Rainbow Electronics MAX4399 - Manual (Page 17)

I 2 C Compatibility
The MAX4399 is compatible with existing I 2 C systems.
SCL and SDA are high-impedance inputs. SDA has an
open drain that pulls the data line low during the 9th
clock pulse.
Figure 8 shows a typical I 2 C interface
application. The communication protocol supports the
standard I
2 C 8-bit communications. The general call
address is ignored, and CBUS formats are not supported.
The MAX4399 address is compatible with the 7-bit I
2 C
addressing protocol only. No 10-bit formats are support-
ed. RESTART protocol is supported, but an immediate
STOP condition is necessary to update the MAX4399.
Digital Inputs and Interface Logic
The I 2 C-compatible, 2-wire interface has logic levels
defined as V OL = 0.8V and V OH = 2.0V. All of the inputs
include Schmitt-trigger buffers to accept slow-transition
interfaces. The digital inputs are compatible with 3V
CMOS logic levels.
INTERRUPT_OUT Signal
INTERRUPT_OUT is an open-drain output that
becomes high impedance when a change in any of the
slow-switch signals occurs. Clear INTERRUPT_OUT by
setting bit 3 of register 04h low.
Data Format of the 2-Wire Interface
Write mode
Read mode
Where S = Start Condition, A = Acknowledge, P = Stop
Condition.
S
Slave
Address
A
Register
Address
A Data A P
S
Slave
Address
A
Register
Address
A Data A P
MAX4399
Audio/Video Switch for Three SCART
Connectors
______________________________________________________________________________________ 17
µC
SDA SCL
R S *
V DD
R S * IS OPTIONAL.
SCL
SDA
V_DIG
MAX4399
SCL
SDA
V DD
OTHER DEVICE #1
SCL
SDA
V DD
OTHER DEVICE #2
Figure 6. Multiple Devices Controlled by a 2-Wire Interface
SCL
SDA
START CONDITION STOP CONDITION
Figure 7. Start and Stop Conditions on a 2-Wire Interface
µC
SDA SCL
V DD
SCL
SDA
V_DIG
MAX4399
SCL
SDA
V DD
OTHER DEVICE #1
SCL
SDA
V DD
OTHER DEVICE #2
Figure 8. A Typical I 2 C Interface Application