HA4314B
capacitance, C
L
, driven. Bandwidth and slew rate degrade
as C
L
increases (as shown in the Electrical Specification
table), so give careful consideration to component
placement to minimize trace length. In big matrix
configurations where C
L
is large, better frequency response
is obtained by cascading two levels of crosspoints in the
case of multiplexed outputs (see Figure 2), or distributing the
load between two drivers if C
L
is due to bussing and
subsequent stage input capacitance.
matrix, and the HFA1112 (programmable gain buffer) as the
gain of two output driver. Figure 2 details a 16 x 1 switcher
(basically a 16:1 mux) which uses the HA4201 (1 x 1
crosspoint) and the HA4314B in a cascaded stage
configuration to minimize capacitive loading at each output
node, thus increasing system bandwidth.
Power Up Considerations
No signals should be applied to the analog or digital inputs
before the power supplies are activated. Latch-up may occur
if the inputs are driven at the time of power up. To prevent
latch-up, the input currents during power up must not exceed
the values listed in the Absolute Maximum Ratings.
Control Signals
CS - This is a TTL/CMOS compatible, active low Chip Select
input. When driven high, CS forces the output to a true high
impedance state and reduces the power dissipation by a
factor of 25. The CS input has no on-chip pull-down resistor,
so it must be connected to a logic low (recommend GND) if
the enable function isn’t utilized.
A0, A1 - These are binary coded, TTL/CMOS compatible
address inputs that select which one of the four inputs
connect to the crosspoint output.
Intersil’s Crosspoint Family
Intersil offers a variety of 4 x 1 and 1 x 1 crosspoint switches.
In addition to the HA4314B, the 4 x 1 family includes the
HA4404 and HA4344. The HA4404 is a 16 lead device with
Tally outputs to indicate the selected channel. The HA4344
is a 16 lead crosspoint with synchronized control lines (A0,
A1, CS). With synchronization, the control information for the
next channel switch can be loaded into the crosspoint
without affecting the current state. On a subsequent clock
edge the stored control state effects the desired channel
switch.
The 1 x 1 family is comprised of the HA4201 and HA4600.
They are essentially similar devices, but the HA4201
includes a Tally output (enable indicator). The 1 x 1s are
useful as high performance video input buffers, or in a switch
matrix requiring very high off isolation.
Switcher/Router Applications
Figure 1 illustrates one possible implementation of a
wideband, low power, 4 x 4 switcher/router utilizing the
HA4314B for the switch matrix. A 4 x 4 switcher/router allows
any of the four outputs to be driven by any one of the four
inputs (e.g., each of the four inputs may connect to a
different output, or an input may connect to multiple outputs).
This application utilizes the HA4600 (video buffer with output
disable) for the input buffer, the HA4314B as the switch
INPUT BUFFERS
+5V
EN
SOURCE 0
75Ω
OUT
HA4600
R
S
IN0
SOURCE 1
75Ω
HA4314
CS
IN0
SWITCH MATRIX
IN0
HA4314
CS
IN0
HA4314
CS
HA4314
CS
SOURCE 2
75Ω +5V
EN
SOURCE 3
75Ω
OUT
IN3
R
S
OUT
IN3
R
S
OUT
IN3
R
S
OUT
IN3
R
S
X2
75Ω
X2
75Ω
X2
75Ω
OUT0
OUT1
OUT2
OUT3
FIGURE 1. 4 x 4 SWITCHER/ROUTER APPLICATION
4
-
+
-
+
-
+
-
+
OUT R
S
HA4600
OUTPUT BUFFERS
(HFA1112 OR HFA1115)
X2
75Ω
INTERSIL [ INTERSIL CORPORATION ]
