LTC1563-3CGN#TRPBF [Linear]
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| 型号： | LTC1563-3CGN#TRPBF |
| 厂家： | 
Linear |
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LTC1563-2/LTC1563-3
Active RC, 4th Order
Lowpass Filter Family
U
DESCRIPTIO
FEATURES
The LTC®1563-2/LTC1563-3 are a family of extremely
easy-to-use, active RC lowpass filters with rail-to-rail
inputs and outputs and low DC offset suitable for systems
with a resolution of up to 16 bits. The LTC1563-2, with a
single resistor value, gives a unity-gain Butterworth
response. The LTC1563-3, with a single resistor value,
gives a unity-gain Bessel response. The proprietary
architecture of these parts allows for a simple resistor
calculation:
■
Extremely Easy to Use—A Single Resistor Value
Sets the Cutoff Frequency (256Hz < fC < 256kHz)
Extremely Flexible—Different Resistor Values
■
Allow Arbitrary Transfer Functions with or without
Gain (256Hz < fC < 256kHz)
■
Supports Cutoff Frequencies Up to 360kHz Using
FilterCADTM
■
LTC1563-2: Unity-Gain Butterworth Response Uses a
Single Resistor Value, Different Resistor Values
Allow Other Responses with or without Gain
LTC1563-3: Unity-Gain Bessel Response Uses a
R = 10k (256kHz/fC); fC = Cutoff Frequency
■
where fC is the desired cutoff frequency. For many appli-
cations, this formula is all that is needed to design a filter.
By simply utilizing different valued resistors, gain and
other responses are achieved.
Single Resistor Value, Different Resistor Values
Allow Other Responses with or without Gain
Rail-to-Rail Input and Output Voltages
Operates from a Single 3V (2.7V Min) to ±5V Supply
Low Noise: 36µVRMS for fC = 25.6kHz, 60µVRMS for
fC = 256kHz
fC Accuracy < ±2% (Typ)
DC Offset < 1mV
Cascadable to Form 8th Order Lowpass Filters
Available in Narrow SSOP-16 Package
■
■
■
The LTC1563-X features a low power mode, for the lower
frequency applications, where the supply current is re-
duced by an order of magnitude and a near zero power
shutdown mode.
■
■
■
■
The LTC1563-Xs are available in the narrow SSOP-16
package (Same footprint as an SO-8 package).
, LTC and LT are registered trademarks of Linear Technology Corporation.
FilterCAD is trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
U
APPLICATIO S
■
Discrete RC Active Filter Replacement
■
Antialiasing Filters
■
Smoothing or Reconstruction Filters
■
Linear Phase Filtering for Data Communication
■
Phase Locked Loops
U
TYPICAL APPLICATIO
Frequency Response
10
0
Single 3.3V, 256Hz to 256kHz Butterworth Lowpass Filter
3.3V
LTC1563-2
–10
0.1µF
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
OUT
+
LP
V
R = 10k
= 256kHz
R
R
–20
f
C
SA
LPB
NC
–30
–40
–50
–60
–70
–80
NC
R
R
R = 10M
= 256Hz
INVA
NC
INVB
NC
f
C
LPA
AGND
SB
R
NC
–
R
V
EN
V
IN
0.1µF
100
1k
10k
FREQUENCY (Hz)
100k
1M
10k
R
f
= 256kHz
C
1563 TA01
(
)
1563 TA02
156323fa
1
LTC1563-2/LTC1563-3
W W U W
U
W U
ABSOLUTE MAXIMUM RATINGS
PACKAGE/ORDER INFORMATION
(Note 1)
TOP VIEW
ORDER PART
NUMBER
Total Supply Voltage (V+ to V–)............................... 11V
Maximum Input Voltage at
+
LP
SA
1
2
3
4
5
6
7
8
16
V
15 LPB
Any Pin ....................... (V– – 0.3V) ≤ VPIN ≤ (V+ + 0.3V)
Power Dissipation.............................................. 500mW
Operating Temperature Range
LTC1563-2CGN
LTC1563-3CGN
LTC1563-2IGN
LTC1563-3IGN
NC
14
13
12
11
10
9
NC
INVA
NC
INVB
NC
LTC1563C ............................................... 0°C to 70°C
LTC1563I............................................ –40°C to 85°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
LPA
AGND
SB
NC
GN PART
MARKING
–
V
EN
GN PACKAGE
16-LEAD PLASTIC SSOP
15632
15633
15632I
15633I
TJMAX = 150°C, θJA = 135°C/ W
NOTE: PINS LABELED NC ARE NOT CONNECTED
INTERNALLY AND SHOULD BE CONNECTED TO THE
SYSTEM GROUND
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for Military grade parts.
ELECTRICAL CHARACTERISTICS
The
S
●
denotes specifications which apply over the full operating temperature range, otherwise specifications are T = 25°C.
A
V = Single 4.75V, EN pin to logic “low,” Gain = 1, R = R11 = R21 = R31 = R12 = R22 = R32, specifications apply to both the high
FIL
speed (HS) and low power (LP) modes unless otherwise noted.
PARAMETER CONDITIONS
Specifications for Both LTC1563-2 and LTC1563-3
Total Supply Voltage (V ), HS Mode
MIN
TYP
MAX
UNITS
●
●
3
11
11
V
V
S
Total Supply Voltage (V ), LP Mode
2.7
S
Output Voltage Swing High (LPB Pin)
HS Mode
V = 3V, f = 25.6kHz, R = 100k, R = 10k to GND
●
●
●
2.9
4.55
4.8
2.95
4.7
4.9
V
V
V
S
C
FIL
L
V = 4.75V, f = 25.6kHz, R = 100k, R = 10k to GND
S
C
FIL
L
V = ±5V, f = 25.6kHz, R = 100k, R = 10k to GND
S
C
FIL
L
Output Voltage Swing Low (LPB Pin)
HS Mode
V = 3V, f = 25.6kHz, R = 100k, R = 10k to GND
●
●
●
0.015
0.02
–4.95
0.05
0.05
–4.9
V
V
V
S
C
FIL
L
V = 4.75V, f = 25.6kHz, R = 100k, R = 10k to GND
S
C
FIL
L
V = ±5V, f = 25.6kHz, R = 100k, R = 10k to GND
S
C
FIL
L
Output Swing High (LPB Pin)
LP Mode
V = 2.7V, f = 25.6kHz, R = 100k, R = 10k to GND
●
●
●
2.6
4.55
4.8
2.65
4.65
4.9
V
V
V
S
C
FIL
L
V = 4.75V, f = 25.6kHz, R = 100k, R = 10k to GND
S
C
FIL
L
V = ±5V, f = 25.6kHz, R = 100k, R = 10k to GND
S
C
FIL
L
Output Swing Low (LPB Pin)
LP Mode
V = 2.7V, f = 25.6kHz, R = 100k, R = 10k to GND
●
●
●
0.01
0.015
–4.95
0.05
0.05
–4.9
V
V
V
S
C
FIL
L
V = 4.75V, f = 25.6kHz, R = 100k, R = 10k to GND
S
C
FIL
L
V = ±5V, f = 25.6kHz, R = 100k, R = 10k to GND
S
C
FIL
L
DC Offset Voltage, HS Mode
(Section A Only)
V = 3V, f = 25.6kHz, R = 100k
●
●
●
±1.5
±1.0
±1.5
±3
±3
±3
mV
mV
mV
S
C
FIL
V = 4.75V, f = 25.6kHz, R = 100k
S
C
FIL
V = ±5V, f = 25.6kHz, R = 100k
S
C
FIL
DC Offset Voltage, LP Mode
(Section A Only)
V = 2.7V, f = 25.6kHz, R = 100k
●
●
●
±2
±2
±2
±6
±6
±7
mV
mV
mV
S
C
FIL
V = 4.75V, f = 25.6kHz, R = 100k
S
C
FIL
V = ±5V, f = 25.6kHz, R = 100k
S
C
FIL
DC Offset Voltage, HS Mode
(Input to Output, Sections A, B Cascaded)
V = 3V, f = 25.6kHz, R = 100k
●
●
●
±1.5
±1.0
±1.5
±3
±3
±3
mV
mV
mV
S
C
FIL
V = 4.75V, f = 25.6kHz, R = 100k
S C FIL
V = ±5V, f = 25.6kHz, R = 100k
S
C
FIL
156323fa
2
LTC1563-2/LTC1563-3
ELECTRICAL CHARACTERISTICS
The
S
●
denotes specifications which apply over the full operating temperature range, otherwise specifications are T = 25°C.
