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. Montonicity Guaranteed Over Temperature
t TTL and CMOS Log ..
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(TA = +25° C, Vcc = +15V (MX565A only), VEE = -15V, unless noted)
..
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NDM3000 ,3 Phase Brushless Motor DriverMay 1996 NDM30003 Phase Brushless Motor Driver
MX536AJEWE-MX636JCWE+
True RMS-to-DC Converters
Not Recommended for New Designs This product was manufactured for Maxim by an outside wafer foundry
using a process that is no longer available. It is not recommended for
new designs. The data sheet remains available for existing users.
A Maxim replacement or an industry second-source may be available.
Please see the QuickView data sheet for this part or contact technical
support for assistance.
For further information, contact Maxim’s Applications Tech Support.
General DescriptionThe MX536A and MX636 are true RMS-to-DC convert-
ers. They feature low power and are designed to accept
low-level input signals from 0 to 7VRMSfor the MX536A
and 0 to 200mVRMSfor the MX636. Both devices accept
complex input waveforms containing AC and DC com-
ponents. They can be operated from either a single sup-
ply or dual supplies. Both devices draw less than 1mA
of quiescent supply current, making them ideal for bat-
tery-powered applications.
Input and output offset, positive and negative waveform
symmetry (DC reversal), and full-scale accuracy are
laser trimmed, so that no external trims are required to
achieve full rated accuracy.
________________________ApplicationsDigital Multimeters
Battery-Powered Instruments
Panel Meters
Process Control
____________________________FeaturesTrue RMS-to-DC ConversionComputes RMS of AC and DC SignalsWide Response:
2MHz Bandwidth for VRMS> 1V (MX536A)
1MHz Bandwidth for VRMS> 100mV (MX636)Auxiliary dB Output:60dB Range (MX536A)
50dB Range (MX636)Single- or Dual-Supply OperationLow Power:1.2mA typ (MX536A)
800μA typ (MX636)ue RMS-to-DC Converters+VS
N.C.
N.C.
N.C.
COMMON
IOUT
VIN
N.C.
-VS
CAV
BUF OUT
BUF IN
MX536A
MX636
DIPTOP VIEW
MX536A
MX636B
TO-10010
BUF IN
BUF OUT
CAV
-VS
+VS
IOUT
COMMON
VIN
Pin ConfigurationsABSOLUTE
VALUE
SQUARER
DIVIDER
CURRENT
MIRROR
BUF
VIN
-VS
+VS
VOUT
CAV
_________Typical Operating Circuits19-0824; Rev 2; 3/96
PART
MX536AJC/DMX536AJCWE
MX536AJD0°C to +70°C
0°C to +70°C
0°C to +70°C
TEMP. RANGEPIN-PACKAGEDice**
16 Wide SO
14 Ceramic
Ordering Information
Ordering Information continued at end of data sheet.Maxim reserves the right to ship ceramic packages in lieu of
CERDIP packages.
** Dice are specified at TA= +25°C.
MX536AJH
MX536AJN0°C to +70°C
0°C to +70°C10 TO-100
14 Plastic DIP
MX536AJQ*
MX536AKCWE0°C to +70°C
0°C to +70°C14 CERDIP
16 Wide SO
MX536AKD
MX536AKH0°C to +70°C
0°C to +70°C14 Ceramic
10 TO-100
MX536AKN0°C to +70°C14 Plastic DIP
Pin Configurations continued at end of data sheet.Typical Operating Circuits continued at end of data sheet.
MX536AKQ*0°C to +70°C14 CERDIP
MX536ASD-55°C to +125°C14 Ceramic
True RMS-to-DC Converters
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS—MX536A(TA= +25°C, +VS= +15V, -VS= -15V, unless otherwise noted.)
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.
