DS24B33G+T&R【PDF 17/23 页】IC EEPROM 4KBIT 2SFN

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DS24B33

1-Wire 4Kb EEPROM

1-Wire Signaling

The DS24B33 requires strict protocols to ensure data

integrity. The protocol consists of four types of signaling

on one line: reset sequence with reset pulse and pres-

ence pulse, write-zero, write-one, and read-data.

Except for the presence pulse, the bus master initiates

all falling edges. The DS24B33 can communicate at

two different speeds: standard speed and overdrive

speed. If not explicitly set into the overdrive mode, the

DS24B33 communicates at standard speed. While in

overdrive mode the fast timing applies to all waveforms.

To get from idle to active, the voltage on the 1-Wire line

needs to fall from V PUP below the threshold V TL . To get

from active to idle, the voltage needs to rise from

V ILMAX past the threshold V TH . The time it takes for the

voltage to make this rise is seen in Figure 10 as ε , and

its duration depends on the pullup resistor (R PUP ) used

and the capacitance of the 1-Wire network attached.

The voltage V ILMAX is relevant for the DS24B33 when

determining a logical level, not triggering any events.

Figure 10 shows the initialization sequence required to

begin any communication with the DS24B33. A reset

pulse followed by a presence pulse indicates that the

DS24B33 is ready to receive data, given the correct

ROM and memory function command. If the bus master

uses slew-rate control on the falling edge, it must pull

down the line for t RSTL + t F to compensate for the edge.

A t RSTL duration of 480μs or longer exits the overdrive

mode, returning the device to standard speed. If the

DS24B33 is in overdrive mode and t RSTL is no longer

than 80μs, the device remains in overdrive mode. If the

device is in overdrive mode and t RSTL is between 80μs

and 480μs, the device resets, but the communication

speed is undetermined.

MASTER Tx "RESET PULSE"

V PUP

V IHMASTER

V TH

V TL

V ILMAX

ε

After the bus master has released the line it goes into

receive mode. Now the 1-Wire bus is pulled to V PUP

through the pullup resistor, or in case of a DS2482-x00

or DS2480B driver, by active circuitry. When the thresh-

old V TH is crossed, the DS24B33 waits for t PDH and

then transmits a presence pulse by pulling the line low

for t PDL . To detect a presence pulse, the master must

test the logical state of the 1-Wire line at t MSP .

The t RSTH window must be at least the sum of t PDHMAX ,

t PDLMAX , and t RECMIN . Immediately after t RSTH is

expired, the DS24B33 is ready for data communication.

In a mixed population network, t RSTH should be extend-

ed to minimum 480μs at standard speed and 48μs at

overdrive speed to accommodate other 1-Wire devices.

Read/Write Time Slots

Data communication with the DS24B33 takes place in

time slots, which carry a single bit each. Write time slots

transport data from bus master to slave. Read time

slots transfer data from slave to master. Figure 11 illus-

trates the definitions of the write and read time slots.

All communication begins with the master pulling the

data line low. As the voltage on the 1-Wire line falls

below the threshold V TL , the DS24B33 starts its internal

timing generator that determines when the data line is

sampled during a write time slot and how long data is

valid during a read time slot.

Master-to-Slave

For a write-one time slot, the voltage on the data line

must have crossed the V TH threshold before the write-

one low time t W1LMAX is expired. For a write-zero time

slot, the voltage on the data line must stay below the

V TH threshold until the write-zero low time t W0LMIN is

expired. For the most reliable communication, the

MASTER Rx "PRESENCE PULSE"

t MSP

0V

t RSTL

t PDH

t PDL

t REC

t F

t RSTH

RESISTOR

Figure 10. Initialization Procedure: Reset and Presence Pulse

Maxim Integrated

MASTER

DS24B33

17

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相关代理商/技术参数

DS24B33G+U 功能描述:电可擦除可编程只读存储器 1-WIRE 4KB 电可擦除可编程只读存储器 RoHS:否制造商:Atmel 存储容量:2 Kbit 组织:256 B x 8 数据保留:100 yr 最大时钟频率:1000 KHz 最大工作电流:6 uA 工作电源电压:1.7 V to 5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8

DS24B33Q+T&R 制造商:Maxim Integrated Products 功能描述:1-WIRE 4KB EEPROM - Tape and Reel 制造商:Maxim Integrated Products 功能描述:IC EEPROM 4KBIT 6TDFN 制造商:Maxim Integrated Products 功能描述:EEPROM 1-Wire 4kbit EEPROM

DS24B33Q+T&R 功能描述:电可擦除可编程只读存储器 1-Wire 4kbit 电可擦除可编程只读存储器 RoHS:否制造商:Atmel 存储容量:2 Kbit 组织:256 B x 8 数据保留:100 yr 最大时钟频率:1000 KHz 最大工作电流:6 uA 工作电源电压:1.7 V to 5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8

DS24B33Q+U 功能描述:电可擦除可编程只读存储器 1-WIRE 4KB 电可擦除可编程只读存储器 RoHS:否制造商:Atmel 存储容量:2 Kbit 组织:256 B x 8 数据保留:100 yr 最大时钟频率:1000 KHz 最大工作电流:6 uA 工作电源电压:1.7 V to 5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8

DS24B33S 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:1-Wire 4Kb EEPROM

DS24B33S R 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:1-Wire 4Kb EEPROM

DS24B33S T 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:1-Wire 4Kb EEPROM

DS24B33S TR 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:1-Wire 4Kb EEPROM