MAX7413CUA [MAXIM]
5th-Order, Lowpass, Switched-Capacitor Filters; 5阶，低通，开关电容滤波器
| 型号： | MAX7413CUA |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 5th-Order, Lowpass, Switched-Capacitor Filters |
| 文件： | 总12页 (文件大小：135K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-4766; Rev 1; 9/98
5 t h -Ord e r, Lo w p a s s ,
S w it c h e d -Ca p a c it o r Filt e rs
903/MAX714
Ge n e ra l De s c rip t io n
Fe a t u re s
The MAX7409/MAX7410/MAX7413/MAX7414 5th-order,
lowpass, switched-capacitor filters (SCFs) operate from
a single +5V (MAX7409/MAX7410) or +3V (MAX7413/
MAX7414) supply. These devices draw only 1.2mA of
supply current and allow corner frequencies from 1Hz
to 15kHz, making them ideal for low-power post-DAC
filtering and anti-aliasing applications. They feature a
shutdown mode, which reduces the supply current to
0.2µA.
♦ 5th-Order Lowpass Filters
Bessel Response (MAX7409/MAX7413)
Butterworth Response (MAX7410/MAX7414)
♦ Clock-Tunable Corner Frequency (1Hz to 15kHz)
♦ Single-Supply Operation
+5V (MAX7409/MAX7410)
+3V (MAX7413/MAX7414)
♦ Low Power
Two clocking options are available on these devices:
self-clocking (through the use of an external capacitor)
or external clocking for tighter corner-frequency control.
An offset adjust pin allows for adjustment of the DC out-
put level.
1.2mA (operating mode)
0.2µA (shutdown mode)
♦ Available in 8-Pin µMAX/DIP Packages
♦ Low Output Offset: ±4mV
The MAX7409/MAX7413 Bessel filters provide low over-
shoot and fast settling, while the MAX7410/MAX7414
Butterworth filters provide a maximally flat passband
response. Their fixed response simplifies the design
task to selecting a clock frequency.
Ord e rin g In fo rm a t io n
PART
TEMP. RANGE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 µMAX
MAX7409CUA
MAX7409CPA
MAX7409EUA
MAX7409EPA
MAX7410CUA
MAX7410CPA
MAX7410EUA
MAX7410EPA
Ap p lic a t io n s
8 Plastic DIP
8 µMAX
ADC Anti-Aliasing
DAC Postfiltering
Air-Bag Electronics
CT2 Base Stations
Speech Processing
8 Plastic DIP
8 µMAX
8 Plastic DIP
8 µMAX
S e le c t o r Gu id e
8 Plastic DIP
OPERATING
VOLTAGE (V)
PART
FILTER RESPONSE
Ordering Information continued at end of data sheet.
MAX7409
MAX7410
MAX7413
MAX7414
Bessel
+5
+5
+3
+3
Butterworth
Bessel
Typ ic a l Op e ra t in g Circ u it
Butterworth
V
SUPPLY
P in Co n fig u ra t io n
0.1µF
TOP VIEW
V
DD
SHDN
OUT
INPUT
IN
OUTPUT
COM
1
2
3
4
8
7
6
5
CLK
SHDN
OS
MAX7409
MAX7410
MAX7413
MAX7414
IN
MAX7409
MAX7410
MAX7413
MAX7414
CLOCK
CLK
COM
OS
GND
0.1µF
V
DD
OUT
GND
µMAX/DIP
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.
