DS2490Y Maxim Integrated Products, DS2490Y Datasheet - Page 9

• Manufacturer Part Number: DS2490Y
• Description: IC BRIDGE CLIP USB TO 1-W 24SOIC
• Manufacturer: Maxim Integrated Products

Specifications of DS2490Y

• Applications: USB
• Interface: 1-Wire
• Voltage - Supply: 3 V ~ 5.5 V
• Package / Case: 24-SOIC (7.5mm Width)
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

DS2490
Pulse Wave Forms
The PULSE COMMUNICATION COMMAND can be used to generate a strong pullup to 5V. The
duration of the pulses is specified with the STRONG PULLUP DURATION mode register. Figure 8
shows timing of the pulse. For predefined pulse durations, t
is a known value, for semi-infinite and
SPU
infinite durations these pulse times vary and depend on the characteristics of attached 1-Wire devices
and/or host processor intervention. See the MODE COMMAND section for details on duration times. As
shown in the figure, at t
processing of the PULSE command begins, at t
the pulse ends.
1
2
Certain applications may require a duration for a strong pullup that cannot be realized using one of the
predefined values (see MODE COMMANDS section for values). Selecting infinite duration allows the
host to generate pulses of any length. As a consequence, however, the host becomes responsible to
actively control the duration of the pulse. Failing to do so may require a power-on reset or master-reset
cycle of the DS2490. For this reason, infinite duration should only be used if absolutely necessary. The
HALT EXECUTION WHEN DONE or HALT EXECUTION WHEN IDLE control commands are used
to terminate an infinite duration pulse.
STRONG PULLUP TO 5V, PRE-DEFINED DURATION Figure 8
USB COMMUNICATION
Communication with the DS2490 is performed using USB standard requests, also referred to as core
commands or requests in this document, and DS2490 vendor specific USB commands. All command
communication with the DS2490 is performed over the default control pipe. Non-command
communication, including 1-Wire device data I/O and DS2490 status information, occurs in a vendor-
specific fashion over bulk and interrupt pipes. Configuration of the DS2490 USB controller is shown in
Figure 9. As shown, a Dallas Semiconductor vendor-specific 1-Wire device exists with a single 1-Wire
interface. The USB vendor-specific 1-Wire function of the DS2490 will be implemented and controlled
by the device driver at the device level of the device class hierarchy, i.e, vendor-specific commands, will
be directed to the device level. Within the 1-Wire interface, four endpoints exist to control and
communicate with the device. Four alternate settings of the 1-Wire interface exist that correspond to
different operating modes for the endpoints. Endpoint and interface descriptions are summarized in the
following paragraphs.
The DS2490 provides USB remote wake-up capability. Per the USB specification, if a device supports
remote wake-up, it must also provide the ability to enable or disable the remote wake-up function. In
addition, the remote wake-up feature must be disabled as the power up default or device reset state. When
the remote wake-up feature is enabled, the DS2490 will send USB resume signaling to a suspended host
system upon detecting a 1-Wire device attachment. It then becomes the responsibility of host system
software to resume operation and to determine what servicing is required for the 1-Wire device.
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