DS2490 View Datasheet(PDF) - Dallas Semiconductor -> Maxim Integrated

Part Name

Description

Manufacturer

DS2490

USB to 1-WireTM Bridge Chip

Dallas Semiconductor -> Maxim Integrated 

USB TRANSCEIVER

OSCILLATOR

SUSPEND OUTPUT

ELECTRICAL CHARACTERISTICS

APPLICATION INFORMATION

APPENDIX 1

APPENDIX 2

APPENDIX 3

APPENDIX 4

DS2490

Transceiver connection requirements

Oscillator connection requirements

SUSO signal operation and purpose

DC and AC specifications

HW and SW application information

CONTROL COMMANDS – USB setup packet encoding

COMMUNICATION COMMANDS - USB setup packet

encoding

MODE COMMANDS - USB setup packet encoding

USB command and command type constant codes

OVERVIEW

The DS2490 directly interfaces a USB port to a 1-Wire bus. As shown in Figure 1, the DS2490

incorporates a USB physical interface, a USB device controller coupled with a 1-Wire specific USB

function core, and a 1-Wire bus interface controller. The 1-Wire interface controller shapes the slopes of

the 1-Wire wave-forms, 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. 1-Wire waveform timing is accurately controlled with a crystal-based oscillator.

The DS2490 also supports USB remote wakeup which enables the DS2490 based USB peripheral to send

resume signaling to a suspended host system. If the remote wakeup function is enabled and the host

system is in a suspended state, a 1-Wire device attachment will cause the DS2490 to perform a host

system wakeup and allow the 1-Wire device to be serviced.

DS2490 FUNCTIONAL BLOCK DIAGRAM Figure 1

SUSO

D+

D-

USB

XCVR

USB

DESC

ROM

USB

DEVICE

CONTROLLER

USB

1-WIRE

FUNCTION

CORE

EP

FIFOS

1-WIRE

I/F

CONTROLLER

1-WIRE

PWR

VB

CLK

CNTL

OSC

GEN

VD

XI XO

GND

VPP

Typical application examples of the DS2490 are shown in Figure 2 (a-c). As shown in all the examples,

all host control and communication with the device is accomplished over a USB communication link. A

USB vendor-specific command set, as defined in this document, is used to select operational modes

(MODE commands), control command processing (CONTROL commands), and communicate over the

1-Wire interface (COMMUNICATION commands). Shown in Figure 2 example (a) is a DS2490 based

USB peripheral application. The peripheral function is a USB to 1-Wire adapter and provides both USB

and 1-Wire I/O connections. In this example the peripheral is attached to the USB enabled host computer

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