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

Simultaneous-Sampling ADCs

10

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Detailed Description

The MAX11044/MAX11045/MAX11046 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 MAX11044/MAX11045/MAX11046 ideal for

motor control and power monitoring. The MAX11044/

MAX11045/MAX11046 are available with ±5V input

ranges that feature ±20mA overrange, fault-tolerant

inputs. The MAX11044/MAX11045/MAX11046 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 MAX11044/MAX11045/MAX11046 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 configu-

ration register. The MAX11044/MAX11045/MAX11046

feature a reference buffer, which is driven by an internal

REFIO with an external reference or bypass with 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 band-

widths exceeding the ADC’s sampling rate by using

undersampling techniques. Use anti-alias filtering to

avoid high-frequency signals being aliased into the fre-

quency band of interest.

Input Range and Protection

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

erence voltage. For the MAX11044/MAX11045/

MAX11046, the full-scale input is bipolar in the range of:

3.0V to 4.25V source, resulting in an input range of

±3.662V to ±5.188V, respectively.

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

The MAX11044/MAX11045/MAX11046 include an input

clamping circuit that activates when the input voltage at

impedance while the input signal is within the range of

begin to turn on and shunt current to/from the AVDD

supply. Consequently, to obtain the highest accuracy,

Note that the input clamp circuit also has a small

amount of hysteresis and once triggered remains

engaged, shunting current to/from AVDD until the input

returns to within the convertible range by several hun-

dredths of a volt. This effect can cause some errors at

±(

.

)

Vx

REFIO

5

4 096

Pin Description (continued)

PIN

TQFP

TQFN

NAME

FUNCTION

42

37

CH4

Channel 4 Analog Input

44

39

CH5

Channel 5 Analog Input

47

42

CH6

Channel 6 Analog Input

50

45

CH7

Channel 7 Analog Input

61

52

WR

Active-Low Write Input. Drive

WR low to write to the ADC. Configuration registers are

loaded on the rising edge of

WR.

62

53

CS

Active-Low Chip-Select Input. Drive

CS low when reading from or writing to the ADC.

63

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.

64

55

DB15

16-Bit Parallel Data Bus Digital Out Bit 15

——

EP

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

maximize thermal performance. Not intended as an electrical connection point.