5 t h -Ord e r, Lo w p a s s ,
S w it c h e d -Ca p a c it o r Filt e rs
ABSOLUTE MAXIMUM RATINGS
V
DD
to GND..............................................................-0.3V to +6V
Operating Temperature Ranges
IN, OUT, COM, OS, CLK, SHDN ................-0.3V to (V + 0.3V)
OUT Short-Circuit Duration...................................................1sec
MAX74 _ _C_A ...................................................0°C to +70°C
MAX74 _ _E_A ................................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
DD
Continuous Power Dissipation (T = +70°C)
A
8-Pin DIP (derate 9.09mW/°C above +70°C)...............727mW
8-Pin µMAX (derate 4.1mW/°C above +70°C) .............330mW
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS—MAX7409/MAX7410
(V
DD
= +5V, filter output measured at OUT, 10kΩ || 50pF load to GND at OUT, OS = COM, 0.1µF capacitor from COM to GND,
SHDN = V , f
= 100kHz, T = T
to T , unless otherwise noted. Typical values are at T = +25°C.)
MAX A
DD CLK
A
MIN
PARAMETER
FILTER CHARACTERISTICS
Corner Frequency
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
f
c
(Note 1)
0.001 to 15
100:1
kHz
Clock-to-Corner Ratio
Clock-to-Corner Tempco
Output Voltage Range
Output Offset Voltage
f
/ f
CLK c
10
ppm/°C
V
0.25
-0.2
V
DD
- 0.25
±25
V
V
IN
= V
= V / 2
±4
0
mV
OFFSET
COM
DD
DC Insertion Gain with
Output Offset Removed
V
COM
= V / 2 (Note 2)
0.2
dB
DD
MAX7409
MAX7410
-85
-78
1
Total Harmonic Distortion
plus Noise
f
= 200Hz, V = 4Vp-p,
IN IN
THD+N
dB
V/V
V
measurement bandwidth = 22kHz
Offset Voltage Gain
COM Voltage Range
A
OS
OS to OUT
Input, COM externally driven
Output, COM unconnected
Input, OS externally driven
2.0
2.3
2.5
2.5
3.0
2.7
V
COM
Input Voltage Range at OS
Input Resistance at COM
Clock Feedthrough
V
OS
V
±0.1
V
kΩ
COM
R
110
180
COM
5
1
mVp-p
kΩ
Resistive Output Load Drive
R
C
10
50
L
L
Maximum Capacitive Output
Load Drive
500
pF
903/MAX714
Input Leakage Current at COM
Input Leakage Current at OS
CLOCK
±0.1
±0.1
±10
±10
µA
µA
SHDN = GND, V
= 0 to V
DD
COM
V
= 0 to V
DD
OS
Internal Oscillator Frequency
f
C
= 1000pF (Note 3)
= 0 or 5V
CLK
21
30
38
kHz
µA
OSC
OSC
Clock Output Current
(Internal Oscillator Mode)
I
V
±13.5
±20
CLK
Clock Input High
Clock Input Low
V
4.5
V
V
IH
V
IL
0.5
2
_______________________________________________________________________________________
5 t h -Ord e r, Lo w p a s s ,
S w it c h e d -Ca p a c it o r Filt e rs
903/MAX714
ELECTRICAL CHARACTERISTICS—MAX7409/MAX7410
(V
DD
= +5V, filter output measured at OUT, 10kΩ || 50pF load to GND at OUT, OS = COM, 0.1µF capacitor from COM to GND,
SHDN = V , f
= 100kHz, T = T
to T , unless otherwise noted. Typical values are at T = +25°C.)
MAX A
DD CLK
A
MIN
PARAMETER
POWER REQUIREMENTS
Supply Voltage
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
DD
4.5
5.5
1.5
1
V
Supply Current
I
DD
Operating mode, no load
1.2
0.2
70
mA
µA
dB
Shutdown Current
I
SHDN
SHDN = GND
Power-Supply Rejection Ratio
SHUTDOWN
PSRR
IN = COM (Note 4)
V
4.5
V
V
SHDN Input High
SDH
V
SDL
0.5
SHDN Input Low
±0.2
±10
µA
SHDN Input Leakage Current
V
= 0 to V
DD
SHDN
ELECTRICAL CHARACTERISTICS—MAX7413/MAX7414
(V = +3V, filter output measured at OUT pin, 10kΩ || 50pF load to GND at OUT, OS = COM, 0.1µF capacitor from COM to GND,
DD
SHDN = V , f
= 100kHz, T = T
to T , unless otherwise noted. Typical values are at T = +25°C.)
