Analog Devices AD536ASH, AD536ASE-883B, AD536ASD-883B, AD536ASD, AD536ASCHIPS Datasheet

a		Integrated Circuit
		True RMS-to-DC Converter
		AD536A

FEATURES

True RMS-to-DC Conversion Laser-Trimmed to High Accuracy

0.2% Max Error (AD536AK)

0.5% Max Error (AD536AJ) Wide Response Capability:

Computes RMS of AC and DC Signals 450 kHz Bandwidth: V rms > 100 mV 2 MHz Bandwidth: V rms > 1 V Signal Crest Factor of 7 for 1% Error

dB Output with 60 dB Range

Low Power: 1.2 mA Quiescent Current Single or Dual Supply Operation Monolithic Integrated Circuit

–55 C to +125 C Operation (AD536AS)

PRODUCT DESCRIPTION

The AD536A is a complete monolithic integrated circuit which performs true rms-to-dc conversion. It offers performance which is comparable or superior to that of hybrid or modular units costing much more. The AD536A directly computes the true rms value of any complex input waveform containing ac and dc components. It has a crest factor compensation scheme which allows measurements with 1% error at crest factors up to 7. The wide bandwidth of the device extends the measurement capability to 300 kHz with 3 dB error for signal levels above 100 mV.

An important feature of the AD536A not previously available in rms converters is an auxiliary dB output. The logarithm of the rms output signal is brought out to a separate pin to allow the dB conversion, with a useful dynamic range of 60 dB. Using an externally supplied reference current, the 0 dB level can be conveniently set by the user to correspond to any input level from 0.1 to 2 volts rms.

The AD536A is laser trimmed at the wafer level for input and output offset, positive and negative waveform symmetry (dc reversal error), and full-scale accuracy at 7 V rms. As a result, no external trims are required to achieve the rated unit accuracy.

There is full protection for both inputs and outputs. The input circuitry can take overload voltages well beyond the supply levels. Loss of supply voltage with inputs connected will not cause unit failure. The output is short-circuit protected.

The AD536A is available in two accuracy grades (J, K) for commercial temperature range (0°C to +70°C) applications, and one grade (S) rated for the –55°C to +125°C extended range. The AD536AK offers a maximum total error of ± 2 mV ± 0.2% of reading, and the AD536AJ and AD536AS have maximum errors of ± 5 mV ± 0.5% of reading. All three versions are available in either a hermetically sealed 14-lead DIP or 10-pin TO-100 metal can. The AD536AS is also available in a 20-leadless hermetically sealed ceramic chip carrier.

REV. B

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

PIN CONFIGURATIONS AND FUNCTIONAL BLOCK DIAGRAMS

TO-116 (D-14) and
		Q-14 Package
VIN	1	ABSOLUTE	14	+VS
		VALUE
NC 2		AD536A	13	NC
–VS	3	SQUARER	12	NC
		DIVIDER
CAV	4		11	NC
dB 5		CURRENT	10	COM
BUF		MIRROR
	6		9	RL
OUT		25k
BUF
	7	BUF	8	IOUT
IN

NC = NO CONNECT

		TO-100 (H-10A)
		Package
		IOUT
		RL	BUF IN
		25k	25k
	COM	AD536A	BUF
		CURRENT	OUT
		MIRROR	BUF
	+VS	SQUARER	dB
		DIVIDER
		ABSOLUTE
		VALUE	CAV
		VIN

–VS

LCC (E-20A) Package

	NC VIN		NC +VS		NC
	3	2	1	20	19
–VS	4		ABSOLUTE			18	NC
				VALUE
	5 AD536A
NC			SQUARER			17	NC
				DIVIDER
CAV	6					16	NC
NC	7	25k		CURRENT		15	NC
				MIRROR
dB	8	BUF		25k		14	COM

9 10 11 12 13

BUF BUF NC IOUT RL OUT IN

NC = NO CONNECT

PRODUCT HIGHLIGHTS

1.The AD536A computes the true root-mean-square level of a complex ac (or ac plus dc) input signal and gives an equivalent dc output level. The true rms value of a waveform is a more useful quantity than the average rectified value since it relates directly to the power of the signal. The rms value of a statistical signal also relates to its standard deviation.

