LTC1562 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC1562' PDF : 28 Pages View PDF
LTC1562
PIN FUNCTIONS
INV A, INV B, INV C, INV D: Each of the INV pins is a virtual-
ground summing point for the corresponding 2nd order
section. For each section, external components ZIN, R2,
RQ connect to the INV pin as shown in Figure 3 and
described further in the Applications Information. Note
that the INV pins are sensitive internal nodes of the filter
and will readily receive any unintended signals that are
capacitively coupled into them. Capacitance to the INV
nodes will also affect the frequency response of the filter
sections. For these reasons, printed circuit connections to
the INV pins must be kept as short as possible, less than
one inch (2.5cm) total and surrounded by a ground plane.
V1 A, V1 B, V1 C, V1 D: Output Pins. Provide a bandpass,
highpass or other response depending on external cir-
cuitry (see Applications Information section). Each V1 pin
also connects to the RQ resistor of the corresponding 2nd
order filter section (see Figure 3 and Applications Informa-
tion). Each output is designed to drive a nominal net load
of 5kΩ and 30pF, which includes the loading due to the
external RQ. Distortion performance improves when the
outputs are loaded as lightly as possible. Some earlier
literature refers to these outputs as “BP” rather than V1.
V2 A, V2 B, V2 C, V2 D: Output Pins. Provide a lowpass,
bandpass or other response depending on external cir-
cuitry (see Applications Information section). Each V2 pin
also connects to the R2 resistor of the corresponding 2nd
order filter section (see Figure 3 and Applications Informa-
tion). Each output is designed to drive a nominal net load
of 5kΩ and 30pF, which includes the loading due to the
external R2. Distortion performance improves when the
outputs are loaded as lightly as possible. Some earlier
literature refers to these outputs as “LP” rather than V2.
BLOCK DIAGRA
V+
V–
SHDN
Overall Block Diagram Showing Four 3-Terminal 2nd Order Sections
INV
V1
V2
INV
V1
V2
A
B
V+
SHUTDOWN
SWITCH
–
C
+
∫
–
C
+
∫
R
2ND ORDER SECTIONS
R
SHUTDOWN AGND
SWITCH
D
+
V–
∫
–
C
C
+
∫
–
C
6
1562 BD
INV
V1
V2
INV
V1
V2
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