MAX A
DD CLK
A
MIN
PARAMETER
FILTER CHARACTERISTICS
Corner Frequency
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
f
C
(Note 1)
0.001 to 15
100:1
kHz
Clock-to-Corner Ratio
Clock-to-Corner Tempco
Output Voltage Range
Output Offset Voltage
f
/ f
CLK C
10
ppm/°C
V
0.25
-0.2
V
- 0.25
±25
DD
V
V
IN
= V
= V / 2
±4
0
mV
OFFSET
COM
DD
DC Insertion Gain with
Output Offset Removed
V
COM
= V / 2 (Note 2)
+0.2
dB
dB
DD
MAX7413
MAX7414
-83
-81
1
Total Harmonic Distortion
plus Noise
f
= 200Hz, V = 2.5Vp-p,
IN IN
THD+N
measurement bandwidth = 22kHz
Offset Voltage Gain
COM Voltage Range
A
OS
OS to OUT
V/V
V
Input, COM externally driven
Output, COM unconnected
Input, OS externally driven
1.4
1.4
1.5
1.5
1.6
1.6
V
COM
V
Input Voltage Range at OS
Input Resistance at COM
Clock Feedthrough
V
OS
V
±0.1
V
COM
R
110
180
kΩ
COM
3
1
mVp-p
kΩ
Resistance Output Load Drive
R
C
10
50
L
L
Maximum Capacitive Output
Load Drive
500
pF
Input Leakage Current at COM
Input Leakage Current at OS
±0.1
±0.1
±10
±10
µA
µA
SHDN = GND, V
= 0 to V
DD
COM
V
= 0 to V
DD
OS
_______________________________________________________________________________________
3
5 t h -Ord e r, Lo w p a s s ,
S w it c h e d -Ca p a c it o r Filt e rs
ELECTRICAL CHARACTERISTICS—MAX7413/MAX7414 (continued)
(V = +3V, filter output measured at OUT pin, 10kΩ || 50pF load to GND at OUT, OS = COM, 0.1µF capacitor from COM to GND,
DD
SHDN = V , f
= 100kHz, T = T
to T , unless otherwise noted. Typical values are at T = +25°C.)
MAX A
DD CLK
A
MIN
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
CLOCK
Internal Oscillator Frequency
f
C
= 1000pF (Note 3)
OSC
21
2.5
2.7
30
38
kHz
µA
OSC
Clock Output Current
(Internal Oscillator Mode)
I
V
CLK
= 0 or 3V
±13.5
±20
CLK
Clock Input High
V
V
V
IH
Clock Input Low
V
IL
0.5
POWER REQUIREMENTS
Supply Voltage
V
3.6
1.5
1
V
DD
Supply Current
I
Operating mode, no load
SHDN = GND
1.2
0.2
70
mA
µA
dB
DD
Shutdown Current
Power-Supply Rejection Ratio
SHUTDOWN
I
SHDN
PSRR
IN = COM (Note 4)
V
2.5
V
V
SHDN Input High
SDH
V
SDL
0.5
SHDN Input Low
V
= 0 to V
0.2
±10
µA
SHDN Input Leakage Current
SHDN
DD
FILTER CHARACTERISTICS
(V = +5V for MAX7409/MAX7410, V = +3V for MAX7413/MAX7414, filter output measured at OUT, 10kΩ || 50pF load to GND at
DD
DD
OUT, SHDN = V , f
= 100kHz, T = T
to T , unless otherwise noted.)
