TLC3544, TLC3548

5-V ANALOG, 3-/5-V DIGITAL, 14-BIT, 200-KSPS, 4-/8-CHANNELS SERIAL

ANALOG-TO-DIGITAL CONVERTERS WITH 0-5 V (PSEUDODIFFERENTIAL) INPUTS

SLAS266C – OCTOBER 2000 – REVISED MAY 2003

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POST OFFICE BOX 655303

FIFO operation (continued)

The device has an 8-level FIFO that can be programmed for different thresholds. An interrupt is sent to the host

after the preprogrammed threshold is reached. The FIFO is used to store conversion results in mode 01, 10,

and 11, from either a fixed channel or a series of channels according to a preprogrammed sweep sequence.

For example, an application may require eight measurements from channel 3. In this case, if the threshold is

set to full, the FIFO is filled with 8 data conversions sequentially taken from channel 3. Another application may

require data from channel 0, 2, 4, and 6 in that order. The threshold is set to 1/2 full and sweep sequence is

selected as 0–2–4–6–0–2–4–6. An interrupt is sent to the host as soon as all four data conversions are in the

FIFO. The FIFO is reset after a power on and a WRITE CFR operation. The contents of the FIFO are retained

during autopower down and software power down.

Powerdown: The device has two power-down modes.

AutoPower-Down Mode: The device enters the autopower-down state at the end of a conversion.

In autopower-down, the power consumption reduces to about 1.8 mA when an internal reference is selected.

The built-in reference is still on to allow the device to resume quickly. The resumption is fast enough for use

between cycles. An active CS, FS, or CSTART resumes the device from power-down state. The power current

is 20

µA when an external reference is programmed and SCLK stops.

Software Power-Down Mode: Writing 8000h to the device puts the device into the software power-down state,

and the entire chip (including the built-in reference) is powered down. The power current is reduced to about

20

µA if SCLK stops. Deselect CS to save power once the device is in the software power-down mode. An active

CS, FS, or CSTART restores the device. There is no time delay when an external reference is selected.

However, if an internal reference is used, it takes about 20 ms to warm up.

The configuration register is not affected by any of the power-down modes but the sweep operation sequence

must be started over again. All FIFO contents are retained in both power-down modes.