MAX1407 Datasheet, PDF(16/48 Page) Maxim Integrated Products – Low-Power, 16-Bit Multichannel DAS with Internal Reference,10-Bit DACs, and RTC

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MAX1407 Datasheet, PDF (16/48 Pages) Maxim Integrated Products – Low-Power, 16-Bit Multichannel DAS with Internal Reference,10-Bit DACs, and RTC

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Low-Power, 16-Bit Multichannel DAS with

Internal Reference,10-Bit DACs, and RTC

AVDD

CPLL FOUT CLKIN CLKOUT

DVDD

SCLK

DIN

DOUT

IN3

IN2

IN1

IN0

SERIAL

INTERFACE

OUT2

OUT1

REF

AVDD

8:1

INPUT

MUX

2.4576MHz

PLL

32.768kHz

OSCILLATOR

RTC AND

ALARM

WAKE-UP

LOGIC

MAX1407/MAX1414

COMPARATOR

INTERRUPT

GENERATOR

BUF

DIGITAL

PGA

16-BIT ADC OUTPUT

BUF

WU2

WU1

SHDN

INT

DRDY

FB2

FB1

IN3

IN2

IN1

IN0

REF

AGND

8:1

INPUT

MUX

1.8V/2.7V

ÂµP

SUPERVISORS

RESET

GENERATOR

1.25V

BANDGAP

REFERENCE

BUF

10-BIT DAC

AGND

RESET

REF

*MAX1414 HAS A +50mV SIGNAL-DETECT COMPARATOR THRESHOLD.

DGND

OUT1

FB1

OUT2

FB2

Figure 1. MAX1407/MAX1414 Functional Diagram

With the use of two external resistors, the DAC output

can go from 0.05V to AVDD - 0.2V. The ADCs and

DACs both utilize a precise low-drift 1.25V internal

bandgap reference for conversions and setting of the

full-scale range. For applications that require increased

accuracy, power-down the internal reference and con-

nect an external reference at REF. The RTC is leap year

compensated until 9999 and provides an alarm function

that can be used to wake-up the system or cause an

interrupt at a predefined time. The power-supply volt-

age monitors detect when AVDD falls below a trip

threshold voltage at either +1.8V or +2.7V causing the

reset to be asserted. The 4-wire serial interface is used

to communicate directly between SPI, QSPI, and

MICROWIRE devices for system configuration and

readback functions.

Analog Input Protection

Internal protection diodes clamp the analog input to

AVDD and AGND, which allow the channel input pins to

swing from AGND - 0.3V to AVDD + 0.3V without dam-

age. However, for accurate conversions near full scale,

the inputs must not exceed AVDD by more than 50mV

or be lower than AGND by 50mV.

Analog Mux

The MAX1407/MAX1408/MAX1414 include a dual 8 to 1

multiplexer for the positive and negative inputs of the

ADC. The MAX1409 has a dual 4 to 1 multiplexer at the

inputs of the ADC. Figures 1, 2, and 3 illustrate which

signals are present at the inputs of each multiplexer for

the MAX1407/MAX1408/MAX1409/MAX1414. The

MUXP and MUXN bits of the MUX register choose

which inputs will be seen at the input to the ADC

(Tables 4 and 5) and the signal-detect comparator. See

the MUX Register description under the On-Chip

Registers section for multiplexer functionality.

Input Buffers

The MAX1407/MAX1408/MAX1409/MAX1414 provide

input buffers to isolate the analog inputs from the capaci-

tive load presented by the ADC modulator (Figure 5 and

6). The buffers are chopper stabilized to reduce the effect

of their DC offsets and low-frequency noise. Since the

buffers can represent more than 25% of the total analog

power dissipation (typically 220ÂµA), they may be shut

down in applications where minimum power dissipation is

required and the capacitive input load is not a concern

(see ADC and Power1 Registers). Disable the buffers in

applications where the inputs must operate close to

AGND or above +1.4V. The buffers are individually

enabled or disabled.

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