MAX
DD CLK
A
MIN
PARAMETER
BESSEL FILTERS—MAX7409/MAX7413
= 0.5f
CONDITIONS
MIN
TYP
MAX
UNITS
f
IN
-1
-0.74
-3.0
C
f
= f
-3.6
-2.4
-35
-58
IN
C
Insertion Gain Relative to
DC Gain
dB
f
IN
= 4f
-41.0
-64.3
C
f
IN
= 7f
C
BUTTERWORTH FILTERS—MAX7410/MAX7414
= 0.5f
903/MAX714
f
IN
-0.3
-3.6
0
C
f
= f
-3.0
-47.5
-70
-2.4
-43
-65
IN
C
Insertion Gain Relative to
DC Gain
dB
f
IN
= 3f
C
f
IN
= 5f
C
Note 1: The maximum f is defined as the clock frequency f
= 100 x f at which the peak S / (THD+N) drops to 68dB with a
C
C
CLK
sinusoidal input at 0.2f .
C
Note 2: DC insertion gain is defined as ∆V
/ ∆V .
IN
OUT
3
Note 3: f
(kHz) 30 x 10 / C
(pF).
OSC
OSC
Note 4: PSRR is the change in output voltage from a V of 4.5V and a V of 5.5V.
DD
DD
4
_______________________________________________________________________________________
5 t h -Ord e r, Lo w p a s s ,
S w it c h e d -Ca p a c it o r Filt e rs
903/MAX714
Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s
(V = +5V for MAX7409/MAX7410, V = +3V for MAX7413/MAX7414, f
= 100kHz, SHDN = V , COM = OS = V / 2, T = +25°C,
CLK
DD
DD
DD DD A
unless otherwise noted.)
MAX7409/MAX7413
FREQUENCY RESPONSE
(BESSEL)
MAX7410/MAX7414
FREQUENCY RESPONSE
(BUTTERWORTH)
MAX7409/MAX7413
PASSBAND FREQUENCY RESPONSE
(BESSEL)
8
0
10
0
0
f = 1kHz
C
f = 1kHz
C
f = 1kHz
C
-0.4
-0.8
-1.2
-1.6
-2.0
-2.4
-3.0
-3.2
-8
-10
-20
-30
-40
-50
-60
-70
-16
-24
-32
-40
-48
-56
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
INPUT FREQUENCY (kHz)
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
INPUT FREQUENCY (kHz)
0
102 204 306 408 510 612 714 816 918 1.02k
INPUT FREQUENCY (Hz)
MAX7409/MAX7413
PHASE RESPONSE
(BESSEL)
MAX7410/MAX7414
PHASE RESPONSE
(BUTTERWORTH)
MAX7410/MAX7414
PASSBAND FREQUENCY RESPONSE
(BUTTERWORTH)
0
-50
0
-50
0.5
0
f = 1kHz
C
f = 1kHz
C
f = 1kHz
C
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
-3.5
-100
-150
-200
-250
-300
-350
-100
-150
-200
-250
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
INPUT FREQUENCY (kHz)
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
INPUT FREQUENCY (kHz)
0
102 204 306 408 510 612 714 816 918 1.02k
INPUT FREQUENCY (Hz)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
Table A. THD+N vs. Input Signal
Amplitude Plot Characteristics
1.19
1.18
1.17
1.16
1.15
1.14
1.13
1.12
1.11
f
f
f
CLK
(kHz)
MEASUREMENT
BANDWIDTH (kHz)
IN
C
LABEL
(Hz)
(kHz)
A
B
200
1k
1
5
100
500
22
80
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5
5 t h -Ord e r, Lo w p a s s ,
S w it c h e d -Ca p a c it o r Filt e rs
Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s (c o n t in u e d )
(V = +5V for MAX7409/MAX7410, V = +3V for MAX7413/MAX7414, f
= 100kHz, SHDN = V , COM = OS = V / 2, T = +25°C,
CLK
DD
DD
DD DD A
unless otherwise noted.)