2.The crest factor of a waveform is the ratio of the peak signal swing to the rms value. The crest factor compensation scheme of the AD536A allows measurement of highly complex signals with wide dynamic range.

3.The only external component required to perform measurements to the fully specified accuracy is the capacitor which sets the averaging period. The value of this capacitor determines the low frequency ac accuracy, ripple level and settling time.

4.The AD536A will operate equally well from split supplies or a single supply with total supply levels from 5 to 36 volts. The one milliampere quiescent supply current makes the device well-suited for a wide variety of remote controllers and battery powered instruments.

5.The AD536A directly replaces the AD536 and provides improved bandwidth and temperature drift specifications.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: [phone]	World Wide Web Site: http://www.analog.com
Fax: [phone]	© Analog Devices, Inc., 1999

AD536A–SPECIFICATIONS (@ +25 C, and 15 V dc unless otherwise noted)

Model		AD536AJ			AD536AK		AD536AS
	Min	Typ	Max	Min	Typ	Max	Min	Typ	Max	Units
TRANSFER FUNCTION	VOUT	= avg . (VIN )2		VOUT =	avg . (VIN )2		VOUT	= avg . (VIN )2
CONVERSION ACCURACY										mV ± % of Reading
Total Error, Internal Trim1 (Figure 1)			5 0.5			2 0.2			5 0.5
vs. Temperature, TMIN to +70°C			± 0.1 ± 0.01			± 0.05 ± 0.005			0.1 0.005	mV ± % of Reading/°C
+70°C to +125°C									0.3 0.005	mV ± % of Reading/°C
vs. Supply Voltage		± 0.1 ± 0.01			± 0.1 ± 0.01			± 0.1 ± 0.01		mV ± % of Reading/V
dc Reversal Error		± 0.2			± 0.1			± 0.2		± % of Reading
Total Error, External Trim1 (Figure 2)		± 3 ± 0.3			± 2 ± 0.1			± 3 ± 0.3		mV ± % of Reading
ERROR VS. CREST FACTOR2
Crest Factor 1 to 2	Specified Accuracy			Specified Accuracy			Specified Accuracy
Crest Factor = 3		–0.1			–0.1			–0.1		% of Reading
Crest Factor = 7		–1.0			–1.0			–1.0		% of Reading
FREQUENCY RESPONSE3
Bandwidth for 1% Additional Error (0.09 dB)
VIN = 10 mV		5			5			5		kHz
VIN = 100 mV		45			45			45		kHz
VIN = 1 V		120			120			120		kHz
± 3 dB Bandwidth
VIN = 10 mV		90			90			90		kHz
VIN = 100 mV		450			450			450		kHz
VIN = 1 V		2.3			2.3			2.3		MHz
AVERAGlNG TlME CONSTANT (Figure 5)		25			25			25		ms/µF CAV
INPUT CHARACTERISTICS
Signal Range, ± 15 V Supplies
Continuous rms Level		0 to 7	± 20		0 to 7	± 20		0 to 7	± 20	V rms
Peak Transient Input										V peak
Continuous rms Level, ± 5 V Supplies		0 to 2			0 to 2			0 to 2		V rms
Peak Transient Input, ± 5 V Supplies			± 7			± 7			± 7	V peak
Maximum Continuous Nondestructive			± 25			± 25			± 25
