DS2480B

DS2480B Datasheet

DS2480B

Part	Datasheet
DS2480B	DS2480B (pdf)

PDF Datasheet Preview
DS2480B Serial 1-Wire Line Driver with Load Sensor § Universal, Common-Ground Serial Port to Line Driver for MicroLAN Applications § Works with All and MicroLAN- Compatible 1-Wire Slave Devices § Communicates at Regular and Overdrive 1- Wire speed and Serial Port Data Rates of 9600 default , 19200, 57600, and 115200 bps § Supports 12V EPROM Programming and Stiff 5V Pullup for Crypto iButton, Sensors and EEPROM § Load Sensor to Terminate the Stiff Pullup as the Energy Demand of the Crypto iButton Drops § Self-Calibrating Time Base with ±5% Tolerance for Serial and 1-Wire Communication § Slew Rate Controlled 1-Wire Pulldown and Active Pullup to Accommodate Long Lines and Reduce Radiation § User-Selectable RXD/TXD Polarity Minimizes Component Count When Interfacing to 5V Based RS232 Systems or Directly to UARTs § Programmable 1-Wire Timing and Driver Characteristics Accommodate a Wide Range of MicroLAN Configurations at Regular Speed § Smart Protocol Combines Data and Control Information Without Requiring Extra Pins § Compatible with Optical, IR, and RF to RS232 Converters § Low-Cost 8-Pin SO Surface-Mount Package § Operates Over 4.5V to 5.5V from -40°C to +85°C PIN ASSIGNMENT 8-Pin SO 150 mil PIN DESCRIPTION - Ground - 1-Wire Input/Output - No Connection - 4.5V to 5.5V - Optional EPROM Programming Voltage - RXD/TXD Polarity Select - Serial Data from UART - Serial Data to UART ORDERING INFORMATION DS2480B 8-pin SO DS2480B/T&R Tape-and-Reel Version of the DS2480B The DS2480B is a serial port to 1-Wire interface chip that supports regular and overdrive speeds. It connects directly to UARTs and 5V RS232 systems. Interfacing to RS232C ±12V levels requires a passive clamping circuit and one 5V to ±12V level translator. Internal timers relieve the host of the burden of generating the time-critical 1-Wire communication waveforms. In contrast to the DS9097 E where a full 1-Wire and iButton are registered trademarks of Dallas Semiconductor. 1 of 31 082004 DS2480B character must be sent by the host for each 1-Wire time slot, the DS2480B can translate each character into eight 1-Wire time slots, thereby increasing the data throughput significantly. In addition, the DS2480B can be set to communicate at four different data rates, including 115.2kbps, 57.6kbps, and 19.2kbps, with 9.6kbps being the power-on default. Command codes received from the host’s crystal controlled UART serve as a reference to continuously calibrate the on-chip timing generator. The DS2480B uses a unique protocol that merges data and control information without requiring control pins. This approach maintains compatibility to off-the-shelf serial to wireless converters, allowing easy realization of 1-Wire media jumpers. The various control functions of the DS2480B are optimized for MicroLAN 1-Wire networks and support the special needs of all current 1-Wire devices including the crypto iButton, EPROM-based add-only memories, EEPROM devices, and 1-Wire thermometers. See Application Note 192 Using the DS2480B Serial 1-Wire Driver for detailed software examples. DETAILED PIN DESCRIPTION PIN SYMBOL DESCRIPTION GND Ground Pin. Common ground reference and ground return for 1-Wire bus 1-Wire Input/Output Pin. 1-Wire bus with slew-rate-controlled pulldown, active pullup, ability to switch in VPP to program EPROM, and ability to switch in VDD through a low-impedance path to program EEPROM, perform a temperature conversion, or operate the crypto iButton. N.C. No Connection Power Input Pin. Power supply for the chip and 1-Wire pullup voltage, 5V VDD ±10%, must always be lower than or equal to VPP. VDD should be derived from VPP by a separate voltage regulator whenever possible. EPROM Programming Voltage. 12V supply input for EPROM programming. If EPROM programming is not required, connect this pin directly to the system’s 5V supply. RXD/TXD Polarity Select. RXD/TXD polarity select tied to GND for RS232 12V or 5V connection tied to VDD for direct connection to UART chip. Serial Data from UART. Data input from host inverted or true maximum voltage swing -0.3V to VDD + 0.3V for logic thresholds see DC specifications. Serial Data to UART. Signal output to host push-pull driver with CMOS RXD compatible levels for true ±12V RS232 systems an external level translator must be provided. OVERVIEW The DS2480B directly interfaces a 5V serial communication port with its lines TXD transmit and RXD receive to a 1-Wire bus. In addition the device performs a speed conversion allowing the data rate at the communication port to be different from the 1-Wire data rate. Several parameters relating to the 1-Wire port and its timing as well as the communication speed at both the port and the 1-Wire bus are configurable. The circuit to achieve these functions is outlined in the block diagram see Figure The device gets its input data from the serial communication port of the host computer through pin TXD. For compatibility with active-high as well as active-low systems, the incoming signal can be inverted by means of the polarity input POL. The polarity chosen by hard-wiring the logic level of this pin is also valid for the output pin RXD. If for minimizing the interface hardware an asymmetry between RXD and TXD is desired, this can be achieved by setting the most significant bit of the speed control parameter to a 1 see Configuration Parameter Value Codes . With the MS bit of the speed control set to 1, the polarity at TXD is still selected by the logic level at POL, but the polarity at RXD will be the opposite of what the logic level at POL specifies. 2 of 31 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 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 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 VDD operating voltage at which calibration is performed. Post-calibration changes in VDD by more than 5% may cause calibration error to exceed 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. 3 of 31

