MX7705EPE ,16-Bit, Low-Power, 2-Channel, Sigma-Delta ADCFeaturesThe MX7705 low-power, 2-channel, serial-output ana- Pin Compatible and Software Compatible ..
MX7820KCWP ,CMOS High Speed 8Bit A/D Converter with Refrence and Track/Hold FunctionELECTRICAL CHARACTERISTICS
(VDD = +5V, VREF+ = HN,1/rur- = GND, RD-MODE, TA = TMIN to TMAX, unle ..
MX7820KN ,CMOS High Speed 8Bit A/D Converter with Refrence and Track/Hold FunctionFeatures
. Fast Conversion Time: 1.34ps Max.
. Built-in Track-and-Hold Function
. No Adjustment ..
MX7820KN+ ,CMOS, 1.3µs, 8-Bit ADC with Voltage Reference and Track/HoldFeatures
. Fast Conversion Time: 1.34ps Max.
. Built-in Track-and-Hold Function
. No Adjustment ..
MX7820LCWP ,CMOS High Speed 8Bit A/D Converter with Refrence and Track/Hold FunctionGeneral Description
The MAX150/MX7820 is a high speed, microprocessor
compatible, 8 bit analog ..
MX7820LN ,CMOS High Speed 8Bit A/D Converter with Refrence and Track/Hold FunctionELECTRICAL CHARACTERISTICS (continued)
(VDD = HN, VREF+ = HN, VREF_ =
GND, RD-MODE, TA = TMIN ..
NDS8926 ,Dual N-Channel Enhancement Mode Field Effect TransistorELECTRICAL CHARACTERISTICS (T = 25°C unless otherwise noted)ASymbol Parameter Conditions M in Typ M ..
NDS8928 ,Dual N & P-Channel Enhancement Mode Field Effect TransistorElectrical Characteristics (T = 25°C unless otherwise noted)ASymbol Parameter Conditions Type Min T ..
NDS8936 ,Dual N-Channel Enhancement Mode Field Effect TransistorJuly 1996 N NDS8936Dual N-Channel Enhancement M ode Field Effect Transistor
NDS8947 ,Dual P-Channel Enhancement Mode Field Effect Transistor
NDS8947 ,Dual P-Channel Enhancement Mode Field Effect Transistor
NDS8947 ,Dual P-Channel Enhancement Mode Field Effect Transistor
MX7705EPE
16-Bit, Low-Power, 2-Channel, Sigma-Delta ADC
General DescriptionThe MX7705 low-power, 2-channel, serial-output ana-
log-to-digital converter (ADC) includes a sigma-delta
modulator with a digital filter to achieve 16-bit resolution
with no missing codes. This ADC is pin compatible and
software compatible with the AD7705. The MX7705 fea-
tures an on-chip input buffer and programmable-gain
amplifier (PGA). The device offers an SPI-/QSPI-/
MICROWIRE-compatible serial interface.
The MX7705 operates from a single 2.7V to 5.25V supply.
The operating supply current is 320µA (typ) with a 3V
supply. Power-down mode reduces the supply current to
2µA (typ).
Self-calibration and system calibration allow the MX7705
to correct for gain and offset errors. Excellent DC perfor-
mance (±0.003% FSR INL) and low noise (650nV) make
the MX7705 ideal for measuring low-frequency signals
with a wide dynamic range. The device accepts fully dif-
ferential bipolar/unipolar inputs. An internal input buffer
allows for input signals with high source impedances. An
on-chip digital filter, with a programmable cutoff and out-
put data rate, processes the output of the sigma-delta
modulator. The first notch frequency of the digital filter is
chosen to provide 150dB rejection of common-mode
50Hz or 60Hz noise and 98dB rejection of normal-mode
50Hz or 60Hz noise. A PGA and digital filtering allow sig-
nals to be directly acquired with little or no signal-condi-
tioning requirements.
The MX7705 is available in 16-pin PDIP, SO, and
TSSOP packages.