Input Level (All Supply Voltages)										V peak
Input Resistance	13.33	16.67	20	13.33	16.67	20	13.33	16.67	20	kΩ
Input Offset Voltage		0.8	± 2		0.5	± 1		0.8	± 2	mV
OUTPUT CHARACTERISTICS		± 1	± 2		± 0.5	± 1
Offset Voltage, VIN = COM (Figure 1)									2	mV
vs. Temperature		± 0.1			± 0.1				0.2	mV/°C
vs. Supply Voltage		± 0.1			± 0.1			± 0.2		mV/V
Voltage Swing, ± 15 V Supplies	0 to +11	+12.5		0 to +11	+12.5		0 to +11	+12.5		V
± 5 V Supply	0 to +2			0 to +2			0 to +2			V
dB OUTPUT (Figure 13)		± 0.4			± 0.2			± 0.5
Error, VlN 7 mV to 7 V rms, 0 dB = 1 V rms			0.6			0.3			0.6	dB
Scale Factor		–3			–3			–3		mV/dB
Scale Factor TC (Uncompensated, see Fig-										dB/°C
ure 1 for Temperature Compensation)		–0.033			–0.033			–0.033
		+0.33			+0.33			+0.33		% of Reading/°C
IREF for 0 dB = 1 V rms	5	20	80	5	20	80	5	20	80	µA
IREF Range	1		100	1		100	1		100	µA
IOUT TERMINAL										µA/V rms
IOUT Scale Factor		40			40			40
IOUT Scale Factor Tolerance		± 10	± 20		± 10	± 20		± 10	± 20	%
Output Resistance	20	25	30	20	25	30	20	25	30	kΩ
Voltage Compliance		–VS to (+VS			–VS to (+VS			–VS to (+VS
		–2.5 V)			–2.5 V)			–2.5 V)		V
BUFFER AMPLIFIER
Input and Output Voltage Range	–VS to (+VS			–VS to (+VS			–VS to (+VS			V
	–2.5 V)	± 0.5		–2.5 V)	± 0.5		–2.5 V)	± 0.5
Input Offset Voltage, RS = 25 k			4			4			4	mV
Input Bias Current		20	60		20	60		20	60	nA
Input Resistance		108			108			108		Ω
Output Current	(+5 mA,			(+5 mA,			(+5 mA,
Short Circuit Current	–130 µA)	20		–130 µA)	20		–130 µA)	20		mA
Output Resistance			0.5			0.5			0.5	Ω
Small Signal Bandwidth		1			1			1		MHz
Slew Rate4		5			5			5		V/µs
POWER SUPPLY		± 15			± 15			± 15
Voltage Rated Performance	± 3.0		± 18	± 3.0		± 18	± 3.0		± 18	V
Dual Supply										V
Single Supply	+5		+36	+5		+36	+5		+36	V
Quiescent Current
Total VS, 5 V to 36 V, TMIN to TMAX		1.2	2		1.2	2		1.2	2	mA
TEMPERATURE RANGE										°C
Rated Performance	0		+70	0		+70	–55		+125
Storage	–55		+150	–55		+150	–55		+150	°C
NUMBER OF TRANSISTORS		65			65			65

NOTES

1Accuracy is specified for 0 V to 7 V rms, dc or 1 kHz sine wave input with the AD536A connected as in the figure referenced. 2Error vs. crest factor is specified as an additional error for 1 V rms rectangular pulse input, pulsewidth = 200 µs.

3Input voltages are expressed in volts rms, and error is percent of reading. 4With 2k external pull-down resistor.

Specifications subject to change without notice.

Specifications shown in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels. All min and max specifications are guaranteed, although only those shown in boldface are tested on all production units.

