Datasheet

14
LTC1563-2/LTC1563-3
156323fa
Table 2. Resistor Values, Normalized to 256kHz Cutoff Frequency (f
C
), Figure 6. The Passband
Gain, of the 4th Order LTC1563-3 Lowpass Filter, Is Set to Unity. (Note 1)
TRANSITIONAL TRANSITIONAL
BESSEL GAUSSIAN TO 6dB GAUSSIAN TO 12dB
LP Mode Max f
C
25.6kHz 20kHz 21kHz
HS Mode Max f
C
256kHz 175kHz 185kHz
R11 = R21 = 10k(256kHz/f
C
) 17.4k(256kHz/f
C
) 15k(256kHz/f
C
)
R31 = 10k(256kHz/f
C
) 13.3k(256kHz/f
C
) 11.8k(256kHz/f
C
)
R12 = R22 = 10k(256kHz/f
C
) 14.3k(256kHz/f
C
) 10.5k(256kHz/f
C
)
R32 = 10k(256kHz/f
C
) 6.04k(256kHz/f
C
) 6.19k(256kHz/f
C
)
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.
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
LP
SA
NC
INVA
NC
LPA
AGND
V
–
V
+
LPB
NC
INVB
NC
SB
NC
EN
V
OUT
LTC1563-3
V
IN
1563 F06
R31
R32
R22
R21
R11
R12
Figure 6. 4th Order Filter Connections (Power Supply, Ground,
EN and LP Connections Not Shown for Clarity). Table 2 Shows
Resistor Values
FREQUENCY (Hz)
0.1
GAIN (dB)
–20
–40
–60
–80
–90
10
0
101
1563 F06a
NORMALIZED TO f
C
= 1Hz
BESSEL
TRANSITIONAL
GAUSSIAN TO 12dB
TRANSITIONAL
GAUSSIAN TO 6dB
4th Order Filter Responses Using the LTC1563-3
Figure 6a. Frequency Response
Figure 6b. Step Response Figure 6c. Step Response—Settling
TIME (s)
0
OUTPUT VOLTAGE (V)
1.2
1.0
0.8
0.6
0.4
0.2
0
1.00.5 1.5 2.0
1563 F06b
2.5 3.0
BESSEL
TRANSITIONAL
GAUSSIAN TO 12dB
TRANSITIONAL
GAUSSIAN TO 6dB
NORMALIZED TO f
C
= 1Hz
TIME (s)
0
OUTPUT VOLTAGE (V)
2.0
1563 F06c
0.5
1.0
1.5
1.05
1.00
0.95
BESSEL
TRANSITIONAL
GAUSSIAN TO 12dB
TRANSITIONAL
GAUSSIAN TO 6dB
NORMALIZED TO f
C
= 1Hz
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