A
V = Single 4.75V, EN pin to logic “low,” Gain = 1, R = R11 = R21 = R31 = R12 = R22 = R32, specifications apply to both the high
FIL
speed (HS) and low power (LP) modes unless otherwise noted.
PARAMETER
CONDITIONS
V = 2.7V, f = 25.6kHz, R = 100k
MIN
TYP
MAX
UNITS
DC Offset Voltage, LP Mode
(Input to Output, Sections A, B Cascaded)
●
●
●
±2
±2
±2
±7
±7
±8
mV
mV
mV
S
C
FIL
V = 4.75V, f = 25.6kHz, R = 100k
S C FIL
V = ±5V, f = 25.6kHz, R = 100k
S
C
FIL
DC Offset Voltage Drift, HS Mode
(Input to Output, Sections A, B Cascaded)
V = 3V, f = 25.6kHz, R = 100k
●
●
●
10
10
10
µV/°C
µV/°C
µV/°C
S
C
FIL
V = 4.75V, f = 25.6kHz, R = 100k
S C FIL
V = ±5V, f = 25.6kHz, R = 100k
S
C
FIL
DC Offset Voltage Drift, LP Mode
(Input to Output, Sections A, B Cascaded)
V = 2.7V, f = 25.6kHz, R = 100k
●
●
●
10
10
10
µV/°C
µV/°C
µV/°C
S
C
FIL
V = 4.75V, f = 25.6kHz, R = 100k
S C FIL
V = ±5V, f = 25.6kHz, R = 100k
S
C
FIL
AGND Voltage
V = 4.75V, f = 25.6kHz, R = 100k
●
2.35
2.375
2.40
V
S
C
FIL
Power Supply Current, HS Mode
V = 3V, f = 25.6kHz, R = 100k
●
●
●
8.0
10.5
15
14
17
23
mA
mA
mA
S
C
FIL
V = 4.75V, f = 25.6kHz, R = 100k
S
C
FIL
V = ±5V, f = 25.6kHz, R = 100k
S
C
FIL
Power Supply Current, LP Mode
Shutdown Mode Supply Current
V = 2.7V, f = 25.6kHz, R = 100k
●
●
●
1.0
1.4
2.3
1.8
2.5
3.5
mA
mA
mA
S
C
FIL
V = 4.75V, f = 25.6kHz, R = 100k
S
C
FIL
V = ±5V, f = 25.6kHz, R = 100k
S
C
FIL
V = 4.75V, f = 25.6kHz, R = 100k
●
1
20
µA
S
C
FIL
EN Input
Logic Low Level
V = 3V
●
●
●
0.8
1
1
V
V
V
S
V = 4.75V
S
V = ±5V
S
EN Input
Logic High Level
V = 3V
●
●
●
2.5
4.3
4.4
V
V
V
S
V = 4.75V
S
V = ±5V
S
LP
V = 3V
●
●
●
0.8
1
1
V
V
V
S
Logic Low Level
V = 4.75V
S
V = ±5V
S
LP
V = 3V
●
●
●
2.5
4.3
4.4
V
V
V
S
Logic High Level
V = 4.75V
S
V = ±5V
S
LTC1563-2 Transfer Function Characteristics
Cutoff Frequency Range, f
HS Mode
(Note 2)
V = 3V
●
●
●
0.256
0.256
0.256
256
256
256
kHz
kHz
kHz
C
S
V = 4.75V
S
V = ±5V
S
Cutoff Frequency Range, f
LP Mode
(Note 2)
V = 2.7V
●
●
●
0.256
0.256
0.256
25.6
25.6
25.6
kHz
kHz
kHz
C
S
V = 4.75V
S
V = ±5V
S
Cutoff Frequency Accuracy, HS Mode
f = 25.6kHz
C
V = 3V, R = 100k
●
●
●
–2.0
–2.0
–2.0
±1.5
±1.5
±1.5
3.5
3.5
3.5
%
%
%
S
FIL
V = 4.75V, R = 100k
S FIL
V = ±5V, R = 100k
S
FIL
Cutoff Frequency Accuracy, HS Mode
f = 256kHz
C
V = 3V, R = 10k
●
●
●
–5
–5
–5
±1.5
±1.5
±1.5
2.5
2.5
2.5
%
%
%
S
FIL
V = 4.75V, R = 10k
S FIL
V = ±5V, R = 10k
S
FIL
Cutoff Frequency Accuracy, LP Mode
f = 25.6kHz
C
V = 2.7V, R = 100k
●
●
●
–3
–3
–3
±1.5
±1.5
±1.5
3
3
3
%
%
%
S
FIL
V = 4.75V, R = 100k
S FIL
V = ±5V, R = 100k
S
FIL
Cutoff Frequency Temperature Coefficient
(Note 3)
●
±1
ppm/°C
156323fa
3
LTC1563-2/LTC1563-3
ELECTRICAL CHARACTERISTICS
The
S
●
denotes specifications which apply over the full operating temperature range, otherwise specifications are T = 25°C.
A
V = Single 4.75V, EN pin to logic “low,” Gain = 1, R = R11 = R21 = R31 = R12 = R22 = R32, specifications apply to both the high
FIL
speed (HS) and low power (LP) modes unless otherwise noted.
