MAX4357ECD MAXIM [Maxim Integrated Products], MAX4357ECD Datasheet - Page 38

• Manufacturer Part Number: MAX4357ECD
• Description: 32 x 16 Nonblocking Video Crosspoint Switch with I/O Buffers
• Manufacturer: MAXIM [Maxim Integrated Products]

32 x 16 Nonblocking Video Crosspoint Switch
with I/O Buffers
The MAX4357 operates from a single +5V or dual ±3V
to ±5V supply. For single-supply operation, connect all
V EE pins to ground and bypass all power-supply pins
with a 0.1µF capacitor to ground. For dual-supply sys-
tems, bypass all supply pins to ground with 0.1µF
capacitors.
T
supplies down to ±3V or a single supply of +5V.
Operating at the minimum supply voltages reduces the
power dissipation by as much 40% to 50%. At ±5V, the
MAX4357 consumes 220mW (0.43mW/point).
The MAX4357 output buffers can be programmed to
either A V = +1V/V or +2V/V. The +1V/V configuration is
typically used when driving short-length (less than
3cm), high-impedance “local” PC board traces. To
drive a cable or a 75
the gain of the output buffer to +2V/V and place a 75
resistor in series with the output. The series termination
resistor and the 75
divider that divides the video signal in half. Set the gain
to +2V/V to transmit a standard 1V video signal down a
cable. The series 75 resistor is called the back-match,
reverse termination, or series termination. This 75
resistor reduces reflections and provides isolation,
increasing the output-capacitive-driving capability.
The MAX4357’s unique digital interface simplifies pro-
gramming multiple MAX4357 devices in an array.
Multiple devices are connected with DOUT of the first
device connecting to DIN of the second device, and so
on (Figure 9). Two distinct programming modes,
38
Table 7. 7-Bit Serial Control Word Bit Assignments (Mode 1: Complete Matrix Mode
Programming)
he MAX4357 has been designed to operate with split
Driving a PC Board Interconnect or Cable
6 (MSB)
0 (LSB)
______________________________________________________________________________________
BIT
5
4
3
2
1
Input Address 4
Input Address 3
Input Address 2
Input Address 1
Input Address 0
load impedance act as a voltage-
Output Enable
transmission line trace, program
Power-Supply Bypassing
Gain Set
Power in Large Systems
NAME
(A
Matrix Programming
V
= +1V/V or +2V/V)
Enable bit for output, 0 = disable, 1 = enable.
Gain select for output buffer, 0 = gain of +1V/V, 1 = gain of +2V/V.
MSB of input channel select address
MSB of input channel select address
MSB of input channel select address
MSB of input channel select address
LSB of input channel select address
Individual Output Address Mode (MODE = 0) and
Complete Matrix Mode (MODE = 1) are selected by
toggling a single MODE control pin high or low. Both
modes operate with the same physical board layout.
This allows initial programming of the IC by daisy-
chaining and sending one long data word while still
being able to immediately address and update individ-
ual locations in the matrix.
In Individual Output Address Mode, the devices are
connected in a serial-bus configuration, with the data-
routing gate (Figure 3) connecting DIN to DOUT, mak-
ing each device a virtual node on the serial bus. A
single 16-bit control word is sent to all devices simulta-
neously. Only the device with the corresponding chip
address responds to the programming word and
updates its output. In this mode the chip address is set
through hardware pin strapping of A3–A0. The host
communicates with the device by sending a 16-bit
word consisting of 1 don’t-care bit, 4-chip address bits,
and 11 bits of data to make the word exactly 2 bytes in
length. The 11 data bits are broken down into 4 bits to
select the output to be programmed; 1 bit to set the
output enable, 1 bit to set gain, and 5 bits to the select
the input to be connected to that output. In this method,
the matrix is programmed one output at a time.
I
a daisy-chain fashion where n
program the entire matrix, where n = the number of
MAX4357 devices connected in series. The data word
is structured such that the first bit is the LSB of the last
device in the chain and the last data bit is the MSB of
the first device in the chain. The total length of the data
word is equal to the number of crosspoint devices to be
n Complete Matrix Mode, the devices are connected in
FUNCTION
Individual Output Address Mode
Complete Matrix Mode (Mode = 1)
112 bits are sent to
(Mode = 0)