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MAX8738
Applications Information
I2C-Bus-Compatible Interface
The MAX8738 is a receive-only device with an I2C
address of 5Eh. The 2-wire, I2C-bus-compatible serial
interface (pins SCL and SDA) is designed to attach to a
I2C bus. Connect both SCL and SDA lines to the positive
bus supply through individual pullup resistors. Calculate
the required value of the pullup resistors using:
where tR is the rise time in the Electrical Char-
acteristics, and CBUS is the total capacitance on the
bus.
The MAX8738 is compatible with the standard I2C inter-
face protocol as defined in the following subsections.
See Figure 6.
Bus Not Busy
The I2C bus is not busy when both data and clock lines
remain HIGH. Data transfers may be initiated only when
the bus is not busy.
START Data Transfer (S)
Starting from an idle bus state (both SDA and SCL are
high), a START condition consists of a HIGH to LOW
transition of the SDA line while the clock (SCL) is HIGH.
All commands must be preceded by a START condition.
STOP Data Transfer (P)
A STOP condition consists of a LOW to HIGH transition
of the SDA line while the clock (SCL) is HIGH. All oper-
ations must be ended with a STOP condition.
R
t
C
PULLUP
R
BUS
≤
EEPROM-Programmable TFT VCOM
Calibrator with I2C Interface
10
______________________________________________________________________________________
MAX8738
AVDD
RSET
R2
R1
VCOM
SET
GND
AVDD
OUT
MAX8738
EQUIVALENT CIRCUIT
MECHANICAL
POTENTIOMETER
RD
RE
RF
R1 = RD
R2 = RF
RSET =
RD x (RD + RE + RF)
20 x RE
Figure 5. Replacement of Mechanical Potentiometer Circuit
SCL
SDA
START
CONDITION
S
STOP
CONDITION
P
DATA LINE
STABLE
DATA VALID
CHANGE
OF DATA
ALLOWED
Figure 6. I2C Bus START, STOP, and Data Change Conditions