PARAMETER CONDITIONS
Passband Gain, HS Mode, f = 25.6kHz Test Frequency = 2.56kHz (0.1 • f )
MIN
TYP
MAX
UNITS
●
●
–0.2
–0.3
0
0
0.2
0.3
dB
dB
C
C
V = 4.75V, R = 100k
Test Frequency = 12.8kHz (0.5 • f )
S
FIL
C
Stopband Gain, HS Mode, f = 25.6kHz
Test Frequency = 51.2kHz (2 • f )
●
●
–24
–48
–21.5
–46
d B
dB
C
C
V = 4.75V, R = 100k
Test Frequency = 102.4kHz (4 • f )
S
FIL
C
Passband Gain, HS Mode, f = 256kHz
Test Frequency = 25.6kHz (0.1 • f )
●
●
–0.2
–0.5
0
0
0.2
0.5
dB
dB
C
C
V = 4.75V, R = 10k
Test Frequency = 128kHz (0.5 • f )
S
FIL
C
Stopband Gain, HS Mode, f = 256kHz
Test Frequency = 400kHz (1.56 • f )
●
●
–15.7
–23.3
–13.5
–21.5
dB
dB
C
C
V = 4.75V, R = 10k
Test Frequency = 500kHz (1.95 • f )
S
FIL
C
Passband Gain, LP Mode, f = 25.6kHz
Test Frequency = 2.56kHz (0.1 • f )
●
●
–0.25
–0.6
0
0.25
0.6
dB
dB
C
C
V = 4.75V, R = 100k
Test Frequency = 12.8kHz (0.5 • f )
–0.02
S
FIL
C
Stopband Gain, LP Mode, f = 25.6kHz
Test Frequency = 51.2kHz (2 • f )
●
●
–24
–48
–22
–46.5
dB
dB
C
C
V = 4.75V, R = 100k
Test Frequency = 102.4kHz (4 • f )
S
FIL
C
LTC1563-3 Transfer Function Characteristics
Cutoff Frequency Range, f
HS Mode
(Note 2)
V = 3V
●
●
●
0.256
0.256
0.256
256
256
256
kHz
kHz
kHz
C
S
V = 4.75V
S
V = ±5V
S
Cutoff Frequency Range, f
LP Mode
(Note 2)
V = 2.7V
●
●
●
0.256
0.256
0.256
25.6
25.6
25.6
kHz
kHz
kHz
C
S
V = 4.75V
S
V = ±5V
S
Cutoff Frequency Accuracy, HS Mode
f = 25.6kHz
C
V = 3V, R = 100k
●
●
●
–3
–3
–3
±2
±2
±2
5.5
5.5
5.5
%
%
%
S
FIL
V = 4.75V, R = 100k
S FIL
V = ±5V, R = 100k
S
FIL
Cutoff Frequency Accuracy, HS Mode
f = 256kHz
C
V = 3V, R = 10k
●
●
●
–3
–3
–3
±2
±2
±2
6
6
6
%
%
%
S
FIL
V = 4.75V, R = 10k
S FIL
V = ±5V, R = 10k
S
FIL
Cutoff Frequency Accuracy, LP Mode
f = 25.6kHz
C
V = 2.7V, R = 100k
●
●
●
–4
–4
–4
±3
±3
±3
7
7
7
%
%
%
S
FIL
V = 4.75V, R = 100k
S FIL
V = ±5V, R = 100k
S
FIL
Cutoff Frequency Temperature Coefficient
(Note 3)
●
±1
ppm/°C
Passband Gain, HS Mode, f = 25.6kHz
Test Frequency = 2.56kHz (0.1 • f )
●
●
–0.2
–1.0
–0.03
–0.72
0.2
–0.25
dB
dB
C
C
V = 4.75V, R = 100k
Test Frequency = 12.8kHz (0.5 • f )
S
FIL
C
Stopband Gain, HS Mode, f = 25.6kHz
Test Frequency = 51.2kHz (2 • f )
●
●
–13.6
–34.7
–10
–31
dB
dB
C
C
V = 4.75V, R = 100k
Test Frequency = 102.4kHz (4 • f )
S
FIL
C
Passband Gain, HS Mode, f = 256kHz
Test Frequency = 25.6kHz (0.1 • f )
●
●
–0.2
–1.1
–0.03
–0.72
0.2
–0.5
dB
dB
C
C
V = 4.75V, R = 10k
Test Frequency = 128kHz (0.5 • f )
S
FIL
C
Stopband Gain, HS Mode, f = 256kHz
Test Frequency = 400kHz (1.56 • f )
●
●
–8.3
–13
–6
–10.5
dB
dB
C
C
V = 4.75V, R = 10k
Test Frequency = 500kHz (1.95 • f )
S
FIL
C
Passband Gain, LP Mode, f = 25.6kHz
Test Frequency = 2.56kHz (0.1 • f )
●
●
–0.2
–1.0
–0.03
–0.72
0.2
–0.25
dB
dB
C
C
V = 4.75V, R = 100k
Test Frequency = 12.8kHz (0.5 • f )
S
FIL
C
Stopband Gain, LP Mode, f = 25.6kHz
Test Frequency = 51.2kHz (2 • f )
●
●
–13.6
–34.7
–11
–32
dB
dB
C
C
V = 4.75V, R = 100k
Test Frequency = 102.4kHz (4 • f )
S
FIL
C
Note 1: Absolute Maximum Ratings are those value beyond which the life
of a device may be impaired.
assembly practices are required. There may also be greater DC offset at
high temperatures when using such large valued resistors.
Note 2: The minimum cutoff frequency of the LTC1563 is arbitrarily listed
as 256Hz. The limit is arrived at by setting the maximum resistor value
limit at 10MΩ. The LTC1563 can be used with even larger valued resistors.
When using very large values of resistance careful layout and thorough
Note 3: The cutoff frequency temperature drift at low frequencies is as
listed. At higher cutoff frequencies (approaching 25.6kHz in low power
mode and approaching 256kHz in high speed mode) the internal
amplifier’s bandwidth can effect the cutoff frequency. At these limits the
cutoff frequency temperature drift is ±15ppm/°C.
156323fa
4
LTC1563-2/LTC1563-3
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Output Voltage Swing High vs
Load Resistance
Output Voltage Swing High vs
Load Resistance
Output Voltage Swing High vs
Load Resistance
3.4
3.2
3.0
2.8
2.6
2.4
2.2
2.0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
5.5
V
= SINGLE 3.3V
V
= SINGLE 5V
V = ±5V
S
S
S
5.0
4.5
4.0
3.5
3.0
2.5
HS MODE
LP MODE
HS MODE
LP MODE
HS MODE
LP MODE
100
1k
10k
100k
100
1k
10k
100k
100
1k
10k
100k
LOAD RESISTANCE—LOAD TO GROUND (Ω)
LOAD RESISTANCE—LOAD TO GROUND (Ω)
LOAD RESISTANCE—LOAD TO GROUND (Ω)
1563 G01
1563 G02
1563 G03
Output Voltage Swing Low vs
Load Resistance
Output Voltage Swing Low vs
Load Resistance
Output Voltage Swing Low vs
Load Resistance
0.025
0.020
0.015
0.010
0.005
0
0.025
0.020
0.015
0.010
0.005
0
–4.3
–4.4
–4.5
–4.6
–4.7
–4.8
–4.9
–5.0
V
= SINGLE 3.3V
V
= SINGLE 5V
V = ± 5V
S
S
S
HS MODE
HS MODE
LP MODE
LP MODE
HS MODE
LP MODE
100
1k
10k
100k
100
1k
10k
100k
100
1k
10k
100k
LOAD RESISTANCE—LOAD TO GROUND (Ω)
LOAD RESISTANCE—LOAD TO GROUND (Ω)
LOAD RESISTANCE—LOAD TO GROUND (Ω)
1563 G04
1563 G05
1563 G06
THD + Noise vs Input Voltage
THD + Noise vs Input Voltage
THD + Noise vs Input Voltage
–40
–50
–60
–70
–80
–90
–100
–40
–50
–60
–70
–80
–90
–100
–40
–50
–60
–70
–80
–90
–100
3.3V SUPPLY
5V SUPPLY
±5V SUPPLY
3.3V SUPPLY
5V SUPPLY
±5V SUPPLY
3.3V SUPPLY
5V SUPPLY
±5V SUPPLY
f
= 25.6kHz
f
= 25.6kHz
f = 256kHz
C
C
C
LOW POWER MODE
= 5kHz
HIGH SPEED MODE
= 5kHz
HIGH SPEED MODE
f = 50kHz
IN
f
IN
f
IN
0.1
1
10
0.1
1
10
0.1
1
10
INPUT VOLTAGE (V
)
INPUT VOLTAGE (V
)
INPUT VOLTAGE (V
)
P-P
P-P
P-P
1563 G07
1563 G08
1563 G09
156323fa
5
LTC1563-2/LTC1563-3
U W
TYPICAL PERFOR A CE CHARACTERISTICS
THD + Noise vs Input Frequency
THD + Noise vs Input Frequency
THD + Noise vs Input Frequency
–40
–50
–60
–70
–80
–90
–100
–60
–70
–60
–70
V
= SINGLE 3.3V
V
= SINGLE 3.3V
V = SINGLE 3V
S
S
S
LOW POWER MODE
= 25.6kHz
HIGH SPEED MODE
= 25.6kHz
HIGH SPEED MODE
f
C
f
C
f
C
= 256kHz
1V
2V
P-P
P-P
1V
2V
P-P
P-P
–80
–80
1V
2V
P-P
–90
–90
P-P
–100
–100
1
10
INPUT FREQUENCY (kHz)
20
20
20
1
10
INPUT FREQUENCY (kHz)
