register.
control, and status information between the TL16C552A and the CPU. These lines are normally in the
high-impedance state except during read operations. DB0 is the least significant bit (LSB) and is the
first serial data bit to be received or transmitted.
(DCD) of the modem status registers. MSR3 (∆DCD) of the modem status register indicates whether
DCD
Data set ready. The logical state of the DSRx terminals is reflected in MSR5 of its associated modem
status register. ∆DSR (MSR1) indicates whether the associated DSRx
since the previous reading of the MSR.
Data terminal ready. Each DTRx can be set low by setting MCR0, modem control register bit 0 of its
associated ACE. DTRx
When active (low), DTRx
In AT mode, INT2 is internally connected to ACK
is enabled and INT2 is internally tied to the inverse of the PRINT
INT2 is latched high on the rising edge of ACK
clears the PRINT
during the error condition.
Ground (0 V). All terminals must be tied to GND for proper operation.
allows the printer initialization routine to be started. INIT
approximately 10 kΩ.
MCR) goes active (high) when one of the following interrupts has an active (high) condition and is
enabled by the interrupt enable register of its associated channel: receiver error flag, received data
available, transmitter holding register empty , and modem status. The interrupt is cleared on appropriate
service. Upon reset, the interrupt output is in the high-impedance state.
). CS2 enables the signals to the printer port.
terminal since the previous reading of the associated MSR causes the setting of ∆CTS
has changed states since the previous reading of the MSR. DCD has no effect on the receiver.
is cleared (high) by clearing the DTR bit (MCR0) or whenever a reset occurs.
indicates that its ACE is ready to receive data.
status bit and INT2.
NO.
FNPN
ACK6810ILine printer acknowledge. ACK goes low to indicate a successful data transfer has taken place. ACK
AFD5675I/O
A0, A1, A235, 34,3351, 50,49IAddress. The address lines A0–A2 select the internal registers during CPU bus operations. See T able
BDO4463OBus buffer. BDO is the active-high output and is asserted when either the serial channel or the parallel
BUSY668ILine printer busy. BUSY is an input line from the printer that goes high when the printer is not ready
CLK414IClock. CLK is the external clock input to the baud rate divisor of each ACE.
CS0, CS1,
CS2
CTS0,
CTS1
DB0 –
DB7
DCD0,
DCD1
DSR0,
DSR1
DTR0,
DTR1
ENIRQ4359IParallel port interrupt source mode selection. When ENIRQ is low, the A T mode of interrupts is enabled.
ERR635ILine printer error. ERR is an input line from the printer. The printer reports an error by holding ERR low
GND7, 27,5417, 43,
INIT5776I/O Line printer initialize. INIT is an open-drain line that provides the printer with an active-low signal that
INT0, INT145, 6064, 79OExternal serial channel interrupt. Each serial channel interrupt 3-state output (enabled by bit 3 of the
32, 3,3848, 13,54I
28, 1344, 26IClear to send. The logical state of each CTSx terminal is reflected in the CTS bit of the modem status
14 – 21 27 – 34 I/O Data bits DB0–DB7. The data bus provides eight I/O lines with 3-state outputs for the transfer of data,
29, 845, 18IData carrier detect. DCD is a modem input. Its condition can be tested by the CPU by reading MSR7
31, 547, 15I
25, 1138, 24O
4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TL16C552A, TL16C552AM
NAME
DUAL ASYNCHRONOUS COMMUNICATIONS ELEMENT
WITH FIFO
SLLS189D – NOVEMBER 1994 – REVISED JANUARY 1999
Terminal Functions (Continued)
TERMINAL
NO.
FNPN
INT25978OPrinter port interrupt. INT2 is an active-high, 3-state output generated by the positive transition of
IOR3753IInput/output read strobe. IOR is an active-low input that enables the selected channel to output data
IOW3652IInput/output write strobe. IOW is an active-low input causing data from the data bus to be input to either
PD0–PD753–4672–65I/O Parallel data bits (0–7). PD0–PD7 provide a byte wide input or output port to the system.
PE679ILine printer paper empty. PE is an input line from the printer that goes high when the printer runs out
PEMD111IPrinter enhancement mode. When low, PEMD enables the write data register to the PD0–PD7 lines.