ApplicationsIndustrial Instruments
Weigh Scales
Strain-Gauge Measurements
Loop-Powered Systems
Flow and Gas Meters
Medical Instrumentation
Pressure Transducers
Thermocouple Measurements
RTD Measurements
FeaturesPin Compatible and Software Compatible with the
AD770516-Bit Sigma-Delta ADCTwo Fully Differential Input Channels0.003% Integral Nonlinearity with No Missing CodesInterface with Schmitt Triggers on InputsInternal Analog Input BuffersPGA from 1 to 128Single (2.7V to 3.6V) or (4.75V to 5.25V) SupplyLow Power
1mW (max), 3V Supply
2µA (typ) Power-Down CurrentSPI-/QSPI-/MICROWIRE-Compatible 3-Wire Serial
Interface16-Pin PDIP, SO, and TSSOP Packages
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
Pin Configuration
Ordering Information19-3051; Rev 0; 10/03
SPI/QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
*Future product—contact factory for availability.
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VDD= 3V or 5V, GND = 0, VREF+= 1.225V for VDD= 3V and VREF+= 2.5V for VDD= 5V, VREF-= GND, external fCLKIN=
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
VDDto GND..............................................................-0.3V to +6V
All Other Pins to GND.................................-0.3V to (VDD+ 0.3V)
Maximum Current Input into Any Pin..................................50mA
Continuous Power Dissipation (TA= +70°C)
PDIP (derate 10.5mW/°C above +70°C)......................842mW
TSSOP (derate 9.4mW/°C above +70°C)....................755mW
Wide SO (derate 9.5mW/°C above +70°C)..................762mW
Operating Temperature Range ..........................-40°C to +85°C
Storage Temperature Range.............................-60°C to +150°C
Junction Temperature......................................................+150°C
Lead Temperature (soldering, 10s).................................+300°C
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
ELECTRICAL CHARACTERISTICS (continued)(VDD= 3V or 5V, GND = 0, VREF+= 1.225V for VDD= 3V and VREF+= 2.5V for VDD= 5V, VREF-= GND, external fCLKIN=
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
ELECTRICAL CHARACTERISTICS (continued)(VDD= 3V or 5V, GND = 0, VREF+= 1.225V for VDD= 3V and VREF+= 2.5V for VDD= 5V, VREF-= GND, external fCLKIN=
2.4576MHz, CLKDIV bit = 0, CREF+ to GND = 0.1µF, CREF- to GND = 0.1µF, TA= TMINto TMAX, unless otherwise noted.)
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
ELECTRICAL CHARACTERISTICS (continued)(VDD= 3V or 5V, GND = 0, VREF+= 1.225V for VDD= 3V and VREF+= 2.5V for VDD= 5V, VREF-= GND, external fCLKIN=
2.4576MHz, CLKDIV bit = 0, CREF+ to GND = 0.1µF, CREF- to GND = 0.1µF, TA= TMINto TMAX, unless otherwise noted.)
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
TIMING CHARACTERISTICS(VDD= 3V or 5V, GND = 0, VREF+= 1.225V for VDD= 3V and VREF+= 2.5V for VDD= 5V, VREF-= GND, external fCLKIN=
2.4576MHz, CLKDIV bit = 0, CREF+ to GND = 0.1µF, CREF- to GND = 0.1µF, TA= TMINto TMAX, unless otherwise noted.) (Note 16)
(Figures 8, 9)
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
Note 1:These errors are in the order of the conversion noise shown in Tables 1 and 3. This applies after calibration at the given
temperature.
Note 2:Recalibration at any temperature removes these drift errors.
Note 3:Positive full-scale error includes zero-scale errors (unipolar offset error or bipolar zero error) and applies to both unipolar
and bipolar input ranges.
Note 4:Full-scale drift includes zero-scale drift (unipolar offset drift or bipolar zero drift) and applies to both unipolar and bipolar
input ranges.
Note 5:Gain error does not include zero-scale errors. It is calculated as (full-scale error - unipolar offset error) for unipolar ranges,
and (full-scale error - bipolar zero error) for bipolar ranges.
Note 6:Gain-error drift does not include unipolar offset drift or bipolar zero drift. Effectively, it is the drift of the part if only zero-
scale calibrations are performed.
Note 7:The analog input voltage range on AIN+ is given with respect to the voltage on AIN- on the MX7705.
Note 8:This common-mode voltage range is allowed, provided that the input voltage on analog inputs does not go more positive
than (VDD+ 30mV) or more negative than (GND - 30mV). Parts are functional with voltages down to (GND - 200mV), but
with increased leakage at high temperature.
