MAX195BCWE+ Maxim Integrated Products, MAX195BCWE+ Datasheet - Page 5

• Manufacturer Part Number: MAX195BCWE+
• Description: IC ADC 16BIT 85KSPS SHTDN 16SOIC
• Manufacturer: Maxim Integrated Products

Specifications of MAX195BCWE+

• Number Of Bits: 16
• Sampling Rate (per Second): 85k
• Data Interface: QSPI™, Serial, SPI™
• Number Of Converters: 2
• Power Dissipation (max): 80mW
• Voltage Supply Source: Analog and Digital, Dual ±
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (0.300", 7.50mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MAX195 uses a successive-approximation register
(SAR) to convert an analog input to a 16-bit digital
code, which outputs as a serial data stream. The data
bits can be read either during the conversion, at the
CLK clock rate, or between conversions asynchronous
with CLK at the SCLK rate (up to 5Mbps).
The MAX195 includes a capacitive digital-to-analog
converter (DAC) that provides an inherent track/hold
input. The interface and control logic are designed for
easy connection to most microprocessors (µPs), limiting
the need for external components. In addition to the
SAR and DAC, the MAX195 includes a serial interface, a
sampling comparator used by the SAR, ten calibration
DACs, and control logic for calibration and conversion.
The DAC consists of an array of 16 capacitors with
binary weighted values plus one “dummy LSB” capaci-
tor (Figure 1). During input acquisition in unipolar
mode, the array’s common terminal is connected to
AGND and all free terminals are connected to the input
signal (AIN). After acquisition, the common terminal is
disconnected from AGND and the free terminals are
______________________________________________________________Pin Description
_______________Detailed Description
PIN
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
BP/UP/SHDN
NAME
DGND
RESET
CONV
AGND
VDDD
DOUT
VDDA
SCLK
VSSD
VSSA
EOC
CLK
REF
AIN
CS
16-Bit, 85ksps ADC with 10µA Shutdown
_______________________________________________________________________________________
Bipolar/Unipolar/Shutdown Input. Three-state input selects bipolar or unipolar input range, or shutdown.
0V = shutdown, +5V = unipolar, floating = bipolar.
Conversion Clock Input
Serial Clock Input is used to shift data out between conversions. May be asynchronous to CLK.
+5V Digital Power Supply
Serial Data Output, MSB first
Digital Ground
End-of-Conversion/Calibration Output—normally low. Rises one clock cycle after the beginning of conversion
or calibration and falls one clock cycle after the end of either. May be used as an output framing signal.
Chip-Select Input—active low. Enables the serial interface and the three-state data output (DOUT).
Convert-Start Input—active low. Conversion begins on the falling edge after CONV goes low if the input
signal has been acquired; otherwise, on the falling clock edge after acquisition.
Reset Input. Pulling RESET low places the ADC in an inactive state. Rising edge resets control logic and
begins calibration.
-5V Digital Power Supply
Reference Input, 0 to 5V
Analog Input, 0 to V
Analog Ground
-5V Analog Power Supply
+5V Analog Power Supply
REF
unipolar or ±V
REF
bipolar range
disconnected from AIN, trapping a charge proportional
to the input voltage on the capacitor array.
The free terminal of the MSB (largest) capacitor is con-
nected to the reference (REF), which pulls the common
terminal (connected to the comparator) positive.
Simultaneously, the free terminals of all other capaci-
tors in the array are connected to AGND, which drives
the comparator input negative. If the analog input is
near V
only pulls the comparator input slightly positive.
However, connecting the remaining capacitor’s free ter-
minals to ground drives the comparator input well
below ground, so the comparator input is negative, the
comparator output is low, and the MSB is set high. If
the analog input is near ground, the comparator output
is high and the MSB is low.
Following this, the next largest capacitor is disconnect-
ed from AGND and connected to REF, and the com-
parator determines the next bit. This continues until all
bits have been determined. For a bipolar input range,
the MSB capacitor is connected to REF rather than AIN
during input acquisition, which results in an input range
of V
REF
FUNCTION
REF
to -V
, connecting the MSB’s free terminal to REF
REF
.
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