Philips Universal Serial Bus ISP1122 - Manual (Page 37)

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 [1] 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 [2] - - 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