LTC1562-2 Linear Technology, LTC1562-2 Datasheet - Page 5

• Manufacturer Part Number: LTC1562-2
• Description: Very Low Noise/ Low Distortion Active RC Quad Universal Filter
• Manufacturer: Linear Technology

should be connected to the ground plane (Figure 1). For
single supply operation, the AGND pin should be bypassed
to the ground plane with at least a 0.1 F capacitor (at least
1 F for best AC performance) (Figure 2).
PIN
U
ANALOG
GROUND
PLANE
V
0.1 F
+
FUNCTIONS
Figure 2. Single Supply Ground Plane Connection
(Including Substrate Pins 4, 7, 14, 17)
ANALOG
GROUND
PLANE
Figure 1. Dual Supply Ground Plane Connection
(Including Substrate Pins 4, 7, 14, 17)
V
0.1 F
+
SINGLE-POINT
SYSTEM GROUND
U
SINGLE-POINT
SYSTEM GROUND
10
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
U
LTC1562-2
LTC1562-2
GROUND PLANE
20
19
18
17
16
15
14
13
12
11
GROUND PLANE
DIGITAL
(IF ANY)
20
19
18
17
16
15
14
13
12
11
(IF ANY)
DIGITAL
REFERENCE
V
–
V
0.1 F
+
/2
1 F
1562-2 F01
1562-2 F01
Shutdown (SHDN): When the SHDN input goes high or is
open-circuited, the LTC1562-2 enters a “zero-power”
shutdown state and only junction leakage currents flow.
The AGND pin and the amplifier outputs (see Figure 3)
assume a high impedance state and the amplifiers effec-
tively disappear from the circuit. (If an input signal is
applied to a complete filter circuit while the LTC1562-2 is
in shutdown, some signal will normally flow to the output
through passive components around the inactive op amps.)
A small pull-up current source at the SHDN input defaults
the LTC1562-2 to the shutdown state if the SHDN pin is left
floating . Therefore, the user must connect the SHDN pin
to a logic “low” (0V for 5V supplies, V
supply) for normal operation of the LTC1562-2. (This
convention permits true “zero-power” shutdown since not
even the driving logic must deliver current while the part
is in shutdown.) With a single supply voltage, use V
logic “low,” do not connect SHDN to the AGND pin.
Figure 3. Equivalent Circuit of a Single 2nd Order Section
(Inside Dashed Line) Shown in Typical Connection. Form of
Z
IN
Determines Response Types at the Two Outputs (See Table)
Z
1/4 LTC1562-2
IN
TYPE
R
C
V2
BANDPASS
RESPONSE
HIGHPASS
AT V1
R2
RESPONSE
BANDPASS
LOWPASS
sR1C*
AT V2
1
Z
+
–
IN
*R1 AND C ARE PRECISION
INV
V
INTERNAL COMPONENTS
IN
IN EACH CASE,
f
Q =
–
+
O
LTC1562-2
= (200kHz)
RQ
R2
R
Q
C
200kHz
–
f
O
for 5V total
7958
1562-2 F03
R2
V1
–
5
for