ADC14L040 datasheet(3/23 Pages) NSC

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Pin Descriptions and Equivalent Circuits

Pin No.

Symbol

Equivalent Circuit

Description

ANALOG I/O

IN+

Differential analog input pins. With a 1.0V reference voltage the

differential full-scale input signal level is 2.0 V

P-P with each

input pin voltage centered on a common mode voltage, V

CM.

The negative input pins may be connected to V

CM for

single-ended operation, but a differential input signal is

required for best performance.

IN−

REF

This pin is the reference select pin and the external reference

input.

If (V

A - 0.3V) < VREF < VA, the internal 1.0V reference is

selected.

If AGND < V

REF < (AGND + 0.3V), the internal 0.5V reference

is selected.

If a voltage in the range of 0.4V to (V

A - 0.4V) is applied to this

pin, that voltage is used as the reference.

The full scale differential voltage range is2*V

REF.VREF

should be bypassed to AGND with a 0.1 µF capacitor when an

external reference is used.

These pins should each be bypassed to AGND with a low ESL

(equivalent series inductance) 0.1 µF capacitor. A 10 µF

capacitor should be placed between the V

RP and VRN.

RM may be loaded to 1mA for use as a temperature stable

1.5V reference. The remaining pins should not be loaded.

RM may be used to provide the common mode voltage, VCM,

for the differential inputs.

DF/DCS

This is a four-state pin.

DF/DCS = V

A, output data format is offset binary with duty

cycle stabilization applied to the input clock

DF/DCS = AGND, output data format is 2’s complement, with

duty cycle stabilization applied to the input clock.

DF/DCS = V

RM , output data is 2’s complement without duty

cycle stabilization applied to the input clock

DF/DCS = "float", output data is offset binary without duty cycle

stabilization applied to the input clock.

DIGITAL I/O

CLK

Digital clock input. The range of frequencies for this input is as

specified in the electrical tables with guaranteed performance

at 40 MHz. The input is sampled on the rising edge.

8PD

PD is the Power Down input pin. When high, this input puts the

converter into the power down mode. When this pin is low, the

converter is in the active mode.

ADC14L040 Datasheet(PDF) 3 Page - National Semiconductor (TI)

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