Detailed Description

The MAX1102/MAX1103/MAX1104 are 8-bit CODECs in

a compact 8-pin package. These devices consist of an

8-bit ADC, an 8-bit DAC, track/hold (T/H), DAC output

buffer amplifier, internal voltage reference, input multi-

plexer (mux) and a 6MHz SPI, QSPI and MICROWIRE

compatible 4-wire serial interface. A single 8-bit word

configures the MAX1102/MAX1103/MAX1104, provid-

ing a simple interface to a microcontroller (µC).

Analog-to-Digital Converter

The MAX1102/MAX1103/MAX1104 ADC section uses a

successive-approximation (SAR) conversion technique

and input T/H circuitry to convert an analog signal to an

8-bit digital output. No external hold capacitors are

required. The MAX1102/MAX1103 have an input multi-

the T/H, allowing these devices to either convert the

analog input, or monitor the power supply. Figure 1

shows the detailed functional diagram of the ADC

block.

ADC Operation

The input architecture of the ADC is illustrated in Figure

2, the equivalent input circuit, and is composed of the

T/H, input mux (MAX1102/MAX1103), input comparator,

switched capacitor DAC, and the auto-zero rail. The

switched capacitor DAC is independent of the R-2R

ladder DAC and does not provide the converted analog

output on OUT.

The T/H is in hold mode while a conversion is taking

place. Once the conversion is completed, the T/H

enters acquisition mode, and tracks the input signal

until the start of the next conversion. In single conver-

sion mode, conversion starts at the falling clock edge

corresponding to the last bit of the control word. In con-

tinuous conversion mode, the first conversion following

the control word starts on the falling clock edge of the

8-Bit CODECs

8

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Pin Description

PIN

NAME

FUNCTION

Voltage Supply

2

GND

Ground

3

AIN

ADC Analog Input

4

OUT

DAC Analog Voltage Output

5

CS

Chip Select Input. Device ignores all logic signals when CS is high.

6

SCLK

Serial Clock Input. Data in is latched on the rising edge, data out transitions on the falling edge.

7

DOUT

ADC Digital Output. Output is high impedance when CS is high.

8

DIN

DAC Digital Input. Input ignores all signals when CS is high.

DIN

ANALOG

INPUT

MUX

ANALOG

INPUT

MUX

CONTROL

LOGIC/2

AIN

T/H

SCLK

CS

MAX1102

MAX1103

SUCCESSIVE

APPROXIMATION

REGISTER

INTERNAL

OSCILLATOR

INTERNAL

OSCILLATOR

DOUT

CHARGE

REDISTRIBUTION

DAC

OUTPUT

SHIFT

REGISTER

Figure 1. ADC Detailed Functional Diagram