Note 9: The REF differential voltage, VREF, is the voltage on REF+ referenced to REF- (VREF= VREF+- VREF-).
Note 10:Guaranteed by design.
Note 11:These calibration and span limits apply, provided that the absolute voltage on the analog inputs does not exceed (VDD+
30mV) or go more negative than (GND - 30mV). The offset calibration limit applies to both the unipolar zero point and the
bipolar zero point.
Note 12:When using a crystal or ceramic resonator across the CLKIN and CLKOUT as the clock source for the device, the supply
current and power dissipation varies depending on the crystal or resonator type. Supply current is measured with the digi-
tal inputs connected to 0 or VDD, CLKIN connected to an external clock source, and CLKDIS = 1.
Note 13:If the external master clock continues to run in power-down mode, the power-down current typically increases to 67µA at
3V. When using a crystal or ceramic resonator across the CLKIN and CLKOUT as the clock source for the device, the
clock generator continues to run in power-down mode and the power dissipation depends on the crystal or resonator type
(see the Power-Down Modessection).
Note 14:Measured at DC and applied in the selected passband. PSRR at 50Hz exceeds 120dB with filter notches of 25Hz or 50Hz.
Note 15:Provide fCLKINwhenever the MX7705 is not in power-down mode. If no clock is present, the device can draw higher than
specified current and can possibly become uncalibrated.
Note 16:All input signals are specified with tr= tf= 5ns (10% to 90% of VDD) and timed from a voltage level of 1.6V.
TIMING CHARACTERISTICS (continued)(VDD= 3V or 5V, GND = 0, VREF+= 1.225V for VDD= 3V and VREF+= 2.5V for VDD= 5V, VREF-= GND, external fCLKIN=
2.4576MHz, CLKDIV bit = 0, CREF+ to GND = 0.1µF, CREF- to GND = 0.1µF, TA= TMINto TMAX, unless otherwise noted.) (Note 16)
(Figures 8, 9)
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
Table 1. Output RMS Noise vs. Gain and Output Data Rate (VDD= 5V)
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
TYPICAL OUTPUT NOISEMX7705 toc01
READING NUMBER
CODE READ
HISTOGRAM OF TYPICAL OUTPUT NOISE
MX7705 toc02
CODE
OCCURENCE
OFFSET ERROR vs. SUPPLY VOLTAGE (3V)
MX7705 toc03
SUPPLY VOLTAGE (V)
OFFSET ERROR (%FSR)
Typical Operating Characteristics
(VDD= 3V or 5V, VREF+= 1.225V for VDD= 3V, VREF+= 2.5V for VDD= 5V, VREF- = GND, TA= +25°C, unless otherwise noted.)
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADCOFFSET ERROR vs. SUPPLY VOLTAGE (5V)
MX7705 toc04
SUPPLY VOLTAGE (V)
OFFSET ERROR (%FSR)3510-15
OFFSET ERROR vs. TEMPERATURE
MX7705 toc05
TEMPERATURE (°C)
OFFSET ERROR (%FSR)
GAIN ERROR vs. SUPPLY VOLTAGE (3V)MX7705 toc06
SUPPLY VOLTAGE (V)
GAIN ERROR (%FSR)
GAIN ERROR vs. SUPPLY VOLTAGE (5V)
MX7705 toc07
SUPPLY VOLTAGE (V)
GAIN ERROR (%FSR)
GAIN ERROR vs. TEMPERATURE
MX7705 toc08
TEMPERATURE (°C)
GAIN ERROR (%FSR)3510-15
Typical Operating Characteristics (continued)
(VDD= 3V or 5V, VREF+= 1.225V for VDD= 3V, VREF+= 2.5V for VDD= 5V, VREF- = GND, TA= +25°C, unless otherwise noted.)
