4-/6-/8-Channel, 16-Bit,

Simultaneous-Sampling ADCs

10

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Detailed Description

The MAX11047/MAX11048/MAX11049 are fast, low-

power ADCs that combine 4, 6, or 8 independent ADC

channels in a single IC. Each channel includes simulta-

neously sampling independent T/H circuitry that pre-

serves relative phase information between inputs

making the MAX11047/MAX11048/MAX11049 ideal for

motor control and power monitoring. The MAX11047/

MAX11048/MAX11049 are available with a 0 to 5V input

range that features ±20mA overrange, fault-tolerant

inputs. The MAX11047/MAX11048/MAX11049 operate

with a single 4.75V to 5.25V supply. A separate 2.7V to

5.25V supply for digital circuitry makes the devices

compatible with low-voltage processors.

The MAX11047/MAX11048/MAX11049 perform conver-

sions for all channels in parallel by activating indepen-

dent ADCs. Results are available through a high-speed,

20MHz, parallel data bus after a conversion time of 3μs

following the end of a sample. The data bus is bidirec-

tional and allows for easy programming of the configura-

tion register. The MAX11047/MAX11048/MAX11049

feature a reference buffer, which is driven by an internal

REFIO with an external reference or bypass with a 0.1μF

capacitor to ground when using the internal reference.

Analog Inputs

Track and Hold (T/H)

To preserve phase information across all channels,

each input includes a dedicated T/H circuitry. The input

tracking circuitry provides a 4MHz small-signal band-

width, enabling the device to digitize high-speed tran-

sient events and measure periodic signals with

bandwidths exceeding the ADC’s sampling rate by

using undersampling techniques. Use anti-alias filtering

to avoid high-frequency signals being aliased into the

frequency band of interest.

Input Range and Protection

The full-scale analog input voltage is a product of the

reference voltage. For MAX11047/MAX11048/

MAX11049, the input is unipolar in the range of:

4.25V source, resulting in a full-scale input range of

3.662V to 5.188V, respectively.

All analog inputs are fault-protected up to ±20mA. The

MAX11047/MAX11048/MAX11049 include an input

clamping circuit that activates when the input voltage at

-300mV. The clamp circuit remains high impedance

while the input signal is within the range of 0V to

the clamps begin to turn on. Consequently, to obtain

the highest accuracy, ensure that the input voltage

To make use of the input clamps, connect a resistor

to limit the voltage at the analog input so that the fault

current into the MAX11047/MAX11048/MAX11049 does

not exceed ±20mA. Note that the voltage at the analog

input pin limits to approximately 7V during a fault condi-

tion so the following equation can be used to calculate

0

50

4 096

to

V

x

REFIO

+

.

.

Pin Description (continued)

PIN

NAME

FUNCTION

42

CH6

Channel 6 Analog Input for MAX11049. Channel 5 for MAX11048.

45

CH7

Channel 7 Analog Input for MAX11049

52

WR

Active-Low Write Input. Drive

WR low to write to the ADC. Configuration registers are loaded on the

rising edge of

WR.

53

CS

Active-Low Chip-Select Input. Drive

CS low when reading from or writing to the ADC.

54

RD

Active-Low Read Input. Drive

RD low to read from the ADC. Each rising edge of RD advances the

channel output on the data bus.

55

DB15

16-Bit Parallel Data Bus Digital Out Bit 15

56

DB14

16-Bit Parallel Data Bus Digital Out Bit 14

—EP

Exposed Pad. Internally connected to AGND. Connect to a large ground plane to maximize thermal

performance. Not intended as an electrical connection point.