DS2490Y Maxim Integrated Products, DS2490Y Datasheet - Page 29

• 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

DEVICE FEEDBACK
DS2490 state and result feedback are provided to the host over the EP1 interrupt pipe. The host interrupt
polling period for EP1 transfers is controlled by the alternate setting of the 1-Wire USB Interface as
described in the section: 1-Wire Interface Summary Description. As shown in Table 15, up to 32 bytes of
feedback data are returned. As a minimum, 16 bytes of STATE REGISTER data will be delivered at each
polling interval (or USB IN transaction to EP1); the position and definition of these data values are listed
in Table 16. In addition, as shown in Table 17, between 0 and 16 extra bytes of RESULT REGISTER
data will be delivered with feedback data. This consists of communication command processing result
data as controlled by the embedded communication command bits ICP and NTF and notification bytes for
1-Wire device arrival detection. If there are less than 32 bytes of result and state register data to return,
the DS2490 will terminate the IN transaction with a short or zero data packet.
Data is loaded into the RESULT REGISTER buffer based on embedded communication command bits
NTF and ICP or upon detection of a 1-Wire device attachment. There is no defined offset position for
data values in this buffer. Knowledge of communication command ordering sent to the DS2490 must be
maintained on the host to properly interpret the returned data values. In addition, a parse of the data is
required to determine whether or not a 1-Wire detect value is included; the value of the 1-Wire detect
byte is unique. Table 18 defines the 1-Wire detect byte and data values that result from Communication
command processing.
Interrupt Transfer Data Summary Table 15
Notes:
1. The number of RESULT RESIGTER values will vary depending on the setting of embedded
DS2490 STATE REGISTERS Table 16
Description
Enable Flags
1-Wire Speed
Strong Pullup Duration
(Reserved)
Pulldown Slew Rate
Control
communication command bits NTF and ICP, the number of communication commands processed
since the previous EP1 polling period, or whether a 1-Wire device was detected.
0x10 to 0x1F
0x00 to 0x0F
OFFSET
1
Offset
0x00
0x01
0x02
0x03
0x04
RESULT REGISTERS
STATE REGISTERS
current 1-Wire bus speed code
current pullup duration
current pulldown slew rate code
bit7
bit 3..7 These bits are reserved.
--
SPUE If set to 1, the strong pullup to 5V is enabled, if set to 0,
SPCE If set to 1, a dynamic 1-Wire bus speed change through a
DATA
bit6 bit5
--
it is disabled.
Communication command is enabled, if set to 0, it is
disabled.
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--
bit4
--
bit3
--
Data
SPCE
bit2
bit1
0
SPUE
bit0