20
20
20
1
10
INPUT FREQUENCY (kHz)
100 200
1563 G10
1563 G11
1563 G12
THD + Noise vs Input Frequency
THD + Noise vs Input Frequency
THD + Noise vs Input Frequency
–40
–50
–60
–70
–80
–90
–100
–60
–70
–60
–70
V
= SINGLE 5V
V = SINGLE 5V
S
HIGH SPEED MODE
f = 25.6kHz
C
V
= SINGLE 5V
S
S
LOW POWER MODE
= 25.6kHz
HIGH SPEED MODE
f
C
f
C
= 256kHz
1V
2V
P-P
P-P
1V
2V
P-P
P-P
1V
P-P
2V
–80
–80
P-P
–90
–90
3V
P-P
3V
P-P
3V
P-P
–100
–100
1
10
INPUT FREQUENCY (kHz)
1
10
INPUT FREQUENCY (kHz)
1
10
INPUT FREQUENCY (kHz)
100 200
1563 G13
1563 G14
1563 G15
THD + Noise vs Input Frequency
THD + Noise vs Input Frequency
THD + Noise vs Input Frequency
–40
–50
–60
–70
–80
–90
–100
–60
–70
–60
–70
V
= ± 5V
V = ± 5V
S
HIGH SPEED MODE
f = 25.6kHz
C
V
= ± 5V
S
S
LOW POWER MODE
= 25.6kHz
HIGH SPEED MODE
f
f
= 256kHz
C
C
1V
2V
5V
P-P
P-P
P-P
1V
2V
5V
P-P
P-P
P-P
1V
5V
–80
–80
P-P
2V
P-P
–90
–90
P-P
–100
–100
1
10
INPUT FREQUENCY (kHz)
1
10
INPUT FREQUENCY (kHz)
1
10
INPUT FREQUENCY (kHz)
100 200
1563 G16
1563 G17
1563 G18
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LTC1563-2/LTC1563-3
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TYPICAL PERFOR A CE CHARACTERISTICS
Output Voltage Noise vs Cutoff
Frequency
THD + Noise vs Output Load
THD + Noise vs Output Load
60
–70
–75
–80
–85
–90
–95
–100
–70
–75
–80
–85
–90
–95
–100
V
= SINGLE 5V
= 25.6kHz
= 5kHz
S
T
= 25°C
A
LP MODE,
P-P
f
f
C
IN
3V SIGNAL
50
40
30
20
10
0k
2V , 50kHz
P-P
2V , 20kHz
P-P
LP MODE
LP MODE,
2V SIGNAL
P-P
HS MODE
3V , 50kHz
P-P
3V , 20kHz
P-P
HS MODE,
3V SIGNAL
HS MODE,
2V SIGNAL
V
= SINGLE 5V
S
P-P
HIGH SPEED MODE
P-P
f
f
= 256kHz
C
IN
= 20kHz, 50kHz
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
0.1
1
10
100
1000
f
(Hz)
OUTPUT LOAD RESISTANCE—LOAD TO GROUND (kΩ)
OUTPUT LOAD RESISTANCE—LOAD TO GROUND (kΩ)
C
1563 G21
1563 G19
1563 G20
THD + Noise vs Output Load
Stopband Gain vs Input Frequency
THD + Noise vs Output Load
10
0
–70
–70
V
= ± 5V
S
f
= 256kHz
C
f
f
= 25.6kHz
= 5kHz
C
IN
LP MODE,
5V SIGNAL
–75
–80
–75
P-P
–10
–20
–30
–40
–50
–60
–70
–80
–90
2V , 50kHz
P-P
–80
–85
LP MODE,
2V SIGNAL
P-P
5V , 50kHz
P-P
LTC1563-2
LTC1563-3
2V , 20kHz
P-P
–85
HS MODE,
2V SIGNAL
–90
–90
P-P
2V , 20kHz
P-P
V
= ± 5V
S
HIGH SPEED MODE
–95
–95
HS MODE,
5V SIGNAL
f
f
= 256kHz
C
IN
P-P
= 20kHz, 50kHz
–100
–100
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
10k
100k
1M
FREQUENCY (Hz)
10M
100M
OUTPUT LOAD RESISTANCE—LOAD TO GROUND (kΩ)
OUTPUT LOAD RESISTANCE—LOAD TO GROUND (kΩ)
1563 G24
1563 G22
1563 G23
Crosstalk Rejection vs Frequency
Crosstalk Rejection vs Frequency
–60
–70
–60
–70
DUAL SECOND ORDER
BUTTERWORTH
DUAL SECOND ORDER
BUTTERWORTH
f
= 25.6kHz
f
= 256kHz
C
C
HS OR LP MODE
HIGH SPEED MODE
–80
–80
–90
–90
–100
–110
–100
–110
1
10
FREQUENCY (kHz)
100
1k
10k
100k
1M
FREQUENCY (Hz)
1563 G26
1563 G25
156323fa
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LTC1563-2/LTC1563-3
U
U
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PIN FUNCTIONS
LP (Pin 1): Low Power. The LTC1563-X has two operating
modes:LowPowerandHighSpeed.Mostapplicationswill
use the High Speed operating mode. Some lower fre-
quency, lower gain applications can take advantage of the
Low Power mode. When placed in the Low Power mode,
the supply current is nearly an order of magnitude lower
than the High Speed mode. Refer to the Applications
Information section for more information on the Low
Power mode.
LPA, LPB (Pins 6, 15): Lowpass Output. These pins are
the rail-to-rail outputs of an op amp. Each output is
designed to drive a nominal net load of 5kΩ and 20pF.
Refer to the Applications Information section for more
details on output loading effects.
AGND (Pin 7): Analog Ground. The AGND pin is the
midpointofaninternalresistivevoltagedividerdeveloping
a potential halfway between the V+ and V– pins. The
equivalentseriesresistanceisnominally10kΩ.Thisserves
as an internal ground reference. Filter performance will
reflect the quality of the analog signal ground. An analog
ground plane surrounding the package is recommended.
The analog ground plane should be connected to any
digital ground at a single point. Figures 1 and 2 show the
proper connections for dual and single supply operation.
The LTC1563-X is in the High Speed mode when the
LPinputisatalogichighlevelorisopen-circuited. Asmall
pull-up current source at the LP input defaults the
LTC1563-X to the High Speed mode if the pin is left open.
The part is in the Low Power mode when the pin is pulled
to a logic low level or connected to V–.
SA, SB (Pins 2, 11): Summing Pins. These pins are a
summing point for signals fed forward and backward.
Capacitance on the SA or SB pin will cause excess peaking
of the frequency response near the cutoff frequency. The
three external resistors for each section should be located
as close as possible to the summing pin to minimize this
effect. Refer to the Applications Information section for
more details.
V–, V+ (Pins 8, 16): The V– and V+ pins should be
bypassed with 0.1µF capacitors to an adequate analog
ground or ground plane. These capacitors should be
connected as closely as possible to the supply pins. Low
noise linear supplies are recommended. Switching sup-
plies are not recommended as they will decrease the
filter’s dynamic range. Refer to Figures 1 and 2 for the
proper connections for dual and single supply operation.
NC (Pins 3, 5, 10, 12, 14): These pins are not connected
internally. For best performance, they should be con-
nected to ground.
EN (Pin 9): ENABLE. When the EN input goes high or is
open-circuited, the LTC1563-X enters a shutdown state
andonlyjunctionleakagecurrentsflow.TheAGNDpin,the
LPA output and the LPB output assume high impedance
states. If an input signal is applied to a complete filter
circuit while the LTC1563-X is in shutdown, some signal
will normally flow to the output through passive compo-
nents around the inactive part.