RESET3955IReset. When low, RESET forces the TL16C552A into an idle mode in which all serial data activities
RTS0,
RTS1
RXRDY0,
RXRDY1
RI0, RI130, 646, 16IRing indicator. The RI signal is a modem control input. Its condition is tested by reading MSR6 (RI) of
SIN0,
SIN1
SLCT657ILine printer select. SLCT is an input line from the printer that goes high when the printer is selected.
SLIN5877I/O Line printer select. SLIN is an open-drain I/O that selects the printer when active (low). SLIN has an
24, 1237, 25ORequest to send. The RTS outputs are set low by setting MCR1 of its UARTs modem control register .
9, 6119, 3O
41, 6257, 4ISerial data. SIN0 and SIN1 move information from the communication line or modem to the
I/O
ACK
. INT2 is enabled by bit 4 of the write control register. Upon reset, INT2 is in the high-impedance
state. Its mode is also controlled by ENIRQ
to the data bus (DB0–DB7). The data output depends on the register selected by the address inputs
A0, A1, A2, and chip select. Chip select 0 (CS0
and chip select 2 (CS2
ACE or to the parallel port. The destination depends on the register selected by the address inputs A0,
A1, A2, and chip selects CS0
of paper.
A high on PEMD allows direction control of the PD0–PD7 port by the DIR bit in the control register.
PEMD is usually tied low for the printer operation.
are suspended. The modem control register and its associated outputs are cleared. The line status
register is cleared except for the transmitter holding register empty (THRE) and TEMT bits, which are
set. All functions of the device remain in an idle state until programmed to resume serial data activities.
RESET
has a hysteresis level of typically 400 mV.
Both RTS
transmit. In half-duplex operations, RTS
Receiver ready. Receiver direct memory access (DMA) signaling is also available through this output.
One of two types of DMA signaling can be selected using FCR3 when in FIFO mode. Only DMA mode
0 is allowed when in TL16C450 mode. For signal transfer DMA (a transfer is made between CPU bus
cycles), mode 0 is used. Multiple transfers that are made continuously until the receiver FIFO has been
emptied are supported by mode 1.
Mode 0. RXRDY is active (low) in FIFO mode (FCR0 = 1, FCR3 = 0) or in TL16C450 mode (FCR0 =
0) and the receiver FIFO or receiver holding register contains at least one character. When there are
no more characters in the FIFO or holding register, RXRDY
Mode 1. RXRDY goes active (low) in the FIFO mode (FCR0 = 1) when FCR3 = 1 and the time-out or
trigger levels have been reached. RXRDY
empty.
each ACE. The modem status register output TERI (MSR2) indicates whether RI
high to low since the previous reading of the modem status register.
TL16C552A receiver circuits. Mark is a high state and space is a low state. Data on serial data inputs
is disabled in loop mode.
internal pullup resistor to VDD of approximately 10 kΩ.
terminals are reset high by RESET. A low on RTS indicates that its ACE has data ready to
goes inactive (high) when the FIFO or holding register is
has changed from
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
5
TL16C552A, TL16C552AM
NAME
DUAL ASYNCHRONOUS COMMUNICATIONS ELEMENT
WITH FIFO
SLLS189D – NOVEMBER 1994 – REVISED JANUARY 1999
Terminal Functions (Continued)
TERMINAL
DESCRIPTION
is active (low). Once
goes inactive
56
I/O
A mark is a high state and a space is a low state. Each SOUT is held in the mark condition when the
transmitter is disabled (RESET
mode.
is active (low), it provides the printer with a signal to latch the data currently on the parallel port. STB
has an internal pullup resistor to VDD of approximately 10 kΩ.
is asserted, all I/Os and outputs are in the high-impedance state, allowing board level testers to drive
the outputs without overdriving internal buffers. TRI is level sensitive and is pulled down with an internal
resistor that is approximately 5 kΩ.
operating in FIFO mode. Only DMA mode 0 is allowed when in TL16C450 mode. Single-transfer DMA
(a transfer is made between CPU bus cycles) is supported by mode 0. Multiple transfers that are made
continuously until the transmitter FIFO has been filled are supported by mode 1.
