Linear DC266B-A, DC266B-B Demo Manual
Description
DEMO MANUAL DC266B
LTC1562/LTC1562-2
Quad 2nd Order Active RC Filter IC
Demonstration circuit DC266B-A is for the evaluation of
8th order filter circuits using an LTC1562 (no dash) and
DC266B-B for an LTC1562-2. LTC1562 and LTC1562-2
are quad 2nd order active-RC filter building blocks. The
LTC1562 or LTC1562-2 2nd order sections can be con
figured with external resistors to implement lowpass and
narrow or wide band bandpass filters. The frequency
range for a
lowpass
filter is 10kHz to 150kHz and 20kHz to
For other possible LTC1562 or LTC1562-2 configurations,
the DC226B-A and DC226B-B have unused pads for 0805
surface mount resistors and capacitors preconfigured
with PCB traces to allow for the following filter circuits:
-
1. 8th order lowpass filter
2. Dual 4th or 5th order lowpass filter
3. 8th order narrow band bandpass
300kHz for the LTC1562 and LTC1562-2 respectively. The
frequency range for a bandpass filter is 20kHz to 120kHz
and 40kHz to 250kHz for the LTC1562 and LTC1562-2
respectively (the LTC1562A is higher precision version
of the LTC1562).
For testing and evaluation, the DC266B-A is configured as
an 8th order, 50kHz bandpass filter and the DC266B-B is
configured as an 8th order, 200kHz bandpass filter.
4. 8th order wide band bandpass.
Refer to the LTC1562 or LTC1562-2 data sheet for com
prehensive filter design information.
Design files for this circuit board are available at
http://www.linear.com/demo/DC266B
L, LT, LTC, LTM, Linear Technology, LTspce, FilterCAD and the Linear logo are registered
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
Ltc1562 anD Ltc1562-2 BLock Diagram
+
V
V
V
–
16
V
14
17
5
+
SHUTDOWN
SWITCH
R
R
SHUTDOWN
SWITCH
–
PINS 4, 7, 14
4
AND 17 MUST BE
7
CONNECTED TO
–
, PIN 16
V
10 9 8 1 2 3
INV V1 V2
A B
C
–
∫ ∫
2ND ORDER SECTIONS
SHDN
15
AGND
+
6
D C
+
∫ ∫
–
C C
11 12 13 20 19 18
INV V1 V2 INV V1 V2
R2
R
IN
V
IN
A B
2ND ORDER LOWPASS (V2) AND BANDPASS (V1) 2ND ORDER BANDPASS (V2) AND HIGHPASS (V1)
R
Q
INV V1 V2
C
–
*
+
∫ ∫
*100kHz FOR
LTC1562 AND
200kHz FOR
LTC1562-2
INV V1 V2
–
+
+
–
C
IN
V
IN
INV V1 V2
–
+
-
C
R2
R
Q
C
*
THE MAXIMUM
FREQUENCY ERROR IS
±0.6% FOR LTC162A,
±1.0% FOR LTC1562 AND
±1.7% FOR LTC1562-2
DC266 BD
dc266bf
1
DEMO MANUAL DC266B
Quick start proceDure
See Figure 1 for proper measurement equipment setup
and follow the procedure below.
1. Set SW1 to DUAL.
2. With power off, connect a dual 5V power supply to +V
and –V.
3. Connect a function generator to IN.
4. For a DC266B-A, set the function generator to a 2V
50kHz, sine wave.
5. For a DC266B-B, set the function generator to a 2V
200kHz, sine wave.
P-P
P-P
,
,
6. Connect an oscilloscope channel to OUT.
7. For a DC266B-A, set the scaling of an oscilloscope to
1V/20µs per division.
For a DC266B-B, set the scaling of an oscilloscope to
1V/5µs per division.
8. Power up the system and the oscilloscope should show
sine wave.
2V
P-P
9. To test stopband attenuation of DC266B-A, set the
input frequency to 25kHz or 75kHz.
10. To test stopband attenuation of DC266B-B, set the
input frequency to 150kHz or 250kHz.
2
Figure 1. Quick Start Test Equipment Setup
dc266bf
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