DS3502 データシートの表示（PDF） - Maxim Integrated
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DS3502 Datasheet PDF : 11 Pages
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High-Voltage, NV, I2C POT
TYPICAL I2C WRITE TRANSACTION
MSB
LSB
MSB
LSB
MSB
LSB
START 0 1 0 1 0 A1 A0 R/W SLAVE b7 b6 b5 b4 b3 b2 b1 b0 SLAVE b7 b6 b5 b4 b3 b2 b1 b0 SLAVE STOP
ACK
ACK
ACK
SLAVE
ADDRESS*
READ/
WRITE
REGISTER ADDRESS
DATA
*THE SLAVE ADDRESS IS DETERMINED BY ADDRESS PINS A0 AND A1.
EXAMPLE I2C TRANSACTIONS (WHEN A0 AND A1 ARE CONNECTED TO GND).
A) SINGLE-BYTE WRITE
REGISTER 00h
50h
00h
START 0 1 0 1 0 0 0 0 SLAVE 0 0 0 0 0 0 0 0 SLAVE
DATA
ACK
ACK
SLAVE STOP
ACK
B) SINGLE-BYTE READ
-READ CR REGISTER
50h
02h
51h
START
0 1010000
SLAVE
ACK
00000 010
SLAVE
ACK
REPEATED 0 1 0 1 0 0 0 1 SLAVE
START
ACK
DATA
MASTER
NACK
STOP
Figure 3. I2C Communication Examples
Manipulating the address counter for reads: A
dummy write cycle can be used to force the address
counter to a particular value. To do this the master gen-
erates a START condition, writes the slave address
byte (R/W = 0), writes the memory address where it
desires to read, generates a repeated START condi-
tion, writes the slave address byte (R/W = 1), reads
data with ACK or NACK as applicable, and generates a
STOP condition.
See Figure 3 for a read example using the repeated
START condition to specify the starting memory location.
Applications Information
Power-Supply Decoupling
To achieve the best results when using the DS3502,
decouple both the power-supply pin (VCC) and the
wiper-bias voltage pin (V+) with a 0.01µF or 0.1µF
capacitor. Use a high-quality ceramic surface-mount
capacitor if possible. Surface-mount components mini-
mize lead inductance, which improves performance,
and ceramic capacitors tend to have adequate high-
frequency response for decoupling applications.
SDA and SCL Pullup Resistors
SDA is an I/O with an open-collector output that
requires a pullup resistor to realize high-logic levels. A
master using either an open-collector output with a
pullup resistor or a push-pull output driver must be
used for SCL. Pullup resistor values should be chosen
to ensure that the rise and fall times listed in the I2C AC
Electrical Characteristics are within specification. A typ-
ical value for the pullup resistors is 4.7kΩ.
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