LTC2489CDEPBF datasheet(8/24 Pages) LINER

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LTC2489

2489f

FO(Pin1):FrequencyControlPin.Digitalinputthatcontrols

the internal conversion clock rate. When FO is connected

to GND, the converter uses its internal oscillator running at

307.2kHz. The conversion clock may also be overridden by

driving the FO pin with an external clock in order to change

the output rate and the digital ﬁlter rejection null.

CA0, CA1 (Pins 2, 3): Chip Address Control Pins. These

pins are conﬁgured as a three-state (LOW, HIGH, Floating)

address control bits for the device’s I2C address.

SCL (Pin 4): Serial Clock Pin of the I2C Interface. The

LTC2489 can only act as a slave and the SCL pin only ac-

cepts an external serial clock. Data is shifted into the SDA

pin on the rising edges of the SCL clock and output through

the SDA pin on the falling edges of the SCL clock.

SDA (Pin 5): Bidirectional Serial Data Line of the I2C

Interface. In the transmitter mode (Read), the conver-

sion result is output through the SDA pin, while in the

receiver mode (Write), the device channel select bits are

input through the SDA pin. The pin is high impedance

during the data input mode and is an open drain output

(requires an appropriate pull-up device to VCC) during the

data output mode.

GND (Pin 6): Ground. Connect this pin to a common ground

plane through a low impedance connection.

COM (Pin 7): The Common Negative Input (IN–) for All

Single-Ended Multiplexer Conﬁgurations. The voltage

on CH0-CH3 and COM pins can have any value between

GND – 0.3V to VCC + 0.3V. Within these limits, the two

selected inputs (IN+ and IN– ) provide a bipolar input

range (VIN = IN+ – IN– ) from –0.5 • VREF to 0.5 • VREF.

Outside this input range, the converter produces unique

over-range and under-range output codes.

CH0 to CH3 (Pin 8-Pin 11): Analog Inputs. May be pro-

grammed for single-ended or differential mode.

VCC (Pin 12): Positive Supply Voltage. Bypass to GND with

a 10μF tantalum capacitor in parallel with a 0.1μF ceramic

capacitor as close to the part as possible.

REF+, REF– (Pin 13, Pin 14):

Differential Reference Input.

The voltage on these pins can have any value between

GND and VCC as long as the reference positive input, REF+,

remains more positive than the negative reference input,

REF–, by at least 0.1V. The differential voltage (VREF = REF+

– REF–) sets the full-scale range for all input channels.

Exposed Pad (Pin 15): Ground. This pin is ground and

must be soldered to the PCB ground plane. For prototyping

purposes, this pin may remain ﬂoating.

PIN FUNCTIONS

FUNCTIONAL BLOCK DIAGRAM

AUTOCALIBRATION

AND CONTROL

DIFFERENTIAL

3RD ORDER

ΔΣ MODULATOR

DECIMATING FIR

ADDRESS

INTERNAL

OSCILLATOR

I2C

INTERFACE

GND

VCC

CH0

CH1

CH2

CH3

COM

MUX

IN+

IN–

CA0

SCL

REF+

REF –

CA1

SDA

(INT/EXT)

2489 BD

–

1.7k

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