LTC1069-1CN8 Linear Technology, LTC1069-1CN8 Datasheet - Page 6

• Manufacturer Part Number: LTC1069-1CN8
• Description: IC FILTR 8TH ORDER LOWPASS 8-DIP
• Manufacturer: Linear Technology

Specifications of LTC1069-1CN8

• Filter Type: Elliptic, Lowpass Switched Capacitor
• Frequency - Cutoff Or Center: 12kHz
• Number Of Filters: 1
• Max-order: 8th
• Voltage - Supply: 3.14 V ~ 11 V, ±1.57 V ~ 5.5 V
• Mounting Type: Through Hole
• Package / Case: 8-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

PIN FUNCTIONS
LTC1069-1
AGND (Pin 1): Analog Ground. The quality of the analog
signal ground can affect the fi lter performance. For either
single or dual supply operation, an analog ground plane
surrounding the package is recommended. The analog
ground plane should be connected to any digital ground
at a single point. For dual supply operation Pin 1 should
be connected to the analog ground plane.
For single supply operation Pin 1 should be bypassed to
the analog ground plane with a 0.47μF or larger capaci-
tor. An internal resistive divider biases Pin 1 to 1/2 the
total power supply. Pin 1 should be buffered if used to
bias other ICs. Figure 1 shows the connections for single
supply operation.
V
the V
to an adequate analog ground. The fi lter’s power supplies
should be isolated from other digital or high voltage analog
supplies. A low noise linear supply is recommended. Using
switching power supplies will lower the signal-to-noise
ratio of the fi lter. Unlike previous monolithic fi lters, the
power supplies can be applied at any order, that is, the
positive supply can be applied before the negative supply
and vice versa. Figure 2 shows the connection for dual
supply operation.
NC (Pins 3, 6): No Connection. Pins 3 and 6 are not con-
nected to any internal circuity; they should be preferably
tied to ground.
V
connected to the inverting input of an op amp through a
43k resistor.
6
+
IN
, V
(Pin 4): Filter Input Pin. The fi lter input pin is internally
–
–
Figure 1. Connections for Single Supply Operation
(Pins 2, 7): Power Supply Pins. The V
(Pin 7) should be bypassed with a 0.1μF capacitor
STAR
SYSTEM
GROUND
V
0.1μF
0.47μF
IN
V
ANALOG GROUND PLANE
+
1
2
3
4
GROUND
DIGITAL
PLANE
AGND
V
NC
V
+
IN
LTC1069-1
V
CLK
OUT
NC
V
–
SOURCE
CLOCK
8
7
6
5
1k
V
OUT
10691 F01
+
(Pin 2) and
CLK (Pin 5): Clock Input Pin. Any TTL or CMOS clock source
with a square wave output and 50% duty cycle (±10%) is
an adequate clock source for the device. The power supply
for the clock source should not necessarily be the fi lter’s
power supply. The analog ground of the fi lter should be
connected to clock’s ground at a single point only. Table 1
shows the clock’s low and high level threshold value for a
dual or a single supply operation. A pulse generator can be
used as a clock source provided the high level ON time is
greater than 0.42μs (V
are not recommended for clock signal because excessive
slow clock rise or fall times generate internal clock jitter.
The maximum clock rise or fall is 1μs. The clock signal
should be routed from the right side of the IC package to
avoid coupling into any input or output analog signal path.
A 1k resistor between the clock source and the clock input
pin (5) will slow down the rise and fall times of the clock
to further reduce charge coupling, Figure 1.
Table 1. Clock Source High and Low Thresholds
POWER SUPPLY
Dual Supply = ±5V
Single Supply = 10V
Single Supply = 5V
Single Supply = 3.3V
V
fi lter and it can source or sink 1mA. Driving coaxial cables
or resistive loads less than 20k will degrade the total har-
monic distortion of the fi lter. When evaluating the device’s
dynamic range, a buffer is required to isolate the fi lter’s
output from coax cables and instruments.
OUT
(Pin 8): Filter Output Pin. Pin 8 is the output of the
Figure 2. Connections for Dual Supply Operation
STAR
SYSTEM
GROUND
V
+
0.1μF
ANALOG GROUND PLANE
S
V
IN
= ±5V). Sine waves less than 100kHz
1
2
3
4
GROUND
DIGITAL
PLANE
AGND
V
NC
V
+
IN
LTC1069-1
HIGH LEVEL
V
CLK
OUT
NC
V
1.5V
6.5V
1.5V
1.2V
–
SOURCE
CLOCK
8
7
6
5
V
1k
OUT
0.1μF
V
10691 F02
–
LOW LEVEL
0.5V
5.5V
0.5V
0.5V
10691fa