PDF Datasheet Preview

DS2480B

Serial 1-Wire Line Driver with Load Sensor
§ Universal, Common-Ground Serial Port to Line Driver for MicroLAN

Applications § Works with All and MicroLAN-

Compatible 1-Wire Slave Devices § Communicates at Regular and Overdrive 1-

Wire speed and Serial Port Data Rates of
9600 default , 19200, 57600, and 115200 bps § Supports 12V EPROM Programming and

Stiff 5V Pullup for Crypto iButton, Sensors
and EEPROM § Load Sensor to Terminate the Stiff Pullup as
the Energy Demand of the Crypto iButton

Drops § Self-Calibrating Time Base with ±5%

Tolerance for Serial and 1-Wire

Communication § Slew Rate Controlled 1-Wire Pulldown and

Active Pullup to Accommodate Long Lines
and Reduce Radiation § User-Selectable RXD/TXD Polarity

Minimizes Component Count When

Interfacing to 5V Based RS232 Systems or

Directly to UARTs § Programmable 1-Wire Timing and Driver

Characteristics Accommodate a Wide Range
of MicroLAN Configurations at Regular

Speed § Smart Protocol Combines Data and Control

Information Without Requiring Extra Pins § Compatible with Optical, IR, and RF to

RS232 Converters § Low-Cost 8-Pin SO Surface-Mount Package § Operates Over 4.5V to 5.5V from -40°C to
+85°C

PIN ASSIGNMENT
8-Pin SO 150 mil

PIN DESCRIPTION
- Ground
- 1-Wire Input/Output
- No Connection
- 4.5V to 5.5V
- Optional EPROM

Programming Voltage
- RXD/TXD Polarity Select
- Serial Data from UART
- Serial Data to UART
ORDERING INFORMATION

DS2480B
8-pin SO

DS2480B/T&R

Tape-and-Reel Version of
the DS2480B

The DS2480B is a serial port to 1-Wire interface chip that supports regular and overdrive speeds. It connects directly to UARTs and 5V RS232 systems. Interfacing to RS232C ±12V levels requires a passive clamping circuit and one 5V to ±12V level translator. Internal timers relieve the host of the burden of generating the time-critical 1-Wire communication waveforms. In contrast to the DS9097 E where a full
1-Wire and iButton are registered trademarks of Dallas Semiconductor.
1 of 31
082004

