DS2490Y Maxim Integrated Products, DS2490Y Datasheet - Page 15

• 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

STRONG PULLUP DURATION—This command is used to set the time duration of a 1-Wire strong
pullup. As shown in Table 7, the time is controlled with an unsigned 8-bit binary number between 0x00
and 0xFE which specifies the duration in multiples of 16ms. A value of 0x01 specifies 16ms, 0x02 equals
32ms, etc. A value of 0x00 specifies infinite duration. Parameter value 0xFF is reserved and will cause
the device to deliver a pullup duration of <1μs. To terminate an infinite duration pullup use either the
HALT EXECUTION WHEN DONE or HALT EXECUTION WHEN IDLE Control commands as
described in Appendix 1. The DS2490 power-up default strong pullup duration register value is 512ms.
Strong Pullup Duration Codes Table 7
PULLDOWN SLEW RATE—This command is used to select the pulldown slew rate for 1-Wire bus
Flexible Speed operation; eight pulldown slew rates are possible. The parameter codes to select the
desired or required slew rate are as listed in Table 8. The slew rate numbers in the table represent nominal
values. The nominal pulldown slew rate for Regular speed is 0.83V/s and for Overdrive speeds it is
15V/s. The DS2490 decodes the three LSBs of the slew rate code. Sending a code other than the defined
values in Table 8 will result in undefined behavior. The DS2490 pulldown slew rate power-up default
value for Flexible speed is 0.83V/
Flexible Speed Pulldown Slew Rate Codes Table 8
WRITE-1 LOW TIME—This command is used to select the Write-1 low time for 1-Wire bus Flexible
speed operation; eight Write-1 low time durations are possible. The parameter codes to select the desired
or required low time are as listed in Table 9. The low time numbers in the table represent nominal values.
The nominal Write-1 Low Time for Regular speed is 4s, at Overdrive speed it is 1.4s. The DS2490
decodes the three LSBs of the low time code. Sending a code other than the defined values in Table 9 will
result in undefined behavior. The DS2490 Write-1 Low Time power-up default value for Flexible speed is
8

Value
s.
0xFE
0xFF
0x00
0x01
0x02
…
0x8..0xF
Code
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x7
Nominal Strong Pullup Duration
infinite
16ms
32ms
…
4.064s
reserved

Nominal Pulldown slew rate
s.
2.20V/s
1.65V/s
1.37V/s
1.10V/s
0.83V/s
0.70V/s
0.55V/s
reserved
15V/s
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