INVA, INVB (Pins 4, 13): Inverting Input. Each of the INV
pins is an inverting input of an op amp. Note that the INV
pins are high impedance, sensitive nodes of the filter and
very susceptible to coupling of unintended signals.
Capacitance on the INV nodes will also affect the fre-
quency response of the filter sections. For these reasons,
printed circuit connections to the INV pins must be kept as
short as possible.
A small internal pull-up current source at the EN input
defaults the LTC1563 to the shutdown state if the EN pin
isleftfloating. Therefore, theusermustconnecttheENpin
to V– (or a logic low) to enable the part for normal
operation.
156323fa
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LTC1563-2/LTC1563-3
U
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PIN FUNCTIONS
Dual Supply Power and Ground Connections
Single Supply Power and Ground Connections
LTC1563-X
ANALOG
LTC1563-X
ANALOG
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
16
15
14
13
12
11
10
9
+
+
+
+
LP
LP
V
V
V
V
GROUND
PLANE
GROUND
PLANE
0.1µF
0.1µF
SA
SA
LPB
NC
LPB
NC
NC
NC
INVA
NC
INVA
NC
INVB
NC
INVB
NC
LPA
AGND
LPA
AGND
SB
SB
NC
NC
+
–
–
–
0.1µF
V
V
EN
V
EN
0.1µF
SINGLE POINT
SYSTEM GROUND
SINGLE POINT
SYSTEM GROUND
DIGITAL
GROUND PLANE
(IF ANY)
DIGITAL
GROUND PLANE
(IF ANY)
1563 PF02
1563 PF01
W
BLOCK DIAGRA
R21
R22
V
OUT
R11
R31
R32
R12
V
IN
+
V
16
C1B
C1A
SHUTDOWN
SWITCH
–
+
–
+
11
SB
C2B
13
2
SA
C2A
4
20k
20k
LPA
6
15 LPB
INVB
INVA
AGND
7
AGND
AGND
AGND
SHUTDOWN
SWITCH
9
1
EN
LP
–
8
V
LTC1563-X
1563 BD
PATENT PENDING
156323fa
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LTC1563-2/LTC1563-3
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APPLICATIONS INFORMATION
Functional Description
resistance in parallel, yields a net effective resistance of
9.52M and an error of –5%. Note that the gain is also
limited to unity at the minimum fC.
The LTC1563-2/LTC1563-3 are a family of easy-to-use,
4th order lowpass filters with rail-to-rail operation. The
LTC1563-2, with a single resistor value, gives a unity-gain
filter approximating a Butterworth response. The
LTC1563-3, with a single resistor value, gives a unity-gain
filter approximating a Bessel (linear phase) response. The
proprietary architecture of these parts allows for a simple
unity-gain resistor calculation:
At intermediate fC, the gain is limited by one of the two
reasons discussed above. For best results, design filters
with gain using FilterCAD Version 3 (or newer) or contact
the Linear Technology Filter Applications Group for
assistance.
Whilethesimpleformulaandthetablesintheapplications
section deliver good approximations of the transfer func-
tions,amoreaccurateresponseisachievedusingFilterCAD.
FilterCAD calculates the resistor values using an accurate
and complex algorithm to account for parasitics and op
amplimitations. AdesignusingFilterCADwillalwaysyield
the best possible design. By using the FilterCAD design
tool you can also achieve filters with cutoff frequencies
beyond 256kHz. Cutoff frequencies up to 360kHz are
attainable.
R = 10k(256kHz/fC)
where fC is the desired cutoff frequency. For many appli-
cations, this formula is all that is needed to design a filter.
For example, a 50kHz filter requires a 51.2k resistor. In
practice, a 51.1k resistor would be used as this is the
closest E96, 1% value available.
The LTC1563-X is constructed with two 2nd order sec-
tions. The output of the first section (section A) is simply
fed into the second section (section B). Note that section
A and section B are similar, but not identical. The parts are
designed to be simple and easy to use.
Contact the Linear Technology Filter Applications Group
for a copy the FilterCAD software. FilterCAD can also be
downloaded from our website at www.linear.com.
By simply utilizing different valued resistors, gain, other
transfer functions and higher cutoff frequencies are
achieved. For these applications, the resistor value calcu-
lation gets more difficult. The tables of formulas provided
later in this section make this task much easier. For best
results,designthesefiltersusingFilterCADVersion3.0(or
newer) or contact the Linear Technology Filter Applica-
tions group for assistance.
DC Offset, Noise and Gain Considerations
The LTC1563-X is DC offset trimmed in a 2-step manner.
First, section A is trimmed for minimum DC offset. Next,
section B is trimmed to minimize the total DC offset
(section A plus section B). This method is used to give the
minimum DC offset in unity gain applications and most
higher gain applications.
Cutoff Frequency (fC) and Gain Limitations
Forgainsgreaterthanunity, thegainshouldbedistributed
such that most of the gain is taken in section A, with
section B at a lower gain (preferably unity). This type of
gain distribution results in the lowest noise and lowest DC
offset. For high gain, low frequency applications, all of the
gain is taken in section A, with section B set for unity-gain.
In this configuration, the noise and DC offset is dominated
by those of section A. At higher frequencies, the op amps’
finite bandwidth limits the amount of gain that section A
can reliably achieve. The gain is more evenly distributed in
this case. The noise and DC offset of section A is now
multiplied by the gain of section B. The result is slightly
higher noise and offset.
The LTC563-X has both a maximum fC limit and a mini-
mumfC limit.ThemaximumfC limit(256kHzinHighSpeed
mode and 25.6kHz in the Low Power mode) is set by the
speed of the LTC1563-X’s op amps. At the maximum fC,
the gain is also limited to unity.
A minimum fC is dictated by the practical limitation of
reliably obtaining large valued, precision resistors. As the
desiredfC decreases,theresistorvaluerequiredincreases.
When fC is 256Hz, the resistors are 10M. Obtaining a
reliable, precise 10M resistance between two points on a
printed circuit board is somewhat difficult. For example, a
10M resistor with only 200MΩ of stray, layout related
156323fa
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LTC1563-2/LTC1563-3
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APPLICATIONS INFORMATION
Output Loading: Resistive and Capacitive
near the cutoff frequency. Poor layout can give 0.5dB to
1dB of excess peaking.
The op amps of the LTC1563-X have a rail-to-rail output
stage. To obtain maximum performance, the output load-
ing effects must be considered. Output loading issues can
be divided into resistive effects and capacitive effects.
To minimize the effects of parasitic layout capacitance, all
of the resistors for section A should be placed as close as
possible to the SA pin. Place the R31 resistor first so that
it is as close as possible to the SA pin on one end and as
close as possible to the INVA pin on the other end. Use the
same strategy for the layout of section B, keeping all of the
resistors as close as possible to the SB node and first
placing R32 between the SB and INVB pins. It is also best
if the signal routing and resistors are on the same layer as
the part without any vias in the signal path.
Resistiveloadingaffectsthemaximumoutputsignalswing
and signal distortion. If the output load is excessive, the
output swing is reduced and distortion is increased. All of
theoutputvoltageswingtestingontheLTC1563-Xisdone
withR22=100kanda10kloadresistor.Forbestundistorted
outputswing, theoutputloadresistanceshouldbegreater
than 10k.
Figure 1 illustrates a good layout using the LTC1563-X
with surface mount 0805 size resistors. An even tighter
layout is possible with smaller resistors.
Capacitive loading on the output reduces the stability of
the op amp. If the capacitive loading is sufficiently high,
the stability margin is decreased to the point of oscillation
at the output. Capacitive loading should be kept below
30pF. Good, tight layout techniques should be maintained
at all times. These parts should not drive long traces and
must never drive a long coaxial cable. When probing the
LTC1563-X,alwaysusea10xprobe.Neverusea1xprobe.
A standard 10x probe has a capacitance of 10pF to 15pF
while a 1x probe’s capacitance can be as high as 150pF.
