19-0352; Rev 2; 7/02
Microprocessor Programmable
Universal Active Filters
General Description
The MAX260/MAX261/MAX262 CMOS dual second-
order universal switched-capacitor active filters allow
microprocessor control of precise filter functions. No
external components are required for a variety of band-
pass, lowpass, highpass, notch, and allpass configura-
tions. Each device contains two second-order filter
sections that place center frequency, Q, and filter oper-
ating mode under programmed control.
An input clock, along with a 6-bit f
0
program input,
determine the filter's center or corner frequency without
affecting other filter parameters. The filter Q is also pro-
grammed independently. Separate clock inputs for
each filter section operate with either a crystal, RC net-
work, or external clock generator.
The MAX260 has offset and DC specifications superior
to the MAX261 and MAX262 and a center frequency
(f
0
) range of 7.5kHz. The MAX261 handles center fre-
quencies to 57kHz, while the MAX262 extends the cen-
ter frequency range to 140kHz by employing lower
clock-to-f
0
ratios. All devices are available in 24-pin DIP
and small outline packages in commercial, extended,
and military temperature ranges.
o
Filter Design Software Available
o
Microprocessor Interface
o
64-Step Center Frequency Control
o
128-Step Q Control
o
Independent Q and f
0
Programming
o
Guaranteed Clock to f
0
Ratio-1% (A grade)
o
75kHz f
0
Range (MAX262)
o
Single +5V and ±5V Operation
Features
MAX260/MAX261/MAX262
Ordering Information
PART
MAX260ACNG
MAX260BCNG
MAX260AENG
MAX260BENG
MAX260ACWG
MAX260BCWG
MAX260AMRG
MAX260BMRG
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
-55°C to +125°C
-55°C to +125°C
PACKAGE
Plastic DIP
Plastic DIP
Plastic DIP
Plastic DIP
Wide SO
Wide SO
CERDIP
CERDIP
ACCURACY
1%
2%
1%
2%
1%
2%
1%
2%
Applications
µP-Tuned Filters
Anti-Aliasing Filters
Digital Signal Processing
Adaptive Filters
Signal Analysis
Phase-Locked Loops
*All
devices—24-pin packages 0.3in-wide packages
Ordering Information continued at end of data sheet.
Pin Configurations
Functional Diagram
TOP VIEW
BP
A
1
N.C. 2
24 LP
A
23 IN
B
22 LP
B
21 BP
B
BP
A
1
OP OUT 2
HP
A
3
OP IN 4
IN
A
5
D1 6
A3 7
CLK OUT 8
V
+
9
A2 10
CLK
A
11
CLK
B
12
24 LP
A
23 IN
B
22 LP
B
21 BP
B
INPUT
IN
+5V
V
+
LP HP
FILTER
A
BP
IN
LP HP BP
FILTER
B
OUTPUT
HP
A
3
N.C. 4
IN
A
5
D1 6
MAX260
20 D0
19 OSC OUT
18 GND
17 V
-
16 WR
15 A0
14 HP
B
13 A1
MAX261
MAX262
20 HP
B
19 D0
18 OSC OUT
17 GND
16 V
-
15 WR
14 A0
13 A1
GND
A3 7
CLK OUT 8
V
+
9
-5V
V
-
CLK
A
MAX260
MAX261
MAX262
OSC CLKOUT
CLK
B
PROGRAM
INPUTS
CRYSTAL
FOURTH-ORDER BANDPASS FILTER
A2 10
CLK
A
11
CLK
B
12
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Microprocessor Programmable
Universal Active Filters
MAX260/MAX261/MAX262
ABSOLUTE MAXIMUM RATINGS
Total Supply Voltage (V
+
to V
-
) .............................................15V
Input Voltage, any pin ..........................(V
-
- 0.3V) to (V
+
+ 0.3V)
Input Current, any pin ......................................................±50mA
Power Dissipation
Plastic DIP (derate 8.33mW/°C above 70°C) ...............660mW
CERDIP (derate 12.5mW/°C above 70°C) .................1000mW
Wide SO (derate 11.8mW/°C above 70°C) ..................944mW
Operating Temperature Ranges
MAX260/MAX261/MAX262XCXG .......................0°C to +70°C
MAX260/MAX261/MAX262XEXG .....................-40°C to +85°C
MAX260/MAX261/MAX262XMXG ..................-55°C to +125°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (Soldering, 10s) ................................+300°C
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
(V
+
= +5V, V
-
= -5V, CLK
A
= CLK
B
= ±5V 350kHz for the MAX260 and 1.5MHz for the MAX261/MAX262, f
CLK
/f
0
= 199.49 for
MAX260/MAX261 and 139.80 for MAX262, Filter Mode 1, T
A
= +25°C, unless otherwise noted.)