MAX7413
MAX7409
MAX7410
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. INPUT SIGNAL AMPLITUDE
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. INPUT SIGNAL AMPLITUDE
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. INPUT SIGNAL AMPLITUDE
0
0
0
SEE TABLE A
SEE TABLE A
SEE TABLE A
-10
-20
-30
-40
-50
-60
-70
-80
-90
-10
-20
-30
-40
-50
-60
-70
-80
-90
-10
-20
-30
-40
-50
-60
-70
-80
-90
B
A
B
B
A
A
0
0.5
1.0
1.5
2.0
2.5
3.0
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
AMPLITUDE (Vp-p)
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
AMPLITUDE (Vp-p)
AMPLITUDE (Vp-p)
MAX7414
INTERNAL OSCILLATOR PERIOD
vs. SMALL CAPACITANCE
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. INPUT SIGNAL AMPLITUDE
SUPPLY CURRENT vs. TEMPERATURE
1.19
1.18
1.17
1.16
1.15
1.14
1.13
1.12
1.11
0
120
100
80
60
40
20
0
SEE TABLE A
-10
-20
-30
-40
-50
-60
-70
-80
-90
V
DD
= +5V
V
DD
= +5V
V
DD
= +3V
B
V
DD
= +3V
A
0
0.5
1.0
1.5
2.0
2.5
3.0
0
500 1000 1500 2000 2500 3000 3500
CAPACITANCE (pF)
-40 -20
0
20
40
60
80 100
AMPLITUDE (Vp-p)
TEMPERATURE (°C)
903/MAX714
INTERNAL OSCILLATOR FREQUENCY
vs. SUPPLY VOLTAGE
INTERNAL OSCILLATOR FREQUENCY
vs. TEMPERATURE
INTERNAL OSCILLATOR PERIOD
vs. LARGE CAPACITANCE
31.5
31.0
30.5
30.0
29.5
29.0
30.2
30.1
30.0
29.9
29.8
29.7
29.6
29.5
29.4
12
10
8
C
= 1000pF
OSC
C
= 1000pF
OSC
V
= +5V
DD
V
= +3V
DD
V
DD
= +3V
6
4
2
V = +5V
DD
0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
-40 -20
0
20
40
60
80 100
0
50 100 150 200 250 300 350
CAPACITANCE (nF)
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
6
_______________________________________________________________________________________
5 t h -Ord e r, Lo w p a s s ,
S w it c h e d -Ca p a c it o r Filt e rs
903/MAX714
Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s (c o n t in u e d )
(V = +5V for MAX7409/MAX7410, V = +3V for MAX7413/MAX7414, f
= 100kHz, SHDN = V , COM = OS = V / 2, T = +25°C,
CLK
DD
DD
DD DD A
unless otherwise noted.)
OUTPUT OFFSET VOLTAGE
vs. SUPPLY VOLTAGE
OUTPUT OFFSET VOLTAGE
vs. TEMPERATURE
-2.0
-2.5
-3.0
-3.5
-4.0
-4.5
-5.0
-3.00
-3.25
-3.50
-3.75
-4.00
-4.25
-4.50
V
DD
= +3V
V
DD
= +5V
2.5
3.0
3.5
4.0
4.5
5.0
5.5
-40 -20
0
20
40
60
80 100
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
P in De s c rip t io n
PIN
NAME
FUNCTION
Common Input Pin. Biased internally at midsupply. Bypass COM externally to GND with a 0.1µF capacitor.
To override internal biasing, drive COM with an external supply.
1
COM
2
3
4
5
IN
Filter Input
GND
Ground
V
DD
Positive Supply Input: +5V for MAX7409/MAX7410, +3V for MAX7413/MAX7414.
Filter Output
OUT
Offset Adjust Input. To adjust output offset, connect OS to an external supply through a resistive voltage-
divider (Figure 3). Connect OS to COM if no offset adjustment is needed. Refer to the Offset and Common-
Mode Input Adjustment section.
6
OS
7
8
Shutdown Input. Drive low to enable shutdown mode; drive high or connect to V for normal operation.
