PCA9516 Philips Semiconductors (Acquired by NXP), PCA9516 Datasheet - Page 4

• Manufacturer Part Number: PCA9516
• Description: PCA9516; 5-channel I2C Hub
• Manufacturer: Philips Semiconductors (Acquired by NXP)

Philips Semiconductors
FUNCTIONAL DESCRIPTION
The PCA9516 BiCMOS integrated circuit is a five way hub repeater,
which enables I
only one repeater delay and no functional degradation of system
performance.
The PCA9516 BiCMOS integrated circuit contains five bi-directional,
open drain buffers specifically designed to support the standard
low-level-contention arbitration of the I
arbitration or clock stretching, the PCA9516 acts like five pairs of
non-inverting, open drain buffers, one for SDA and one for SCL.
Enable
The enable pins EN1 through EN4 are active high and have internal
pull-up resistors. Each enable pin ENn controls its associated SDAn
and SCLn ports. When low the ENn pin blocks the inputs from SDAn
and SCLn as well as disabling the output drivers on the SDAn and
SCLn pins. The enable pins should only change state when both the
global bus and the local port are in an idle state to prevent system
failures.
The active high enable pins allow the use of open drain drivers
which can be wire-ORed to create a distributed enable where either
centralized control signal (master) or spoke signal (submaster) can
enable the channel when it is idle.
I
As with the standard I
provide the logic HIGH levels on the Buffered bus. (Standard
open-collector configuration of the I
pull-up resistors depends on the system, but each side of the
repeater must have a pull-up resistor. This part designed to work
with standard mode and fast mode I
devices. Standard mode I
this limits the termination current to 3 mA in a generic I
where standard mode devices and multiple masters are possible.
Under certain conditions higher termination currents can be used.
Please see Application Note AN255 “I
and Expanders” for additional information on sizing resistors and
precautions when using more than one PCA9515/PCA9516 in a
system or using the PCA9515/16 in conjunction with the P82B96.
APPLICATION INFORMATION
A typical application is shown in Figure 4. In this example, the
system master is running on a 3.3 V I
connected to a 5 V bus. All buses run at 100 kHz unless slave 3 and
4 are isolated and then the master bus and slave 1 and 2 can run at
400 kHz.
Any segment of the hub can talk to any other segment of the hub.
Bus masters and slaves can be located on all five segments with
400 pF load allowed on each segment.
The PCA9516 is 5 V tolerant so it does not require any additional
circuitry to translate between the different bus voltages.
When one side of the PCA9516 is pulled low by a device on the
I
causes an internal driver on the other side to turn on, thus causing
2002 May 13
2
2
C-bus, a CMOS hysteresis type input detects the falling edge and
C Systems
5-channel I
2
C and similar bus systems to be expanded with
2
2
C system, pull-up resistors are required to
C hub
2
C devices only specify 3 mA output drive,
2
2
C-bus). The size of these
C devices in addition to SMBus
2
2
2
C-bus while the slave is
C & SMBus Repeaters, Hubs
C-bus. Except during
2
C system
4
the other side to also go low. The side driven low by the PCA9516
will typically be at V
In order to illustrate what would be seen in a typical application,
refer to Figures 5 and 6. If the bus master in Figure 4 were to write
to the slave through the PCA9516, we would see the waveform
shown in Figure 5 on Bus 0. This looks like a normal I
transmission until the falling edge of the 8th clock pulse. At that
point, the master releases the data line (SDA) while the slave pulls it
low through the PCA9516. Because the V
typically around 0.5 V, a step in the SDA will be seen. After the
master has transmitted the 9th clock pulse, the slave releases the
data line.
BUS
MASTER
400 kHz
SDA
SCL
Figure 4. Typical application
OL
3.3 V
= 0.5 V.
SDA0
SCL0
EN1
EN2
EN3
EN4
PCA9516
SDA1
SDA2
SCL1
SCL2
SDA3
SDA4
SCL3
SCL4
OL
of the PCA9516 is
3.3 V
5 V
5 V
5 V
PCA9516
2
SDA
SCL
SDA
SCL
SDA
SCL
SDA
SCL
C
Product data
SLAVE 1
400 kHz
SLAVE 2
400 kHz
SLAVE 3
100 kHz
SLAVE 4
100 kHz
SW00923