Supply Voltage:Dual Supplies (MX536A)............................±18V
(MX636).............................±12V
Single Supply (MX536A)...........................+36V
(MX636).............................+24V
Input Voltage (MX536A).......................................................±25V
(MX636).........................................................±12V
Power Dissipation (Package)
Plastic DIP (derate 12mW/°C above +75°C)...............450mW
Small Outline (derate 10mW/°C above +75°C)............400mW
Ceramic (derate 10mW/°C above +75°C)...................500mW
TO-100 metal can (derate 7mW/°C above +75°C)......450mW
Output Short-Circuit Duration........................................Indefinite
Operating Temperature Ranges
Commercial (J, K)...............................................0°C to +70°C
Military (S)......................................................-55°C to +125°C
Storage Temperature Range.............................-55°C to +150°C
Lead Temperature (soldering, 10sec)................................300°C
MX536AJ, AS
TMINto +70°C
+70°C to +125°C
MHz2.3
±3dB Bandwidth450kHz90
Bandwidth for 1%
Additional Error (0.09dB)45kHz
Additional Error-0.1% of
Reading
Specified Accuracy
±2 ±0.1
Total Error, External Trim
(Note 1)
mV ±% of
Reading
±3 ±0.3
±2 ±0.2Total Error, Internal Trim (Note 1)mV ±% of
Reading
±5 ±0.5
VOUT= [avg. (VIN)2] 1/2Transfer Equation
±0.1Total Error vs. DC Reversal% of
Reading
±0.2
mV ±% of
Reading/V±0.1 ±0.01Total Error vs. Supply
Total Error vs. TemperaturemV ±% of
Reading/°C
±0.1 ±0.01
±0.05 ±0.005
±0.1 ±0.005
±0.03 ±0.005
UNITSMINTYPMAXPARAMETERVIN= 1V
VIN= 100mV
VIN= 10mV
MX536AK
VIN= 1V
VIN= 100mV
MX536AJ, AS
VIN= 10mV
Crest Factor = 7
Crest Factor = 3
Crest Factor 1 to 2
MX536AJ
MX536AK
MX536AS
MX536AK
MX536AS
MX536AJ, AS
CONDITIONSMX536AK
Figure 3ms/μF CAV25Averaging Time Constant
CONVERSION ACCURACY
ERROR vs. CREST FACTOR(Note 2)
FREQUENCY RESPONSE(Note 3)
ue RMS-to-DC ConvertersUNITSMINTYPMAXCONDITIONSPARAMETERVRMS0 to 7±15V Supplies
Continuous RMS Peak Transient±20VPK
0 to 2VRMSInput Signal Range
±5V Supplies
Continuous RMS Peak Transient±7VPK
Safe InputAll Supplies±25VPK
Input Resistance13.3316.720.00kΩ
MX536AJ, AS0.8±2mVInput Offset VoltageMX536AK0.5±1
MX536AJ±1±2
MX536AK±0.5±1TA= +25°C
MX536AS±2
MX536AJ, AK±0.1TA= TMINto TMAXMX536AS±0.2mV/°C
MX536AJ, AK±0.1
Offset Voltage
Supply VoltageMX536AS±0.2mV/V
±15V Supplies0 to 1112.5Output Voltage Swing±5V Supplies0 to 2V
Source5mAOutput CurrentSink-130μA
Short Circuit Current20mA
Output Resistance0.5Ω
MX536AJ±0.4±0.6MX536AK±0.2±0.3ErrorVIN= 7mV to 7VRMS,
0dB = 1VRMS
MX536AS±0.5±0.6
Scale Factor-3mV/dB
Scale Factor TC (Uncompensated)0.33% of
Reading/°C
ELECTRICAL CHARACTERISTICS—MX536A (continued)(TA= +25°C, +VS= +15V, -VS= -15V, unless otherwise noted.)
IREF0dB = 1VRMS52080μA
IREFRange1100μA
IOUTScale Factor 40μA/VRMS
IOUTScale Factor Tolerance±10±20%
Output Resistance202530kΩ
Voltage Compliance-VSto
(+VS- 2.5)V
INPUT CHARACTERISTICS
OUTPUT CHARACTERISTICS
dB OUTPUT
IOUTTERMINAL
True RMS-to-DC ConvertersInput Bias Current20300nA
Input Resistance108Ω
Output CurrentSource+5mA
Sink-130μA
Short-Circuit Current20mA
UNITSMINTYPMAXCONDITIONSPARAMETERInput and Output Voltage Range-VSto
(+VS- 2.5)V
Input Offset VoltageRS= 25kΩ
Small-Signal Bandwidth
±0.5±4mVMHz
Slew Rate (Note 4)5V/μs
ELECTRICAL CHARACTERISTICS—MX536A (continued)(TA= +25°C, +VS= +15V, -VS= -15V, unless otherwise noted.)
