Philips Semiconductors
ISP1122
USB stand-alone hub
Product specification
Rev. 03 — 29 March 2000
37 of 48
9397 750 07002
© Philips Electronics N.V. 2000. All rights reserved.
[1]
f
SCL
=
1
⁄
64
f
XTAL
.
[2]
Rise time is determined by C
b
and pull-up resistor value R
p
(typ. 4.7 k
Ω
).
Full-speed timing symbols have a subscript prefix ‘F’, low-speed timings a prefix ‘L’.
Fig 20. Hub EOP delay and EOP skew.
handbook, full pagewidth
MGR778
tEOP
+
tEOP
−
tEOP
+
tEOP
−
crossover
point
extended
crossover
point
extended
EOP delay:
tEOP = max (tEOP
−
, tEOP
+
)
EOP delay relative to tHDD:
tEOPD = tEOP
−
tHDD
EOP skew:
tHESK = tEOP
+
−
tEOP
−
(A) downstream EOP delay
(B) upstream EOP delay
upstream
differential
data lines
downstream
port
crossover
point
extended
crossover
point
extended
upstream
end of cable
downstream
differential
data lines
+
3.3 V
0 V
+
3.3 V
0 V
Table 34: Dynamic characteristics: I
2
C-bus pins (SDA, SCL)
V
CC
and T
amb
within recommended operating range; V
DD
=
+5 V; V
SS
= V
GND
; V
IL
and V
IH
between V
SS
and V
DD
.
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
f
SCL
SCL clock frequency
f
XTAL
= 6 MHz
0
93.75
100
kHz
t
BUF
bus free time
4.7
-
-
µ
s
t
SU;STA
START condition set-up time
250
-
-
ns
t
HD;STA
hold time START condition
4.0
-
-
µ
s
t
LOW
SCL LOW time
4.7
-
-
µ
s
t
HIGH
SCL HIGH time
4.0
-
-
µ
s
t
r
SCL and SDA rise time
-
-
1000
ns
t
f
SCL and SDA fall time
-
-
300
ns
t
SU;DAT
data set-up time
250
-
-
ns
t
HD;DAT
data hold time
0
-
-
µ
s
t
VD;DAT
SCL LOW to data out valid
time
-
-
0.4
µ
s
t
SU;STO
STOP condition set-up time
4.0
-
-
µ
s
C
b
capacitive load for each bus
line
-
-
400
pF