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
SUPPLY CURRENT vs. SUPPLY VOLTAGE (3V)MX7705 toc09
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
A: BUFFERED MODE
fCLKIN = 2.4576MHz,
GAIN = 8 TO 128
B: BUFFERED MODE
fCLKIN = 2.4576MHz,
GAIN = 1 TO 4
E: UNBUFFERED MODE
fCLKIN = 1MHz,
GAIN = 1 TO 128
C: BUFFERED MODE
fCLKIN = 1MHz,
GAIN = 1 TO 128
D: UNBUFFERED MODE
fCLKIN = 2.4576MHz,
GAIN = 1 TO 128
SUPPLY CURRENT vs. SUPPLY VOLTAGE (5V)
MX7705 toc10
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
A: BUFFERED MODE
fCLKIN = 2.4576MHz,
GAIN = 8 TO 128
B: BUFFERED MODE
fCLKIN = 2.4576MHz,
GAIN = 1 TO 4
E: UNBUFFERED MODE
fCLKIN = 1MHz,
GAIN = 1 TO 128
C: BUFFERED MODE
fCLKIN = 1MHz,
GAIN = 1 TO 128
D: UNBUFFERED MODE
fCLKIN = 2.4576MHz,
GAIN = 1 TO 1283510-15
SUPPLY CURRENT vs. TEMPERATURE (3V)
MX7705 toc11
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
A: BUFFERED MODE
fCLKIN = 2.4576MHz,
GAIN = 8 TO 128
B: BUFFERED MODE
fCLKIN = 2.4576MHz,
GAIN = 1 TO 4
E: UNBUFFERED MODE
fCLKIN = 1MHz,
GAIN = 1 TO 128
C: BUFFERED MODE
fCLKIN = 1MHz,
GAIN = 1 TO 128
D: UNBUFFERED MODE
fCLKIN = 2.4576MHz,
GAIN = 1 TO 1283510-15
SUPPLY CURRENT vs. TEMPERATURE (5V)
MX7705 toc12
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
A: BUFFERED MODE
fCLKIN = 2.4576MHz,
GAIN = 8 TO 128
B: BUFFERED MODE
fCLKIN = 2.4576MHz,
GAIN = 1 TO 4
E: UNBUFFERED MODE
fCLKIN = 1MHz,
GAIN = 1 TO 128
C: BUFFERED MODE
fCLKIN = 1MHz,
GAIN = 1 TO 128
D: UNBUFFERED MODE
fCLKIN = 2.4576MHz,
GAIN = 1 TO 128
Typical Operating Characteristics (continued)(VDD= 3V or 5V, VREF+= 1.225V for VDD= 3V, VREF+= 2.5V for VDD= 5V, VREF- = GND, TA= +25°C, unless otherwise noted.)
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
SUPPLY CURRENT vs. fCLKIN (3V)fCLKIN (MHz)
MX7705 toc13
SUPPLY CURRENT (mA)
A: BUFFERED MODE
CLK = 1,
GAIN = 128
B: BUFFERED MODE
CLK = 1,
GAIN = 1
E: UNBUFFERED MODE
CLK = 0,
GAIN = 1, 128
C: BUFFERED MODE
CLK = 0,
GAIN = 1, 128
D: UNBUFFERED MODE
CLK = 1,
GAIN = 1, 128
SUPPLY CURRENT vs. fCLKIN (5V)fCLKIN (MHz)
MX7705 toc14
SUPPLY CURRENT (mA)
A: BUFFERED MODE
CLK = 1,
GAIN = 128
B: BUFFERED MODE
CLK = 1,
GAIN = 1
E: UNBUFFERED MODE
CLK = 0,
GAIN = 1, 128
C: BUFFERED MODE
CLK = 0,
GAIN = 1, 128
D: UNBUFFERED MODE
CLK = 1,
GAIN = 1, 128
GAIN32168421128
SUPPLY CURRENT vs. GAIN (3V)MX7705 toc15
SUPPLY CURRENT (mA)
A: BUFFERED MODE
CLK = 1, CLKDIV = 1,
fCLKIN = 2.4576MHz
B: BUFFERED MODE
CLK = 1, CLKDIV = 0,
fCLKIN = 2.4576MHz
E: UNBUFFERED MODE
CLK = 1, CLKDIV = 0,
fCLKIN = 2.4576MHz
F: UNBUFFERED MODE
CLK = 0, CLKDIV = 0,
fCLKIN = 1MHz
C: BUFFERED MODE
CLK = 0, CLKDIV = 0,
fCLKIN = 1MHz
D: UNBUFFERED MODE
CLK = 1, CLKDIV = 1,
fCLKIN = 2.4576MHz
GAIN32168421128
SUPPLY CURRENT vs. GAIN (5V)MX7705 toc16
SUPPLY CURRENT (mA)
A: BUFFERED MODE
CLK = 1, CLKDIV = 0,
fCLKIN = 2.4576MHz
B: BUFFERED MODE
CLK = 1, CLKDIV = 1,
fCLKIN = 2.4576MHz
E: UNBUFFERED MODE
CLK = 1, CLKDIV = 0,
fCLKIN = 2.4576MHz
F: UNBUFFERED MODE
CLK = 0, CLKDIV = 0,
fCLKIN = 1MHz
C: BUFFERED MODE
CLK = 0, CLKDIV = 0,
fCLKIN = 1MHz
D: UNBUFFERED MODE
CLK = 1, CLKDIV = 1,
fCLKIN = 2.4576MHz
Typical Operating Characteristics (continued)(VDD= 3V or 5V, VREF+= 1.225V for VDD= 3V, VREF+= 2.5V for VDD= 5V, VREF- = GND, TA= +25°C, unless otherwise noted.)