ELECTRICAL CHARACTERISTICS—MX636(TA= +25°C, +VS= +3V, -VS= -5V, unless otherwise noted.)
VIN= 200mV
MHz1.5VIN= 200mV
±3dB Bandwidth900VIN= 100mVkHz100VIN= 10mV
MX636K
Bandwidth for 1%
Additional Error (0.09dB)90
VIN= 200mV
kHz
VIN= 100mV
MX636J
VIN= 10mV
Additional Error-0.2±% of
Reading
Specified Accuracy
Crest Factor = 6
±0.1 ±0.1
Crest Factor = 3
Total Error, External Trim
(Note 5)
mV ±% of
Reading
±0.3 ±0.1
MX636K
±0.2 ±0.5
MX636J
Total Error, Internal Trim
(Notes 5, 6)
mV ±% of
Reading
±0.5 ±1.0
Crest Factor 1 to 2
VOUT= [avg. (VIN)2]1/2Transfer Equation
±0.1Total Error vs. DC Reversal±% of
Reading
±0.2
mV ±% of
Reading/V±0.1 ±0.01
MX636J
Total Error vs. Supply
MX636K
Total Error vs. Temperature
(0°C to +70°C)
mV ±% of
Reading/°C
±0.1 ±0.01
±0.1 ±0.005
MX636K
MX636J
UNITSMINTYPMAXCONDITIONSPARAMETER
BUFFER AMPLIFIERFigure 3ms/μF CAV25Averaging Time Constant
CONVERSION ACCURACY
ERROR vs. CRESTFACTOR(Note 3)
FREQUENCYRESPONSE(Notes 6, 8)
ue RMS-to-DC ConvertersELECTRICAL CHARACTERISTICS—MX636 (continued)(TA= +25°C, +VS= +3V, -VS= -5V, unless otherwise noted.)
IREF
±2.848Input Signal Range
Peak Transient
VPK
Safe Input
IREFRange
±12VPK
Input Resistance5.336.78.00kΩ50
MX636J±0.5mVInput Offset VoltageMX636K±0.2
MX636J±0.5TA= +25°CMX636K±0.2mV
IOUTScale Factor = TMINto TMAX±10
With Supply Voltage±0.1
μV/°C
Offset Voltage
μA/VRMS
IOUTScale Factor Tolerance
+3V, -5V Supplies0 to 1Output Voltage Swing±5V to ±16.5V Supplies0 to 11.4V
-20±10+20%
Output Resistance81012kΩ
UNITSMINTYPMAXCONDITIONSPARAMETERMX636J±0.3±0.5Error7mV ≤VIN≤300mVMX636K±0.1±0.2
Scale Factor-3mV/dB
Scale Factor Tempco
Output Resistance
0 to 200
+0.33%/°C1012kΩ
Voltage Compliance-VSto
(+VS- 2.0)V
Continuous RMS, All Supplies
All Supplies
±5V Supplies
±2.5V Supplies
+3V, -5V Supplies
mVRMS
Input and Output Voltage Range-VSto
(+VS- 2)V= 10kΩ±0.8±2mVInput Offset Voltage±0.5±1
Input Current100300nA
Input Resistance108Ω
Source+5mAOutput CurrentSink-130μA
Short-Circuit Current20mA
Small-Signal Bandwidth1MHz
Slew Rate (Note 9)5V/μs
0dB = 1VRMS
MX636J
MX636K
-0.033dB/°C
mV/V
INPUTCHARACTERISTICS
OUTPUTCHARACTERISTICS (Note 5)
dB OUTPUT
IOUTTERMINAL
BUFFERAMPLIFIER
_______________Detailed DescriptionThe MX536A/MX636 uses an implicit method of RMS
computation that overcomes the dynamic range as well
as other limitations inherent in a straightforward compu-
tation of the RMS. The actual computation performed
by the MX536A/MX636 follows the equation:
VRMS= Avg. [VIN2/VRMS]
The input voltage, VIN, applied to the MX536A/MX636 is
processed by an absolute-value/voltage to current con-
verter that produces a unipolar current I1(Figure 1).