Mode 0. In FIFO mode (FCR0 = 1, FCR3 = 0) or in TL16C450 mode (FCR0 = 0) when there are no
characters in the transmitter holding register or transmitter FIFO, TXRDYx
TXRDYx
of the transmitter FIFO.
Mode 1. TXRDY goes active (low) in FIFO mode (FCR0 = 1) when FCR3 = 1 and there are no
characters in the transmitter FIFO. When the transmitter FIFO is completely full, TXRDY
(high).
Power supply. The VDD requirement is 5 V ±5%.
is activated (low), it goes inactive after the first character is loaded into the holding register
is asserted low), the transmitter register is empty, or when in the loop
NO.
FNPN
SOUT0,
SOUT1
STB5574I/O Line printer strobe. STB provides communication between the TL16C552A and the printer. When STB
TRI212I3-state output control input. TRI controls the 3-state control of all I/O and output terminals. When TRI
TXRDY0
TXRDY1
V
DD
26, 1039, 23OSerial data outputs. SOUT0 and SOUT1 are the serial data outputs from the ACE transmitter circuitry .
22, 4235, 58OTransmitter ready . T wo types of DMA signaling are available. Either can be selected using FCR3 when
23, 40,646, 36,
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
Supply voltage range, V
Input voltage range, V
Output voltage range, V
Operating free-air temperature range, T
Storage temperature range, T
†
Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
NOTE 1: All voltage levels are with respect to GND.
Supply voltage, V
Clock high-level input voltage, V
Clock low-level input voltage, V
High-level input voltage, V
Low-level input voltage, V
Clock frequency, f
p
DD
clock
IH(CLK)
IL(CLK)
IH
IL
p
A
I suffix–4085
M suffix–55125
package thermal characteristics
R
Junction-to-ambient thermal impedanceBoard mounted, no air flow5274°C/W
θJA
R
Junction-to-case thermal impedance143°C/W
θJC
T
Junction temperature115150°C/W
J
TL16C552A, TL16C552AM
DUAL ASYNCHRONOUS COMMUNICATIONS ELEMENT
WITH FIFO
SLLS189D – NOVEMBER 1994 – REVISED JANUARY 1999
MINNOMMAXUNIT
4.7555.25V
2V
00.8V
2V
00.8V
FN PackageHV Package
MINTYPMAXMINTYPMAX
DD
DD
V
V
16MHz
°
electrical characteristics over recommended ranges of operating free-air temperature and supply
voltage (unless otherwise noted)
PARAMETERTEST CONDITIONSMINMAXUNIT
V
OH
V
OL
I
I
I
I(CLK)
I
NOTES: 2. Excluding INIT, AFD, STB, and SLIN. They are open-drain terminals with an internal pullup resistor to VDD of approximately 10 KΩ.
High-level output voltage
Low-level output voltage
Input current
Clock input currentVI = 0 to 5.25 V±10µA
High-impedance output current
pp
3. Excluding the TRI input terminal. It contains an internal pulldown resistor of approximately 5 kΩ.
IOH = –12 mA for PD0–PD7,
IOH = –4 mA for all other outputs (see Note 2),
IOL = 12 mA for PD0–PD7,
IOL = 12 mA for INIT
IOL = 4 mA for all other outputs
VDD = 5.25 V (see Note 3),
All other terminals are floating
= 5.25 V,
=
O
= 5.25 V,
DD
p
, AFD, STB, and SLIN,
= 0
p and write mode selected (see Note
,
= 8
p
s on outputs,
2.4V
0.4V
±10µA
±20
A
clock timing requirements over recommended ranges of operating free-air temperature and supply
voltage
TL16C552A, TL16C552AM
DUAL ASYNCHRONOUS COMMUNICATIONS ELEMENT
WITH FIFO
SLLS189D – NOVEMBER 1994 – REVISED JANUARY 1999
read cycle timing requirements over recommended ranges of operating free-air temperature and
supply voltage (see Note 4 and Figure 4)
MINMAXUNIT
t
w4
t
su1
t
su2
t
h1
t
h2
t
d1
t
d2
NOTES: 4. These parameters are not production tested.
write cycle timing requirements over recommended ranges of operating free-air temperature and
supply voltage (see Note 7 and Figure 5)
t
w5
t
su4
t
su5
t
su6
t
h3
t
h4
t
h5
t
d3
t
d4
NOTES: 7. These parameters are not production tested.