The use of a 1x probe will probably cause oscillation.
R11
V
IN
LTC1563-X
V
OUT
R12
For larger capacitive loads, a series isolation resistor can
be used between the part and the capacitive load. If the
load is too great, a buffer must be used.
1653 F01
Figure 1. PC Board Layout
Layout Precautions
Single Pole Sections and Odd Order Filters
The LTC1563-X is an active RC filter. The response of the
filter is determined by the on-chip capacitors and the
external resistors. Any external, stray capacitance in par-
allel with an on-chip capacitor, or to an AC ground, can
alter the transfer function.
The LTC1563 is configured to naturally form even ordered
filters (2nd, 4th, 6th and 8th). With a little bit of work,
singlepolesectionsandoddorderfiltersareeasilyachieved.
To form a single pole section you simply use the op amp,
the on-chip C1 capacitor and two external resistors as
shown in Figure 2. This gives an inverting section with the
gain set by the R2-R1 ratio and the pole set by the R2-C1
time constant. You can use this pole with a 2nd order
section to form a noninverting gain 3rd order filter or as a
stand alone inverting gain single pole filter.
Capacitance to an AC ground is the most likely problem.
Capacitance on the LPA or LPB pins does not affect the
transfer function but does affect the stability of the op
amps. Capacitance on the INVA and INVB pins will affect
the transfer function somewhat and will also affect the
stability of the op amps. Capacitance on the SA and SB
pins alters the transfer function of the filter. These pins are
the most sensitive to stray capacitance. Stray capacitance
on these pins results in peaking of the frequency response
Figure 3 illustrates another way of making odd order
filters. The R1 input resistor is split into two parts with an
additional capacitor connected to ground in between the
resistors.This“TEE”networkformsasinglerealpole.RB1
156323fa
11
LTC1563-2/LTC1563-3
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APPLICATIONS INFORMATION
RA1
RB1
P
R2
R3
C1
should be much larger than RA1 to minimize the interac-
tion of this pole with the 2nd order section. This circuit is
useful in forming dual 3rd order filters and 5th order filters
with a single LTC1563 part. By cascading two parts, 7th
order and 9th order filters are achieved.
C
S
INV
LP
R1
R2
–
+
V
V
OUT
IN
C2
(OPEN)
S
AGND
INV
LP
C1
1/2 LTC1563
RB1
–
+
1563 F03
C2
RA1 ≈
10
1
F
=
P
RA1 • RB1
AGND
2π •
C
P
(
)
RA1 + RB1
1/2 LTC1563
–R2
Figure 3
DC GAIN =
LTC1563-2: C1A = 53.9pF, C1B = 39.2pF
LTC1563-3: C1A = 35pF, C1B = 26.8pF
R1
What To Do with an Unused Section
1
F
=
P
1563 F02
2π • R2 • C1
If the LTC1563 is used as a 2nd or 3rd order filter, one of
the sections is not used. Do not leave this section uncon-
nected. If the section is left unconnected, the output is left
to float and oscillation may occur. The unused section
should be connected as shown in Figure 4 with the INV pin
connected to the LP pin and the S pin left open.
Figure 2
You can also use the TEE network in both sections of the
part to make a 6th order filter. This 6th order filter does not
conform exactly to the textbook responses. Textbook
responses (Butterworth, Bessel, Chebyshev etc.) all have
three complex pole pairs. This filter has two complex pole
pairs and two real poles. The textbook response always
has one section with a low Q value between 0.5 and 0.6. By
replacing this low Q section with two real poles (two real
poles are the same mathematically as a complex pole pair
with a Q of 0.5) and tweaking the Q of the other two
complex pole pair sections you end up with a filter that is
indistinguishable from the textbook filter. The Typical
Applicationssectionillustratesa100kHz,6thorderpseudo-
Butterworth filter. FilterCAD is a valuable tool for custom
filter design and tweaking textbook responses.
(OPEN)
S
INV
LP
C1
–
+
C2
AGND
1/2 LTC1563
1563 F04
Figure 4
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LTC1563-2/LTC1563-3
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APPLICATIONS INFORMATION
4th Order Filter Responses Using the LTC1563-2
LTC1563-2
10
0
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
+
LP
V
V
OUT
R22
SA
LPB
NC
–20
–40
–60
NC
R31
R21
R32
INVA
NC
INVB
NC
BUTTERWORTH
0.5dB RIPPLE
CHEBYSHEV
0.1dB RIPPLE
CHEBYSHEV
LPA
AGND
SB
NC
R11
R12
–
V
EN
–80
–90
1563 F05
NORMALIZED TO f = 1Hz
C
V
IN
0.1
1
10
FREQUENCY (Hz)
1563 F05a
Figure 5. 4th Order Filter Connections (Power Supply, Ground,
EN and LP Connections Not Shown for Clarity). Table 1 Shows
Resistor Values
Figure 5a. Frequency Response
1.2
1.0
0.8
0.6
0.4
0.2
0
1
0
–2
–4
BUTTERWORTH
0.5dB RIPPLE
CHEBYSHEV
0.1dB RIPPLE
CHEBYSHEV
BUTTERWORTH
0.5dB RIPPLE
CHEBYSHEV
0.1dB RIPPLE
CHEBYSHEV
–6
–8
NORMALIZED TO f = 1Hz
C
NORMALIZED TO f = 1Hz
C
–10
0
0.5
1.0
1.5
2.0
2.5
3.0
0.1
1
2
TIME (s)
FREQUENCY (Hz)
1563 F05b
1563 F05c
Figure 5b. Passband Frequency Response
Figure 5c. Step Response
Table 1. Resistor Values, Normalized to 256kHz Cutoff Frequency (f ), Figure 5. The Passband
C
Gain, of the 4th Order LTC1563-2 Lowpass Filter, Is Set to Unity. (Note 1)
0.1dB RIPPLE
CHEBYSHEV
0.5dB RIPPLE
CHEBYSHEV
BUTTERWORTH
25.6kHz
LP Mode Max f
15kHz
13kHz
C
HS Mode Max f
R11 = R21 =
R31 =
256kHz
135kHz
113kHz
C
10k(256kHz/f )
13.7k(256kHz/f )
20.5k(256kHz/f )
C
C
C
10k(256kHz/f )
10.7k(256kHz/f )
12.4k(256kHz/f )
C
C
C
R12 = R22 =
R32 =
10k(256kHz/f )
10k(256kHz/f )
12.1k(256kHz/f )
C
C
C
10k(256kHz/f )
6.81k(256kHz/f )
6.98k(256kHz/f )
C
C
C
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
LTC1563-2/LTC1563-3
U
W U U
APPLICATIONS INFORMATION
4th Order Filter Responses Using the LTC1563-3
10
0
LTC1563-3
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
+
LP
V
V
OUT
R22
R32
SA
LPB
NC
–20
–40
–60
NC
R31
R21
INVA
NC
INVB
NC
BESSEL
TRANSITIONAL
GAUSSIAN TO 12dB
TRANSITIONAL
GAUSSIAN TO 6dB
LPA
AGND
SB
NC
R11
R12
–
V
EN
–80
–90
NORMALIZED TO f = 1Hz
C
1563 F06
V
IN
0.1
1
10
FREQUENCY (Hz)
1563 F06a
Figure 6. 4th Order Filter Connections (Power Supply, Ground,
EN and LP Connections Not Shown for Clarity). Table 2 Shows
Resistor Values
Figure 6a. Frequency Response
1.2
1.0
0.8
1.05
1.00
0.95
BESSEL
TRANSITIONAL
GAUSSIAN TO 12dB
TRANSITIONAL
GAUSSIAN TO 6dB
0.6
BESSEL
TRANSITIONAL
GAUSSIAN TO 12dB
TRANSITIONAL
GAUSSIAN TO 6dB
0.4
0.2
0
NORMALIZED TO f = 1Hz
C
NORMALIZED TO f = 1Hz
C
0
0.5
1.0
1.5
2.0
2.5
3.0
0
0.5
1.0
1.5
2.0
TIME (s)
TIME (s)
1563 F06b
1563 F06c
Figure 6b. Step Response
Figure 6c. Step Response—Settling
Table 2. Resistor Values, Normalized to 256kHz Cutoff Frequency (f ), Figure 6. The Passband
C
Gain, of the 4th Order LTC1563-3 Lowpass Filter, Is Set to Unity. (Note 1)
TRANSITIONAL
GAUSSIAN TO 6dB
TRANSITIONAL
GAUSSIAN TO 12dB
BESSEL
25.6kHz
256kHz
LP Mode Max f
20kHz
21kHz
C
HS Mode Max f
R11 = R21 =
R31 =
175kHz
185kHz
C
10k(256kHz/f )
17.4k(256kHz/f )
15k(256kHz/f )
C
C
C
10k(256kHz/f )
13.3k(256kHz/f )
11.8k(256kHz/f )
C
C
C
R12 = R22 =
R32 =
10k(256kHz/f )
14.3k(256kHz/f )
10.5k(256kHz/f )
C
C
C
10k(256kHz/f )
6.04k(256kHz/f )
6.19k(256kHz/f )
C
C
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.
