AD534
+15V
39k
X
1
X
2
+V
S
+15V
ADJ 8kHz
3-30p
2
3
82k
7
OUTPUT
15V APPROX.
2k
OUT
AD534
SF
Z
1
Z
2
+
CONTROL
INPUT, E
C
100mV TO 10V –
Y
1
Y
2
–V
S
–15V
ADJ
1kHz
500
2.2k
(= R)
0.01
(= C)
AD211
PINS 5, 6, 8 TO +15V
PINS 1, 4 TO –15V
E
C
1
f=
40 CR
= 1kHz PER VOLT
WITH VALUES SHOWN
CALIBRATION PROCEDURE:
WITH E
C
= 1.0V, ADJUST POT TO SET f = 1.000kHz. WITH E
C
= 8.0V ADJUST
TRIMMER CAPACITOR TO SET f = 8.000kHz. LINEARITY WILL TYPICALLY BE
WITHIN 0.1% OF FS FOR ANY OTHER INPUT.
DUE TO DELAYS IN THE COMPARATOR, THIS TECHNIQUE IS NOT SUITABLE
FOR MAXIMUM FREQUENCIES ABOVE 10kHz. FOR FREQUENCIES ABOVE
10kHz THE AD537 VOLTAGE-TO-FREQUENCY CONVERTER IS RECOMMENDED.
A TRIANGLE-WAVE OF 5V PK APPEARS ACROSS THE 0.01 F CAPACITOR; IF
USED AS AN OUTPUT, A VOLTAGE-FOLLOWER SHOULD BE INTERPOSED.
Figure 14. Differential-Input Voltage-to-Frequency Converter
MATCHED TO 0.025%
20k
10k
–
AD741K
10 F
NONPOLAR
X
1
X
2
+V
S
+15V
10k
OUT
+
5k
+
10 F SOLID Ta
Z
1
–
10k
Y
1
Y
2
20k
Z
2
10M
–V
S
–15V
ZERO
ADJ
+15V
+
AD741J
OUTPUT
0 TO +5V
10k
INPUT
5V RMS FS
10V PEAK
RMS + DC
MODE
AC RMS
AD534
10k
SF
CALIBRATION PROCEDURE:
WITH 'MODE' SWITCH IN 'RMS + DC' POSITION, APPLY AN INPUT OF +1.00VDC.
ADJUST ZERO UNTIL OUTPUT READS SAME AS INPUT. CHECK FOR INPUTS
OF 10V; OUTPUT SHOULD BE WITHIN 0.05% (5mV).
ACCURACY IS MAINTAINED FROM 60Hz TO 100kHz, AND IS TYPICALLY HIGH
BY 0.5% AT 1MHz FOR V
IN
= 4V RMS (SINE, SQUARE OR TRIANGULAR-WAVE).
PROVIDED THAT THE PEAK INPUT IS NOT EXCEEDED, CREST-FACTORS UP
TO AT LEAST TEN HAVE NO APPRECIABLE EFFECT ON ACCURACY .
INPUT IMPEDANCE IS ABOUT 10k ; FOR HIGH (10M ) IMPEDANCE, REMOVE
MODE SWITCH AND INPUT COUPLING COMPONENTS.
FOR GUARANTEED SPECIFICATIONS THE AD536A AND AD636 ARE OFFERED
AS A SINGLE PACKAGE RMS-TO-DC CONVERTER.
Figure 15. Wideband, High-Crest Factor, RMS-to-DC Converter
REV. B
–9–
AD [ ANALOG DEVICES ]
