TLC1542C, TLC1542I, TLC1542M, TLC1542Q, TLC1543C, TLC1543I, TLC1543Q
10-BIT ANALOG-TO-DIGITAL CONVERTERS WITH
SERIAL CONTROL AND 11 ANALOG INPUTS
SLAS052C – MARCH 1992 – REVISED MARCH 1995
4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
detailed description (continued)
There are six basic serial-interface timing modes that can be used with the device. These modes are determined
by the speed of I/O CLOCK and the operation of CS
as shown in Table 1. These modes are (1) a fast mode with
a 10-clock transfer and CS
inactive (high) between conversion cycles, (2) a fast mode with a 10-clock transfer
and CS
active (low) continuously, (3) a fast mode with an 11- to 16-clock transfer and CS inactive (high) between
conversion cycles, (4) a fast mode with a 16-bit transfer and CS
active (low) continuously, (5) a slow mode with
an 11- to 16-clock transfer and CS
inactive (high) between conversion cycles, and (6) a slow mode with a
16-clock transfer and CS
active (low) continuously.
The MSB of the previous conversion appears at DATA OUT on the falling edge of CS
in mode 1, mode 3, and
mode 5, on the rising edge of EOC in mode 2 and mode 4, and following the sixteenth clock falling edge in
mode 6. The remaining nine bits are shifted out on the next nine falling edges of I/O CLOCK. Ten bits of data
are transmitted to the host-serial interface through DATA OUT. The number of serial clock pulses used also
depends on the mode of operation, but a minimum of ten clock pulses is required for conversion to begin. On
the tenth clock falling edge, the EOC output goes low and returns to the high logic level when conversion is
complete and the result can be read by the host. Also, on the tenth clock falling edge, the internal logic takes
DATA OUT low to ensure that the remaining bit values are zero if the I/O CLOCK transfer is more than ten clocks
long.
Table 1 lists the operational modes with respect to the state of CS
, the number of I/O serial transfer clocks that
can be used, and the timing edge on which the MSB of the previous conversion appears at the output.
Table 1. Mode Operation
MODES
CS
NO. OF
I/O CLOCKS
MSB AT DATA OUT
†
TIMING
DIAGRAM
Mode 1 High between conversion cycles 10 CS falling edge Figure 9
Mode 2 Low continuously 10 EOC rising edge Figure 10
as
o
es
Mode 3 High between conversion cycles 11 to 16
‡
CS falling edge Figure 11
Mode 4 Low continuously 16
‡
EOC rising edge Figure 12
Mode 5 High between conversion cycles 11 to 16
‡
CS falling edge Figure 13
ow
o
es
Mode 6 Low continuously 16
‡
16th clock falling edge Figure 14
†
These edges also initiate serial-interface communication.
‡
No more than 16 clocks should be used.
fast modes
The device is in a fast mode when the serial I/O CLOCK data transfer is completed before the conversion is
completed. With a 10-clock serial transfer, the device can only run in a fast mode since a conversion does not
begin until the falling edge of the tenth I/O CLOCK.
mode 1: fast mode, CS inactive (high) between conversion cycles, 10-clock transfer
In this mode, CS is inactive (high) between serial I/O CLOCK transfers and each transfer is ten clocks long. The
falling edge of CS
begins the sequence by removing DATA OUT from the high-impedance state. The rising edge
of CS
ends the sequence by returning DATA OUT to the high-impedance state within the specified delay time.
Also, the rising edge of CS
disables the I/O CLOCK and ADDRESS terminals within a setup time plus two falling
edges of the internal system clock.
mode 2: fast mode, CS active (low) continuously, 10-clock transfer
In this mode, CS is active (low) between serial I/O CLOCK transfers and each transfer is ten clocks long. After
the initial conversion cycle, CS
is held active (low) for subsequent conversions; the rising edge of EOC then
begins each sequence by removing DATA OUT from the low logic level, allowing the MSB of the previous
conversion to appear immediately on this output.