DS2480B Maxim Integrated Products, DS2480B Datasheet - Page 3

• Manufacturer Part Number: DS2480B
• Description: IC LINE DRVR W/SENSOR 1-W 8-SOIC
• Manufacturer: Maxim Integrated Products
• Type: Line Driver, Transmitterr

Specifications of DS2480B

• Number Of Drivers/receivers: 1/0
• Protocol: RS232
• Voltage - Supply: 4.5 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

DS2480B
As data enters the core of the DS2480B’s logic circuitry, it is analyzed to separate data and command
bytes and to calibrate the device’s timing generator. The timing generator controls all speed relations of
the communication interface and the 1-Wire bus as well as the waveforms on the 1-Wire bus.
Command bytes either affect the configuration setting or generate certain waveforms on the 1-Wire bus.
Data bytes are simply translated by the protocol converter into the appropriate 1-Wire activities. Each
data byte generates a return byte from the 1-Wire bus that is communicated back to the host through the
RXD pin as soon as the activity on the 1-Wire bus is completed.
The 1-Wire driver shapes the slopes of the 1-Wire waveforms, applies programming pulses or strong
pullup to 5V and reads the 1-Wire bus using a non-TTL threshold to maximize the noise margin for best
performance on large 1-Wire MicroLAN networks.
Figure 1. DS2480B BLOCK DIAGRAM
DEVICE OPERATION
The DS2480B can be described as a complex state machine with two static and several dynamic states.
Two device-internal flags as well as functions assigned to certain bit positions in the command codes
determine the behavior of the chip, as shown in the state transition diagram (Figure 2). The DS2480B
requires and generates a communication protocol of 8 data bits per character, 1 stop bit and no parity. It is
permissible to use 2 stop bits on the TXD line. However, the DS2480B only asserts a single stop bit on
RXD.
When powering up, the DS2480B performs a master reset cycle and enters the Command Mode, which is one of the two
static states. The device now expects to receive one 1-Wire reset command on the TXD line sent by the host at a data rate of
9600bps (see Communication Commands section for details). This command byte is required solely for calibration of the baud
rate timing generator the DS2480B and is not translated into any activity on the 1-Wire bus. After this first command byte the
device is ready to receive and execute any command as described later in this document. NOTE: Baud rate calibration is valid
only for the V
operating voltage at which calibration is performed. Post-calibration changes in V
by more than 5% may
DD
DD
cause calibration error to exceed ±5%. The DS2480B requires a 1-Wire reset command sent by the host at a data rate of
9600bps for calibration. Data rates of 115200bps or higher during calibration may put the DS2480 in an undefined state,
requiring a power-down reset to restore normal operation.
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