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
POWER-DOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE (3V)SUPPLY VOLTAGE (V)
POWER-DOWN SUPPLY CURRENT (nA)
MX7705 toc17
POWER-DOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE (5V)
SUPPLY VOLTAGE (V)
POWER-DOWN SUPPLY CURRENT (nA)
MX7705 toc18
POWER-DOWN SUPPLY CURRENT
vs. TEMPERATUREMX7705 toc19
TEMPERATURE (°C)
POWER-DOWN SUPPLY CURRENT (3510-15
EXTERNAL OSCILLATOR STARTUP TIME
2ms/div
VDD
5V/div
CLKOUT
5V/div
CLKOUT
5V/div
MX7705 toc20
Typical Operating Characteristics (continued)(VDD= 3V or 5V, VREF+= 1.225V for VDD= 3V, VREF+= 2.5V for VDD= 5V, VREF- = GND, TA= +25°C, unless otherwise noted.)
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
Detailed DescriptionThe MX7705 low-power, 2-channel, serial-output ADC
uses a sigma-delta modulator with a digital filter to
achieve 16-bit resolution with no missing codes. The
device includes a PGA, an on-chip input buffer, and a
bidirectional communications port. The MX7705 oper-
ates with a single 2.7V to 5.25V supply.
Fully differential inputs, an internal input buffer, and an
on-chip PGA (gain = 1 to 128) allow low-level signals to
be directly measured, minimizing the requirements for
external signal conditioning. Self-calibration corrects for
gain and offset errors. A programmable digital filter
allows for the selection of the output data rate and first-
notch frequency from 20Hz to 500Hz.
The bidirectional serial SPI-/QSPI-/MICROWIRE-compati-
ble interface consists of four digital control lines (SCLK,
CS, DOUT, and DIN) and provides an easy interface to
microcontrollers (µCs). Connect CSto GND to configure
the MX7705 for 3-wire operation.
Analog InputsThe MX7705 accepts four analog inputs (AIN1+, AIN1-,
AIN2+, and AIN2-) in buffered or unbuffered mode.
Use Table8 to select the positive and negative input
pair for a fully differential channel. The input buffer iso-
lates the inputs from the capacitive load presented by
the PGA/modulator, allowing for high source-imped-
ance analog transducers. The value of the BUF bit in
the setup register (see the Setup Registersection) deter-
mines whether the input buffer is enabled or disabled.
Internal protection diodes, which clamp the analog
input to VDDand/or GND, allow the input to swing from
(GND - 0.3V) to (VDD+ 0.3V), without damaging the
device. If the analog input exceeds 300mV beyond the
supplies, limit the input current to 10mA.
Input BuffersWhen the analog input buffer is disabled, the analog
input drives a typical 7pF (gain = 1) capacitor, CTOTAL,
in series with the 7kΩtypical on-resistance of the track
and hold (T/H) switch (Figure1). CTOTALis comprised
of the sampling capacitor, CSAMP, and the stray capac-
itance, CSTRAY. During the conversion, CSAMPcharges
to (AIN+ - AIN-). The gain determines the value of
CSAMP(Table5).
MX7705
16-Bit, Low-Power, 2-Channel,
Sigma-Delta ADC
