AD536AKD Analog Devices Inc, AD536AKD Datasheet - Page 12

• Manufacturer Part Number: AD536AKD
• Description: IC TRUE RMS/DC CONV 14-CDIP
• Manufacturer: Analog Devices Inc

Specifications of AD536AKD

• Rohs Status: RoHS non-compliant
• Current - Supply: 1.2mA
• Voltage - Supply: 5.0V ~ 36V, ±3.0V ~ 18V
• Mounting Type: Through Hole
• Package / Case: 14-CDIP (0.300", 7.62mm)
• Accuracy %: 0.2%
• Bandwidth: 450kHz
• Supply Current: 1.2mA
• Power Dissipation Pd: 500mW
• Supply Voltage Range: 5V To 36V
• Digital Ic Case Style: DIP
• No. Of Pins: 14
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

AD536A
FREQUENCY RESPONSE
The AD536A utilizes a logarithmic circuit in performing the
implicit rms computation. As with any log circuit, bandwidth
is proportional to signal level. The solid lines in the graph of
Figure 18 represent the frequency response of the AD536A at
input levels from 10 mV rms to 7 V rms. The dashed lines indicate
the upper frequency limits for 1%, 10%, and ±3 dB of reading
additional error. For example, note that a 1 V rms signal produces
less than 1% of reading additional error up to 120 kHz. A 10 mV
signal can be measured with 1% of reading additional error
(100 μV) up to only 5 kHz.
AC MEASUREMENT ACCURACY AND CREST
FACTOR
Crest factor is often overlooked when determining the accuracy
of an ac measurement. The definition of crest factor is the ratio
of the peak signal amplitude to the rms value of the signal
(CF = V
triangle waves, have relatively low crest factors (<2). Waveforms
that resemble low duty cycle pulse trains, such as those occurring
in switching power supplies and SCR circuits, have high crest
factors. For example, a rectangular pulse train with a 1% duty
cycle has a crest factor of 10 (CF = 1√n).
0.01
0.1
10
1
1k
P
/V rms). Most common waveforms, such as sine and
7V rms INPUT
1V rms INPUT
100mV rms INPUT
10mV rms INPUT
Figure 18. High Frequency Response
10k
1
dB OUT
3mV/dB
SPECIAL TC COMPENSATION RESISTOR, +3300 PPM/°C,
PRECISION RESISTOR COMPANY PART NUMBER AT35 OR PART NUMBER ST35.
+V
0.1µF
S
C2
–V
FREQUENCY (Hz)
S
C1, C
V
IN
BUF OUT
1%
100k
BUF IN
AV
C
–V
V
NC
dB
AV
IN
S
1
2
3
4
5
6
7
10%
AD536A
BUF
1M
25kΩ
ABSOLUTE
SQUARER/
CURRENT
DIVIDER
MIRROR
VALUE
±3dB
25kΩ
10M
14
13
12
11
10
Figure 17. dB Connection
9
8
Rev. D | Page 12 of 16
R
I
+V
COM
OUT
NC
NC
NC
L
S
ZERO dB
ADJUST
OUTPUT
LINEAR
REF.
500kΩ
rms
2.5V
E
R1
OUT
R6
24.9kΩ
Figure 19 illustrates a curve of reading error for the AD536A for
a 1 V rms input signal with crest factors from 1 to 11. A rectan-
gular pulse train (pulse width = 100 μs) was used for this test
because it is the worst-case waveform for rms measurement (all
of the energy is contained in the peaks). The duty cycle and
peak amplitude were varied to produce crest factors from 1 to
11 while maintaining a constant 1 V rms input amplitude.
AD580J
1kΩ
R2
–E
+E
1
–1
–2
–3
–4
1
0
R3
60.4Ω
1
+V
4.6V TO 18V
0
S
Figure 20. Error vs. Pulse Width Rectangular Pulse
V
2
P
33.2kΩ
100µs
2
3
R4
0.1
10
1
1µs
3
OP-77
Figure 19. Error vs. Crest Factor
T
+V
–V
FACTOR ADJUST
7
4
S
S
4
ө
PULSE WIDTH (µs)
dB SCALE
O
10µs
5kΩ
R5
CREST FACTOR
5
6
1V rms CF = 10
1V rms CF = 3
TEMPERATURE
COMPENSATED
dB OUTPUT
+100mV/dB
100µs
6
η = DUTY CYCLE =
CF = 1/√η
ө
IN
(rms) = 1 V rms
7
1000µs
8
9
100µs
T
10
11