TLV1544C, TLV1544I, TLV1548C, TLV1548I, TLV1548M

LOW-VOLTAGE 10-BIT ANALOG-TO-DIGITAL CONVERTERS

WITH SERIAL CONTROL AND 4/8 ANALOG INPUTS

SLAS139C – DECEMBER 1996 – REVISED JANUARY 1999

10

POST OFFICE BOX 655303

tACQ

Aa

Ab

Ab

Ac

Ad

XDa

Db

Db

Dc

CS

CSTART

DATA IN

EOC

DATA OUT

Async Flag

Read Out

Cycle

Read Out

Cycle

Read Out

Cycle

FS

(DSP Mode)

Complete Extended

Sample Cycle

tACQ

NOTES: A. Aa = Address for input channel a.

B. Da = Conversion result from channel a.

Hi–Z

Hi–Z

Hi–Z

Hi–Z

Hi–Z

Hi–Z

Normal

Cycle

Normal

Cycle

Extended

Sample

Cycle

Extended

Sample

Cycle

Figure 2. Extended Sampling Operation

reference voltage inputs

There are two reference inputs used with the TLV1544/TLV1548, REF+ and REF–. These voltage values

establish the upper and lower limits of the analog inputs to produce a full-scale and zero-scale reading

respectively. The values of REF+, REF–, and the analog input should not exceed the positive supply or be lower

than GND consistent with the specified absolute maximum ratings. The digital output is at full scale when the

input signal is equal to or higher than REF+ and is at zero when the input signal is equal to or lower than REF–.

programmable conversion rate

The TLV1544/TLV1548 offers two conversion rates to maximize battery life when high-speed operation is not

necessary. The conversion rate is programmable. Once the conversion rate has been selected, it takes effect

immediately in the same cycle and stays at the same rate until the other rate is chosen. The conversion rate

should be set at power up. Activation and deactivation of the power-down state (digital logic active) has no effect

on the preset conversion rate.