Detailed Description

The MAX1069 analog-to-digital converter (ADC) uses

successive-approximation conversion (SAR) tech-

niques and on-chip track-and-hold (T/H) circuitry to

capture and convert an analog signal to a serial 14-bit

digital output.

The MAX1069 performs a unipolar conversion on its

single analog input using its internal 4MHz clock. The

full-scale analog input range is determined by the inter-

nal reference or by an externally applied reference volt-

The flexible 2-wire serial interface provides easy con-

nection to microcontrollers (µCs) and supports data

typical application circuit.

Power Supply

To maintain a low-noise environment, the MAX1069

provides separate analog and digital power-supply

inputs. The analog circuitry requires a +5V supply and

consumes only 900µA at sampling rates up to

58.6ksps. The digital supply voltage accepts voltages

from +2.7V to +5.5V to ensure compatibility with low-

voltage ASICs. The MAX1069 wakes up in shutdown

Analog Input and Track/Hold

The MAX1069 analog input contains a track-and-hold

(T/H) capacitor, T/H switches, comparator, and a

switched capacitor digital-to-analog converter (DAC)

od is the two clock cycles prior to the conversion peri-

od. The T/H switches are normally in the hold position.

During the acquisition period the T/H switches are in

signal. Before a conversion begins, the T/H switches

as a sample of the analog input signal.

During the conversion interval, the switched capacitive

DAC adjusts to restore the comparator input voltage to

zero within the limits of 14-bit resolution. This is equiva-

lent to transferring a charge of 35pF

58.6ksps, 14-Bit, 2-Wire Serial ADC

in a 14-Pin TSSOP

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Pin Description

PIN

NAME

FUNCTION

1

DGND

Digital Ground

2

SCL

Clock Input

3

SDA

Data Input/Output

4

ADD2

Address Select Input 2

5

ADD1

Address Select Input 1

6

ADD0

Address Select Input 0

Digital Power Input. Bypass to DGND with a 0.1µF capacitor.

Analog Power Input. Bypass to AGND with a 0.1µF capacitor.

9

AGND

Analog Ground

10

AIN

Analog Input

11

AGNDS

Analog Signal Ground. Negative reference for analog input. Connect to AGND.

12

REFADJ

Internal Reference Output and Reference Buffer Input. Bypass to AGND with a 0.1µF capacitor.

13

REF

Reference Buffer Output and External Reference Input. Bypass to AGND with a 10µF capacitor

when using the internal reference.

14

ADD3

Address Select Input 3