156323fa
14
LTC1563-2/LTC1563-3
U
TYPICAL APPLICATIO S
±5V, 2.3mA Supply Current, 20kHz, 4th Order,
Frequency Response
0.5dB Ripple Chebyshev Lowpass Filter
10
0
LTC1563-2
V
OUT
5V
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
+
LP
V
162k
–10
–20
–30
–40
–50
–60
–70
–80
–90
0.1µF
SA
LPB
NC
NC
169k
274k
95.3k
INVA
NC
INVB
NC
274k
–5V
V
IN
LPA
AGND
SB
NC
162k
ENABLE
–
V
EN
0.1µF
1563 TA03
1
10
100
FREQUENCY (kHz)
1563 TA04
Single 3.3V, 2mA Supply Current, 20kHz 8th Order Butterworth Lowpass Filter
3.3V
0.1µF
0.1µF
LTC1563-2
LTC1563-2
210k
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
16
15
14
13
12
11
10
9
+
+
LP
LP
V
V
V
OUT
82.5k
196k
158k
100k
SA
SA
LPB
NC
LPB
NC
NC
NC
115k
137k
75k
INVA
NC
INVA
NC
INVB
NC
INVB
NC
210k
LPA
AGND
LPA
AGND
SB
SB
NC
NC
115k
82.5k
158k
–
–
V
V
EN
EN
0.1µF
0.1µF
V
IN
1563 TA05
ENABLE
Frequency Response
10
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
1
10
100
FREQUENCY (kHz)
1563 TA06
156323fa
15
LTC1563-2/LTC1563-3
U
TYPICAL APPLICATIO S
100kHz, 6th Order Pseudo-Butterworth
Frequency Response
3.3V
10
0
0.1µF
LTC1563-2
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
R22
+
LP
V
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
28.7k
SA
LPB
NC
V
OUT
NC
R32
R31
INVA
NC
INVB
NC
20.5k
17.8k
R21
R
3.16k
R
B1
29.4k
A1
V
IN
LPA
AGND
SB
32.4k
C11
560pF
NC
–
V
EN
0.1µF
R
3.16k
R
25.5k
10k
100k
1M
A2
B2
FREQUENCY (Hz)
C12
560pF
1563 TA07a
1563 TA07
The complex, 2nd order section of the textbook design
withthelowestQisreplacedwithtworealfirstorderpoles.
The Q of another section is slightly altered such that the
final filter’s response is indistinguisable from a textbook
Butterworth response.
TEXTBOOK BUTTERWORTH
PSEUDO-BUTTERWORTH
f 1 = 100kHz Q1 = 1.9319
f 1 = 100kHz
Q1 = 1.9319
Q2 = 0.7071
Q3 = 0.5176
O
O
f 2 = 100kHz
f 2 = 100kHz Q2 = 0.7358
O
O
f 3 = 100kHz
f 3 = 100kHz Real Poles
O
O
f 4 = 100kHz Real Poles
O
Other Pseudo Filter Response Coefficients (All f Are Normalized for a 1Hz Filter Cutoff)
O
BESSEL 0.1dB RIPPLE CHEBYSHEV 0.5dB RIPPLE CHEBYSHEV
TRANSITIONAL GAUSSIAN TO 12dB TRANSITIONAL GAUSSIAN TO 6dB
f 1
1.9070
1.0230
1.6910
0.6110
1.6060
1.6060
1.0600
3.8500
0.8000
1.0000
0.6000
1.0000
1.0100
5.3000
0.7200
1.2000
0.5000
0.8000
2.1000
2.2000
1.2500
0.8000
1.2500
1.2500
1.5000
2.8500
1.0500
0.9000
0.9000
0.9000
O
Q1
f 2
O
Q2
f 3
O
f 4
O
The fO and Q values listed above can be entered in
FilterCAD’s Enhanced Design window as a custom re-
sponse filter. After entering the coefficients, FilterCAD will
produce a schematic of the circuit. The procedure is as
follows:
4. Enter the fO and Q coefficients as listed above. For a
Butterworth filter, use the same coefficients as the
example circuit above except set all of the fO to 1Hz.
5. Set the custom FC to the desired cutoff frequency. This
will automatically multiply all of the fO coefficients. You
have now finished the design of the filter and you can
click on the frequency response or step response
buttons to verify the filter’s response.
1. After starting FilterCAD, select the Enhanced Design
window.
2. Select the Custom Response and set the custom FC to
1Hz.
6. Click on the Implement button to go on to the filter
implementation stage.
3. IntheCoefficientstable,gototheTypecolumnandclick
onthetypeslistedandsetthecolumnwithtwoLPtypes
andtwoLP1types.Thissetsupatemplateofa6thorder
filter with two 2nd order lowpass sections and two 1st
order lowpass sections.
7. In the Enhanced Implement window, click on the Active
RC button to choose the LTC1563-2 part. You are now
done with the filter’s implementation. Click on the
schematic button to view the resulting circuit.
156323fa
16
LTC1563-2/LTC1563-3
U
TYPICAL APPLICATIO S
22kHz, 5th Order, 0.1dB Ripple Chebyshev Lowpass Filter
Driving the LTC1604, 16-Bit ADC
5V
0.1µF
LTC1563-2
10µF
+
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
LTC1604
+
R22
1
2
35
+
–
LP
V
A
A
V
AV
AV
5V
IN
IN
DD
137k
10Ω
560pF
36
49.9Ω
2.2µF
SA
LPB
NC
DD
3
33
NC
SHDN
CS
REF
10µF
R32
R31
4
32
INVA
NC
INVB
NC
REFCOMP
AGND
78.7k
47µF
µP
82.5k
R21
5
31
CONVST
RD
CONTROL
LINES
R
26.7k
R
215k
B1
A1
V
6
30
IN
LPA
AGND
SB
AGND
243k
C11
560pF
7
27
NC
AGND
BUSY
–
–5V
V
8
11 TO 26
EN
AGND
16-BIT
PARALLEL BUS
9
0.1µF
DV
DD
5V
+
R12 137k
10
34
29
DGND
OV
DD
10µF
10µF
5V OR 3V
+
28
V
OGND
10µF
SS
–5V
+
1563 TA08
4096 Point FFT of the Output Data
0
–20
–40
–60
–80
f
f
= 292.6kHz
SAMPLE
= 20kHz
IN
SINAD = 85dB
THD = –91.5dB
–100
–120
–140
0
36.58
73.15
109.73
146.30
FREQUENCY (kHz)
1563 TA08a
156323fa
17
LTC1563-2/LTC1563-3
U
TYPICAL APPLICATIO S
50kHz Wideband Bandpass
4th Order Bessel Lowpass at 128kHz with Two Highpass Poles at 11.7kHz Yields a Wideband Bandpass Centered at 50kHz
10
5V
LTC1563-3
0.1µF
0
–10
–20
–30
–40
–50
–60
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
+
R22
20k
LP
V
SA
LPB
NC
V
OUT
NC
R31
R32
20k
INVA
NC
INVB
NC
C11
680pF
20k
R21
R11
20k
LPA
SB
V
IN
20k
R12
20k
AGND
NC
–
V
EN
–5V
C12
680pF
0.1µF
1k
10k
100k
1M
1563 TA09
FREQUENCY (Hz)
1563 TA09a
To design these wideband bandpass filters with the
LTC1563, start with a 4th order lowpass filter and add two
highpasspoleswiththeinput,ACcouplingcapacitors.The
lowpass cutoff frequency and highpass pole frequencies
dependonthespecificapplication. Someexperimentation
oflowpassandhighpassfrequenciesisrequiredtoachieve
the desired response. FilterCAD does not directly support
this configuration. Use the custom design window in
FilterCAD get the desired response and then use FilterCAD
to give the schematic for the lowpass portion of the filter.
