TLC2543-EP Datasheet, PDF (17/25 Pages) Texas Instruments – 12-BIT ANALOG-TO-DIGITAL CONVERTER WITH SERIAL CONTROL AND 11 ANALOG INPUTS

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TLC2543-EP
12-BIT ANALOG-TO-DIGITAL CONVERTER
WITH SERIAL CONTROL AND 11 ANALOG INPUTS
SGLS125A – JULY 2002 – REVISED NOVEMBER 2006
Chip-Select (CS) Input
CS enables and disables the device. During normal operation, CS should be low. Although the use of CS is not
necessary to synchronize a data transfer, it can be brought high between conversions to coordinate the data
transfer of several devices sharing the same bus.
When CS is brought high, the serial-data output is immediately brought to the high-impedance state, releasing
its output data line to other devices that may share it. After an internally generated debounce time, I/O CLOCK is
inhibited, thus preventing any further change in the internal state.
When CS is subsequently brought low again, the device is reset. CS must be held low for an internal debounce
time before the reset operation takes effect. After CS is debounced low, I/O CLOCK must remain inactive (low)
for a minimum time before a new I/O cycle can start.
CS can interrupt any ongoing data transfer or any ongoing conversion. When CS is debounced low long enough
before the end of the current conversion cycle, the previous conversion result is saved in the internal output
buffer and shifted out during the next I/O cycle.
Power-Down Features
When a binary address of 1110 is clocked into the input data register during the first four I/O CLOCK cycles, the
power-down mode is selected. Power down is activated on the falling edge of the fourth I/O CLOCK pulse.
During power down, all internal circuitry is put in a low-current standby mode. No conversions are performed,
and the internal output buffer keeps the previous conversion cycle data results provided that all digital inputs are
held above V_CC – 0.5 V or below 0.5 V. The I/O logic remains active so the current I/O cycle must be completed,
even when the power-down mode is selected. Upon power-on reset and before the first I/O cycle, the converter
normally begins in the power-down mode. The device remains in the power-down mode until a valid input
address (other than 1110) is clocked in. Upon completion of that I/O cycle, a normal conversion is performed
with the results being shifted out during the next I/O cycle.
Analog Input, Test, and Power-Down Mode
The 11 analog inputs, 3 internal voltages, and power-down mode are selected by the input multiplexer according
to the input addresses shown in Table 3, Table 4, and Table 5. The input multiplexer is a break-before-make
type to reduce input-to-input noise rejection resulting from channel switching. Sampling of the analog input starts
on the falling edge of the fourth I/O CLOCK and continues for the remaining I/O CLOCK pulses. The sample is
held on the falling edge of the last I/O clock pulse. The three internal test inputs are applied to the multiplexer,
then sampled and converted in the same manner as the external analog inputs. The first conversion after the
device has returned from the power-down state may not read accurately due to internal device settling.
Table 3. Analog-Channel-Select Address
ANALOG INPUT
SELECTED
AIN0
AIN1
AIN2
AIN3
AIN4
AIN5
AIN6
AIN7
AIN8
AIN9
AIN10
VALUE SHIFTED INTO DATA INPUT
BINARY
HEX
0000
0
0001
1
0010
2
0011
3
0100
4
0101
5
0110
6
0111
7
1000
8
1001
9
1010
A
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