Detailed description – Rainbow Electronics MAX1326 User Manual

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MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326

8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs

with ±10V, ±5V, and 0 to +5V Analog Input Ranges

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Detailed Description

The MAX1316–MAX1318/MAX1320–MAX1322/MAX1324-
MAX1326 are 14-bit ADCs. They offer two, four, or eight
(independently selectable) input channels, each with its
own T/H circuitry. Simultaneous sampling of all active
channels preserves relative phase information, making
these devices ideal for motor control and power monitor-
ing. These devices are available with 0 to +5V, ±5V, and
±10V input ranges. The 0 to +5V devices feature ±6V
fault-tolerant inputs. The ±5V and ±10V devices feature
±16.5V fault-tolerant inputs. Two channels convert in 2µs;
all eight channels convert in 3.8µs, with a maximum 8-
channel throughput of 263ksps per channel. Internal or
external reference and internal- or external-clock capabil-
ity offer great flexibility and ease of use. A write-only con-
figuration register can mask out unused channels, and a
shutdown feature reduces power. A 16.6MHz, 14-bit, par-
allel data bus outputs the conversion result. Figure 1
shows the functional diagram of these devices.

Analog Inputs

T/H

To preserve phase information across these multichan-
nel devices, each input channel has a dedicated
T/H amplifier.

Use a low-input source impedance to minimize gain-
error harmonic distortion. The time required for the T/H
to acquire an input signal depends on the input source
impedance. If the input signal’s source impedance is
high, the acquisition time lengthens and more time
must be allowed between conversions. The acquisition
time (t

) is the maximum time the device takes to

acquire the signal. Use the following formula to calcu-
late acquisition time:

= 10 (R

+ R

) x 6pF

where R

= 2.2k

Ω, R

= the input signal’s source

impedance, and t

is never less than 180ns. A source

impedance of less than 100

Ω does not significantly

affect the ADC’s performance.

Figure 1. Functional Diagram

MAX1316–MAX1318
MAX1320–MAX1322
MAX1324–MAX1326

CONVST

D13

MSV

DGND

SHDN

CLK

CH0

INTERFACE

AND

CONTROL

8 x 1
MUX

14-BIT

ADC

CH7

AGND

ALLON

REF

REF+
COM

REF-

S/H

8 x 14

SRAM

OUTPUT
DRIVERS

Ω

CONFIGURATION

2.500V

*SWITCH CLOSED ON UNIPOLAR DEVICES, OPEN ON BIPOLAR DEVICES

INTCLK/EXTCLK

EOC

EOLC