PARAMETER
f
0
Center Frequency Range
Maximum Clock Frequency
MAX260A
f
CLK
/f
0
Ratio Error (Note 1)
T
A
= T
MIN
to T
MAX
MAX260B
MAX261/MAX262A
MAX261/MAX262B
f
0
Temperature Coefficient
Q=8
Q=8
Q = 32
Q = 32
Q = 64
Q Accuracy (deviation from ideal
continuous filter) (Note 2)
T
A
= T
MIN
to
T
MAX
Q = 64
Q=8
Q=8
Q = 32
Q = 32
Q = 64
Q = 64
Q Temperature Coefficient
DC Lowpass Gain Accuracy
Lowpass (at D.C.)
Bandpass (at f
0
)
MAX260
MAX261/MAX262
MAX260
Gain Temperature Coefficient
MAX261/MAX262
MAX260/MAX261/MAX262
MAX260A
MAX260B
MAX260A
MAX260B
MAX260A
MAX260B
MAX261/MAX262A
MAX261/MAX262B
MAX261/MAX262A
MAX261/MAX262B
MAX261/MAX262A
MAX261/MAX262B
CONDITIONS
MIN
TYP
See Table 1
See Table 1
±0.2
±0.2
±0.2
±0.2
-5
±1
±1
±2
±2
±4
±4
±1
±1
±2
±2
±4
±4
±20
±0.1
±0.1
-5
-5
+20
ppm/°C
±0.3
±0.5
dB
±6
±10
±10
±15
±20
±25
±6
±10
±10
±15
±20
±25
ppm/°C
%
±1.0
±2.0
±1.0
±2.0
ppm/°C
%
MAX
UNITS
2
_______________________________________________________________________________________
Microprocessor Programmable
Universal Active Filters
ELECTRICAL CHARACTERISTICS (continued)
(V
+
= +5V, V
-
= -5V, CLK
A
= CLK
B
= ±5V 350kHz for the MAX260 and 1.5MHz for the MAX261/MAX262, f
CLK
/f
0
= 199.49 for
MAX260/MAX261 and 139.80 for MAX262, Filter Mode 1, T
A
= +25°C, unless otherwise noted.)
PARAMETER
CONDITIONS
MAX260A
MAX260B
T
A
= T
MIN
to T
MAX
, Q = 4
Mode 1
MAX261A
MAX261B
MAX262A
Offset Voltage At Filter
Outputs—LP, BP, HP (Note 3)
MAX262B
MAX260A
MAX260B
Mode 3
MAX261A
MAX261B
MAX262A
MAX262B
Offset Voltage Temperature
Coefficient
Clock Feedthrough
Crosstalk
Q = 1, 2nd-Order, LP/BP
Wideband Noise
Harmonic Distortion at f
0
Supply Voltage Range
Power Supply Current (Note 5)
4th-Order LP (Figure 26)
4th-Order BP (Figure 24) (Note 4)
Q = 4, V
IN
= 1.5V
P-P
T
A
= T
MIN
to T
MAX
MAX260
T
A
= T
MIN
to T
MAX
CMOS Level Logic Inputs
MAX261
MAX262
Shutdown Supply Current
INTERNAL AMPLIFIERS
Output Signal Swing
Output Signal Circuit Current
Power Supply Rejection Ratio
Gain Bandwidth Product
Slew Rate
T
A
= T
MIN
to T
MAX
, 10kΩ load (Note 6)
Source
Sink
0Hz to 10kHz
±4.75
50
2
-70
2.5
6
V
mA
dB
MHz
V/µs
Q0
A
- Q6
A
= all 0,
CMOS Level Logic Inputs (Note 5)
±2.37
f
CLK
/f
0
= 100.53, Q = 4
T
A
= T
MIN
to T
MAX
MIN
TYP
±0.05
±0.15
±0.40
±0.80
±0.40
±0.80
±0.075
±0.075
±0.50
±0.90
±0.50
±0.90
±0.75
±4
-70
See Typ. Oper. Char.
90
100
-67
±5
15
16
16
1.5
±6.3
20
20
20
mA
mA
dB
V
µV
RMS
MAX
±0.25
±0.45
±1.00
±1.60
±1.20
±1.60
±0.30
±0.50
±1.10
±1.60
±1.30
±1.60
mV/°C
mV
dB
V
UNITS
MAX260/MAX261/MAX262
_______________________________________________________________________________________
3
Microprocessor Programmable
Universal Active Filters
MAX260/MAX261/MAX262
ELECTRICAL CHARACTERISTICS (for V± = ±2.5V ±5%)
(V
+
= +2.37V, V
-
= -2.37V, CLK
A
= CLK
B
= ±2.5V 250kHz for the MAX260 and 1MHz for the MAX261/MAX262, f
CLK
/f
0
= 199.49 for
MAX260/MAX261 and 139.80 for MAX262, Filter Mode 1, T
A
= +25°C, unless otherwise noted.)