Calculate the two highpass poles using the following
formulae:
4. In the Coefficients table, the first two rows are the LP
Type with the fO and Q as previously defined. Go to the
third and fourth rows and click on the Type column
(currently a hyphen is in this space). Change the Type
of each of these rows to type HP1. This sets up a
templateofa6thorderfilterwithtwo2ndorderlowpass
sections and two 1st order highpass sections.
5. Change the frequency of the highpass (HP1) poles to
get the desired frequency response.
6. You may have to perform this loop several times before
you close in on the correct response.
7. Once you have reached a satisfactory response, note
thehighpasspolefrequencies. TheHP1highpasspoles
must now be removed from the Custom design coeffi-
cientstable.Afterremovingthehighpasspoles,clickon
the Implement button to go on to the filter implementa-
tion stage.
1
1
f HPA =
, f HPB =
O
(
)
(
)
O
2• π •R11•C11
2• π •R12•C12
The design process is as follows:
1. After starting FilterCAD, select the Enhanced Design
window.
8. In the Enhanced Implement window, click on the Active
RC button and choose the LTC1563-2 part. Click on the
schematic button to view the resulting circuit.
2. Choose a 4th order Bessel or Butterworth lowpass filter
response and set the cutoff frequency to the high
frequency corner of the desired bandpass.
9. You now have the schematic for the 4th order lowpass
part of the design. Now calculate the capacitor values
from the following formulae:
3. Click on the custom response button. This copies the
lowpass coefficients into the custom design Coeffi-
cients table.
1
1
C11=
, C12 =
2• π •R11• f HPA
2• π •R12• f HPB
(
)
(
)
O
O
156323fa
18
LTC1563-2/LTC1563-3
U
TYPICAL APPLICATIO S
150kHz, 0.5dB Ripple, 4th Order Chebyshev with 10dB of DC Gain
20
10
5V
LTC1563-2
0.1µF
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
+
0
R22
21k
LP
V
–10
–20
–30
–40
–50
–60
–70
SA
LPB
NC
V
OUT
NC
R31
R32
INVA
NC
INVB
NC
9.76k
R21
12.7k
R11
24.3k
LPA
AGND
SB
V
IN
76.8k
R12
21k
NC
–
–5V
V
EN
0.1µF
10k
100k
1M
1563 TA10
FREQUENCY (Hz)
1563 TA10a
U
PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
GN Package
16-Lead Plastic SSOP (Narrow 0.150)
(LTC DWG # 05-08-1641)
.189 – .196*
(4.801 – 4.978)
.045 ±.005
.009
(0.229)
REF
16 15 14 13 12 11 10 9
.254 MIN
.150 – .165
.229 – .244
.150 – .157**
(5.817 – 6.198)
(3.810 – 3.988)
.0165 ± .0015
.0250 BSC
RECOMMENDED SOLDER PAD LAYOUT
1
2
3
4
5
6
7
8
.015 ± .004
(0.38 ± 0.10)
× 45°
.0532 – .0688
(1.35 – 1.75)
.004 – .0098
(0.102 – 0.249)
.007 – .0098
(0.178 – 0.249)
0° – 8° TYP
.016 – .050
(0.406 – 1.270)
.0250
(0.635)
BSC
.008 – .012
GN16 (SSOP) 0204
(0.203 – 0.305)
TYP
NOTE:
1. CONTROLLING DIMENSION: INCHES
INCHES
2. DIMENSIONS ARE IN
(MILLIMETERS)
3. DRAWING NOT TO SCALE
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
156323fa
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
19
LTC1563-2/LTC1563-3
U
TYPICAL APPLICATIO S
Single Supply, 10kHz, Bandpass Filter
Maximum Fcenter = 120kHz (–3dB Bandwidth = Fcenter/10)
Frequency Response
+
3
0
V
LTC1563-2
0.1µF
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
+
R3
LP
V
200k
–3
SA
LPB
NC
V
OUT
R1
31.6k
NC
–6
V
IN
INVA
NC
INVB
NC
–9
R4
200k
R2
4.99k
–12
–15
–18
–21
LPA
AGND
SB
NC
–
0.1µF
V
EN
–24
1563 TA11
5
7.5
10
12.5
20
15
17.5
31.6k
R1
FREQUENCY (kHz)
GAIN AT f
=
MAXIMUM GAIN = 120kHz/f
CENTER
CENTER
R2 = 4.99k
1563 TA11a
R3 = R4 = R
21
10
R =
2
11
f
• (f
+ 5 • 10 )
CENTER
CENTER
Single Supply, 100kHz, Elliptic Lowpass Filter
Maximum Fcutoff = 120kHz
Frequency Response
V
6
OUT
+
V
0
–6
LTC1563-2
0.1µF
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
+
R1
R5
LP
V
32.4k
32.4k
–12
–18
–24
–30
–36
–42
–48
–54
–60
V
SA
IN
LPB
NC
R3
NC
15k
INVA
NC
INVB
NC
R4
32.4k
R2
32.4k
LPA
AGND
SB
R6
21k
NC
C
IN
27pF
–
0.1µF
V
EN
1K
10K
100K
1M
FREQUENCY (Hz)
1563 TA12
PASSBAND GAIN = 0dB
STOPBAND ATTENUATION = 26dB AT 1.5X f
IN
1563 TA12a
CUTOFF
C
= 27pF R2 = R4 = R5 = R1
9
R1
2.16
R1
1.54
3.24 • 10
CUTOFF
R1 =
R3 =
R6 =
f
RELATED PARTS
PART NUMBER
LTC1560-1
LTC1562
DESCRIPTION
COMMENTS
No External Components, SO-8
10kHz < f < 150kHz
5-Pole Elliptic Lowpass, f = 1MHz/0.5MHz
C
Universal Quad 2-Pole Active RC
O
LTC1562-2
LTC1569-6
LTC1569-7
LTC1565-31
LTC1568
Universal Quad 2-Pole Active RC
20kHz < f < 300kHz
O
Low Power 10-Pole Delay Equalized Elliptic Lowpass
10-Pole Delay Equalized Elliptic Lowpass
650kHz Continuous Time, Linear Phase Lowpass
f < 80kHz, One Resistor Sets f , SO-8
C C
f < 256kHz, One Resistor Sets f , SO-8
C
C
f = 650kHz, Differential In/Out
C
th
Very Low Noise 4 Order Filter Building Block
f < 10MHz
C
156323fa
LT 1205 REV A • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
20
●
●
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2005
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