MAX11047_11 Datasheet, PDF (15/25 Pages) Maxim Integrated Products – 4-/6-/8-Channel, 16-/14-Bit, Simultaneous-Sampling ADCs

4-/6-/8-Channel, 16-/14-Bit,
Simultaneous-Sampling ADCs
Input Range and Protection
The full-scale analog input voltage is a product of the
reference voltage. For the devices, the input is unipolar
in the range of:
0
to
+ V_REFIO
x
5.0
4.096
In external reference mode, drive V_REFIO with a 3.0V to
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
devices include an input clamping circuit that activates
when the input voltage at the analog input is above
(V_AVDD + 300mV) or below -300mV. The clamp circuit
remains high impedance while the input signal is within
the range of 0V to +V_AVDD and draws little to no cur-
rent. However, when the input signal exceeds the range
of 0V to +V_AVDD, the clamps begin to turn on.
Consequently, to obtain the highest accuracy, ensure
that the input voltage does not exceed the range of 0V
to +V_AVDD.
To make use of the input clamps, connect a resistor
(R_S) between the analog input and the voltage source
to limit the voltage at the analog input so that the fault
current into the devices does not exceed ±20mA. Note
that the voltage at the analog input pin limits to approxi-
mately 7V during a fault condition so the following
equation can be used to calculate the value of R_S:
R_S
=
V_{FAULT _ MAX}
20mA
− 7V
where V_{FAULT_MAX} is the maximum voltage that the
source produces during a fault condition.
INPUT
SIGNAL
PIN
VOLTAGE
AVDD
R_S
CH0
SOURCE
CH7^†
AGNDS
CLAMP
S/H
16-/14-BIT ADC
CLAMP
S/H
16-/14-BIT ADC
AGND
MAX11047/MAX11048/MAX11049/
MAX11057/MAX11058/MAX11059
INT REF
10kΩ
BANDGAP
REF
REFERENCE
BUF
REFIO
EXT REF
*CONNECTED INTERNALLY ON THE TQFN PARTS
**MAX11047/MAX11048/MAX11049
CONFIGURATION
REGISTERS
INTERFACE
AND
CONTROL
†_{MAX11049/MAX11059}
DVDD
DB15**
DB4
DB3/CR3
DB0/CR0
WRb
RDb
CSb
CONVST
SHDN
EOCb
DGND
RDC
RDC_SENSE*
Figure 1. Required Setup for Clamp Circuit
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