PARAMETER
f
0
Center Frequency Range
Maximum Clock Frequency
f
CLK
/f
0
Ratio Error
(Notes 1, 8)
Q=8
Q=8
f
CLK
/f
0
= 199.49
Q Accuracy (deviation from ideal
continuous filter)
(Notes 2, 8)
f
CLK
/f
0
= 199.49
f
CLK
/f
0
= 139.80
Output Signal Swing
Power Supply Current
Shutdown Current
All Outputs (Note 6)
CMOS Level Logic Inputs (Note 5)
CMOS Level Logic Inputs (Note 5)
MAX26XA
MAX26XB
MAX260A
MAX260B
MAX261A
MAX261B
MAX262A
MAX262B
CONDITIONS
MIN
TYP
(Note 7)
(Note 7)
±0.1
±0.1
±2
±2
±2
±2
±2
±2
±2
7
0.35
1
2
±6
±10
±6
±10
±6
±10
V
mA
mA
%
%
MAX
UNITS
Note 1:
f
CLK
/f
0
accuracy is tested at 199.49 on the MAX260/MAX261, and at 139.8 on the MAX262.
Note 2:
Q accuracy tested at Q = 8, 32, and 64. Q of 32 and 64 tested at 1/2 stated clock frequency.
Note 3:
The offset voltage is specified for the entire filter. Offset is virtually independent of Q and f
CLK
/f
0
ratio setting. The test clock
frequency for mode 3 is 175kHz for the MAX260 and 750kHz for the MAX261/MAX262.
Note 4:
Output noise is measured with an RC output smoothing filter at 4
✕
f
0
to remove clock feedthrough.
Note 5:
TTL logic levels are: HIGH = 2.4V, LOW = 0.8V. CMOS logic levels are: HIGH = 5V, LOW = 0V. Power supply current is typi-
cally 4mA higher with TTL logic and clock input levels.
Note 6:
On the MAX260 only, the HP output signal swing is typically 0.75V less than the LP or BP outputs.
Note 7:
At ±2.5V supplies, the f
0
range and maximum clock frequency are typically 75% of values listed in Table 1.
Note 8:
f
CLK
/f
0
and Q accuracy are a function of the accuracy of internal capacitor ratios. No increase in error is expected at ±2.5V
as compared to ±5V; however, these parameters are only tested to the extent indicated by the MIN or MAX limits.
INTERFACE SPECIFICATIONS (Note 9)
(V
+
= +5V, V
+
= -5V, T
A
= +25°C, unless otherwise noted.)
PARAMETER
WR
Pulse Width
Address Setup
Address Hold
Data Setup
Data Hold
Logic Input High
Logic Input Low
SYMBOL
t
WR
t
AS
t
AH
t
DS
t
DH
V
IH
V
IL
WR,
D0, D1, A0–A3, CLK
A
, CLK
B
T
A
=T
MIN
to T
MAX
WR,
D0, D1, A0–A3, CLK
A
, CLK
B
T
A
=T
MIN
to T
MAX
WR,
D0, D1, A0–A3, CLK
B
CLK
A
T
A
=T
MIN
to T
MAX
WR,
D0, D1, A0–A3, CLK
A
, CLK
B
6
CONDITIONS
MIN
250
25
0
100
10
2.4
0.8
10
60
15
µA
pF
50
0
TYP
150
MAX
UNITS
ns
ns
ns
ns
ns
V
V
Input Leakage Current
Input Capacitance
I
IN
C
IN
Note 9:
Interface timing specifications are guaranteed by design and are not subject to test.
4
_______________________________________________________________________________________
Microprocessor Programmable
Universal Active Filters
Pin Description
PIN
MAX260
9
17
MAX261/
MAX262
9
16
NAME
V
+
-
MAX260/MAX261/MAX262
PIN
FUNCTION
Positive supply voltage
Negative supply voltage
Analog Ground. Connect
to the system ground for
dual supply operation or
mid-supply for single sup-
ply operation. GND should
be well bypassed in single
supply applications.
Input to the oscillator and
clock input to section A.
This clock is internally
divided by 2.
Clock input to filter B. This
clock is internally divided
by 2.
Clock output for crystal
and R-C oscillator operation
Connects to crystal or R-C
for self-clocked operation
MAX260
5, 23
1, 21
24, 22
3, 14
16
15, 13,
10, 7
20, 6
MAX261/
MAX262
5, 23
1, 21
24, 22
3, 20
15
14, 13,
10, 7
19, 6
NAME
IN
A
, IN
B
BP
A
, BP
B
LP
A
, LP
B
HP
A
, HP
B
WR
A0, A1,
A2, A3
D0, D1
FUNCTION
Filter inputs
Bandpass outputs
Lowpass outputs
Highpass/notch/allpass
outputs
Write enable input
Address inputs for f
0
and
Q input data locations
Data inputs for f
0
and Q
programming
Output of uncommitted
op amp on MAX261/
MAX262 only. Pin 2 is a no-
connect on the MAX260.
Inverting input of uncom-
mitted op amp on MAX261/
MAX262 only (noninverting
input is internally connected
to ground). Pin 4 is a no-
connect on the MAX260.
V
18
17
GND
11
11
CLK
A
2
OP OUT
12
12
CLK
B
8
19
8
18
CLK OUT
OSC OUT
4
OP IN
_______________________________________________________________________________________
5
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