Pulse duration, IOR ↓80ns
Setup time, CSx valid before IOR ↓ (see Note 5)15ns
Setup time, A2–A0 valid before IOR ↓ (see Note 5)15ns
Hold time, A2–A0 valid after IOR ↑ (see Note 5)20ns
Hold time, CSx valid after IOR ↑ (see Note 5)20ns
Delay time, t
Delay time, IOR ↑ to IOR or IOW ↓80ns
5. The internal address strobe is always active.
6. In FIFO mode, td1 = 425 ns (min) between reads of the receiver FIFO and the status registers (interrupt identification register and
line status register).
Pulse duration, IOW ↓80ns
Setup time, CSx valid before IOW ↓ (see Note 8)15ns
Setup time, A2–A0 valid before IOW ↓ (see Note 8)15ns
Setup time, DB0–DB7 valid before IOW ↑15ns
Hold time, A2–A0 valid after IOW ↑ (see Note 8)20ns
Hold time, CSx valid after IOW ↑ (see Note 8)20ns
Hold time, DB0–DB7 valid after IOW ↑15ns
Delay time, t
Delay time, IOW ↑ to IOW or IOR ↓80ns
8. The internal address strobe is always active.
+ tw4 + td2 (see Note 6)175ns
su2
MINMAXUNIT
su5
+ tw5 + t
d4
175ns
read cycle switching characteristics over recommended ranges of operating free-air temperature
and supply voltage, C
t
Propagation delay time from IOR ↓ to BDO ↑ or from IOR ↑ to BDO ↓60ns
pd1
t
Enable time from IOR ↓ to DB0–DB7 valid (see Note 10)60ns
en
t
Disable time from IOR ↑ to DB0–DB7 released (see Note 10)60ns
dis
NOTES: 9. These parameters are not production tested.
8
10. VOL and VOH (and the external loading) determine the charge and discharge time.
= 100 pF (see Note 9 and Figure 4)
L
PARAMETERMINMAXUNIT
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TL16C552A, TL16C552AM
DUAL ASYNCHRONOUS COMMUNICATIONS ELEMENT
WITH FIFO
SLLS189D – NOVEMBER 1994 – REVISED JANUARY 1999
transmitter switching characteristics over recommended ranges of operating free-air temperature
and supply voltage (see Note 11 and Figures 6, 7, and 8)
PARAMETERTEST CONDITIONSMINMAXUNIT
t
Delay time, interrupt THRE ↓ to SOUT ↓ at startSee Figure 6824
d5
t
Delay time, SOUT ↓ at start to interrupt THRE ↑See Note 12 and Figure 689
d6
t
Delay time, IOW (WR THR) ↑ to interrupt THRE ↑See Note 12 and Figure 61632
d7
t
Delay time, SOUT ↓ at start to TXRDY ↓
d8
t
Propagation delay time from IOW (WR THR) ↓ to interrupt THRE ↓
pd2
t
Propagation delay time from IOR (RD IIR) ↑ to interrupt THRE ↓
pd4
t
Propagation delay time from IOW (WR THR) ↑ to TXRDY ↑
pd5
NOTES: 11. These parameters are not production tested.
12. When the transmitter interrupt delay is active, this delay is lengthened by one character time minus the last stop bit time.
CL = 100 pF,
See Figures 7 and 8
CL = 100 pF,
See Figure 6
CL = 100 pF,
See Figure 6
CL = 100 pF,
See Figures 7 and 8
RCLK
cycles
RCLK
cycles
RCLK
cycles
RCLK
8
cycles
140ns
140ns
195ns
receiver switching characteristics over recommended ranges of operating free-air temperature
and supply voltage (see Note 13 and Figures 9 through 13)
PARAMETERTEST CONDITIONSMINMAXUNIT
t
Delay time from stop to INT ↑See Note 141
d9
t
Propagation delay time from RCLK ↑ to sample CLK ↑100ns
pd6
t
Propagation delay time from IOR (RD RBR/RD LSR) ↓ to reset interrupt ↓CL = 100 pF150ns
pd7
t
Propagation delay time from IOR (RD RBR) ↓ to RXRDY ↑150ns
pd8
NOTES: 13. These parameters are not production tested.