–2–

REV. B

AD536A

ABSOLUTE MAXIMUM RATINGS1
Supply Voltage	± 18 V
Dual Supply . . . . . . . . . . . . . . . . . . . . . . . .
Single Supply . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . +36 V
Internal Power Dissipation2 . . . . . . . . . . . . . .	. . . . . . 500 mW
Maximum Input Voltage . . . . . . . . . . . . . . . .	. . . . ± 25 V Peak
Buffer Maximum Input Voltage . . . . . . . . . . .	. . . . . . . . . . ± VS
Maximum Input Voltage . . . . . . . . . . . . . . . .	. . . . ± 25 V Peak
Storage Temperature Range . . . . . . . . . . . .	–55°C to +150°C
Operating Temperature Range	0°C to +70°C
AD536AJ/K . . . . . . . . . . . . . . . . . . . . . . . .
AD536AS . . . . . . . . . . . . . . . . . . . . . . . .	–55°C to +125°C
Lead Temperature Range	+300°C
(Soldering 60 sec) . . . . . . . . . . . . . . . . . . .
ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . 1000 V

NOTES

1Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

210-Pin Header: θJA = 150°C/W; 20-Leadless LCC: θJA = 95°C/W; 14-Lead Size Brazed Ceramic DIP: θJA = 95°C/W.

CHIP DIMENSIONS AND PAD LAYOUT

Dimensions shown in inches and (mm).

ORDERING GUIDE

	Temperature	Package	Package
Model	Range	Description	Option
AD536AJD	0°C to +70°C	Side Brazed Ceramic DIP	D-14
AD536AKD	0°C to +70°C	Side Brazed Ceramic DIP	D-14
AD536AJH	0°C to +70°C	Header	H-10A
AD536AKH	0°C to +70°C	Header	H-10A
AD536AJQ	0°C to +70°C	Cerdip	Q-14
AD536AKQ	0°C to +70°C	Cerdip	Q-14
AD536ASD	–55°C to +125°C	Side Brazed Ceramic DIP	D-14
AD536ASD/883B	–55°C to +125°C	Side Brazed Ceramic DIP	D-14
AD536ASE/883B	–55°C to +125°C	LCC	E-20A
AD536ASH	–55°C to +125°C	Header	H-10A
AD536ASH/883B	–55°C to +125°C	Header	H-10A
AD536AJCHIPS	0°C to +70°C	Die
AD536AKH/+	0°C to +70°C	Header	H-10A
AD536ASCHIPS	–55°C to +125°C	Die
5962-89805012A	–55°C to +125°C	LCC	E-20A
5962-8980501CA	–55°C to +125°C	Side Brazed Ceramic DIP	D-14
5962-8980501IA	–55°C to +125°C	Header	H-10A

STANDARD CONNECTION

The AD536A is simple to connect for the majority of high accuracy rms measurements, requiring only an external capacitor to set the averaging time constant. The standard connection is shown in Figure 1. In this configuration, the AD536A will measure the rms of the ac and dc level present at the input, but will show an error for low frequency inputs as a function of the filter capacitor, CAV, as shown in Figure 5. Thus, if a 4 F capacitor is used, the additional average error at 10 Hz will be 0.1%, at

3 Hz it will be 1%. The accuracy at higher frequencies will be according to specification. If it is desired to reject the dc input, a capacitor is added in series with the input, as shown in Figure 3, the capacitor must be nonpolar. If the AD536A is driven with power supplies with a considerable amount of high frequency ripple, it is advisable to bypass both supplies to ground with

0.1 F ceramic discs as near the device as possible.

		CAV
VIN	1	ABSOLUTE	14	+VS
		VALUE
	2	AD536A	13
–VS	3	SQUARER	12
		DIVIDER
	4		11
	5	CURRENT	10
		MIRROR
VOUT	6		9
		25k
	7	BUF	8
		25k
		25k	25k
	AD536A
		CURRENT	BUF	VOUT
		MIRROR

+VS	SQUARER
	DIVIDER

ABSOLUTE

VALUE

VIN

CAV –VS

CAV VIN +VS

3 2 1 20 19

–VS	4	ABSOLUTE	18
		VALUE

AD536A

5SQUARER 17 DIVIDER

6					16
7	25k	CURRENT			15
			MIRROR
dB 8			25k		14
BUF
9	10	11	12	13
VOUT

Figure 1. Standard RMS Connection

REV. B

–3–