DD
SHDN
3
Clock Input. Connect an external capacitor (C
) from CLK to ground: f
(kHz) = 30 x 10 / C
/100.
(pF).
OSC
OSC
OSC
CLK
To override the internal oscillator, connect CLK to an external clock: f = f
C
CLK
higher frequencies). Bessel filters settle quickly—an
important characteristic in applications that use a multi-
plexer (mux) to select an input signal for an analog-to-
digital converter (ADC). An anti-aliasing filter placed
between the mux and the ADC must settle quickly after
a new channel is selected.
_______________De t a ile d De s c rip t io n
The MAX7409/MAX7413 Bessel filters provide low over-
shoot and fast settling responses, and the MAX7410/
MAX7414 Butterworth filters provide a maximally flat
passband response. All parts operate with a 100:1
clock-to-corner frequency ratio and a 15kHz maximum
corner frequency.
Bu t t e rw o rt h Ch a ra c t e ris t ic s
Lowp a s s Butte rworth filte rs s uc h a s the MAX7410/
MAX7414 provide a maximally flat passband response,
making them ideal for instrumentation applications that
require minimum deviation from the DC gain throughout
the passband.
Be s s e l Ch a ra c t e ris t ic s
Lowpass Bessel filters such as the MAX7409/MAX7413
delay all frequency components equally, preserving the
shape of step inputs (subject to the attenuation of the
_______________________________________________________________________________________
7
5 t h -Ord e r, Lo w p a s s ,
S w it c h e d -Ca p a c it o r Filt e rs
R
S
L2
L4
+
-
2V/div
C1
V
IN
C3
C5
R
L
A
2V/div
B
Figure 2. 5th-Order Ladder Filter Network
2V/div
C
Clo c k S ig n a l
External Clock
200µs/div
The MAX7409/MAX7410/MAX7413/MAX7414 family of
SCFs is designed for use with external clocks that have
a 50% ±10% duty cycle. When using an external clock
with these devices, drive CLK with a CMOS gate pow-
A: 1kHz INPUT SIGNAL
B: MAX7409 BESSEL FILTER RESPONSE; f = 5kHz
C: MAX7410 BUTTERWORTH FILTER RESPONSE; f = 5kHz
C
C
ered from 0 to V . Varying the rate of the external
DD
clock adjusts the corner frequency of the filter as fol-
lows:
Figure 1. Bessel vs. Butterworth Filter Response
The difference between Bessel and Butterworth filters
can be observed when a 1kHz square wave is applied
to the filter input (Figure 1, trace A). With the filter cutoff
frequencies set at 5kHz, trace B shows the Bessel filter
re s p ons e a nd tra c e C s hows the Butte rworth filte r
response.
f
= f
/ 100
C
CLK
Internal Clock
When using the internal oscillator, connect a capacitor
(C ) between CLK and ground. The value of the
OSC
capacitor determines the oscillator frequency as follows:
3
f
(kHz) = 30 x 10 / C
(pF)
OSC
OSC
Ba c k g ro u n d In fo rm a t io n
Most switched-capacitor filters (SCFs) are designed with
biquadratic sections. Each section implements two filter-
ing poles, and the sections are cascaded to produce
higher-order filters. The advantage to this approach is
ease of design. However, this type of design is highly
sensitive to component variations if any section’s Q is
high. An alternative approach is to emulate a passive net-
work using switched-capacitor integrators with summing
and scaling. Figure 2 shows a basic 5th-order ladder filter
structure.
Minimize the stray capacitance at CLK so that it does
not affect the internal oscillator frequency. Vary the rate
of the internal oscillator to adjust the filter’s corner fre-
quency by a 100:1 clock-to-corner frequency ratio. For
example, an internal oscillator frequency of 100kHz
produces a nominal corner frequency of 1kHz.
