Datasheet

MAX7409/MAX7410/MAX7413/MAX7414
5th-Order, Lowpass,
Switched-Capacitor Filters
_______________________________________________________________________________________ 7
NAME FUNCTION
1 COM
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.
2 IN Filter Input
PIN
3 GND Ground
4 V
DD
Positive Supply Input: +5V for MAX7409/MAX7410, +3V for MAX7413/MAX7414.
8 CLK
Clock Input. Connect an external capacitor (C
OSC
) from CLK to ground: f
OSC
(kHz) = 30 x 10
3
/ C
OSC
(pF).
To override the internal oscillator, connect CLK to an external clock: f
C
= f
CLK
/100.
7
SHDN
Shutdown Input. Drive low to enable shutdown mode; drive high or connect to V
DD
for normal operation.
6 OS
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.
5 OUT Filter Output
Pin Description
_______________Detailed Description
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.
Bessel Characteristics
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
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.
Butterworth Characteristics
Lowpass Butterworth filters such as 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.
Typical Operating Characteristics (continued)
(V
DD
= +5V for MAX7409/MAX7410, V
DD
= +3V for MAX7413/MAX7414, f
CLK
= 100kHz, SHDN = V
DD
, COM = OS = V
DD
/ 2, T
A
= +25°C,
unless otherwise noted.)
-4.50
-4.00
-4.25
-3.50
-3.75
-3.25
-3.00
-40 20 40-20 0 60 80 100
OUTPUT OFFSET VOLTAGE
vs. TEMPERATURE
MAX7409 toc17
TEMPERATURE (°C)
OFFSET VOLTAGE (mV)
V
DD
= +3V
V
DD
= +5V
-5.0
-4.0
-4.5
-3.0
-3.5
-2.5
-2.0
2.5 3.5 4.03.0 4.5 5.0 5.5
OUTPUT OFFSET VOLTAGE
vs. SUPPLY VOLTAGE
MAX7409 toc18
SUPPLY VOLTAGE (V)
DC OFFSET VOLTAGE (mV)