LTC1563-3 Linear Technology, LTC1563-3 Datasheet - Page 9

• Manufacturer Part Number: LTC1563-3
• Description: Active RC/ 4th Order Lowpass Filter Family
• Manufacturer: Linear Technology

4th Order Filter Responses Using the LTC1563-2
TYPICAL APPLICATIO S
Figure 3. 4th Order Filter Connections (Power Supply, Ground,
EN and LP Connections Not Shown for Clarity). Table 1 Shows
Resistor Values
V
IN
Figure 3b. Passband Frequency Response
–10
R11
–2
–4
–6
–8
1
0
R31
R21
0.1
NORMALIZED TO f
Table 1. Resistor Values, Normalized to 256kHz Cutoff Frequency (f
Gain, of the 4th Order LTC1563-2 Lowpass Filter, Is Set to Unity. (Note 1)
Example: In HS mode, 0.1dB ripple Chebyshev, 100kHz cutoff frequency, R11 = R21 = 35k 34.8k (1%),
R31 = 27.39k 27.4k (1%), R12 = R22 = 256k 255k (1%), R32 = 17.43k 17.4k (1%)
Note 1: The resistor values listed in this table provide good approximations of the listed transfer functions. For the
optimal resistor values, higher gain or other transfer functions, use FilterCAD Version 3.0 (or newer) or contact the
Linear Technology Filter Applications group for assistance.
LP Mode Max f
HS Mode Max f
R11 = R21 =
R31 =
R12 = R22 =
R32 =
BUTTERWORTH
0.5dB RIPPLE
CHEBYSHEV
0.1dB RIPPLE
CHEBYSHEV
1
2
3
4
5
6
7
8
LP
SA
NC
INVA
NC
LPA
AGND
V
–
LTC1563-2
FREQUENCY (Hz)
C
= 1Hz
INVB
LPB
NC
NC
SB
NC
EN
C
V
C
+
16
15
14
13
12
11
10
9
U
1
BUTTERWORTH
10k(256kHz/f
10k(256kHz/f
10k(256kHz/f
10k(256kHz/f
1563 F03b
R22
R32
25.6kHz
256kHz
2
1563 F03
R12
V
OUT
C
C
C
C
)
)
)
)
13.7k(256kHz/f
10.7k(256kHz/f
6.81k(256kHz/f
10k(256kHz/f
0.1dB RIPPLE
CHEBYSHEV
135kHz
15kHz
C
C
C
C
)
)
)
)
–20
–40
–60
–80
–90
1.2
1.0
0.8
0.6
0.4
0.2
10
0
0
C
0.1
), Figure 3. The Passband
0
Figure 3a. Frequency Response
NORMALIZED TO f
Figure 3c. Step Response
LTC1563-2/LTC1563-3
0.5
BUTTERWORTH
0.5dB RIPPLE
CHEBYSHEV
0.1dB RIPPLE
CHEBYSHEV
20.5k(256kHz/f
12.4k(256kHz/f
12.1k(256kHz/f
6.98k(256kHz/f
0.5dB RIPPLE
1.0
CHEBYSHEV
FREQUENCY (Hz)
113kHz
13kHz
TIME (s)
NORMALIZED TO f
C
= 1Hz
1.5
1
BUTTERWORTH
0.5dB RIPPLE
CHEBYSHEV
0.1dB RIPPLE
CHEBYSHEV
2.0
C
C
C
C
)
)
)
)
2.5
C
1563 F03a
= 1Hz
1563 F03C
3.0
10
9