Rainbow Electronics DS1990A User Manual
Page 10
DS1990A
10 of 10
NOTES:
1. All voltages are referenced to ground.
2. V
PUP
= external pullup 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
µ
s of this falling edge and will remain valid for 14
µ
s minimum. (15
µ
s total from falling edge on 1-Wire bus.)
6. V
IH
is a function of the external pullup resistor and the V
CC
supply.
7. 30 nanocoulombs per 72 time slots @ 5.0V.
8. At V
CC
=5.0V with a 5 k
Ω
pullup to V
CC
and a maximum time slot of 120
µ
s.
9. Capacitance on the I/O pin could be 800 pF when power is first applied. If a 5 k
Ω
resistor is used to
pull up the I/O line to V
CC
, 5
µ
s after power has been applied the parasite capacitance will not affect
normal communications.
10. The reset low time (t
RSTL
) should be restricted to a maximum of 960
µ
s, to allow interrupt signaling,
otherwise, it could mask or conceal interrupt pulses if this device is used in parallel with a DS1994.