14. The receiver data available indicator, the overrun error indicator, the trigger level interrupts, and the active RXRDY
delayed three RCLK cycles in FIFO mode (FCR0 = 1). After the first byte has been received, status indicators (PE, FE, BI) are
delayed three RCLK cycles. These indicators are updated immediately for any further bytes received after RDRBR goes active.
There are eight RCLK cycle delays for trigger change level interrupts.
RCLK
cycle
indicator are
modem control switching characteristics over recommended ranges of operating free-air
temperature and supply voltage, C
t
Propagation delay time from IOW (WR MCR) ↑ to RTS (DTR) ↓↑100ns
pd9
t
Propagation delay time from modem input (CTS, DSR) ↓↑ to interrupt ↑170ns
pd10
t
Propagation delay time from IOR (RD MSR) ↑ to interrupt ↓140ns
pd11
t
Propagation delay time from RI ↑ to interrupt ↑170ns
pd12
NOTE 15: These parameters are not production tested.
= 100 pF (see Note 15 and Figure 14)
L
PARAMETERMINMAXUNIT
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
9
TL16C552A, TL16C552AM
DUAL ASYNCHRONOUS COMMUNICATIONS ELEMENT
WITH FIFO
SLLS189D – NOVEMBER 1994 – REVISED JANUARY 1999
parallel port timing requirements over recommended ranges of supply voltage and operating
free-air temperature (see Note 16 and Figures 15, 16, and 17)
MINMAXUNIT
t
su7
t
h6
t
w6
t
d10
t
d11
t
w7
t
w8
t
d12
t
d13
t
d14
t
d15
t
d16
NOTES: 16. These parameters are not production tested.
Setup time, data valid before STB ↓1µs
Hold time, data valid after STB ↑1µs
Pulse duration, STB ↓1µs
Delay time, BUSY ↑ to ACK ↓Defined by printer
Delay time, BUSY ↓ to ACK ↓Defined by printer
Pulse duration, BUSY ↑Defined by printer
Pulse duration, ACK ↓Defined by printer
Delay time, BUSY ↑ after STB ↑Defined by printer
Delay time, INT2 ↓ after ACK ↓ (see Note 17)22ns
Delay time, INT2 ↑ after ACK ↑ (see Note 17)20ns
Delay time, INT2 ↑ after ACK ↑ (see Note 17)24ns
Delay time, INT2 ↓ after IOR ↑ (see Note 17)25ns
17. t
d13–td16
are all measured with a 15-pF load.
PARAMETER MEASUREMENT INFORMATION
t
w1
CLK (XTAL1)
f
clock
2 V
0.8 V
t
w2
= 16 MHz MAX
Figure 1. CLK Voltage Waveform
2.54 V
Device Under T est
TL16C552A
NOTE A: This includes scope and jig capacitance.
Figure 2. Output Load Circuit
2 V
0.8 V
680 Ω
82 pF
(see Note A)
10
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TL16C552A, TL16C552AM
DUAL ASYNCHRONOUS COMMUNICATIONS ELEMENT
SLLS189D – NOVEMBER 1994 – REVISED JANUARY 1999
PARAMETER MEASUREMENT INFORMATION
TL16C552A
WITH FIFO
A2, A1, A0
, CS1, CS2
CS0
Data Bus
Address Bus
Control Bus
Serial
Channel 1
Buffers
Dual
ACE and
Printer
Port
Option
Jumpers
Serial
Channel 2
Buffers
Parallel
Port
R/C
Network
Figure 3. Basic Test Configuration
50%50%
50%50%
t
su1
t
su2
Valid
Valid
t
h1
t
t
d1
h2
9-Pin D Connector
9-Pin D Connector
25-Pin D Connector
IOR
IOW
BDO
DB0–DB7
Active
50%50%
t
w4
t
pd1
50%50%
t
en
Valid Data
Figure 4. Read Cycle Timing Waveforms
t
dis
t
pd1
50%
t
d2
50%
Active
or
Active
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
11
TL16C552A, TL16C552AM
DUAL ASYNCHRONOUS COMMUNICATIONS ELEMENT
WITH FIFO