DS2480B
character must be sent by the host for each 1-Wire time slot, the DS2480B can translate each character into eight 1-Wire time slots, thereby increasing the data throughput significantly. In addition, the DS2480B can be set to communicate at four different data rates, including 115.2kbps, 57.6kbps, and 19.2kbps, with 9.6kbps being the power-on default. Command codes received from the host’s crystal controlled UART serve as a reference to continuously calibrate the on-chip timing generator. The DS2480B uses a unique protocol that merges data and control information without requiring control pins. This approach maintains compatibility to off-the-shelf serial to wireless converters, allowing easy realization of 1-Wire media jumpers. The various control functions of the DS2480B are optimized for MicroLAN 1-Wire networks and support the special needs of all current 1-Wire devices including the crypto iButton, EPROM-based add-only memories, EEPROM devices, and 1-Wire thermometers. See Application Note 192 Using the DS2480B Serial 1-Wire Driver for detailed software examples.

DETAILED PIN DESCRIPTION

PIN SYMBOL DESCRIPTION

GND Ground Pin. Common ground reference and ground return for 1-Wire bus
1-Wire Input/Output Pin. 1-Wire bus with slew-rate-controlled pulldown,
active pullup, ability to switch in VPP to program EPROM, and ability to switch in VDD through a low-impedance path to program EEPROM, perform a
temperature conversion, or operate the crypto iButton.

N.C. No Connection

Power Input Pin. Power supply for the chip and 1-Wire pullup voltage, 5V

VDD ±10%, must always be lower than or equal to VPP. VDD should be derived from

VPP by a separate voltage regulator whenever possible.

EPROM Programming Voltage. 12V supply input for EPROM programming.

If EPROM programming is not required, connect this pin directly to the system’s
5V supply.

RXD/TXD Polarity Select. RXD/TXD polarity select tied to GND for RS232 12V or 5V connection tied to VDD for direct connection to UART chip.

Serial Data from UART. Data input from host inverted or true maximum voltage swing -0.3V to VDD + 0.3V for logic thresholds see DC specifications.

Serial Data to UART. Signal output to host push-pull driver with CMOS

RXD compatible levels for true ±12V RS232 systems an external level translator must
be provided.

OVERVIEW

The DS2480B directly interfaces a 5V serial communication port with its lines TXD transmit and RXD receive to a 1-Wire bus. In addition the device performs a speed conversion allowing the data rate at the communication port to be different from the 1-Wire data rate. Several parameters relating to the 1-Wire port and its timing as well as the communication speed at both the port and the 1-Wire bus are configurable. The circuit to achieve these functions is outlined in the block diagram see Figure

The device gets its input data from the serial communication port of the host computer through pin TXD. For compatibility with active-high as well as active-low systems, the incoming signal can be inverted by means of the polarity input POL. The polarity chosen by hard-wiring the logic level of this pin is also valid for the output pin RXD. If for minimizing the interface hardware an asymmetry between RXD and TXD is desired, this can be achieved by setting the most significant bit of the speed control parameter to a 1 see Configuration Parameter Value Codes . With the MS bit of the speed control set to 1, the polarity at TXD is still selected by the logic level at POL, but the polarity at RXD will be the opposite of what the logic level at POL specifies.
2 of 31

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 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 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 VDD operating voltage at which calibration is performed. Post-calibration changes in VDD by more than 5% may cause calibration error to exceed 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.
3 of 31

Notice: we do not provide any warranties that information, datasheets, application notes, circuit diagrams, or software stored on this website are up-to-date or error free. The archived DS2480B Datasheet file may be downloaded here without warranties.

Datasheet ID: DS2480B 647171