MAX132CWG+ Maxim Integrated Products, MAX132CWG+ Datasheet - Page 7

• Manufacturer Part Number: MAX132CWG+
• Description: IC ADC 18BIT W/SRL INTRFC 24SOIC
• Manufacturer: Maxim Integrated Products

Specifications of MAX132CWG+

• Number Of Bits: 18
• Sampling Rate (per Second): 100
• Data Interface: MICROWIRE™, Serial, SPI™
• Number Of Converters: 1
• Voltage Supply Source: Dual ±
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 24-SOIC (0.300", 7.50mm Width)
• Architecture: Dual Slope
• Conversion Rate: 0.1 KSPs
• Input Type: Voltage
• Interface Type: 4-Wire (SPI, QSPI, MICROWIRE, TMS320)
• Supply Voltage (max): 5 V
• Maximum Power Dissipation: 647 mW
• Maximum Operating Temperature: + 70 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: 0 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

±660mV for 60Hz mode operation or between ±390mV
and ±550mV for 50Hz mode operation. The pseudo-
differential input voltage is applied across pins 14 and
15 (IN HI, IN LO), and can range to within 2V of either
supply rail.
The inputs IN HI and IN LO lead directly to CMOS tran-
sistor gates, yielding extremely high input impedances
that are useful when converting signals from a high
input source impedance, such as a sensor. Input cur-
rents are only 2pA typical at +25°C. Figure 6 shows an
RC filter at the input to optimize noise performance.
Fault protection is accomplished by the 100kΩ series
resistance. Internal protection diodes, which clamp the
analog inputs from V+ to V-, allow the channel input
pins to swing from (V- - 0.3V) to (V+ + 0.3V) without
damage. However, if the analog input voltage at the
pins IN HI or IN LO exceed the supplies, limit the cur-
rent into the device to less than 1mA, as excessive cur-
rent will damage the device.
The reference voltage sets the analog input voltage
range. For the nominal ±512mV full-scale input range, a
545mV reference voltage is used for the 60Hz mode
and a 655mV reference voltage is used in the 50Hz mode.
The reference voltage can be calculated as follows:
Figure 5. Analog Section Block Diagram
AGND
IN LO
IN HI
CREF+
INT
INT
REF+
Reference Voltage Selection
_______________________________________________________________________________________
DE
DE+
DE-
C
REF
INT
DE+
DE-
±18-Bit ADC with Serial Interface
DE
REF-
CREF-
REST
BUFFER
BUFFER
The recommended reference voltage range is 500mV
to 700mV. The MAX132 is tested with the nominal
545mV reference voltage in 60Hz mode. Use amplifiers
or attenuators (resistor dividers) to scale other full-scale
input signal ranges to the recommended ±512mV full-
scale range.
References outside the recommended range may be
used with a degradation of linearity. A reference volt-
age from 200mV to 500mV will result in a lower signal-
to-noise ratio; a reference voltage from 700mV to 2V will
increase the rollover error.
The MAX872 2.50V reference, with its 10µA supply cur-
rent, is ideally suited for the MAX132. Figure 7 shows
how 2.50V can be divided to obtain the desired refer-
ence voltage. The reference input accepts voltages
anywhere within the converter’s power-supply range;
however, for best performance, neither REF+ nor REF-
should come within 2V of the supplies.
60
or
50
Hz Mode
Hz Mode
R
INT
INT IN
:
:
V
V
REF
REF
C
INTEGRATOR
INT
(
(
INT OUT
545
655
8pF
64pF
counts
counts
262 144
262 144
X8
COMPARATOR 1
) (
) (
,
,
Z1+ x 8
MAX132
COMPARATOR 2
512
512
)
)
SECTION
V
V
DIGITAL
IN FS
IN FS
(
(
TO
)
)
)
)
7