DS2406P datasheet(30/30 Pages) DALLAS

30 / 30 page

DS2406

30 of 30

PIO SINK CURRENT

10 mA

20 mA

30 mA

40 mA

50 mA

60 mA

70 mA

80 mA

90 mA

100 mA

I SA , I SB

@ 0.4V

VPUP

PIO-B

max.

min.

PIO-A

max.

min.

2.8V

NOTES:

1. All voltages are referenced to ground.

2. VPUP, VPUPA, VPUPB = external pull-up voltage.

3. Input load is to ground.

4. An additional reset or communication sequence cannot begin until the reset high time has expired.

5. Read data setup time refers to the time the host must pull the 1-Wire bus low to read a bit. Data is

guaranteed to be valid within 1 µs of this falling edge and will remain valid for 14 µs minimum (15

µs total from falling edge on 1-Wire bus).

6. VIH is a function of the chip-internal supply voltage. This voltage is determined by either the external

pull-up resistor and VPUP or the VCC supply, whichever is higher. Without VCC supply, VIH for either

PIO pin should always be greater than or equal to VPUP -0.3V.

7. Capacitance on the data pin could be 800 pF when power is first applied. If a 5 k

Ω resistor is used to

pull up the data line to VPUP, 5 µs after power has been applied the parasite capacitance will not affect

normal communications.

8. tRSTL should be limited to maximum 5 ms. Otherwise a parasitically powered DS2406 may perform a

power-on reset.

9. Input resistance is to ground.

10. VCC must be at least 4.0V if it is to be connected during a programming pulse.

11. If the current at PIO-A reaches 200 mA the gate voltage of the output transistor will be reduced to

limit the sink current to 200 mA. The user-supplied circuitry should limit the current flow through the

PIO-transistor to no more than 100 mA. Otherwise the DS2406 may be damaged.

12. PIO-A has a controlled turn-on output. The indicated currents are DC values. At VPUP = 4.0V or

higher the sink current typically reaches 80% of its DC value 1 µs after turning on the transistor.

13. Under certain low voltage conditions VILMAX may have to be reduced to as much as 0.5V to always

guarantee a presence pulse.

14. The accumulative duration of the programming pulses for each address must not exceed 5 ms.

15. The optimal sampling point for the master is as close as possible to the end time of the 15

µs t

RDV

period without exceeding tRDV. For the case of a Read-one time slot, this maximizes the amount of

time for the pull-up resistor to recover the line to a high level. For a Read-zero time slot it ensures

that a read will occur before the fastest 1-Wire devices(s) release the line (tRELEASE = 0).

DS2406P 数据表(PDF) 30 Page - Dallas Semiconductor

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