In p u t Im p e d a n c e vs . Clo c k Fre q u e n c ie s
The MAX7409/MAX7410/MAX7413/MAX7414’s input
impedance is effectively that of a switched-capacitor
resistor (see the following equation), and is inversely
proportional to frequency. The input impedance values
determined below represent the average input imped-
ance, since the input current is not continuous. As a
rule, use a driver with an output impedance less than
10% of the filter’s input impedance. Estimate the input
impedance of the filter using the following formula:
903/MAX714
A s witc he d -c a p a c itor filte r s uc h a s the MAX7409/
MAX7410/MAX7413/MAX7414 emulates a passive ladder
filter. The filter’s component sensitivity is low when com-
pared to a cascaded biquad design, because each
component affects the entire filter shape, not just one
pole-zero pair. In other words, a mismatched component
in a biquad design will have a concentrated error on its
respective poles, while the same mismatch in a ladder
filter design results in an error distributed over all poles.
Z
= 1 / ( f
x 2.1pF)
IN
CLK
For example, an f
of 100kHz results in an input
CLK
impedance of 4.8MΩ.
8
_______________________________________________________________________________________
5 t h -Ord e r, Lo w p a s s ,
S w it c h e d -Ca p a c it o r Filt e rs
903/MAX714
Lo w -P o w e r S h u t d o w n Mo d e
V
SUPPLY
These devices feature a shutdown mode that is activat-
ed by driving SHDN low. In shutdown mode, the filter’s
supply current reduces to 0.2µA and its output becomes
high impedance. For normal operation, drive SHDN
0.1µF
V
DD
SHDN
OUT
high or connect it to V
.
DD
OUTPUT
INPUT
IN
COM
__________Ap p lic a t io n s In fo rm a t io n
0.1µF
0.1µF
50k
MAX7409
MAX7410
MAX7413
MAX7414
Offs e t a n d Co m m o n -Mo d e
In p u t Ad ju s t m e n t
50k
50k
CLOCK
CLK
OS
The COM pin sets the common-mode input voltage and
is biased at mid-supply with an internal resistor-divider.
If the application does not require offset adjustment,
connect OS to COM. For applications requiring offset
adjustment, apply an external bias voltage through a
resistor-divider network to OS such as shown in Fig-
ure 3. For applications that require DC level shifting,
adjust OS with respect to COM. (Note: OS should not
be left unconnected.) The output voltage is represent-
ed by this equation:
GND
Figure 3. Offset Adjustment Circuit
V+
V
OUT
= (V - V
) + V
COM OS
IN
*
V
DD
SHDN
OUT
with V
= V / 2 (typical), and where (V - V
)
COM
DD
IN
COM
OUTPUT
is lowpass filtered by the SCF, and OS is added at the
output stage. See the Electrical Characteristics for the
voltage range of COM and OS. Changing the voltage
on COM or OS significantly from midsupply reduces
the filter’s dynamic range.
INPUT
IN
COM
MAX7409
MAX7410
MAX7413
MAX7414
V+
V-
CLOCK
CLK
OS
0.1µF
0.1µF
P o w e r S u p p lie s
The MAX7409/MAX7410 operate from a single +5V
supply and the MAX7413/MAX7414 operate from a sin-
GND
g le +3V s up p ly. Byp a s s V
to GND with a 0.1µF
DD
V-
c a p a c itor. If d ua l s up p lie s a re re q uire d (± 2.5V for
MAX7409/MAX7410, ±1.5V for MAX7413/MAX7414),
connect COM to system ground and connect GND to
the negative supply. Figure 4 shows an example of
dual-supply operation. Single- and dual-supply perfor-
mance are equivalent. For either single- or dual-supply
operation, drive CLK and SHDN from GND (V- in dual-
*DRIVE SHDN TO V- FOR LOW-POWER SHUTDOWN MODE.
