LTC1563-2 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC1563-2' PDF : 20 Pages View PDF
LTC1563-2/LTC1563-3
APPLICATIONS INFORMATION
4th Order Filter Responses Using the LTC1563-2
R31
R21
R11
VIN
LTC1563-2
1
LP
2
SA
3
NC
4
INVA
5
NC
6
LPA
7
AGND
8 V–
V+ 16
15
LPB
14
NC
13
INVB
12
NC
11
SB
10
NC
9
EN
R22
VOUT
R32
R12
1563 F05
Figure 5. 4th Order Filter Connections (Power Supply, Ground,
EN and LP Connections Not Shown for Clarity). Table 1 Shows
Resistor Values
1
0
–2
–4
BUTTERWORTH
–6
0.5dB RIPPLE
CHEBYSHEV
0.1dB RIPPLE
–8
CHEBYSHEV
NORMALIZED TO fC = 1Hz
–10
0.1
1
2
FREQUENCY (Hz)
1563 F05b
Figure 5b. Passband Frequency Response
10
0
–20
–40
BUTTERWORTH
0.5dB RIPPLE
–60
CHEBYSHEV
0.1dB RIPPLE
CHEBYSHEV
–80
NORMALIZED TO fC = 1Hz
–90
0.1
1
FREQUENCY (Hz)
10
1563 F05a
Figure 5a. Frequency Response
1.2
1.0
0.8
0.6
0.4
0.2
0
0
BUTTERWORTH
0.5dB RIPPLE
CHEBYSHEV
0.1dB RIPPLE
CHEBYSHEV
NORMALIZED TO fC = 1Hz
0.5 1.0 1.5 2.0
TIME (s)
2.5 3.0
1563 F05c
Figure 5c. Step Response
Table 1. Resistor Values, Normalized to 256kHz Cutoff Frequency (fC), Figure 5. The Passband
Gain, of the 4th Order LTC1563-2 Lowpass Filter, Is Set to Unity. (Note 1)
BUTTERWORTH
0.1dB RIPPLE
CHEBYSHEV
0.5dB RIPPLE
CHEBYSHEV
LP Mode Max fC
HS Mode Max fC
R11 = R21 =
R31 =
R12 = R22 =
R32 =
25.6kHz
256kHz
10k(256kHz/fC)
10k(256kHz/fC)
10k(256kHz/fC)
10k(256kHz/fC)
15kHz
135kHz
13.7k(256kHz/fC)
10.7k(256kHz/fC)
10k(256kHz/fC)
6.81k(256kHz/fC)
13kHz
113kHz
20.5k(256kHz/fC)
12.4k(256kHz/fC)
12.1k(256kHz/fC)
6.98k(256kHz/fC)
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.
156323fa
13
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