This current drives one input of a squarer/divider that
produces a current I4that has a transfer function:= I12
The current I4drives the internal current mirror through
a lowpass filter formed by R1 and an external capaci-
tor, CAV. As long as the time constant of this filter is
greater than the longest period of the input signal, I4is
averaged. The current mirror returns a current, I3, to the
square/divider to complete the circuit. The current I4is
then a function of the average of (I12/I4), which is equal
to I1RMS.
The current mirror also produces a 2 · I4output current,
IOUT, that can be used directly or converted to a volt-
age using resistor R2 and the internal buffer to provide
a low-impedance voltage output. The transfer function
for the MX536A/MX636 is:
VOUT= 2 · R2 · IRMS= VIN
The dB output is obtained by the voltage at the emitter
of Q3, which is proportional to the -log VIN. The emitter
follower Q5 buffers and level shifts this voltage so that
the dB output is zero when the externally set emitter
current for Q5 approximates I3.
andard Connection
(Figure 2)The standard RMS connection requires only one exter-
nal component, CAV. In this configuration the
MX536A/MX636 measures the RMS of the AC and DC
levels present at the input, but shows an error for low-
frequency inputs as a function of the CAVfilter capaci-
tor. Figure 3 gives practical values of CAVfor various
values of averaging error over frequency for the stan-
dard RMS connections (no post filtering). If a 3μF
capacitor is chosen, the additional error at 100Hz will
be 1%. If the DC error can be rejected, a capacitor
should be connected in series with the input, as would
typically be the case in single-supply operation.
The input and output signal ranges are a function of the
supply voltages. Refer to the electrical characteristics for
guaranteed performance. The buffer amplifier can be
used either for lowering the output impedance of the cir-
cuit, or for other applications such as buffering high-
impedance input signals. The MX536A/MX636 can be
used in current output mode by disconnecting the inter-
nal load resistor, RL, from ground. The current output is
available at pin 8 (pin 10 on the “H” package) with a
nominal scale of 40μA/VRMSinput for the MX536A and
100μA/VRMSinput for the MX636. The output is positive.
True RMS-to-DC Converters
ELECTRICAL CHARACTERISTICS—MX636 (continued)(TA= +25°C, +VS= +3V, -VS= -5V, unless otherwise noted.)
Rated Performance+3/-5V
Dual Supplies+2/-2.5±16.5V
Single Supply+5+24V
UNITSMINTYPMAXCONDITIONSPARAMETERQuiescent Current (Note 10)0.81mA
Note 1:Accuracy is specified for 0 to 7VRMS, DC or 1kHz sine-wave input with the MX536A connected as in Figure 2.
Note 2:Error vs. crest factor is specified as an additional error for 1VRMSrectangular pulse stream, pulse width = 200μs.
Note 3:Input voltages are expressed in volts RMS, and error as % of reading.
Note 4:With 2kΩexternal pull-down resistor.
Note 5:Accuracy is specified for 0 to 200mV, DC or 1kHz sine-wave input. Accuracy is degraded at higher RMS signal levels.
Note 6:Measured at pin 8 of DIP and SO (IOUT), with pin 9 tied to COMMON.
Note 7:Error vs. crest factor is specified as an additional error for 200mVRMSrectangular pulse input, pulse width = 200μs.
Note 8:Input voltages are expressed in volts RMS.
Note 9:With 10kΩexternal pull-down resistor from pin 6 (BUF OUT) to -VS.
Note 10:With BUF input tied to COMMON.
POWERSUPPLY