Figure 4. Dual-Supply Operation
An t i-Alia s in g a n d DAC P o s t filt e rin g
When using these devices for anti-aliasing or DAC
postfiltering, synchronize the DAC (or ADC) and the fil-
ter clocks. If the clocks are not synchronized, beat fre-
quencies will alias into the desired passband.
supply operation) to V . For ±5V dual-supply applica-
DD
tions, use the MAX291–MAX297.
In p u t S ig n a l Am p lit u d e Ra n g e
The op tima l inp ut s ig na l ra ng e is d e te rmine d b y
observing the voltage level at which the Total Harmonic
Distortion + Noise is minimized for a given corner fre-
quency. The Typical Operating Characteristics show
graphs of the devices’ Total Harmonic Distortion plus
Noise Response as the input signal’s peak-to-peak
amplitude is varied.
Ha rm o n ic Dis t o rt io n
Harmonic distortion arises from nonlinearities within the
filter. These nonlinearities generate harmonics when a
pure sine wave is applied to the filter input. Table 1 lists
typical harmonic-distortion values for the MAX7410/
MAX7414 with a 10kΩ load at T = +25°C. Table 2 lists
typical harmonic-distortion values for the MAX7409/
A
MAX7413 with a 10kΩ load at T = +25°C.
A
_______________________________________________________________________________________
9
5 t h -Ord e r, Lo w p a s s ,
S w it c h e d -Ca p a c it o r Filt e rs
Table 1. MAX7410/MAX7414 Typical Harmonic Distortion
TYPICAL HARMONIC DISTORTION (dB)
f
f
V
IN
(Vp-p)
CLK
IN
FILTER
MAX7410
MAX7414
(kHz)
(Hz)
2nd
-85
3rd
-67
4th
5th
-82
500
100
500
100
1k
200
1k
-86.7
-88.7
-87.1
-85.8
4
-84
-78
-88.5
-87.6
-86.4
-85.3
-86.1
-74
2
200
-85.5
Table 2. MAX7409/MAX7413 Typical Harmonic Distortion
TYPICAL HARMONIC DISTORTION (dB)
f
f
V
IN
(Vp-p)
CLK
IN
FILTER
MAX7409
MAX7413
(kHz)
(Hz)
2nd
-82.5
-83.5
-86
3rd
-79
4th
5th
500
100
500
100
1k
200
1k
-88.8
-88.4
-87.3
-87.9
-91.1
-88.8
-87.9
-88.3
4
-85.4
-81
2
200
-86.4
-86.9
Ch ip In fo rm a t io n
Ord e rin g In fo rm a t io n (c o n t in u e d )
PART
TEMP. RANGE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 µMAX
TRANSISTOR COUNT: 1457
MAX7413CUA
MAX7413CPA
MAX7413EUA
MAX7413EPA
MAX7414CUA
MAX7414CPA
MAX7414EUA
MAX7414EPA
8 Plastic DIP
8 µMAX
8 Plastic DIP
8 µMAX
8 Plastic DIP
8 µMAX
903/MAX714
8 Plastic DIP
10 ______________________________________________________________________________________
5 t h -Ord e r, Lo w p a s s ,
S w it c h e d -Ca p a c it o r Filt e rs
903/MAX714
________________________________________________________P a c k a g e In fo rm a t io n
______________________________________________________________________________________ 11
5 t h -Ord e r, Lo w p a s s ,
S w it c h e d -Ca p a c it o r Filt e rs
P a c k a g e In fo rm a t io n (c o n t in u e d )
903/MAX714
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12 ____________________Ma x im In t e g ra t e d P ro d u c t s , 1 2 0 S a n Ga b rie l Drive , S u n n yva le , CA 9 4 0 8 6 4 0 8 -7 3 7 -7 6 0 0
© 1998 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
相关型号：
MAX7413EPA+
Switched Capacitor Filter, 1 Func, Bessel, Lowpass, CMOS, PDIP8, 0.300 INCH, PLASTIC, DIP-8
MAXIM
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