MAX4397 MAXIM [Maxim Integrated Products], MAX4397 Datasheet - Page 17

• Manufacturer Part Number: MAX4397
• Description: Audio/Video Switch For Dual SCART Connectors
• Manufacturer: MAXIM [Maxim Integrated Products]

Write and Read Mode
S = Start Condition, A = Acknowledge, P = Stop Condition
The MAX4397 is compatible with existing I
SCL and SDA are high-impedance inputs. SDA has an
open drain that pulls the bus line to a logic-low during
the 9th clock pulse. Figure 6 shows a typical I
face application. The communication protocol supports
the standard I
address is compatible with the 7-bit I
protocol only; 10-bit format is not supported.
The I
defined as V
include Schmitt-trigger buffers to accept low-transition
interfaces. The digital inputs are compatible with 3V
CMOS logic levels.
Figure 6. Typical I
Audio/Video Switch for Dual SCART Connectors
S
2
Address
C-compatible, 2-wire interface has logic levels
Slave
SDA
Digital Inputs and Interface Logic
IL
µC
2
= 0.8V and V
C 8-bit communications. The MAX4397
SCL
2
C Interface Application
A
______________________________________________________________________________________
Register
Address
2-Wire Interface Data Format
IH
SDA
SDA
SDA
SCL
SCL
SCL
= 2.0V. All of the inputs
A
I
MAX4397
DEVICE 1
DEVICE 2
2
C Compatibility
Data2
2
V
V
V
VID
C addressing
DD
DD
2
C systems.
2
A
C inter-
P
Connect DEV_ADDR to ground to set the MAX4397
write and read address as shown in Table 2.
Program the SCART video and audio switches by writ-
ing to registers 00h through 0Eh. Registers 00h through
0Eh can also be read, allowing read-back of data after
programming and facilitating system debugging. The
status register is read-only and can be read from
address 0Eh. See Tables 3–12 for register program-
ming information.
The MAX4397 features high-ESD protection on all
SCART inputs and outputs, and requires no external
transient-voltage suppressor (TVS) devices to protect
against floating chassis discharge. Some set-top boxes
have a floating chassis problem in which the chassis is
not connected to earth ground. As a result, the chassis
can charge up to 500V. When a SCART cable is con-
nected to the SCART connector, the charged chassis
can discharge through a signal pin. The equivalent cir-
cuit is a 2200pF capacitor charged to 311V connected
through less than 0.1Ω to a signal pin. The MAX4397 is
soldered on the PC board when it experiences such a
discharge. Therefore, the current spike flows through
the ESD protection diodes and is absorbed by the sup-
ply bypass capacitors, which have high capacitance
and low ESR.
To better protect the MAX4397 against excess voltages
during the cable discharge condition, place an addi-
tional 75Ω resistor in series with all inputs and outputs
to the SCART connector. For harsh environments where
±15kV protection is needed, the MAX4385E and
MAX4386E single and quad high-speed op amps fea-
ture the industry’s first integrated ±15kV ESD protection
on video inputs and outputs.
Table 2. Slave Address Programming
ADDRESS PIN
GNDVID
STATE
V
VID
Data Register Writing and Reading
Applications Information
Hot-Plug of SCART Connectors
ADDRESS
WRITE
96h
94h
Programming
READ ADDRESS
97h
95h
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