
Philips Semiconductors
Product specification
PCA9544
4-channel I
2
C multiplexer and interrupt controller
1999 Oct 07
9
AC CHARACTERISTICS
SYMBOL
PARAMETER
STANDARD-MODE
I
2
C-BUS
MIN
FAST-MODE I
2
C-BUS
UNIT
MAX
0.3
1
100
–
MIN
MAX
0.3
1
400
–
t
pd
f
SCL
t
BUF
Propagation delay from SDA to SD
n
or SCL to SC
n
SCL clock frequency
Bus free time between a STOP and START condition
Hold time (repeated) START condition
After this period, the first clock pulse is generated
LOW period of the SCL clock
HIGH period of the SCL clock
Set-up time for a repeated START condition
Data hold time:
for CBUS compatible masters
for I
2
C-bus devices
Data set-up time
Set-up time for STOP condition
Rise time of both SDA and SCL signals
Fall time of both SDA and SCL signals
Capacitive load for each bus line
ns
KHz
μ
s
0
0
4.7
1.3
t
HD:STA
4.0
–
0.6
–
μ
s
t
LOW
t
HIGH
t
SU:STA
4.7
4.0
4.7
–
–
–
1.3
0.6
0.6
–
–
μ
s
μ
s
μ
s
t
HD:DAT
5.0
0
2
250
–
–
4.0
–
–
–
–
0
2
–
μ
s
μ
s
ns
ns
ns
μ
s
pF
0.9
3
–
300
300
–
400
t
SU:DAT
t
SU:STO
t
r
t
f
C
b
INT
t
iv
t
ir
L
pwr
H
pwr
NOTES:
1. Pass gate propagation delay is calculated from the 20
typical R
ON
and and the 15pF load capacitance.
2. A device must internally provide a hold time of at least 300ns for the SDA signal (referred to the VIH
min
of the SCL signal) in order to bridge
the undefined region of the falling edge of SCL.
3. The maximum t
HD:DAT
has only to be met if the device does not stretch the LOW period (t
LOW
) of the SCL signal.
4. A fast-mode I
2
C bus device can be used in a standard-mode I
2
C-bus system, but the requirement t
SU:DAT
≥
250ns must then be met. This
will automatically be the case if the device does not stretch the LOW period of the SCL signal. If such a device does stretch the LOW period
of the SCL signal, it must output the next data bit to the SDA line t
rmax
+ t
SU:DAT
= 1000 + 250 = 1250ns (according to the standard-mode
I
2
C-bus specification) before the SCL line is released.
5. C
b
= total capacitance of one bus line in pF.
100
4
–
–
0.6
–
1000
300
–
400
INTn to INT active valid time
INTn to INT inactive delay time
LOW level pulse width rejection or INTn inputs
HIGH level pulse width rejection or INTn inputs
4
2
4
2
μ
s
μ
s
ns
ns
1
1
500
500
t
SP
t
BUF
t
HD;STA
P
P
S
t
LOW
t
R
t
HD;DAT
t
F
t
HIGH
t
SU;DAT
t
SU;STA
Sr
t
HD;STA
t
SU;STO
SDA
SCL
SU00645
Figure 8. Definition of timing on the I
2
C-bus