HA4201 Datasheet, PDF (4/7 Pages) Intersil Corporation – 480MHz, 1 x 1 Video Crosspoint Switch with Tally Output

HA4201
Control Signals
EN - The ENABLE input is a TTL/CMOS compatible, active
high input. When driven low this input forces the output to a
true high impedance state and reduces the power
dissipation by two orders of magnitude. The EN input has no
on-chip pull-up resistor, so it must be connected to a logic
high (recommend V+) if the enable function isn’t utilized.
Tally - The Tally output is an open collector PNP transistor
connected to V+. When EN = 1, the PNP transistor is enabled
and current is delivered to the load. When the crosspoint is
disabled, the Tally output presents a very high impedance to
the external circuitry. Several Tally outputs may be wire OR’d
together to generate complex control signals, as shown with the
HA4404 in the application circuits below. The Tally load may be
terminated to GND or to V- as long as the continuous output
current doesn’t exceed 3mA (6mA at 50% duty cycle, etc.).
Switcher/Router Applications
Figure 1 illustrates one possible implementation of a
wideband, low power, 4 x 4 switcher/router. 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 HA4201 for the
input buffer, the HA4404 (4 x 1 crosspoint switch) as the
switch 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 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.
Intersil’s Crosspoint Family
Intersil offers a variety of 1 x 1 and 4 x 1 crosspoint switches.
In addition to the HA4201, the 1 x 1 family includes the
HA4600 which is an essentially similar device but without the
Tally output. The 4 x 1 family is comprised of the HA4314,
HA4404, and HA4344. The HA4314 is a 14 lead basic 4 x 1
crosspoint. 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.
INPUT BUFFERS
EN
SOURCE0
75Ω
OUT _RS
HA4201
IN0
T0
SWITCH MATRIX
IN0
T0
IN0
T0
10kΩ
IN0
T0
SOURCE1
75Ω
SOURCE2
75Ω
SOURCE3
75Ω
CS
CS
CS
CS
HA4404
OUT
R_S
IN3
T3
EN
OUT _RS
HA4201
OUTPUT BUFFERS
+-
X2
(HFA1112 OR HFA1115)
75Ω
HA4404
OUT
IN3
T3
R_S
+-
X2
75Ω
HA4404
OUT
IN3
T3
R_S
+-
X2
75Ω
HA4404
OUT
R_S
IN3
T3
10kΩ
+-
X2
75Ω
OUT0
OUT1
FIGURE 1. 4 x 4 SWITCHER/ROUTER APPLICATION
OUT2
OUT3
4